Water

16 pages, 2391 KiB

Open AccessEditor’s ChoiceArticle

Shift Detection in Hydrological Regimes and Pluriannual Low-Frequency Streamflow Forecasting Using the Hidden Markov Model

by Larissa Zaira Rafael Rolim and Francisco de Assis de Souza Filho

Water 2020, 12(7), 2058; https://doi.org/10.3390/w12072058 - 20 Jul 2020

Cited by 11 | Viewed by 2985

Abstract

Improved water resource management relies on accurate analyses of the past dynamics of hydrological variables. The presence of low-frequency structures in hydrologic time series is an important feature. It can modify the probability of extreme events occurring in different time scales, which makes [...] Read more.

Improved water resource management relies on accurate analyses of the past dynamics of hydrological variables. The presence of low-frequency structures in hydrologic time series is an important feature. It can modify the probability of extreme events occurring in different time scales, which makes the risk associated with extreme events dynamic, changing from one decade to another. This article proposes a methodology capable of dynamically detecting and predicting low-frequency streamflow (16–32 years), which presented significance in the wavelet power spectrum. The Standardized Runoff Index (SRI), the Pruned Exact Linear Time (PELT) algorithm, the breaks for additive seasonal and trend (BFAST) method, and the hidden Markov model (HMM) were used to identify the shifts in low frequency. The HMM was also used to forecast the low frequency. As part of the results, the regime shifts detected by the BFAST approach are not entirely consistent with results from the other methods. A common shift occurs in the mid-1980s and can be attributed to the construction of the reservoir. Climate variability modulates the streamflow low-frequency variability, and anthropogenic activities and climate change can modify this modulation. The identification of shifts reveals the impact of low frequency in the streamflow time series, showing that the low-frequency variability conditions the flows of a given year. Full article

(This article belongs to the Special Issue Hydrology of Rivers and Lakes under Climate Change)

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42 pages, 7352 KiB

Open AccessEditor’s ChoiceReview

State of the Art and Recent Advancements in the Modelling of Land Subsidence Induced by Groundwater Withdrawal

by Artur Guzy and Agnieszka A. Malinowska

Water 2020, 12(7), 2051; https://doi.org/10.3390/w12072051 - 19 Jul 2020

Cited by 86 | Viewed by 13536

Abstract

Land subsidence is probably one of the most evident environmental effects of groundwater pumping. Globally, freshwater demand is the leading cause of this phenomenon. Land subsidence induced by aquifer system drainage can reach total values of up to 14.5 m. The spatial extension [...] Read more.

Land subsidence is probably one of the most evident environmental effects of groundwater pumping. Globally, freshwater demand is the leading cause of this phenomenon. Land subsidence induced by aquifer system drainage can reach total values of up to 14.5 m. The spatial extension of this phenomenon is usually extensive and is often difficult to define clearly. Aquifer compaction contributes to many socio-economic effects and high infrastructure-related damage costs. Currently, many methods are used to analyze aquifer compaction. These include the fundamental relationship between groundwater head and groundwater flow direction, water pressure and aquifer matrix compressibility. Such solutions enable satisfactory modelling results. However, further research is needed to allow more efficient modelling of aquifer compaction. Recently, satellite radar interferometry (InSAR) has contributed to significant progress in monitoring and determining the spatio-temporal land subsidence distributions worldwide. Therefore, implementation of this approach can pave the way to the development of more efficient aquifer compaction models. This paper presents (1) a comprehensive review of models used to predict land surface displacements caused by aquifer drainage, as well as (2) recent advances, and (3) a summary of InSAR implementation in recent years to support the aquifer compaction modelling process. Full article

(This article belongs to the Special Issue Groundwater Resilience to Climate Change and High Pressure)

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14 pages, 1866 KiB

Open AccessEditor’s ChoiceArticle

Kinetic and Prediction Modeling Studies of Organic Pollutants Removal from Municipal Wastewater using Moringa oleifera Biomass as a Coagulant

by Bashir Adelodun, Matthew Segun Ogunshina, Fidelis Odedishemi Ajibade, Taofeeq Sholagberu Abdulkadir, Hashim Olalekan Bakare and Kyung Sook Choi

Water 2020, 12(7), 2052; https://doi.org/10.3390/w12072052 - 19 Jul 2020

Cited by 30 | Viewed by 5451

Abstract

This study investigated the potential of Moringa oleifera (MO) seed biomass as a coagulant for the removal of turbidity, biochemical oxygen demand (BOD), and chemical oxygen demand (COD) of municipal wastewater. Triplicated laboratory experiments using MO coagulant added at varying treatment dosages of [...] Read more.

This study investigated the potential of Moringa oleifera (MO) seed biomass as a coagulant for the removal of turbidity, biochemical oxygen demand (BOD), and chemical oxygen demand (COD) of municipal wastewater. Triplicated laboratory experiments using MO coagulant added at varying treatment dosages of 50, 100, 150, 200 mg/L, and a control (0 mg/L) treatment were performed for a settling period of 250 min at room temperature. Kinetics and prediction variables of cumulative turbidity, BOD, and COD removal were estimated using simplified first order and modified Gompertz models. Results showed that the maximum removal of turbidity, BOD, and COD were 94.44%, 68.72%, and 57.61%, respectively, using an MO dose of 150 mg/L. Various kinetic parameters, such as rate constant (r), measured (RE_m) versus predicted (RE_p) cumulative removal, and specific pollutant removal rate (µ_m), were also maximum when an MO dose of 150 mg/L was added, the standard error being below 5%. The developed models were successfully validated over multiple observations. This study suggests low cost and sustainable removal of turbidity, BOD, and COD of municipal wastewater using MO seed biomass as a coagulant. Full article

(This article belongs to the Special Issue Water Quality Engineering and Wastewater Treatment)

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19 pages, 2056 KiB

Open AccessEditor’s ChoiceArticle

A Comparison and Validation of Saturated Hydraulic Conductivity Models

by Kaylyn S. Gootman, Elliott Kellner and Jason A. Hubbart

Water 2020, 12(7), 2040; https://doi.org/10.3390/w12072040 - 18 Jul 2020

Cited by 28 | Viewed by 5452

Abstract

Saturated hydraulic conductivity (K_sat) is fundamental to shallow groundwater processes. There is an ongoing need for observed and model validated K_sat values. A study was initiated in a representative catchment of the Chesapeake Bay Watershed in the Northeast USA, [...] Read more.

Saturated hydraulic conductivity (K_sat) is fundamental to shallow groundwater processes. There is an ongoing need for observed and model validated K_sat values. A study was initiated in a representative catchment of the Chesapeake Bay Watershed in the Northeast USA, to collect observed K_sat and validate five K_sat pedotransfer functions. Soil physical characteristics were quantified for dry bulk density (bdry), porosity, and soil texture, while K_sat was quantified using piezometric slug tests. Average bdry and porosity ranged from 1.03 to 1.30 g/cm³ and 0.51 to 0.61, respectively. Surface soil (0–5 cm) bdry and porosity were significantly (p < 0.05) lower and higher, respectively, than deeper soils (i.e., 25–30 cm; 45–50 cm). bdry and porosity were significantly different with location (p < 0.05). Average soil composition was 92% sand. Average K_sat ranged from 0.29 to 4.76 m/day and significantly differed (p < 0.05) by location. Four models showed that spatial variability in farm-scale K_sat estimates was small (CV < 0.5) and one model performed better when K_sat was 1.5 to 2.5 m/day. The two-parameter model that relied on silt/clay fractions performed best (ME = 0.78 m/day; SSE = 20.68 m²/day²; RMSE = 1.36 m/day). Results validate the use of simple, soil-property-based models to predict K_sat, thereby increasing model applicability and transferability. Full article

(This article belongs to the Special Issue Integrated Water Resources Research: Advancements in Understanding to Improve Future Sustainability)

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13 pages, 2333 KiB

Open AccessEditor’s ChoiceArticle

The Use of Permeable Interlocking Concrete Pavement to Filter Stormwater for Non-Potable Uses in Buildings

by Enedir Ghisi, Thiago Belotto and Liseane Padilha Thives

Water 2020, 12(7), 2045; https://doi.org/10.3390/w12072045 - 18 Jul 2020

Cited by 19 | Viewed by 8651

Abstract

A reduction in potable water demand in buildings could be made by using non-potable water for certain uses, such as flushing toilets. This represents a sustainable strategy that results in potable water savings while also using an underutilised resource. This work assesses the [...] Read more.

A reduction in potable water demand in buildings could be made by using non-potable water for certain uses, such as flushing toilets. This represents a sustainable strategy that results in potable water savings while also using an underutilised resource. This work assesses the use of permeable interlocking concrete pavement to filter stormwater that could be used for non-potable purposes in buildings. Two pavement model systems were tested. One of the model systems presents a filter course layer with coarse sand and the other model system has no filter course layer. In order to evaluate the filtering capacity, the model systems were exposed to rain events. The amount of water infiltrated through the layers was measured to represent the potential quantity available for use. Stormwater runoff samples were collected from a parking lot paved with impermeable interlocked blocks and then, these were tested in both model systems. Water samples were subjected to quality tests according to the parameters recommended by the Brazilian National Water Agency. The model system with no filter course showed filtering capacity higher (88.1%) than the one with a filter course layer (78.8%). The model system with a filter course layer was able to reduce fecal coliforms (54.7%), total suspended solids (62.5%), biochemical oxygen demand (78.8%), and total phosphorus concentrations (55.6%). Biochemical oxygen demand (42.4%) and total phosphorus concentrations (44.4%) increased in the model system with no filter course layer. In conclusion, one can state that the filter course layer used in permeable interlocking concrete pavement can contribute to decreasing pollutants and can improve stormwater quality. The use of permeable interlocking concrete pavement showed to be a potential alternative for filtering stormwater prior to subsequent treatment for non-potable uses in buildings. Full article

(This article belongs to the Special Issue Permeable Pavement Systems: Advances and Challenges in Stormwater Management)

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22 pages, 2723 KiB

Open AccessEditor’s ChoiceArticle

Students’ Scientific Evaluations of Water Resources

by Josh Medrano, Joshua Jaffe, Doug Lombardi, Margaret A. Holzer and Christopher Roemmele

Water 2020, 12(7), 2048; https://doi.org/10.3390/w12072048 - 18 Jul 2020

Cited by 13 | Viewed by 5139

Abstract

Socially-relevant and controversial topics, such as water issues, are subject to differences in the explanations that scientists and the public (herein, students) find plausible. Students need to be more evaluative of the validity of explanations (e.g., explanatory models) based on evidence when addressing [...] Read more.

Socially-relevant and controversial topics, such as water issues, are subject to differences in the explanations that scientists and the public (herein, students) find plausible. Students need to be more evaluative of the validity of explanations (e.g., explanatory models) based on evidence when addressing such topics. We compared two activities where students weighed connections between lines of evidence and explanations. In one activity, students were given four evidence statements and two models (one scientific and one non-scientific alternative); in the other, students chose four out of eight evidence statements and three models (two scientific and one non-scientific). Repeated measures analysis of variance (ANOVA) showed that both activities engaged students’ evaluations and differentially shifted students’ plausibility judgments and knowledge. A structural equation model suggested that students’ evaluation may influence post-instructional plausibility and knowledge; when students chose their lines of evidence and explanatory models, their evaluations were deeper, with stronger shifts toward a scientific stance and greater levels of post-instructional knowledge. The activities may help to develop students’ critical evaluation skills, a scientific practice that is key to understanding both scientific content and science as a process. Although effect sizes were modest, the results provided critical information for the final development and testing stage of these water resource instructional activities. Full article

(This article belongs to the Special Issue Water Literacy and Education)

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24 pages, 5501 KiB

Open AccessEditor’s ChoiceReview

Flood Risk Analysis and Assessment, Applications and Uncertainties: A Bibliometric Review

by Andrés Díez-Herrero and Julio Garrote

Water 2020, 12(7), 2050; https://doi.org/10.3390/w12072050 - 18 Jul 2020

Cited by 62 | Viewed by 11112

Abstract

Studies looking at flood risk analysis and assessment (FRA) reviews are not customary, and they usually approach to methodological and spatial scale issues, uncertainty, mapping or economic damage topics. However, most of these reviews provide a snapshot of the scientific state of the [...] Read more.

