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Special Issue "Selected Papers from the 1st International Electronic Conference on the Hydrological Cycle (ChyCle-2017)"

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Hydrology".

Deadline for manuscript submissions: closed (30 September 2018)

Special Issue Editors

Guest Editor
Prof. Raquel Nieto

Environmental Physics Laboratory (EPhysLab), Facultade de Ciencias, Universidade de Vigo, 32004 Ourense, Spain
Website | E-Mail
Phone: +34-988-387248
Interests: sources of moisture; Lagrangian models; atmospheric transport; climate diagnosis; sinoptic meteorology; modes of variability
Guest Editor
Prof. Luis Gimeno

Ephyslab. Universidad Vigo. Facultad de Ciencias de Ourense. Ourense. Spain
Website | E-Mail
Phone: +34-988-387208
Interests: climate diagnosis; offshore renewable energy; environmental impact
Guest Editor
Prof. Jose A. Marengo

CEMADEN
Website | E-Mail
Phone: +55-11-3186-9236
Interests: climate change; climate variability; disasters risk redcution
Guest Editor
Prof. Diego Miralles

Department of Forest and Water Management, Ghent University
Website | E-Mail
Phone: +32 9 264 61 35
Interests: dynamics of the global water cycle; impact of climate change on hydrology; use of satellite-based evaporation to identify land–atmospheric feedbacks; characterization of evaporation at the regional scales; hydrological and climatic extremes; impact of hydro-climatic anomalies on vegetation; study of ocean–atmospheric oscillations and their impact on terrestrial hydrology
Guest Editor
Dr. Sergio M. Vicente Serrano

Spanish National Research Council
Website | E-Mail
Phone: +34-976-369393
Interests: global change; drought; extreme events; remote sensing; climatology; hydrology
Guest Editor
Prof. Ana María Durán‐Quesada

University of Costa Rica
Website | E-Mail
Phone: (506) 2511 5096
Interests: tropical dynamics; climate variability; numerical modeling; biogeochemical cycling

Special Issue Information

Dear Colleagues,

This Special Issue comprises selected papers from the Proceedings of the 1st International Electronic Conference on the Hydrological Cycle (ChyCle-2017, http://sciforum.net/conference/CHyCle-2017), 12–16 November, 2017, on sciforum.net, an online platform for hosting scholarly e-conferences and discussion groups.

The main aim of this Special Issue is advance towards a better understanding of the hydrological cycle, including its observed changes and projections under future climate.

The range of topics will mainly cover the following subtopics:

i) Global Distribution of Water Vapor: Evaporation and precipitation, water vapor flux and divergence, long-range transport of water vapor, clouds;

ii) Source–Sink Relationships and Methodologies: Methods used to establish source-receptor relationships, analytical or box models, numerical water vapor tracers, physical water vapor tracers (isotopes);

iii) Global Source and Sink Regions of Moisture and Processes: Identifying large-scale oceanic sources, terrestrial sources, and sinks of moisture, investigating the mechanisms associated with source and sink regions;

iv) Extreme Events: Atmospheric Rivers, floods, evaporation Hot Spots, anomalies of moisture transport linked to Drought Periods;

v) Low-Level Jets, Warm Pools, Monsoons and their role in the transport of moisture;

vi) The identification and characteristics of moisture sources, megadroughts, and megapluvials within the scope of Paleoclimatic Studies;

vii) Implications of Climate Change Impact on Hydrology: changes in water vapor, changes in large-scale circulation related to moisture transport, changes in precipitation, aridity, evapotranpiration, soil moisture, streamflow, cloud distribution, and other usable water sources (snow, lake levels, reservoirs, glaciers, etc.);

viii) Impacts of Climate Change in Soil Hydrological Processes, with special focus on forest hydrology, including experimental plots and catchments;

ix) Eco-hydrological Modelling at different spatial scales;

x) Water Resources Management and Impacts of Climate Change, including adaptation strategies, with special focus in the Mediterranean region.