Studies looking at flood risk analysis and assessment (FRA) reviews are not customary, and they usually approach to methodological and spatial scale issues, uncertainty, mapping or economic damage topics. However, most of these reviews provide a snapshot of the scientific state of the art of FRA that shows only a partial view, focused on a limited number of selected methods and approaches. In this paper, we apply a bibliometric analysis using the Web of Science (WoS) database to assess the historic evolution and future prospects (emerging fields of application) of FRA. The scientific production of FRA has increased considerably in the past decade. At the beginning, US researchers dominated the field, but now they have been overtaken by the Chinese. The Netherlands and Germany may be highlighted for their more complete analyses and assessments (e.g., including an uncertainty analysis of FRA results), and this can be related to the presence of competitive research groups focused on FRA. Regarding FRA fields of application, resilience analysis shows some growth in recent years while land planning, risk perception and risk warning show a slight decrease in the number of papers published. Global warming appears to dominate part of future FRA production, which affects both fluvial and coastal floods. This, together with the improvement of economic evaluation and psycho-social analysis, appear to be the main trends for the future evolution of FRA. Finally, we cannot ignore the increase in analysis using big data analysis, machine learning techniques, and remote sensing data (particularly in the case of UAV sensors data). Full article

(This article belongs to the Special Issue Flood Risk Assessments: Applications and Uncertainties)

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32 pages, 1447 KiB

Open AccessEditor’s ChoiceReview

The Application of Modified Natural Polymers in Toxicant Dye Compounds Wastewater: A Review

by Siti Aisyah Ishak, Mohamad Fared Murshed, Hazizan Md Akil, Norli Ismail, Siti Zalifah Md Rasib and Adel Ali Saeed Al-Gheethi

Water 2020, 12(7), 2032; https://doi.org/10.3390/w12072032 - 17 Jul 2020

Cited by 71 | Viewed by 8368

Abstract

The utilization of various types of natural and modified polymers for removing toxicant dyes in wastewater generated by the dye industry is reviewed in this article. Dye wastewater contains large amounts of metals, surfactants, and organic matter, which have adverse effects on human [...] Read more.

The utilization of various types of natural and modified polymers for removing toxicant dyes in wastewater generated by the dye industry is reviewed in this article. Dye wastewater contains large amounts of metals, surfactants, and organic matter, which have adverse effects on human health, potentially causing skin diseases and respiratory problems. The removal of dyes from wastewaters through chemical and physical processes has been addressed by many researchers. Currently, the use of natural and modified polymers for the removal of dyes from wastewater is becoming more common. Although modified polymers are preferred for the removal of dyes, due to their biodegradability and non-toxic nature, large amounts of polymers are required, resulting in higher costs. Surface-modified polymers are more effective for the removal of dyes from the wastewater. A survey of 80 recently published papers demonstrates that modified polymers have outstanding dye removal capabilities, and thus have a high applicability in industrial wastewater treatment. Full article

(This article belongs to the Special Issue Water Quality Engineering and Wastewater Treatment)

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20 pages, 9283 KiB

Open AccessEditor’s ChoiceArticle

Drought Vulnerability in the United States: An Integrated Assessment

by Johanna Engström, Keighobad Jafarzadegan and Hamid Moradkhani

Water 2020, 12(7), 2033; https://doi.org/10.3390/w12072033 - 17 Jul 2020

Cited by 46 | Viewed by 12646

Abstract

Droughts are among the costliest natural hazards in the U.S. and globally. The severity of the hazard is closely related to a region’s ability to cope and recover from the event, an ability that depends on the region’s sensitivity and adaptive capacity. Here, [...] Read more.

Droughts are among the costliest natural hazards in the U.S. and globally. The severity of the hazard is closely related to a region’s ability to cope and recover from the event, an ability that depends on the region’s sensitivity and adaptive capacity. Here, the vulnerability to drought of each state within the contiguous U.S. is assessed as a function of exposure, sensitivity, and adaptive capacity, using socio-economic, climatic, and environmental indicators. The division of vulnerability into three sub-indices allows for an assessment of the driver(s) of vulnerability of a state and as such provides a foundation for drought mitigation and planning efforts. In addition, a probabilistic approach is used to investigate the sensitivity of vulnerability to the weighting scheme of indicators. The resulting geographic distribution of relative vulnerability of the states is partially a reflection of their heterogeneous climates but also highlights the importance of sustainable adaptation of the local economy to water availability in order to reduce sensitivity and to limit the impact of drought. As such, the study at hand offers insights to local and regional planners on how to effectively distribute funds and plan accordingly in order to reduce state-level drought vulnerability today and in the future. Full article

(This article belongs to the Special Issue Global Changes in Drought Frequency and Severity)

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21 pages, 4488 KiB

Open AccessEditor’s ChoiceArticle

Experimental Study at the Reservoir Head of Run-of-River Hydropower Plants in Gravel Bed Rivers. Part I: Delta Formation at Operation Level

by Christine Sindelar, Thomas Gold, Kevin Reiterer, Christoph Hauer and Helmut Habersack

Water 2020, 12(7), 2035; https://doi.org/10.3390/w12072035 - 17 Jul 2020

Cited by 10 | Viewed by 4124

Abstract

This study concerns scaled physical model tests of the delta formation process at the head of a run-of-river hydropower plant (RoR). It forms part of a larger research project to provide a scientific base for RoR sediment management strategies in medium-sized gravel bed [...] Read more.

This study concerns scaled physical model tests of the delta formation process at the head of a run-of-river hydropower plant (RoR). It forms part of a larger research project to provide a scientific base for RoR sediment management strategies in medium-sized gravel bed rivers. The physical model consisted of an idealized river having a width of 20 m, a mean slope of 0.005, a mean flow rate of 22 m³/s and a 1-year flood flow of 104 m³/s. The model scale was 1:20. For the experiments, five different grain sizes were used, covering a range of 14 to 120 mm at 1:1 scale. Experiments were carried out under mobile-bed conditions at flow rates which correspond to 50%–80% of a 1-year flood HQ₁. Even at the head of the reservoir, which is least influenced by the backwater effect of the RoR, sediment transport practically ceases for sediment fractions >14 mm for a flow rate of 0.7 × HQ₁. The whole sediment load coming from the undisturbed upstream section accumulates at the head of the reservoir. This delta formation is accompanied by a substantial rise in water levels. A spatio-temporal scheme of the delta formation was derived from the experiments. The study proved that the delta formation increases the flood risk at the head of the reservoir. Conversely, reservoir drawdowns at flood events of high probability may be a promising strategy to enhance sediment connectivity under the specified boundary conditions. Full article

(This article belongs to the Special Issue Sediment Management: Hydropower Improvement and Habitat Evaluation)

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18 pages, 2883 KiB

Open AccessEditor’s ChoiceArticle

The Effects of Hydraulic Jumps Instability on a Natural River Confluence: The Case Study of the Chiaravagna River (Italy)

by Annalisa De Leo, Alessia Ruffini, Matteo Postacchini, Marco Colombini and Alessandro Stocchino

Water 2020, 12(7), 2027; https://doi.org/10.3390/w12072027 - 16 Jul 2020

Cited by 10 | Viewed by 3157

Abstract

The occurrence and the effects of hydraulic jump instabilities on a natural river confluence in a small river basin in Liguria (Italy) is here investigated. Hydraulic jump instability has been extensively studied in controlled and simplified laboratory rectangular flumes. In the present study, [...] Read more.

The occurrence and the effects of hydraulic jump instabilities on a natural river confluence in a small river basin in Liguria (Italy) is here investigated. Hydraulic jump instability has been extensively studied in controlled and simplified laboratory rectangular flumes. In the present study, a scaled physical model of the Chiaravagna River and Ruscarolo Creek confluence has been used, retaining the realistic geometry of the reaches. This reach has been subject to frequent floods in the last twenty years and the entire area of the confluence has been redesigned to decrease the flood risk. A series of experiments has been performed varying the discharge on the two reaches and the geometrical configurations. Free surface levels and two dimensional horizontal velocities have been measured in several positions along the physical model. The analysis of the water levels and velocities reveals that oscillations characterised by large amplitude and low frequency occur under particular hydraulic conditions. These oscillations have been found to be triggered by the hydraulic jump toe instability of the smallest reach of the confluence. Aiming at reducing the amplitude of the oscillations, which can be of the order of the flow depth, possible constructive solutions have been tested to control or damp the oscillations. Indeed, the insertion of a longitudinal dyke at the confluence has proven to be an effective solution to limit the amplitude of the transversal oscillations. Full article

(This article belongs to the Section Hydraulics and Hydrodynamics)

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22 pages, 4234 KiB

Open AccessEditor’s ChoiceArticle

Hydrochemical and Isotopic Assessment of Groundwater in the Goda Mountains Range System. Republic of Djibouti (Horn of Africa)

by Ibrahim M. Ahmed, Mohamed Jalludin and Moumtaz Razack

Water 2020, 12(7), 2004; https://doi.org/10.3390/w12072004 - 15 Jul 2020

Cited by 11 | Viewed by 3722

Abstract

The hydrogeological system of the Goda Mountains Range (GMR) in the Republic of Djibouti (Horn of Africa), hosted by volcanic and sedimentary formations, is the only water resource in the Tadjourah region for more than 85,000 inhabitants. Water needs are expected to drastically [...] Read more.

The hydrogeological system of the Goda Mountains Range (GMR) in the Republic of Djibouti (Horn of Africa), hosted by volcanic and sedimentary formations, is the only water resource in the Tadjourah region for more than 85,000 inhabitants. Water needs are expected to drastically increase in the coming years, due to fast socio-economic development of the region. Accordingly, this system is under high pressure and should sustainably be exploited. However, little is known about the hydrogeology of this system. This study aims to improve the understanding of the hydrochemistry and the recharge processes of this system. The study is based on the combined interpretation of major ions, stable isotopes (¹⁸O, ²H), and radiogenic isotopes (³H, ¹⁴C). The interpretation of major ions contents using classical hydrochemical methods and principal component analysis highlighted that alteration of volcanic rocks minerals, coastal rainfall infiltration, and evaporation are the main processes from which groundwater acquires mineralization. Stable isotopes revealed that groundwater is of meteoric origin and has undergone high evaporation during infiltration. Radiogenic isotopes showed that groundwater in the basalts is mostly submodern to old, in relation with low hydraulic conductivity of the rocks and/or longer pathways through fissures from outcrop to subsurface. Groundwater in the rhyolites is much younger compared to the basalts due to faster infiltration. The sedimentary part, in connection with the rhyolites, has younger waters compared to the basalts, but older compared to the rhyolites. The overall results show that GMR is a fairly complex hydrogeological system, containing a resource made up of a mixture of waters of different ages. This study has made significant progress in understanding this system and is an initial step towards the sustainable exploitation of resources. Full article

(This article belongs to the Special Issue Groundwater Resilience to Climate Change and High Pressure)

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20 pages, 9662 KiB

Open AccessEditor’s ChoiceArticle

Hydropower Potential in the Alps under Climate Change Scenarios. The Chavonne Plant, Val D’Aosta

by Tommaso Duratorre, Giovanni Martino Bombelli, Giovanni Menduni and Daniele Bocchiola

Water 2020, 12(7), 2011; https://doi.org/10.3390/w12072011 - 15 Jul 2020

Cited by 19 | Viewed by 6052

Abstract

Present and prospective climate change will likely affect the hydrological cycle in sensitive areas, such as the Alps, thus impacting water-based activities. A most representative example is hydropower production, i.e., exploitation of water to produce energy. In the Italian Alps hydropower is strictly [...] Read more.

Present and prospective climate change will likely affect the hydrological cycle in sensitive areas, such as the Alps, thus impacting water-based activities. A most representative example is hydropower production, i.e., exploitation of water to produce energy. In the Italian Alps hydropower is strictly dependent upon water from snow and ice melt, and both are decreasing in response to global warming. Here, we study the effects of potential climate change scenarios at 2100 upon hydropower production from the Chavonne plant, in Valle d’Aosta region of Italy, a run-of-the-river (ROR) plant taking water from two high altitude glacierized catchments of Val di Cogne, and Valsavarenche. We use Poli-Hydro, a state-of-the-art hydrological model to mimic the hydrological budget of the area, including ice and snow melt share. Projections of the hydrological budget were built until 2100 by means of selected climate change scenarios, under proper downscaling. We used runs of three General Circulation Models (GCMs), EC-Earth, CCSM4, and ECHAM6.0 under three Representative Concentration Pathways RCP 2.6, RCP 4.5, and RCP 8.5 from AR5 of IPCC, and of their updated version under four Shared Socio-Economic Pathways SSP1 2.6, SSP2 4.5, SSP3 7.0, and SSP5 8.5 from AR6. We then assessed hydropower production changes against a recent control run CR period (2005–2015). Mean annual flow is estimated at 14.33 m³ s⁻¹ during CR, with ice melt contribution ca. 2%, and snow melt contribution ca. 44%. Ice cover in 2005 was estimated as 19.2 km², reaching in 2015, 9.93 km². Mean hydropower production was estimated at 153.72 GWh during the CR. Temperature would largely increase throughout the century (+0.93 °C on average at the half century, +2.45 °C at the end of the century). The ice covered area would be largely depleted (ca. −86%, −94% respectively), with reduced contribution of ice melt (0.23%, <0.1%, respectively) and snow melt (ca. 37%, 33%, respectively). Precipitation would show uncertain patterns, and hence incoming discharge at the plant would erratically vary (−29% to +24% half century, −27% to +59% end of century). Hydropower production displays a large dependence upon monthly discharge patterns, with mostly positive variations (+2.90% on average at half century, +6.95% on average at end of century), with its change driven by exceedance of plant’s capacity. Full article

(This article belongs to the Special Issue Impact of River Hydrology on Hydraulic Engineering and Hydropower)

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18 pages, 5312 KiB

Open AccessEditor’s ChoiceArticle

Flooding Urban Landscapes: Analysis Using Combined Hydrodynamic and Hydrologic Modeling Approaches

by Manoj K. Jha and Sayma Afreen

Water 2020, 12(7), 1986; https://doi.org/10.3390/w12071986 - 14 Jul 2020

Cited by 30 | Viewed by 4952

Abstract

The frequency and severity of floods have been found to increase in recent decades, which have adverse effects on the environment, economics, and human lives. The catastrophe of such floods can be confronted with the advance prediction of floods and reliable analyses methods. [...] Read more.

The frequency and severity of floods have been found to increase in recent decades, which have adverse effects on the environment, economics, and human lives. The catastrophe of such floods can be confronted with the advance prediction of floods and reliable analyses methods. This study developed a combined flood modeling system for the prediction of floods, and analysis of associated vulnerabilities on urban infrastructures. The application of the method was tested on the Blue River urban watershed in Missouri, USA, a watershed of historical significance for flood impacts and abundance of data availability for such analyses. The combined modeling system included two models: hydrodynamic model HEC-RAS (Hydrologic Engineering Center—River Analysis System) and hydrologic model SWAT (Soil and Water Assessment Tool). The SWAT model was developed for the watershed to predict time-series hydrograph data at desired locations, followed by the setup of HEC-RAS model for the analysis and prediction of flood extent. Both models were calibrated and validated independently using the observed data. The well-calibrated modeling setup was used to assess the extent of impacts of the hazard by identifying the flood risk zones and threatened critical infrastructures in flood zones through inundation mapping. Results demonstrate the usefulness of such combined modeling systems to predict the extent of flood inundation and thus support analyses of management strategies to deal with the risks associated with critical infrastructures in an urban setting. This approach will ultimately help with the integration of flood risk assessment information in the urban planning process. Full article

(This article belongs to the Special Issue Impacts of Landscape Change on Water Resources)

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18 pages, 7730 KiB

Open AccessEditor’s ChoiceArticle

Energy Dissipation and Hydraulics of Flow over Trapezoidal–Triangular Labyrinth Weirs

by Amir Ghaderi, Rasoul Daneshfaraz, Mehdi Dasineh and Silvia Di Francesco

Water 2020, 12(7), 1992; https://doi.org/10.3390/w12071992 - 14 Jul 2020

Cited by 68 | Viewed by 5986

Abstract

In this work experimental and numerical investigations were carried out to study the influence of the geometric parameters of trapezoidal–triangular labyrinth weirs (TTLW) on the discharge coefficient, energy dissipation, and downstream flow regime, considering two different orientations in labyrinth weir position respective to [...] Read more.

In this work experimental and numerical investigations were carried out to study the influence of the geometric parameters of trapezoidal–triangular labyrinth weirs (TTLW) on the discharge coefficient, energy dissipation, and downstream flow regime, considering two different orientations in labyrinth weir position respective to the reservoir discharge channel. To simulate the free flow surface, the volume of fluid (VOF) method, and the Renormalization Group (RNG) k-ε model turbulence were adopted in the FLOW-3D software. The flow over the labyrinth weir (in both orientations) is simulated as a steady-state flow, and the discharge coefficient is validated with experimental data. The results highlighted that the numerical model shows proper coordination with experimental results and also the discharge coefficient decreases by decreasing the sidewall angle due to the collision of the falling jets for the high value of H/P (H: the hydraulic head, P: the weir height). Hydraulics of flow over TTLW has free flow conditions in low discharge and submerged flow conditions in high discharge. TTLW approximately dissipates the maximum amount of energy due to the collision of nappes in the upstream apexes and to the circulating flow in the pool generated behind the nappes; moreover, an increase in sidewall angle and weir height leads to reduced energy. The energy dissipation of TTLW is largest compared to vertical drop and has the least possible value of residual energy as flow increases. Full article

(This article belongs to the Special Issue Combined Numerical and Experimental Methodology for Fluid–Structure Interactions in Free Surface Flows)

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18 pages, 15342 KiB

Open AccessEditor’s ChoiceArticle

Efficient Urban Inundation Model for Live Flood Forecasting with Cellular Automata and Motion Cost Fields

by Maikel Issermann, Fi-John Chang and Haifeng Jia

Water 2020, 12(7), 1997; https://doi.org/10.3390/w12071997 - 14 Jul 2020

Cited by 7 | Viewed by 3441

Abstract

The mitigation of societal damage from urban floods requires fast hydraulic models for emergency and planning purposes. The simplified mathematical model Cellular Automata is combined with Motion Cost fields, which score the difficulty to traverse an area, to the urban inundation model CAMC. [...] Read more.

The mitigation of societal damage from urban floods requires fast hydraulic models for emergency and planning purposes. The simplified mathematical model Cellular Automata is combined with Motion Cost fields, which score the difficulty to traverse an area, to the urban inundation model CAMC. It is implemented with simple matrix and logic operations to achieve high computational efficiency. The development concentrated on an application in dense urban built-up areas with numerous buildings. CAMC is efficient and flexible enough to be used in a “live” urban flood warning system with current weather conditions. A case study is conducted in the German city of Wuppertal with about 12,000 buildings. The water depth estimation of every time step are visualized in a web-interface on the basis of the virtual globe NASA WorldWind. CAMC is compared with the shallow water equations-based model ANUGA. CAMC is approximatively 5 times faster than ANUGA at high spatial resolution and able to maintain numerical stability. The Nash-Sutcliffe coefficient (0.61), Root Mean Square Error (0.39 m) and Index of Agreement (0.65) indicate acceptable agreement for water depth estimation but identify different areas where important deviations occur. The estimation of velocity performs considerably less well (0.34 for Nash-Sutcliffe coefficient, 0.13 ms

^{- 1}

for Root Mean Square Error, and 0.39 for Index of Agreement) because CA ignores momentum conservation. Full article

(This article belongs to the Special Issue Research on Mathematical Models of Floods)

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23 pages, 5860 KiB

Open AccessEditor’s ChoiceArticle

Sedimentological, Mineralogical and Geochemical Features of Late Quaternary Sediment Profiles from the Southern Tuscany Hg Mercury District (Italy): Evidence for the Presence of Pre-Industrial Mercury and Arsenic Concentrations

by Francesca Pasquetti, Orlando Vaselli, Giovanni Zanchetta, Barbara Nisi, Marco Lezzerini, Monica Bini and Daniela Mele

Water 2020, 12(7), 1998; https://doi.org/10.3390/w12071998 - 14 Jul 2020

Cited by 11 | Viewed by 4100

Abstract

Southern Tuscany (Italy) is an important metallogenic district that hosts relevant S-polymetallic deposits that have intensely been exploited for centuries. Consequently, potential toxic elements, such as Hg and As, are widely distributed in the surrounding environment. In this paper, an extensive sedimentological, mineralogical [...] Read more.

Southern Tuscany (Italy) is an important metallogenic district that hosts relevant S-polymetallic deposits that have intensely been exploited for centuries. Consequently, potential toxic elements, such as Hg and As, are widely distributed in the surrounding environment. In this paper, an extensive sedimentological, mineralogical and geochemical study of two Late Quaternary sediment profiles, partially outcropping along the coast of southern Tuscany (Ansedonia area), was carried out to evaluate the contents and mobility of Hg and As with the aims to contribute to the definition of the geochemical baseline of southern Tuscany before the human intervention and evaluate the potential dispersion of these harmful elements. The sedimentological, mineralogical and geochemical (major elements) features revealed that the studied profiles are mostly related to the local geological characteristics and the Quaternary geological history of the area. The concentrations and the normalized patterns of trace and rare earth elements highlighted the absence of any anthropogenic activity. This implies that the studied samples are to be regarded as good proxies for evaluating the geochemical baseline of southern Tuscany before the intense mining activity. The enrichment factors (EF) of most trace elements were indeed lower or close to 2, indicating a variability close to the average concentration of the Upper Continental Crust (UCC), while other elements slightly enriched, such as Pb, were in agreement with the natural baseline reported for southern Tuscany. Mercury and As displayed EF values >40 when compared to the average contents of UCC, although they decrease down to 4 when compared to the suggested baseline for southern Tuscany. The higher Hg and As contents detected in this study, inferred to natural sources, evidenced (i) the great natural variability occurring in largely mineralized areas and (ii) the importance of estimating reference environmental parameters in order to avoid misleading interpretations of the detected anomalies. Moreover, the results of leaching test on sediment samples denoted a relatively low mobility of Hg and As, suggesting that these elements are preferentially mobilized by transport of clastic sediments and such anomalies may be preserved for relatively long times in Quaternary sediments. However, leachable Hg (0.6–9.7 μg/L) and As (2.1–42.2 μg/L) concentrations are significantly high when compared to those of the Italian limit for groundwater (1 µg/L for Hg and 10 µg/L for As). Quaternary sediments from southern Tuscany could then be a potential, though natural, source of Hg and As to groundwater systems. Full article

(This article belongs to the Special Issue Climate Change and Anthropogenic Impact on Coastal Environments)

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21 pages, 1897 KiB

Open AccessEditor’s ChoiceArticle

Models of Subsidies for Water and Sanitation Services for Vulnerable People in South American Countries: Lessons for Brazil

by Daniel Antonio Narzetti and Rui Cunha Marques

Water 2020, 12(7), 1976; https://doi.org/10.3390/w12071976 - 13 Jul 2020

Cited by 18 | Viewed by 6638

Abstract

Access to water and sanitation services (WSS) in developing countries is constrained by the conditions of social inequality and the services affordability for the poorest households. Therefore, public policies related to WSS need to broaden in scope given the challenge of reaching all [...] Read more.

Access to water and sanitation services (WSS) in developing countries is constrained by the conditions of social inequality and the services affordability for the poorest households. Therefore, public policies related to WSS need to broaden in scope given the challenge of reaching all customers, especially the most vulnerable, in order to achieve a balance between the social and financial objectives of WSS. This paper will contribute to the understanding of the main access and subsidy policies in South American countries focusing on the Brazilian case study. The different experiences in this region have provided some interesting lessons about these issues for Brazil; the conclusion is that the current indirect and cross-subsidy policies are important, but the needed practices for expanding pro-poor access require direct demand-side subsidies. A more proactive intervention through public authorities is also needed. A new subsidization model for Brazil is highlighted and discussed. Full article

(This article belongs to the Collection Water Policy Collection)

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15 pages, 1519 KiB

Open AccessEditor’s ChoiceArticle

A Stakeholder Analysis for a Water-Energy-Food Nexus Evaluation in an Atlantic Forest Area: Implications for an Integrated Assessment and a Participatory Approach

by Giacomo Melloni, Ana Paula Dias Turetta, Michelle Bonatti and Stefan Sieber

Water 2020, 12(7), 1977; https://doi.org/10.3390/w12071977 - 13 Jul 2020

Cited by 23 | Viewed by 5275

Abstract

A water-energy-food (WEF) nexus assessment supports natural resource management by providing an integrated framework for evaluation and decision-making. The participation of a wide range of stakeholders is essential for achieving environmental, economic, and social sustainability in this framework. This analysis supports the decision-making [...] Read more.