Prof. Raquel Nieto
Prof. Luis Gimeno
Prof. Jose A. Marengo
Prof. Diego G. Miralles
Dr. Sergio M. Vicente Serrano
Prof. Ana María Durán Quesada
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Hydrological Cycle
  • Extreme Events
  • Climate Change
  • Water Resources
  • Hydrological Modelling

Published Papers (12 papers)

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Research

Open AccessArticle An Accelerated Tool for Flood Modelling Based on Iber
Water 2018, 10(10), 1459; https://doi.org/10.3390/w10101459
Received: 27 September 2018 / Revised: 11 October 2018 / Accepted: 14 October 2018 / Published: 16 October 2018
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Abstract
This paper presents Iber+, a new parallel code based on the numerical model Iber for two-dimensional (2D) flood inundation modelling. The new implementation, which is coded in C++ and takes advantage of the parallelization functionalities both on CPUs (central processing units) and GPUs
[...] Read more.
This paper presents Iber+, a new parallel code based on the numerical model Iber for two-dimensional (2D) flood inundation modelling. The new implementation, which is coded in C++ and takes advantage of the parallelization functionalities both on CPUs (central processing units) and GPUs (graphics processing units), was validated using different benchmark cases and compared, in terms of numerical output and computational efficiency, with other well-known hydraulic software packages. Depending on the complexity of the specific test case, the new parallel implementation can achieve speedups up to two orders of magnitude when compared with the standard version. The speedup is especially remarkable for the GPU parallelization that uses Nvidia CUDA (compute unified device architecture). The efficiency is as good as the one provided by some of the most popular hydraulic models. We also present the application of Iber+ to model an extreme flash flood that took place in the Spanish Pyrenees in October 2012. The new implementation was used to simulate 24 h of real time in roughly eight minutes of computing time, while the standard version needed more than 15 h. This huge improvement in computational efficiency opens up the possibility of using the code for real-time forecasting of flood events in early-warning systems, in order to help decision making under hazardous events that need a fast intervention to deploy countermeasures. Full article
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Open AccessArticle Using Water Temperature, Electrical Conductivity, and pH to Characterize Surface–Groundwater Relations in a Shallow Ponds System (Doñana National Park, SW Spain)
Water 2018, 10(10), 1406; https://doi.org/10.3390/w10101406
Received: 7 September 2018 / Revised: 26 September 2018 / Accepted: 2 October 2018 / Published: 10 October 2018
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Abstract
The physical limnology of a shallow pond system was characterized using field measurements of water temperature, pH, and electrical conductivity (EC). We determined the spatial variability in surface and groundwater temperature, pH, and EC along the pond’s shore and along the several pond-shore
[...] Read more.
The physical limnology of a shallow pond system was characterized using field measurements of water temperature, pH, and electrical conductivity (EC). We determined the spatial variability in surface and groundwater temperature, pH, and EC along the pond’s shore and along the several pond-shore transects, analyzed the water column temperature gradient and estimated the groundwater discharge rate using a heat transfer model. The fieldwork was conducted in Santa Olalla and Dulce ponds located in Doñana National Park in southwestern Spain during different stages from 2016 to 2018. The results of this study have improved the understanding of the thermal structure and the surface–subsurface heat exchange in the ponds and highlighted the importance of groundwater discharge in the pond water balance. It also showed the heterogeneous nature of groundwater discharge through the bottom sediments of the Santa Olalla pond. These results are consistent with previous studies and strengthen the existing hydrological and limnological knowledge of these ponds located in the protected area which is receiving a great deal of public attention. Full article
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Open AccessArticle A Hydroclimatological Analysis of Precipitation in the Ganges–Brahmaputra–Meghna River Basin
Water 2018, 10(10), 1359; https://doi.org/10.3390/w10101359
Received: 16 July 2018 / Revised: 21 September 2018 / Accepted: 26 September 2018 / Published: 29 September 2018
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Abstract
Understanding seasonal precipitation input into river basins is important for linking large-scale climate drivers with societal water resources and the occurrence of hydrologic hazards such as floods and riverbank erosion. Using satellite data at 0.25-degree resolution, spatial patterns of monsoon (June-July-August-September) precipitation variability