A water-energy-food (WEF) nexus assessment supports natural resource management by providing an integrated framework for evaluation and decision-making. The participation of a wide range of stakeholders is essential for achieving environmental, economic, and social sustainability in this framework. This analysis supports the decision-making process of the nexus assessment by facilitating dialogue between stakeholders in order to achieve long term efficiencies, especially in rural landscapes where most of the services connected to WEF securities are provided. We identify the most relevant stakeholders operating in the connection between agricultural practices and the WEF nexus to stimulate their engagement in the nexus governance. The study area was the Atlantic Forest Reserve of Ribeirão das Lajes, Brazil. A stakeholder analysis, generating qualitative data using snowball sampling interviews was applied and, after the identification of stakeholders, an analytical categorization disclosing potential conflicts among them was performed. We obtained a pool of stakeholders from different organizational types, including a large number of public entities at local and state levels. The main threat to the development of the project is considered to be the lack of communication between the parties. We note that the prior identification of this group of stakeholders facilitates this communication, enhancing social representation in the area. Outcomes of this study demonstrate the relevance of stakeholder analysis in nexus governance for integrated natural resource management. Full article

(This article belongs to the Section Water Resources Management, Policy and Governance)

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17 pages, 4145 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Interannual and Seasonal Shift between Microcystis and Dolichospermum: A 7-Year Investigation in Lake Chaohu, China

by Min Zhang, Zhen Yang, Yang Yu and Xiaoli Shi

Water 2020, 12(7), 1978; https://doi.org/10.3390/w12071978 - 13 Jul 2020

Cited by 31 | Viewed by 3506

Abstract

The shifts among bloom-forming cyanobacteria have attracted increasing attention due to the reductions in nitrogen and phosphorus during the eutrophication mitigation process. However, knowledge is limited regarding the pattern and drivers of the shifts among these cyanobacterial genera. In this study, we performed [...] Read more.

The shifts among bloom-forming cyanobacteria have attracted increasing attention due to the reductions in nitrogen and phosphorus during the eutrophication mitigation process. However, knowledge is limited regarding the pattern and drivers of the shifts among these cyanobacterial genera. In this study, we performed a 7-year long, monthly investigation in Lake Chaohu, to analyze the interannual and seasonal shifts between Microcystis and Dolichospermum. Our results showed that Microcystis was the dominant cyanobacterium in the western lake region in summer, whereas Dolichospermum was dominant in the other regions and seasons. The Microcystis biomass and ratio were driven primarily by total phosphorus and temperature. The sensitivity of Dolichospermum to nutrients and temperature was relatively weak compared to that of Microcystis. The shifts between Microcystis and Dolichospermum might be led by Microcystis. If the temperature and phosphorus level were relatively high, then Microcystis grew rapidly, and competitively excluded Dolichospermum. If the nutrient level, especially the phosphorus level, was low, then the exclusive power of Microcystis was weak, and Dolichospermum maintained its dominance, even in summer. The key temperature (~17 °C) determined the dominance of the two cyanobacteria. Microcystis never dominated, while Dolichospermum was always dominant below the key temperature. Microcystis and Dolichospermum had different means of responding to the interaction of temperature, nitrogen and phosphorus. The Dolichospermum biomass was sensitive to the variation in nitrogen level, and the sensitivity depended on temperature. While the Microcystis biomass was sensitive to the variation in phosphorus level, and the sensitivity depended on temperature and total nitrogen. The different ways might contribute to the succession of the two cyanobacteria. Our findings will be helpful for improving the understanding of the shift process between Microcystis and Dolichospermum. Full article

(This article belongs to the Special Issue Effects of Harmful Cyanobacteria on Ecosystem Functioning, Food Webs, and Water Quality)

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19 pages, 1558 KiB

Open AccessFeature PaperEditor’s ChoiceReview

What’s in a Name? Patterns, Trends, and Suggestions for Defining Non-Perennial Rivers and Streams

by Michelle H. Busch, Katie H. Costigan, Ken M. Fritz, Thibault Datry, Corey A. Krabbenhoft, John C. Hammond, Margaret Zimmer, Julian D. Olden, Ryan M. Burrows, Walter K. Dodds, Kate S. Boersma, Margaret Shanafield, Stephanie K. Kampf, Meryl C. Mims, Michael T. Bogan, Adam S. Ward, Mariana Perez Rocha, Sarah Godsey, George H. Allen, Joanna R. Blaszczak, C. Nathan Jones and Daniel C. Allen Show full author list Hide full author list

Water 2020, 12(7), 1980; https://doi.org/10.3390/w12071980 - 13 Jul 2020

Cited by 71 | Viewed by 10459

Abstract

Rivers that cease to flow are globally prevalent. Although many epithets have been used for these rivers, a consensus on terminology has not yet been reached. Doing so would facilitate a marked increase in interdisciplinary interest as well as critical need for clear [...] Read more.

Rivers that cease to flow are globally prevalent. Although many epithets have been used for these rivers, a consensus on terminology has not yet been reached. Doing so would facilitate a marked increase in interdisciplinary interest as well as critical need for clear regulations. Here we reviewed literature from Web of Science database searches of 12 epithets to learn (Objective 1—O1) if epithet topics are consistent across Web of Science categories using latent Dirichlet allocation topic modeling. We also analyzed publication rates and topics over time to (O2) assess changes in epithet use. We compiled literature definitions to (O3) identify how epithets have been delineated and, lastly, suggest universal terms and definitions. We found a lack of consensus in epithet use between and among various fields. We also found that epithet usage has changed over time, as research focus has shifted from description to modeling. We conclude that multiple epithets are redundant. We offer specific definitions for three epithets (non-perennial, intermittent, and ephemeral) to guide consensus on epithet use. Limiting the number of epithets used in non-perennial river research can facilitate more effective communication among research fields and provide clear guidelines for writing regulatory documents. Full article

(This article belongs to the Special Issue Hydrology, Geomorphology, and Ecology of Intermittent Rivers and Streams)

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27 pages, 5681 KiB

Open AccessEditor’s ChoiceArticle

Regional Isotopic Signatures of Groundwater in Croatia

by Željka Brkić, Mladen Kuhta, Tamara Hunjak and Ozren Larva

Water 2020, 12(7), 1983; https://doi.org/10.3390/w12071983 - 13 Jul 2020

Cited by 19 | Viewed by 4921

Abstract

Tracer methods are useful for investigating groundwater travel times and recharge rates and analysing impacts on groundwater quality. The most frequently used tracers are stable isotopes and tritium. Stable isotopes of oxygen (δ¹⁸O) and hydrogen (δ²H) are [...] Read more.

Tracer methods are useful for investigating groundwater travel times and recharge rates and analysing impacts on groundwater quality. The most frequently used tracers are stable isotopes and tritium. Stable isotopes of oxygen (δ¹⁸O) and hydrogen (δ²H) are mainly used as indicators of the recharge condition. Tritium (³H) is used to estimate an approximate mean groundwater age. This paper presents the results of an analysis of stable isotope data and tritium activity in Croatian groundwater samples that were collected between 1997 and 2014 at approximately 100 sites. The composition of the stable isotopes of groundwater in Croatia originates from recent precipitation and is described using two regional groundwater lines. One of them is applied to groundwater accumulated in the aquifers in the Pannonian part of Croatia and the other is for groundwater accumulated in the Dinaric karst of Croatia. The isotope content shows that the studied groundwater is mainly modern water. A mix of sub-modern and modern water is mostly accumulated in semi-confined porous aquifers in northern Croatia, deep carbonate aquifers, and (sub)thermal springs. Full article

(This article belongs to the Special Issue Application of Stable Isotopes and Tritium in Hydrology)

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23 pages, 5748 KiB

Open AccessEditor’s ChoiceArticle

Analysis of the Evolution of Drought, Flood, and Drought-Flood Abrupt Alternation Events under Climate Change Using the Daily SWAP Index

by Ying Zhao, Zhaohui Weng, Hua Chen and Jiawei Yang

Water 2020, 12(7), 1969; https://doi.org/10.3390/w12071969 - 12 Jul 2020

Cited by 57 | Viewed by 7448

Abstract

With the increase of drought and flood frequency, the drought-flood abrupt alternation events occur frequently. Due to the coexistence and rapid transformation of drought and flood, the drought-flood abrupt alternation events is often more harmful and threatening than the single drought or flood [...] Read more.

With the increase of drought and flood frequency, the drought-flood abrupt alternation events occur frequently. Due to the coexistence and rapid transformation of drought and flood, the drought-flood abrupt alternation events is often more harmful and threatening than the single drought or flood event to the security of the society. This study is to synthetically evaluate the evolving characteristics of drought, flood, and drought-flood abrupt alternation events under climate change, which are identified by using the Standard Weighted Average Precipitation (SWAP) index. The variability of drought, flood, and drought-flood abrupt alternation events in the future is predicted by using GCM projections, whose outputs are corrected by using a daily bias correction method. The results show that: (1) The SWAP index has the capability to judge reliably the onset, duration, and intensity over the study areas, and can be used to monitor drought-flood abrupt alternation events efficiently; (2) In the reference period (1961–2005), for the drought-flood abrupt alternation events, the frequency has a downward trend in the upper reaches and an upward trend in the lower reaches, and the spatial distribution of intensity shows a contrary law to that of frequency; (3) The frequency and intensity of drought-flood abrupt alternation events show an upward trend in the whole basin in the future period (2021–2095), under the RCP4.5 and RCP8.5 scenarios. These results indicate that drought-flood abrupt alternation events can be more frequent, and the intensity will significantly increase in the 21st century, which may likely pose a serious impact on this basin. Full article

(This article belongs to the Special Issue Global Changes in Drought Frequency and Severity)

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18 pages, 3224 KiB

Open AccessEditor’s ChoiceArticle

Urbanization—Its Hidden Impact on Water Losses: Prądnik River Basin, Lesser Poland

by Tomáš Lepeška, Jakub Wojkowski, Andrzej Wałęga, Dariusz Młyński, Artur Radecki-Pawlik and Branislav Olah

Water 2020, 12(7), 1958; https://doi.org/10.3390/w12071958 - 10 Jul 2020

Cited by 20 | Viewed by 3759

Abstract

Urban development causes multiple water losses. Some of them may be ignored but some could have a huge influence on the whole catchment, including soil drought. As urban sprawl rises, space for unaffected infiltration and retention is increasingly limited. The objective of this [...] Read more.

Urban development causes multiple water losses. Some of them may be ignored but some could have a huge influence on the whole catchment, including soil drought. As urban sprawl rises, space for unaffected infiltration and retention is increasingly limited. The objective of this study was to backcast and to estimate water-retention loss due to urbanization during the period of 1990–2018. We used landcover data, meteorological and hydrological data and data on soil water-holding capacity. Water-retention loss was expressed as soil water retention capacity loss, net precipitation loss and total sum of precipitation loss. Historical change in urban extension has led to large impacts on the hydrological cycle of the study area. Progressive urban development caused water-retention losses which range from 3.380 to 14.182 millions of cubic meters—depending on the methodology used. Hydrological analysis showed the lack of a significant trend (decrease trend) of low flow which is caused by the high percentage of natural land use in the upper part of catchment. Our results show that backcasting of water retention change using CLC data (a) brings new and plausible data on retention loss, (b) is possible to replicate and (c) data used are common and easy-to-get. Full article

(This article belongs to the Special Issue Hydrological Impacts of Climate Change and Land Use)

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28 pages, 4996 KiB

Open AccessEditor’s ChoiceArticle

Improvement of SCS-CN Initial Abstraction Coefficient in the Czech Republic: A Study of Five Catchments

by Martin Caletka, Monika Šulc Michalková, Petr Karásek and Petr Fučík

Water 2020, 12(7), 1964; https://doi.org/10.3390/w12071964 - 10 Jul 2020

Cited by 45 | Viewed by 5351

Abstract

The SCS-CN method is a globally known procedure used primarily for direct-runoff estimates. It also is integrated in many modelling applications. However, the method was developed in specific geographical conditions, often making its universal applicability problematic. This study aims to determine appropriate values [...] Read more.

The SCS-CN method is a globally known procedure used primarily for direct-runoff estimates. It also is integrated in many modelling applications. However, the method was developed in specific geographical conditions, often making its universal applicability problematic. This study aims to determine appropriate values of initial abstraction coefficients λ and curve numbers (CNs), based on measured data in five experimental catchments in the Czech Republic, well representing the physiographic conditions in Central Europe, to improve direct-runoff estimates. Captured rainfall-runoff events were split into calibration and validation datasets. The calibration dataset was analysed by applying three approaches: (1) Modifying λ, both discrete and interpolated, using the tabulated CN values; (2) event analysis based on accumulated rainfall depth at the moment runoff starts to form; and (3) model fitting, an iterative procedure, to search for a pair of λ, S (CN, respectively). To assess individual rainfall characteristics’ possible influence, a principal component analysis and cluster analysis were conducted. The results indicate that the CN method in its traditional arrangement is not very applicable in the five experimental catchments and demands corresponding modifications to determine λ and CN (or S, respectively). Both λ and CN should be viewed as flexible, catchment-dependent (regional) parameters, rather than fixed values. The acquired findings show the need for a systematic yet site-specific revision of the traditional CN method, which may help to improve the accuracy of CN-based rainfall-runoff modelling. Full article

(This article belongs to the Special Issue Soil Conservation Service Curve Number (SCS-CN) Method Current Applications, Remaining Challenges, and Future Perspectives)

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25 pages, 5498 KiB

Open AccessEditor’s ChoiceArticle

Insights onto Hydrologic and Hydro-Chemical Processes of Riparian Groundwater Using Environmental Tracers in the Highly Disturbed Shaying River Basin, China

by Baoling Li, Xianfang Song, Lihu Yang, Dongxu Yao and Yingchun Xu

Water 2020, 12(7), 1939; https://doi.org/10.3390/w12071939 - 8 Jul 2020

Cited by 10 | Viewed by 3071

Abstract

Understanding the hydrologic and hydrochemistry processes in the riparian area is of great importance for managing and protecting riparian water resources. This paper took a highly disturbed and polluted Shaying River Basin (SRB) of China as the study area. In this research, environmental [...] Read more.