[...] Read more.
Understanding seasonal precipitation input into river basins is important for linking large-scale climate drivers with societal water resources and the occurrence of hydrologic hazards such as floods and riverbank erosion. Using satellite data at 0.25-degree resolution, spatial patterns of monsoon (June-July-August-September) precipitation variability between 1983 and 2015 within the Ganges–Brahmaputra–Meghna (GBM) river basin are analyzed with Principal Component (PC) analysis and the first three modes (PC1, PC2 and PC3) are related to global atmospheric-oceanic fields. PC1 explains 88.7% of the variance in monsoonal precipitation and resembles climatology with the center of action over Bangladesh. The eigenvector coefficients show a downward trend consistent with studies reporting a recent decline in monsoon rainfall, but little interannual variability. PC2 explains 2.9% of the variance and shows rainfall maxima to the far western and eastern portions of the basin. PC2 has an apparent decadal cycle and surface and upper-air atmospheric height fields suggest the pattern could be forced by tropical South Atlantic heating and a Rossby wave train stemming from the North Atlantic, consistent with previous studies. Finally, PC3 explains 1.5% of the variance and has high spatial variability. The distribution of precipitation is somewhat zonal, with highest values at the southern border and at the Himalayan ridge. There is strong interannual variability associated with PC3, related to the El Nino/Southern Oscillation (ENSO). Next, we perform a hydroclimatological downscaling, as precipitation attributed to the three PCs was averaged over the Pfafstetter level-04 sub-basins obtained from the World Wildlife Fund (Gland, Switzerland). While PC1 was the principal contributor of rainfall for all sub-basins, PC2 contributed the most to rainfall in the western Ganges sub-basin (4524) and PC3 contributed the most to the rainfall in the northern Brahmaputra (4529). Monsoon rainfall within these two sub-basins were the only ones to show a significant relationship (negative) with ENSO, whereas four of the eight sub-basins had a significant relationship (positive) with sea surface temperature (SST) anomalies in the tropical South Atlantic. This work demonstrates a geographic dependence on climate teleconnections in the GBM that deserves further study. Full article
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Open AccessFeature PaperArticle Contribution of Moisture from Mediterranean Sea to Extreme Precipitation Events over Danube River Basin
Water 2018, 10(9), 1182; https://doi.org/10.3390/w10091182
Received: 3 August 2018 / Revised: 24 August 2018 / Accepted: 1 September 2018 / Published: 4 September 2018
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Abstract
In the most recent decades, central Europe and the Danube River Basin area have been affected by an increase in the frequency and intensity of extreme daily rainfall, which has resulted in the more frequent occurrence of significant flood events. This study characterised
[...] Read more.
In the most recent decades, central Europe and the Danube River Basin area have been affected by an increase in the frequency and intensity of extreme daily rainfall, which has resulted in the more frequent occurrence of significant flood events. This study characterised the link between moisture from the Mediterranean Sea and extreme precipitation events, with varying lengths that were recorded over the Danube River basin between 1981 and 2015, and ranked the events with respect to the different time scales. The contribution of the Mediterranean Sea to the detected extreme precipitation events was then estimated using the Lagrangian FLEXPART dispersion model. Experiments were modelled in its forward mode, and particles leaving the Mediterranean Sea were tracked for a period of time determined with respect to the length of the extreme event. The top 100 extreme events in the ranking with durations of 1, 3, 5, 7, and 10 days were analysed, and it was revealed that most of these events occurred in the winter. For extreme precipitation, positive anomalies of moisture support from the Mediterranean were found to be in the order of 80% or more, but this support reached 100% in summer and spring. The results show that extreme precipitation events with longer durations are more influenced by the extreme Mediterranean anomalous moisture supply than those with shorter lengths. However, it is during shorter events when the Mediterranean Sea contributes higher amounts of moisture compared with its climatological mean values; for longer events, this contribution decreases progressively (but still doubles the climatological moisture contribution from the Mediterranean Sea). Finally, this analysis provides evidence that the optimum time period for accumulated moisture to be modelled by the Lagrangian model is that for which the extreme event is estimated. In future studies, this fine characterisation could assist in modelling moisture contributions from sources in relation to individual extreme events. Full article