Understanding the hydrologic and hydrochemistry processes in the riparian area is of great importance for managing and protecting riparian water resources. This paper took a highly disturbed and polluted Shaying River Basin (SRB) of China as the study area. In this research, environmental tracers (hydrochemical and isotopic data of²²²Rn, δ¹⁸O, and δD) and corresponding models (two-component mixing model and ²²²Rn mass balance model) were employed to investigate the hydrologic and associated hydro-chemical process of riparian groundwater. The results indicated that rivers received groundwater discharge located at Xihua (J8), Zhoukou (Y1), Luohe (S2), and Shenqiu (SY2), and the mixing extent with groundwater was greater in wet seasons than in dry seasons. The ²²²Rn mass balance model showed that the flux of river water leakage was 3.27 × 10⁻⁴ m³/(s·m) at the front of Zhoukou sluice while groundwater discharge was 3.50 × 10⁻³ m³/(s·m) at the front of Shenqiu sluice during the sampling period. The cation exchange and the dissolution/precipitation of aquifer minerals (including calcite, dolomite, gypsum, and halite) were dominated by geochemical processes. The untreated sewage discharge and fertilizer usage were the main anthropogenic activities affecting the hydrochemistry process in surface water and riparian groundwater. Additionally, our results found that nitrate pollutants derived by riparian groundwater were potential threats to river quality at the lower reaches of Jialu River and Shenqiu county of Shaying River, where the nitrate inputs could be larger during the wet seasons because of higher groundwater discharge. Full article

(This article belongs to the Special Issue Applying Artificial and Environmental Tracing Techniques in Hydrogeology)

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26 pages, 1197 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Socio-Hydrology: A New Understanding to Unite or a New Science to Divide?

by Kaveh Madani and Majid Shafiee-Jood

Water 2020, 12(7), 1941; https://doi.org/10.3390/w12071941 - 8 Jul 2020

Cited by 52 | Viewed by 13063

Abstract

The socio-hydrology community has been very successful in promoting the need for taking the human factor into account in the mainstream hydrology literature since 2012. However, the interest in studying and modeling human-water systems is not new and pre-existed the post-2012 socio-hydrology. So, [...] Read more.

The socio-hydrology community has been very successful in promoting the need for taking the human factor into account in the mainstream hydrology literature since 2012. However, the interest in studying and modeling human-water systems is not new and pre-existed the post-2012 socio-hydrology. So, it is critical to ask what socio-hydrology has been able to offer that would have been unachievable using the existing methods, tools, and analysis frameworks. Thus far, the socio-hydrology studies show a strong overlap with what has already been in the literature, especially in the water resources systems and coupled human and natural systems (CHANS) areas. Nevertheless, the work in these areas has been generally dismissed by the socio-hydrology literature. This paper overviews some of the general concerns about originality, practicality, and contributions of socio-hydrology. It is argued that while in theory, a common sense about the need for considering humans as an integral component of water resources systems models can strengthen our coupled human-water systems research, the current approaches and trends in socio-hydrology can make this interest area less inclusive and interdisciplinary. Full article

(This article belongs to the Special Issue Application of the Systems Approach to the Management of Complex Water Systems)

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34 pages, 24719 KiB

Open AccessEditor’s ChoiceArticle

Multi-Collocation-Based Estimation of Wave Climate in a Non-Tidal Bay: The Case Study of Bagnoli-Coroglio Bay (Tyrrhenian Sea)

by Pasquale Contestabile, Fabio Conversano, Luca Centurioni, Umberto Mario Golia, Luigi Musco, Roberto Danovaro and Diego Vicinanza

Water 2020, 12(7), 1936; https://doi.org/10.3390/w12071936 - 7 Jul 2020

Cited by 10 | Viewed by 3632

Abstract

In this paper, the advantages of shaping a non-conventional triple collocation-based calibration of a wave propagation model is pointed out. Illustrated through a case study in the Bagnoli-Coroglio Bay (central Tyrrhenian Sea, Italy), a multi-comparison between numerical data and direct measurements have been [...] Read more.

In this paper, the advantages of shaping a non-conventional triple collocation-based calibration of a wave propagation model is pointed out. Illustrated through a case study in the Bagnoli-Coroglio Bay (central Tyrrhenian Sea, Italy), a multi-comparison between numerical data and direct measurements have been carried out. The nearshore wave propagation model output has been compared with measurements from an acoustic Doppler current profiler (ADCP) and an innovative low-cost drifter-derived GPS-based wave buoy located outside the bay. The triple collocation—buoy, ADCP and virtual numerical point—make possible an implicit validation between instrumentations and between instrumentation and numerical model. The procedure presented here advocates for an alternative “two-step” strategy. Indeed, the triple collocation technique has been used solely to provide a first “rough” calibration of one numerical domain in which the input open boundary has been placed, so that the main wave direction is orthogonally aligned. The need for a fast and sufficiently accurate estimation of wave model parameters (first step) and then an ensemble of five different offshore boundary orientations have been considered, referencing for a more detailed calibration to a short time series of a GPS-buoy installed in the study area (second step). Such a stage involves the introduction of an enhancement factor for the European Centre for Medium-Range Weather Forecasts (ECMWF) dataset, used as input for the model. Finally, validation of the final model’s predictions has been carried out by comparing ADCP measurements in the bay. Despite some limitations, the results reveal that the approach is promising and an excellent correlation can be found, especially in terms of significant wave height. Full article

(This article belongs to the Special Issue Coastal Vulnerability and Mitigation Strategies: From Monitoring to Applied Research )

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20 pages, 4294 KiB

Open AccessEditor’s ChoiceArticle

Examining Water Area Changes Accompanying Dam Construction in the Madeira River in the Brazilian Amazon

by Dengqiu Li, Dengsheng Lu, Emilio Moran and Ramon Felipe Bicudo da Silva

Water 2020, 12(7), 1921; https://doi.org/10.3390/w12071921 - 6 Jul 2020

Cited by 16 | Viewed by 3968

Abstract

Two recently constructed run-of-the-river dams (Santo Antônio and Jirau), along the Madeira River in Brazil, have been controversial due to their large unquantified impacts on (1) land use and land cover (LULC) and (2) on the area that would be flooded. Based on [...] Read more.

Two recently constructed run-of-the-river dams (Santo Antônio and Jirau), along the Madeira River in Brazil, have been controversial due to their large unquantified impacts on (1) land use and land cover (LULC) and (2) on the area that would be flooded. Based on annual LULC data from 1985 to 2017, this study integrated intensity analysis and difference components methods to analyze the impacts of the two dams on the annual flooded area in upstream, midstream, and downstream regions of the Madeira River. The dam construction significantly influenced LULC change intensity in the upstream and midstream regions since 2011 and 2010, respectively. An increase of 18.5% of the newly flooded area (462.58 km²) in the post-dam construction period was observed. The water gross gain intensity was active during 2011–2017 and 2011–2014 in upstream and midstream, respectively. The dominant difference components of water change were exchanged in the pre-dam period and became quantity in the post-dam period for both upstream and midstream regions. Forest was the major land category replaced by water; however, the highest gain intensities occurred in other non-vegetated areas in upstream and midstream. This study provided a useful approach for characterizing impacts of dam construction on water area change. Full article

(This article belongs to the Special Issue Impacts of Climate Change and Anthropogenic Activities on the Spatio-Temporal Variability of River Flow)

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16 pages, 11493 KiB

Open AccessEditor’s ChoiceArticle

Estimation of Surface Water Runoff for a Semi-Arid Area Using RS and GIS-Based SCS-CN Method

by Hussein Al-Ghobari, Ahmed Dewidar and Abed Alataway

Water 2020, 12(7), 1924; https://doi.org/10.3390/w12071924 - 6 Jul 2020

Cited by 72 | Viewed by 9092

Abstract

The proper planning of storage structures, waterways, irrigation schemes, water harvesting, erosion control structures, and groundwater development strategies requires accurate estimation of surface runoff. However, hydrologists in Saudi Arabia face serious challenges, specifically due to the rare availability of surface runoff data. In [...] Read more.

The proper planning of storage structures, waterways, irrigation schemes, water harvesting, erosion control structures, and groundwater development strategies requires accurate estimation of surface runoff. However, hydrologists in Saudi Arabia face serious challenges, specifically due to the rare availability of surface runoff data. In this study, the soil conservation service-curve number (SCS-CN) method integrated with geographic information system (GIS) and remote sensing (RS) was utilized to estimate the surface runoff in Wadi-Uranah basin, in the western region of Saudi Arabia. Different thematic maps such as slope, hydrologic soil group (HSG), land use/land cover (LULC), and daily rainfall have been created in GIS environment and processed to generate the curve number (CN) and surface runoff maps. Based on the soil classification results, the study area was categorized into two HSGs (B and C). The dominant HSG was group C, representing about 98.8% of the total area. The LULC analysis showed four main land use types in the study region: urban, rocks, barren soil, and agricultural areas. Furthermore, the finding results showed that CN values for the normal conditions (CN_II) ranged between 74 and 93 in agricultural and both urban and rock areas, respectively. The CN_II values were further corrected using slope data to derive slope-adjusted CN_II. Moreover, the rainfall-runoff results showed an increase in the daily runoff of the study region with a minimum of 15 mm to a maximum of 74 mm. Another interesting result was rainfall-runoff linear regression analysis that showed a good correlation of 0.98. Additionally, the peak runoff hydrograph flows for 10-, 50-, and 100-year return periods obtained from the SCS-based dimensionless unit hydrograph were 828, 1353, and 1603 m³/s, respectively. Therefore, this study highlights that the SCS-CN method integrated with RS and GIS deserves further attention for estimating runoff of ungauged basins for better basins management and conservation purposes. Full article

(This article belongs to the Section Hydrology)

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20 pages, 7632 KiB

Open AccessEditor’s ChoiceArticle

Comparative Analysis of Drought Indicated by the SPI and SPEI at Various Timescales in Inner Mongolia, China

by Zhifang Pei, Shibo Fang, Lei Wang and Wunian Yang

Water 2020, 12(7), 1925; https://doi.org/10.3390/w12071925 - 6 Jul 2020

Cited by 185 | Viewed by 10459

Abstract

The global climate is noticeably warming, and drought occurs frequently. Therefore, choosing a suitable index for drought monitoring is particularly important. The standardized precipitation index (SPI) and the standardized precipitation evapotranspiration index (SPEI) are commonly used indicators in drought monitoring. The SPEI takes [...] Read more.

The global climate is noticeably warming, and drought occurs frequently. Therefore, choosing a suitable index for drought monitoring is particularly important. The standardized precipitation index (SPI) and the standardized precipitation evapotranspiration index (SPEI) are commonly used indicators in drought monitoring. The SPEI takes temperature into account, but the SPI does not. In the context of global warming, what are their differences and applicability in regional drought monitoring? In this study, after calculating the SPI and SPEI at 1-, 3-, 6-, and 12-month timescales at 102 meteorological stations in Inner Mongolia from 1981 to 2018, we compared and analyzed the performances of the SPI and SPEI in drought monitoring from temporal and spatial variations, and the consistency and applicability of the SPI and SPEI were also discussed. The results showed that (1) with increasing timescale, the temporal variations in the SPI and SPEI were increasingly consistent, but there were still slight differences in the fluctuation value and continuity; (2) due to the difference in time series, the drought characteristics identified by the SPI and SPEI were quite different in space at various timescales, and with the increase in timescale, the spatial distributions of the drought trends in Inner Mongolia were basically consistent, except in Alxa; (3) at the shortest timescale, the difference between the SPI and SPEI was the largest, and the drought reflected by the SPI and SPEI may be consistent at long timescales; and (4) compared with typical drought events and vegetation indexes, the SPEI may be more suitable than the SPI for drought monitoring in Inner Mongolia. It should be noted that the adaptability of the SPI and SPEI may be different in different periods and regions, which remains to be analyzed in the future. Full article

(This article belongs to the Section Hydrology)

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13 pages, 2191 KiB

Open AccessEditor’s ChoiceArticle

Man-Induced Discrete Freshwater Discharge and Changes in Flow Structure and Bottom Turbulence in Altered Yeongsan Estuary, Korea

by KiRyong Kang and Guan-hong Lee

Water 2020, 12(7), 1919; https://doi.org/10.3390/w12071919 - 5 Jul 2020

Cited by 7 | Viewed by 2561

Abstract

Flow measurements were performed in the altered Yeongsan estuary, Korea, in August 2011, to investigate changes in flow structure in the water column and turbulence characteristics very close to the bed. Comparison between the bottom turbulent kinetic energy (TKE) and suspended sediment concentration [...] Read more.