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Open AccessArticle New Insights on Land Surface-Atmosphere Feedbacks over Tropical South America at Interannual Timescales
Water 2018, 10(8), 1095; https://doi.org/10.3390/w10081095
Received: 29 May 2018 / Revised: 13 August 2018 / Accepted: 13 August 2018 / Published: 17 August 2018
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Abstract
We present a simplified overview of land-atmosphere feedbacks at interannual timescales over tropical South America as structural sets of linkages among surface air temperature (T), specific humidity at 925 hPa (q925), volumetric soil water content (Θ), precipitation (P), and evaporation (E),
[...] Read more.
We present a simplified overview of land-atmosphere feedbacks at interannual timescales over tropical South America as structural sets of linkages among surface air temperature (T), specific humidity at 925 hPa (q925), volumetric soil water content (Θ), precipitation (P), and evaporation (E), at monthly scale during 1979–2010. Applying a Maximum Covariance Analysis (MCA), we identify the modes of greatest interannual covariability in the datasets. Time series extracted from the MCAs were used to quantify linear and non-linear metrics at up to six-month lags to establish connections among variables. All sets of metrics were summarized as graphs (Graph Theory) grouped according to their highest ENSO-degree association. The core of ENSO-activated interactions is located in the Amazon River basin and in the Magdalena-Cauca River basin in Colombia. Within the identified multivariate structure, Θ enhances the interannual connectivity since it often exhibits two-way feedbacks with the whole set of variables. That is, Θ is a key variable in defining the spatiotemporal patterns of P and E at interannual time-scales. For both the simultaneous and lagged analysis, T activates non-linear associations with q925 and Θ. Under the ENSO influence, T is a key variable to diagnose the dynamics of interannual feedbacks of the lower troposphere and soil interfaces over tropical South America. ENSO increases the interannual connectivity and memory of the feedback mechanisms. Full article
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Open AccessArticle Adaptation Strategies of the Hydrosocial Cycles in the Mediterranean Region
Water 2018, 10(6), 790; https://doi.org/10.3390/w10060790
Received: 7 May 2018 / Revised: 6 June 2018 / Accepted: 13 June 2018 / Published: 15 June 2018
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Abstract
The Spanish Mediterranean region has been affected by several factors over the years (climatic conditions of aridity, high water demands, rapid and intense urban and population growth, climate change), that have generated a negative water balance whereby water resources are unable to meet
[...] Read more.
The Spanish Mediterranean region has been affected by several factors over the years (climatic conditions of aridity, high water demands, rapid and intense urban and population growth, climate change), that have generated a negative water balance whereby water resources are unable to meet the demand. Diversifying supply sources by resorting to new resources has been a necessity that has stimulated the expansion and integration of non-conventional water sources (desalination and reuse of reclaimed water) and sustainable solutions. The aim of this paper is to evaluate the adaptation strategies that have been developed in Alicante, Benidorm and Torrevieja in order to adjust their hydrosocial cycles to development and future scenarios. The theoretical analysis developed in this paper is corroborated by the study of the hydrosocial cycle evolution of three cities in the southeast of Spain, and the adaptive measures that the different stakeholders involved in the cycle have developed in each of them. The input and output of the systems are accounted for with information provided by the management companies in each of the phases (urban consumption; treated, reused and desalinated volumes), which highlight how the diversification of resources and the incorporation of non-conventional resources have been essential for adaptation. Full article
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Open AccessArticle The Atmospheric Branch of the Hydrological Cycle over the Negro and Madeira River Basins in the Amazon Region
Water 2018, 10(6), 738; https://doi.org/10.3390/w10060738
Received: 6 May 2018 / Revised: 1 June 2018 / Accepted: 2 June 2018 / Published: 5 June 2018
Cited by 1 | PDF Full-text (8388 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The Amazon region, in South America, contains the largest rainforest and biodiversity in the world, and plays an important role in the regional and global hydrological cycle. In the present study, we identified the main sources of moisture of two subbasins of the
[...] Read more.