Flow measurements were performed in the altered Yeongsan estuary, Korea, in August 2011, to investigate changes in flow structure in the water column and turbulence characteristics very close to the bed. Comparison between the bottom turbulent kinetic energy (TKE) and suspended sediment concentration (SSC) was conducted to examine how discrete freshwater discharge affects the bottom sediment concentration. The discrete freshwater discharge due to the gate opening of the Yeongsan estuarine dam induced a strong two-layer circulation: an offshore-flowing surface layer and a landward-flowing bottom layer. The fine flow structure from the bed to 0.35 m above the bottom (mab hereafter) exhibited an upside-down-bell-shaped profile for which current speed was nearly uniform above 0.1 mab, with the magnitude of the horizontal and vertical flow speeds reaching 0.1 and 0.01 m/s, respectively. The bottom turbulence responded to the freshwater discharge at the surface layer and the maximum magnitude of the Reynolds stress reached up to 2 × 10⁻⁴ m²/s² during the discharged period, which coincided with increased SSC in the bottom boundary layer. These results indicate that the surface freshwater discharge due to opening of the estuarine dam gate increases the SSC by the discharge-induced intensification of the turbulent flow in the bottom boundary layer. Full article

(This article belongs to the Special Issue Turbulence and Flow–Sediment Interactions in Open-Channel Flows)

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17 pages, 9703 KiB

Open AccessEditor’s ChoiceArticle

Experimental Assessment of the Flow Resistance of Coastal Wooden Fences

by Hoang Tung Dao, Bas Hofland, Marcel J. F. Stive and Tri Mai

Water 2020, 12(7), 1910; https://doi.org/10.3390/w12071910 - 4 Jul 2020

Cited by 14 | Viewed by 5162

Abstract

Wooden fences are applied as a nature-based solution to support mangrove restoration along mangrove coasts in general and the Mekong Delta coast in particular. The simple structure uses vertical bamboo poles as a frame to store horizontal bamboo and tree branches (brushwood). Fence [...] Read more.

Wooden fences are applied as a nature-based solution to support mangrove restoration along mangrove coasts in general and the Mekong Delta coast in particular. The simple structure uses vertical bamboo poles as a frame to store horizontal bamboo and tree branches (brushwood). Fence resistance is quantitatively determined by the drag coefficient exerted by the fence material on the flow; however, the behaviour of drag is predictable only when the arrangement of the cylinders is homogeneous. Therefore, for more arbitrary arrangements, the Darcy–Forchheimer equations need to be considered. In this study, the law of fluid flow was applied by forcing a constant flow of water through the fence material and measuring the loss of hydraulic pressure over a fence thickness. Fences, mainly using bamboo sticks, were installed with model-scale and full-scale diameters applying two main arrangements, inhomogeneous and staggered. Our empirical findings led to several conclusions. The bulk drag coefficient (

\bar{C_{D}}

) is influenced by the flow regime represented by Reynolds number. The drag coefficient decreases with the increase of the porosity, which strongly depends on fence arrangements. Finally, the Forchheimer coefficients can be linked to the drag coefficient through a related porosity parameter at high turbulent conditions. The staggered arrangement is well-predicted by the Ergun-relations for the Darcy–Forchheimer coefficients when an inhomogeneous arrangement with equal porosity and diameter leads to a large drag and flow resistance. Full article

(This article belongs to the Special Issue Nature-Based Solutions for Coastal Engineering and Management)

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11 pages, 439 KiB

Open AccessEditor’s ChoiceArticle

Water–Energy–Food Nexus Framework for Promoting Regional Integration in Central Asia

by Olimjon Saidmamatov, Inna Rudenko, Stephan Pfister and Jacek Koziel

Water 2020, 12(7), 1896; https://doi.org/10.3390/w12071896 - 3 Jul 2020

Cited by 39 | Viewed by 7692

Abstract

This paper focuses on regional integration through the lenses of the Water–Food–Energy (WEF) nexus, a concept putting strong emphasis on cross-sectoral and multi-level interactions as well as on resource interdependencies. There is an extensive amount of published research focusing on the Aral Sea [...] Read more.

This paper focuses on regional integration through the lenses of the Water–Food–Energy (WEF) nexus, a concept putting strong emphasis on cross-sectoral and multi-level interactions as well as on resource interdependencies. There is an extensive amount of published research focusing on the Aral Sea basin. In this paper, the authors build upon these different contributions and provide a meta-analysis of the literature of WEF nexus opportunities in Central Asia (CA) countries. This paper contributes to ongoing discussions regarding how the WEF Nexus can represent an opportunity for reinforced collaboration regarding resources management. To do so, focusing on existing literature, this paper first (1) explores how the nexus can be a relevant instrument for regional integration. Second (2), it provides an overview of water, food, energy conditions and challenges in the Aral Sea basin in particular. Third (3), synthesizing existing research, the authors identify critical variables to be considered as hurdles or leverage points for WEF nexus implementation in the Aral Sea basin. Finally (4), we go back to our initial set of questions and identify some possible avenues for future research. Full article

(This article belongs to the Special Issue Management of Water-Energy-Food Security Nexus)

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20 pages, 6533 KiB

Open AccessEditor’s ChoiceArticle

Hydrologic Assessment of TRMM and GPM-Based Precipitation Products in Transboundary River Catchment (Chenab River, Pakistan)

by Ehtesham Ahmed, Firas Al Janabi, Jin Zhang, Wenyu Yang, Naeem Saddique and Peter Krebs

Water 2020, 12(7), 1902; https://doi.org/10.3390/w12071902 - 3 Jul 2020

Cited by 26 | Viewed by 6693

Abstract

Water resources planning and management depend on the quality of climatic data, particularly rainfall data, for reliable hydrological modeling. This can be very problematic in transboundary rivers with limited disclosing of data among the riparian countries. Satellite precipitation products are recognized as a [...] Read more.

Water resources planning and management depend on the quality of climatic data, particularly rainfall data, for reliable hydrological modeling. This can be very problematic in transboundary rivers with limited disclosing of data among the riparian countries. Satellite precipitation products are recognized as a promising source to substitute the ground-based observations in these conditions. This research aims to assess the feasibility of using a satellite-based precipitation product for better hydrological modeling in an ungauged and riparian river in Pakistan, i.e., the Chenab River. A semidistributed hydrological model of The soil and water assessment tool (SWAT) was set up and two renowned satellite precipitation products, i.e., global precipitation mission (GPM) IMERG-F v6 and tropical rainfall measuring mission (TRMM) 3B42 v7, were selected to assess the runoff pattern in Chenab River. The calibration was done from 2001–2006 with two years of a warmup period. The validation (2007–2010) results exhibit higher correlation between observed and simulated discharges at monthly timescale simulations, IMERG-F (R² = 0.89, NSE = 0.82), 3B42 (R² = 0.85, NSE = 0.72), rather than daily timescale simulations, IMERG-F (R² = 0.66, NSE = 0.61), 3B42 (R² = 0.64, NSE = 0.54). Moreover, the comparison between IMERG-F and 3B42, shows that IMERG-F is superior to 3B42 by indicating higher R², NSE and lower percent bias (PBIAS) at both monthly and daily timescale. The results are strengthened by Taylor diagram statistics, which represent a higher correlation (R) and less RMS error between observed and simulated values for IMERG-F. IMERG-F has great potential utility in the Chenab River catchment as it outperformed the 3B42 precipitation in this study. However, its poor skill of capturing peaks at daily timescale remains, leaving a room for IMERG-F to improve its algorithm in the upcoming release. Full article

(This article belongs to the Section Hydrology)

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18 pages, 2107 KiB

Open AccessEditor’s ChoiceArticle

Ecological Environment Evaluation of Forest Ecosystem Nature Reserves Using an Unweighted Cloud Model

by Mengshi Xiang, Xiaonan Lin, Xiyan Yang and Shanghong Zhang

Water 2020, 12(7), 1905; https://doi.org/10.3390/w12071905 - 3 Jul 2020

Cited by 7 | Viewed by 2946

Abstract

The ecological environment is the foundation of human survival and development, and forest ecosystem nature reserves play an important role in the protection of the ecological environment. The evaluation of forest ecosystem nature reserves facilitates the formulation of relevant management policies. At present, [...] Read more.

The ecological environment is the foundation of human survival and development, and forest ecosystem nature reserves play an important role in the protection of the ecological environment. The evaluation of forest ecosystem nature reserves facilitates the formulation of relevant management policies. At present, the evaluation of the ecological environment of forest ecosystem nature reserves is mainly based on detailed evaluation of some elements of the ecological environment, rather than on a comprehensive quantitative evaluation that reflects the ecological environment in many aspects. To address this shortcoming, the quantitative evaluation indicator system of comprehensive ecological environment for forest ecosystem nature reserves was established based on the water, air, soil, and biological environments, according to the consensus on ecological environment in the past research and characteristics of the research area. The weight is still a necessary and important link in the evaluation of forest ecosystem nature reserves, but the accuracy of the weight results is difficult to get a scientific judgment. To prevent the evaluation results being influenced by weighting uncertainty, an unweighted cloud model was constructed to provide an evaluation mechanism without weight. The ecological environment evaluation was then carried out using the unweighted cloud model, taking Songshan Nature Reserve as a research area. The results show that the grades of the ecological environment of Songshan Nature Reserve are 21% excellent, 67% good, and 12% qualified, and that the state of the ecological environment is stable and performing well. The evaluation results for the grades of the environmental dimension layers are water environment > soil environment > biological environment > air environment. The study’s research results can provide theoretical support for the evaluation of forest ecosystem nature reserves, and for evaluation work in general when weights are difficult to determine or uncertain. Full article

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19 pages, 7964 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Identification of the Optimum Rain Gauge Network Density for Hydrological Modelling Based on Radar Rainfall Analysis

by Yeboah Gyasi-Agyei

Water 2020, 12(7), 1906; https://doi.org/10.3390/w12071906 - 3 Jul 2020

Cited by 24 | Viewed by 5132

Abstract

Rain gauges continue to be sources of rainfall data despite progress made in precipitation measurements using radar and satellite technology. There has been some work done on assessing the optimum rain gauge network density required for hydrological modelling, but without consensus. This paper [...] Read more.

Rain gauges continue to be sources of rainfall data despite progress made in precipitation measurements using radar and satellite technology. There has been some work done on assessing the optimum rain gauge network density required for hydrological modelling, but without consensus. This paper contributes to the identification of the optimum rain gauge network density, using scaling laws and bias-corrected 1 km × 1 km grid radar rainfall records, covering an area of 28,371 km² that hosts 315 rain gauges in south-east Queensland, Australia. Varying numbers of radar pixels (rain gauges) were repeatedly sampled using a unique stratified sampling technique. For each set of rainfall sampled data, a two-dimensional correlogram was developed from the normal scores obtained through quantile-quantile transformation for ordinary kriging which is a stochastic interpolation. Leave-one-out cross validation was carried out, and the simulated quantiles were evaluated using the performance statistics of root-mean-square-error and mean-absolute-bias, as well as their rates of change. A break in the scaling of the plots of these performance statistics against the number of rain gauges was used to infer the optimum rain gauge network density. The optimum rain gauge network density varied from 14 km²/gauge to 38 km²/gauge, with an average of 25 km²/gauge. Full article

(This article belongs to the Special Issue Stochastic Modelling of Hydrometeorological Processes for Engineering Applications)

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23 pages, 70913 KiB

Open AccessEditor’s ChoiceArticle

Beyond Human Interventions on Complex Bays: Effects on Water and Wave Dynamics (Study Case Cádiz Bay, Spain)

by Carmen Zarzuelo, Alejandro López-Ruiz and Miguel Ortega-Sánchez

Water 2020, 12(7), 1907; https://doi.org/10.3390/w12071907 - 3 Jul 2020

Cited by 8 | Viewed by 3009

Abstract

Bays are coastal environments with significant socio-economic importance, which has led to the development of human interventions in their interior that can have an important impact on the water and wave dynamics, which in turn modify their morphodynamics and water renewal capacity. In [...] Read more.

Bays are coastal environments with significant socio-economic importance, which has led to the development of human interventions in their interior that can have an important impact on the water and wave dynamics, which in turn modify their morphodynamics and water renewal capacity. In order to deepen our understanding of these impacts, numerical modeling was used in a bay in southern Spain to analyze the effect of inner harbor expansion and channel deepening, including the baroclinic and wave propagation effects, as well as variations in salinity and temperature. The results show that the deepening of the channel decreases the amplitude and speed of the tidal wave as it propagates through the bay, reducing the effects of friction and increasing the flushing time. The system evolves from convergent to a damping system that can potentially reduce the effects produced by projected sea level rise. In addition, the seasonal variability of salinity and temperature is reduced, increasing the bed shear stresses and resulting in increased turbidity that can affect the biogeochemistry of the bay. Finally, wave heights decrease along the main waterway, although the yearly-average wave energy flux is only slightly modified on the interior beaches of the bay. However, significant variations are observed during storms, which could affect the morphodynamics of these beaches. Full article

(This article belongs to the Section Oceans and Coastal Zones)

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27 pages, 4594 KiB

Open AccessEditor’s ChoiceArticle

Comparison of the MUSLE Model and Two Years of Solid Transport Measurement, in the Bouregreg Basin, and Impact on the Sedimentation in the Sidi Mohamed Ben Abdellah Reservoir, Morocco

by Mohamed Abdellah Ezzaouini, Gil Mahé, Ilias Kacimi and Abdelaziz Zerouali

Water 2020, 12(7), 1882; https://doi.org/10.3390/w12071882 - 1 Jul 2020

Cited by 39 | Viewed by 4777

Abstract

The evaluation and quantification of solids transport in Morocco often uses the Universal Soil Loss Model (USLE) and the revised version RUSLE, which presents a calibration difficulty. In this study, we apply the MUSLE model to predict solid transport, for the first time [...] Read more.

The evaluation and quantification of solids transport in Morocco often uses the Universal Soil Loss Model (USLE) and the revised version RUSLE, which presents a calibration difficulty. In this study, we apply the MUSLE model to predict solid transport, for the first time on a large river basin in the Kingdom, calibrated by two years of solid transport measurements on four main gauging stations at the entrance of the Sidi Mohamed Ben Abdellah dam. The application of the MUSLE on the basin demonstrated relatively small differences between the measured values and those expected for the calibrated version, these differences are, for the non-calibrated version, +5% and +102% for the years 2016/2017 and 2017/2018 respectively, and between −33% and +34% for the calibrated version. Besides, the measured and modeled volumes that do not exceed 1.78 × 10⁶ m³/year remain well below the dam’s siltation rate of 9.49 × 10⁶ m³/year, which means that only 18% of the dam’s sediment comes from upstream. This seems very low because it is calculated from only two years. The main hypothesis that we can formulate is that the sediments of the dam most probably comes from the erosion of its banks. Full article

(This article belongs to the Special Issue Multiscale Impacts of Anthropogenic and Climate Changes on Tropical and Mediterranean Hydrology)

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17 pages, 1732 KiB

Open AccessEditor’s ChoiceArticle

Urban Water Demand Prediction for a City That Suffers from Climate Change and Population Growth: Gauteng Province Case Study

by Salah L. Zubaidi, Sandra Ortega-Martorell, Hussein Al-Bugharbee, Ivan Olier, Khalid S. Hashim, Sadik Kamel Gharghan, Patryk Kot and Rafid Al-Khaddar

Water 2020, 12(7), 1885; https://doi.org/10.3390/w12071885 - 1 Jul 2020

Cited by 147 | Viewed by 13837

Abstract

The proper management of a municipal water system is essential to sustain cities and support the water security of societies. Urban water estimating has always been a challenging task for managers of water utilities and policymakers. This paper applies a novel methodology that [...] Read more.

The proper management of a municipal water system is essential to sustain cities and support the water security of societies. Urban water estimating has always been a challenging task for managers of water utilities and policymakers. This paper applies a novel methodology that includes data pre-processing and an Artificial Neural Network (ANN) optimized with the Backtracking Search Algorithm (BSA-ANN) to estimate monthly water demand in relation to previous water consumption. Historical data of monthly water consumption in the Gauteng Province, South Africa, for the period 2007–2016, were selected for the creation and evaluation of the methodology. Data pre-processing techniques played a crucial role in the enhancing of the quality of the data before creating the prediction model. The BSA-ANN model yielded the best result with a root mean square error and a coefficient of efficiency of 0.0099 mega liters and 0.979, respectively. Moreover, it proved more efficient and reliable than the Crow Search Algorithm (CSA-ANN), based on the scale of error. Overall, this paper presents a new application for the hybrid model BSA-ANN that can be successfully used to predict water demand with high accuracy, in a city that heavily suffers from the impact of climate change and population growth. Full article

(This article belongs to the Special Issue Advanced Applications of Electrocoagulation in Water and Wastewater)

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28 pages, 4267 KiB

Open AccessEditor’s ChoiceArticle

Application of GWO-ELM Model to Prediction of Caojiatuo Landslide Displacement in the Three Gorge Reservoir Area

by Liguo Zhang, Xinquan Chen, Yonggang Zhang, Fuwei Wu, Fei Chen, Weiting Wang and Fei Guo

Water 2020, 12(7), 1860; https://doi.org/10.3390/w12071860 - 29 Jun 2020

Cited by 43 | Viewed by 4035

Abstract

In order to establish an effective early warning system for landslide disasters, accurate landslide displacement prediction is the core. In this paper, a typical step-wise-characterized landslide (Caojiatuo landslide) in the Three Gorges Reservoir (TGR) area is selected, and a displacement prediction model of [...] Read more.

In order to establish an effective early warning system for landslide disasters, accurate landslide displacement prediction is the core. In this paper, a typical step-wise-characterized landslide (Caojiatuo landslide) in the Three Gorges Reservoir (TGR) area is selected, and a displacement prediction model of Extreme Learning Machine with Gray Wolf Optimization (GWO-ELM model) is proposed. By analyzing the monitoring data of landslide displacement, the time series of landslide displacement is decomposed into trend displacement and periodic displacement by using the moving average method. First, the trend displacement is fitted by the cubic polynomial with a robust weighted least square method. Then, combining with the internal evolution rule and the external influencing factors, it is concluded that the main external trigger factors of the periodic displacement are the changes of precipitation and water level in the reservoir area. Gray relational degree (GRG) analysis method is used to screen out the main influencing factors of landslide periodic displacement. With these factors as input items, the GWO-ELM model is used to predict the periodic displacement of the landslide. The outcomes are compared with the nonoptimized ELM model. The results show that, combined with the advantages of the GWO algorithm, such as few adjusting parameters and strong global search ability, the GWO-ELM model can effectively learn the change characteristics of data and has a better and relatively stable prediction accuracy. Full article

(This article belongs to the Section Hydrology)

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16 pages, 2608 KiB

Open AccessEditor’s ChoiceArticle

Mass Balance of the Greenland Ice Sheet from GRACE and Surface Mass Balance Modelling

by Fang Zou, Robert Tenzer, Hok Sum Fok and Janet E. Nichol

Water 2020, 12(7), 1847; https://doi.org/10.3390/w12071847 - 28 Jun 2020

Cited by 12 | Viewed by 4741

Abstract

The Greenland Ice Sheet (GrIS) is losing mass at a rate that represents a major contribution to global sea-level rise in recent decades. In this study, we use the Gravity Recovery and Climate Experiment (GRACE) data to retrieve the time series variations of [...] Read more.

The Greenland Ice Sheet (GrIS) is losing mass at a rate that represents a major contribution to global sea-level rise in recent decades. In this study, we use the Gravity Recovery and Climate Experiment (GRACE) data to retrieve the time series variations of the GrIS from April 2002 to June 2017. We also estimate the mass balance from the RACMO2.3 and ice discharge data in order to obtain a comparative analysis and cross-validation. A detailed analysis of long-term trend and seasonal and inter-annual changes in the GrIS is implemented by GRACE and surface mass balance (SMB) modeling. The results indicate a decrease of −267.77 ± 8.68 Gt/yr of the GrIS over the 16-year period. There is a rapid decline from 2002 to 2008, which accelerated from 2009 to 2012 before declining relatively slowly from 2013 to 2017. The mass change inland is significantly smaller than that detected along coastal regions, especially in the southeastern, southwestern, and northwestern regions. The mass balance estimates from GRACE and SMB minus ice discharge (SMB-D) are very consistent. The ice discharge manifests itself mostly as a long-term trend, whereas seasonal mass variations are largely attributed to surface mass processes. The GrIS mass changes are mostly attributed to mass loss during summer. Summer mass changes are highly correlated with climate changes. Full article

(This article belongs to the Section Hydrology)

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14 pages, 1674 KiB

Open AccessEditor’s ChoiceReview

Protection Motivation Theory: A Proposed Theoretical Extension and Moving beyond Rationality—The Case of Flooding

by Matthew Oakley, Sam Mohun Himmelweit, Paul Leinster and Mónica Rivas Casado

Water 2020, 12(7), 1848; https://doi.org/10.3390/w12071848 - 28 Jun 2020

Cited by 55 | Viewed by 14401

Abstract

Despite the significant financial and non-financial costs of household flooding, and the availability of products that can reduce the risk or impact of flooding, relatively few consumers choose to adopt these products. To help explain this, we combine the existing theoretical literature with [...] Read more.

Despite the significant financial and non-financial costs of household flooding, and the availability of products that can reduce the risk or impact of flooding, relatively few consumers choose to adopt these products. To help explain this, we combine the existing theoretical literature with evidence from 20 one-to-one discussions and three workshops with key stakeholders, as well as five round tables, to draw practical evidence of actual responses to flood risk. This analysis leads us to propose an extension to Protection Motivation Theory (PMT), which more accurately captures the decision-making process of consumers by highlighting the role of ‘ownership appraisal’. We then assess the extent to which behavioral biases impact on this revised framework. By highlighting the interaction with an augmented model of PMT and behavioral biases, the paper sheds light on potential reasons behind the fact that consumers are unlikely to adopt property-level flood resilience measures and identifies strategies to increase flood protection. The Augmented PMT suggests that policymakers might focus on increasing the Ownership Appraisal element, both directly and by targeting the creation of more supportive social norms. The work presented here opens up a wide range of areas for future research in the field. Full article

(This article belongs to the Special Issue Environmental Risk Management)

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21 pages, 9710 KiB

Open AccessEditor’s ChoiceArticle

Experimental Application of Sediment Flow Connectivity Index (SCI) in Flood Monitoring

by Marina Zingaro, Alberto Refice, Annarita D’Addabbo, Renaud Hostache, Marco Chini and Domenico Capolongo

Water 2020, 12(7), 1857; https://doi.org/10.3390/w12071857 - 28 Jun 2020

Cited by 16 | Viewed by 4337

Abstract

Sediment connectivity is considered a powerful geomorphic indicator for defining the most sensitive areas to geomorphological modifications in a fluvial catchment (hotspots). This encourages the development of methods and models for its assessment, to investigate the interrelation of the various phenomena that occur [...] Read more.

Sediment connectivity is considered a powerful geomorphic indicator for defining the most sensitive areas to geomorphological modifications in a fluvial catchment (hotspots). This encourages the development of methods and models for its assessment, to investigate the interrelation of the various phenomena that occur in a river basin (landslides, floods, etc.). This work explores the potential connection of the processes in flood dynamics, by focusing on induced flood hazard, in order to evaluate the applicability of sediment connectivity to flood monitoring. By applying the recently developed sediment flow connectivity index (SCI) computation method to the Severn River basin, in UK, recurrently affected by floods, we investigate the agreement between the hotspot areas (described by the index) and the areas recurrently flooded (as mapped by aerial photography, satellite imagery and hydrodynamic modelling). Qualitative and quantitative approaches are used for the analysis of past (March 2007 and January 2010) as well as predicted (with return periods of 200 and 500 years) flood events. The results show a good correspondence of areas of high sediment connectivity with flood occurrence. Moreover, the detection performance of the SCI is slightly better than that of a simple flow accumulation map, confirming the importance of the initial mapping of sediment availability and mobility. This experiment extends the direct applicability of the SCI from fluvial analysis to flood monitoring, thus opening interesting future scenarios. Full article

(This article belongs to the Special Issue Fluvial Geomorphology and River Management)

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10 pages, 1784 KiB

Open AccessEditor’s ChoiceArticle

Image Segmentation Methods for Flood Monitoring System

by Nur Atirah Muhadi, Ahmad Fikri Abdullah, Siti Khairunniza Bejo, Muhammad Razif Mahadi and Ana Mijic

Water 2020, 12(6), 1825; https://doi.org/10.3390/w12061825 - 26 Jun 2020

Cited by 36 | Viewed by 7381

Abstract

Flood disasters are considered annual disasters in Malaysia due to their consistent occurrence. They are among the most dangerous disasters in the country. Lack of data during flood events is the main constraint to improving flood monitoring systems. With the rapid development of [...] Read more.

Flood disasters are considered annual disasters in Malaysia due to their consistent occurrence. They are among the most dangerous disasters in the country. Lack of data during flood events is the main constraint to improving flood monitoring systems. With the rapid development of information technology, flood monitoring systems using a computer vision approach have gained attention over the last decade. Computer vision requires an image segmentation technique to understand the content of the image and to facilitate analysis. Various segmentation algorithms have been developed to improve results. This paper presents a comparative study of image segmentation techniques used in extracting water information from digital images. The segmentation methods were evaluated visually and statistically. To evaluate the segmentation methods statistically, the dice similarity coefficient and the Jaccard index were calculated to measure the similarity between the segmentation results and the ground truth images. Based on the experimental results, the hybrid technique obtained the highest values among the three methods, yielding an average of 97.70% for the dice score and 95.51% for the Jaccard index. Therefore, we concluded that the hybrid technique is a promising segmentation method compared to the others in extracting water features from digital images. Full article

(This article belongs to the Special Issue Flood Inundation Modelling and Assessment of Current and Future Flood Risk)

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24 pages, 2261 KiB

Open AccessEditor’s ChoiceArticle

Conserving Mekong Megafishes: Current Status and Critical Threats in Cambodia

by Teresa Campbell, Kakada Pin, Peng Bun Ngor and Zeb Hogan

Water 2020, 12(6), 1820; https://doi.org/10.3390/w12061820 - 25 Jun 2020

Cited by 30 | Viewed by 8036

Abstract

Megafishes are important to people and ecosystems worldwide. These fishes attain a maximum body weight of ≥30 kg. Global population declines highlight the need for more information about megafishes’ conservation status to inform management and conservation. The northern Cambodian Mekong River and its [...] Read more.

Megafishes are important to people and ecosystems worldwide. These fishes attain a maximum body weight of ≥30 kg. Global population declines highlight the need for more information about megafishes’ conservation status to inform management and conservation. The northern Cambodian Mekong River and its major tributaries are considered one of the last refugia for Mekong megafishes. We collected data on population abundance and body size trends for eight megafishes in this region to better understand their conservation statuses. Data were collected in June 2018 using a local ecological knowledge survey of 96 fishers in 12 villages. Fishers reported that, over 20 years, most megafishes changed from common to uncommon, rare, or locally extirpated. The most common and rarest species had mean last capture dates of 4.5 and 95 months before the survey, respectively. All species had declined greatly in body size. Maximum body weights reported by fishers ranged from 11–88% of their recorded maxima. Fishers identified 10 threats to megafishes, seven of which were types of illegal fishing. Electrofishing was the most prevalent. Results confirm that Mekong megafishes are severely endangered. Species Conservation Strategies should be developed and must address pervasive illegal fishing activities, alongside habitat degradation and blocked migrations, to recover declining populations. Full article

(This article belongs to the Special Issue Channels for Change: Integrating Multiple Disciplines for New Frontiers in Managing the Mekong River Basin)

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18 pages, 6145 KiB

Open AccessEditor’s ChoiceArticle

Prediction of Chlorophyll-a Concentrations in the Nakdong River Using Machine Learning Methods

by Yuna Shin, Taekgeun Kim, Seoksu Hong, Seulbi Lee, EunJi Lee, SeungWoo Hong, ChangSik Lee, TaeYeon Kim, Man Sik Park, Jungsu Park and Tae-Young Heo

Water 2020, 12(6), 1822; https://doi.org/10.3390/w12061822 - 25 Jun 2020

Cited by 86 | Viewed by 7140

Abstract

Many studies have attempted to predict chlorophyll-a concentrations using multiple regression models and validating them with a hold-out technique. In this study commonly used machine learning models, such as Support Vector Regression, Bagging, Random Forest, Extreme Gradient Boosting (XGBoost), Recurrent Neural Network [...] Read more.

Many studies have attempted to predict chlorophyll-a concentrations using multiple regression models and validating them with a hold-out technique. In this study commonly used machine learning models, such as Support Vector Regression, Bagging, Random Forest, Extreme Gradient Boosting (XGBoost), Recurrent Neural Network (RNN), and Long–Short-Term Memory (LSTM), are used to build a new model to predict chlorophyll-a concentrations in the Nakdong River, Korea. We employed 1–step ahead recursive prediction to reflect the characteristics of the time series data. In order to increase the prediction accuracy, the model construction was based on forward variable selection. The fitted models were validated by means of cumulative learning and rolling window learning, as opposed to the hold–out technique. The best results were obtained when the chlorophyll-a concentration was predicted by combining the RNN model with the rolling window learning method. The results suggest that the selection of explanatory variables and 1–step ahead recursive prediction in the machine learning model are important processes for improving its prediction performance. Full article

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13 pages, 2812 KiB

Open AccessEditor’s ChoiceArticle

Isotopic ‘Altitude’ and ‘Continental’ Effects in Modern Precipitation across the Adriatic–Pannonian Region

by Zoltán Kern, István Gábor Hatvani, György Czuppon, István Fórizs, Dániel Erdélyi, Tjaša Kanduč, László Palcsu and Polona Vreča

Water 2020, 12(6), 1797; https://doi.org/10.3390/w12061797 - 24 Jun 2020

Cited by 45 | Viewed by 5853

Abstract

It is generally observed that precipitation is gradually depleted in ¹⁸O and ²H isotopes as elevation increases (‘altitude’ effect) or when moving inland from seacoasts (‘continental’ effect); the regionally accurate estimation of these large-scale effects is important in isotope hydrological or [...] Read more.

It is generally observed that precipitation is gradually depleted in ¹⁸O and ²H isotopes as elevation increases (‘altitude’ effect) or when moving inland from seacoasts (‘continental’ effect); the regionally accurate estimation of these large-scale effects is important in isotope hydrological or paleoclimatological applications. Nevertheless, seasonal and spatial differences should be considered. Stable isotope composition of monthly precipitation fallen between January 2016 and December 2018 was studied for selected stations situated along an elevation transect and a continental transect in order to assess the isotopic ‘altitude’ and ‘continental’ effects in modern precipitation across the Adriatic–Pannonian region. Isotopic characteristics argue that the main driver of the apparent vertical depletion of precipitation in heavy stable isotopes is different in summer (raindrop evaporation) and winter (condensation), although, there is no significant difference in the resulting ‘altitude’ effect. Specifically, an ‘altitude’ effect of −1.2‰/km for δ¹⁸O and −7.9‰/km for δ²H can be used in modern precipitation across the Adriatic–Pannonian region. Isotopic characteristics of monthly precipitation showed seasonally different patterns and suggest different isotope hydrometeorological regimes along the continental transect. While no significant decrease was found in δ¹⁸O data moving inland from the Adriatic from May to August of the year, a clear decreasing trend was found in precipitation fallen during the colder season of the year (October to March) up to a break at ~400 km inland from the Adriatic coast. The estimated mean isotopic ‘continental’ effect for the colder season precipitation is −2.4‰/100 km in δ¹⁸O and −20‰/100 km in δ²H. A prevailing influence of the Mediterranean moisture in the colder season is detected up to this breakpoint, while the break in the δ¹⁸O data probably reflects the mixture of moisture sources with different isotopic characteristics. A sharp drop in the d-excess (>3‰) at the break in precipitation δ¹⁸O trend likely indicates a sudden switch from the Mediterranean moisture domain to additional (mainly Atlantic) influence, while a gradual change in the d-excess values might suggest a gradual increase of the non-Mediterranean moisture contribution along the transect. Full article

(This article belongs to the Special Issue Use of Water Stable Isotopes in Hydrological Process)

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25 pages, 2371 KiB

Open AccessEditor’s ChoiceArticle

Watershed Hydrological Response to Combined Land Use/Land Cover and Climate Change in Highland Ethiopia: Finchaa Catchment

by Wakjira Takala Dibaba, Tamene Adugna Demissie and Konrad Miegel

Water 2020, 12(6), 1801; https://doi.org/10.3390/w12061801 - 24 Jun 2020

Cited by 125 | Viewed by 7993

Abstract

Land use/land cover (LULC) and climate change affect the availability of water resources by altering the magnitude of surface runoff, aquifer recharge, and river flows. The evaluation helps to identify the level of water resources exposure to the changes that could help to [...] Read more.

Land use/land cover (LULC) and climate change affect the availability of water resources by altering the magnitude of surface runoff, aquifer recharge, and river flows. The evaluation helps to identify the level of water resources exposure to the changes that could help to plan for potential adaptive capacity. In this research, Cellular Automata (CA)-Markov in IDRISI software was used to predict the future LULC scenarios and the ensemble mean of four regional climate models (RCMs) in the coordinated regional climate downscaling experiment (CORDEX)-Africa was used for the future climate scenarios. Distribution mapping was used to bias correct the RCMs outputs, with respect to the observed precipitation and temperature. Then, the Soil and Water Assessment Tool (SWAT) model was used to evaluate the watershed hydrological responses of the catchment under separate, and combined, LULC and climate change. The result shows the ensemble mean of the four RCMs reported precipitation decline and increase in future temperature under both representative concentration pathways (RCP4.5 and RCP8.5). The increases in both maximum and minimum temperatures are higher for higher emission scenarios showing that RCP8.5 projection is warmer than RCP4.5. The changes in LULC brings an increase in surface runoff and water yield and a decline in groundwater, while the projected climate change shows a decrease in surface runoff, groundwater and water yield. The combined study of LULC and climate change shows that the effect of the combined scenario is similar to that of climate change only scenario. The overall decline of annual flow is due to the decline in the seasonal flows under combined scenarios. This could bring the reduced availability of water for crop production, which will be a chronic issue of subsistence agriculture. The possibility of surface water and groundwater reduction could also affect the availability of water resources in the catchment and further aggravate water stress in the downstream. The highly rising demands of water, owing to socio-economic progress, population growth and high demand for irrigation water downstream, in addition to the variability temperature and evaporation demands, amplify prolonged water scarcity. Consequently, strong land-use planning and climate-resilient water management policies will be indispensable to manage the risks. Full article

(This article belongs to the Special Issue Hydrological Impacts of Climate Change and Land Use)

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26 pages, 5171 KiB

Open AccessEditor’s ChoiceArticle

Spatial Dependence Modeling of Flood Risk Using Max-Stable Processes: The Example of Austria

by Hansjörg Albrecher, Dominik Kortschak and Franz Prettenthaler

Water 2020, 12(6), 1805; https://doi.org/10.3390/w12061805 - 24 Jun 2020

Cited by 6 | Viewed by 3087

Abstract

We propose a new approach to model the dependence structure for aggregating the risk of flood damages from a local level to larger areas, which is based on the structure of the river network of a country and can be calibrated with publicly [...] Read more.

We propose a new approach to model the dependence structure for aggregating the risk of flood damages from a local level to larger areas, which is based on the structure of the river network of a country and can be calibrated with publicly available data of river discharges. Building upon a suitable adaptation of max-stable processes for a flood-relevant geometry as recently introduced in the literature, this enables the assessment of flood risk without the need for a hydrological model, and can easily be adapted for different countries. We illustrate its use for the particular case of Austria. We first develop marginal flood models for individual municipalities by intertwining available HORA risk maps with the actual location of buildings. As a second alternative for the marginal modeling, we advocate an approach based on suitably normalized historical damage data of municipalities together with techniques from extreme value statistics. We implement and compare the two alternatives and apply the calibrated dependence structure to each of them, leading to estimates for average flood damage as well as its extreme quantiles on the municipality, state, and country level. This also allows us to quantify the diversification potential for flood risk on each of these levels, a topic of considerable importance in view of the natural and strong spatial dependence of this particular natural peril. Full article

(This article belongs to the Special Issue Recent Advances and New Directions in Flood Forecasting, Modeling, and Mapping)

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