The Amazon region, in South America, contains the largest rainforest and biodiversity in the world, and plays an important role in the regional and global hydrological cycle. In the present study, we identified the main sources of moisture of two subbasins of the Amazon River Basin, the Negro and Madeira River Basins respectively. The source-sink relationships of atmospheric moisture are investigated. The analysis is performed for the period from 1980–2016. The results confirm two main oceanic moisture sources for both basins, i.e., oceanic regions in the Tropical North and South Atlantic oceans. On the continents are, the Negro River Basin itself, and nearby regions to the northeast. For the Madeira River Basin, the most important continental sources are itself, and surrounding regions of the South American continent. Forward-trajectory analysis of air masses over the source regions is used to compute the moisture contribution to precipitation over basins. Oceanic (continental) sources play the most important role in the Negro River Basin (Madeira River Basin). The moisture contribution from the Tropical North Atlantic region modulates the onset and demise of the rainy season in the Negro River Basin; while the moisture contribution from the rest of the Amazon River Basin, the Madeira Basin itself, and Tropical South America leads to the onset of the rainy season in the Madeira River Basin. These regions also played the most important role in decreasing the moisture supply during most severe dry episodes in both basins. During ‘’El Niño’’, generally occurs a reduction (increase) of the moisture contribution to the Negro River Basin (Madeira River Basin; mainly from April to August) from almost all the sources, causing a decrease in the precipitation. Generally, the contrary occurs during ‘’La Niña’’. Full article
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Open AccessFeature PaperArticle The Mediterranean Moisture Contribution to Climatological and Extreme Monthly Continental Precipitation
Water 2018, 10(4), 519; https://doi.org/10.3390/w10040519
Received: 2 March 2018 / Revised: 4 April 2018 / Accepted: 19 April 2018 / Published: 21 April 2018
Cited by 1 | PDF Full-text (4557 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Moisture transport from its sources to surrounding continents is one of the most relevant topics in hydrology, and its role in extreme events is crucial for understanding several processes such as intense precipitation and flooding. In this study, we considered the Mediterranean Sea
[...] Read more.
Moisture transport from its sources to surrounding continents is one of the most relevant topics in hydrology, and its role in extreme events is crucial for understanding several processes such as intense precipitation and flooding. In this study, we considered the Mediterranean Sea as the main water source and estimated its contribution to the monthly climatological and extreme precipitation events over the surrounding continental areas. To assess the effect of the Mediterranean Sea on precipitation, we used the Multi-Source Weighted-Ensemble Precipitation (MSWEP) database to characterize precipitation. The Lagrangian dispersion model known as FLEXPART was used to estimate the moisture contribution of this source. This contribution was estimated by tracking particles that leave the Mediterranean basin monthly and then calculating water loss (E − P < 0) over the continental region, which was modelled by FLEXPART. The analysis was conducted using data from 1980 to 2015 with a spatial resolution of 0.25°. The results showed that, in general, the spatial pattern of the Mediterranean source’s contribution to precipitation, unlike climatology, is similar during extreme precipitation years in the regions under study. However, while the Mediterranean Sea is usually not an important source of climatological precipitation for some European regions, it is a significant source during extreme precipitation years. Full article
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Open AccessFeature PaperArticle Anomalies in Moisture Supply during the 2003 Drought Event in Europe: A Lagrangian Analysis
Water 2018, 10(4), 467; https://doi.org/10.3390/w10040467
Received: 2 March 2018 / Revised: 5 April 2018 / Accepted: 10 April 2018 / Published: 12 April 2018
Cited by 3 | PDF Full-text (30292 KB) | HTML Full-text | XML Full-text
Abstract
In the last few decades, many studies have identified an increasing number of natural hazards associated with extreme precipitation and drought events in Europe. During the 20th century, the climate in Central Europe and the Mediterranean region was characterised by an overall temperature
[...] Read more.
In the last few decades, many studies have identified an increasing number of natural hazards associated with extreme precipitation and drought events in Europe. During the 20th century, the climate in Central Europe and the Mediterranean region was characterised by an overall temperature increase, and the beginning of the 21st century has been marked by severe and prolonged drought events. The aim of this study is to analyse variations in the moisture supply during the 2003 drought episode that affected large portions of Europe. In order to better characterise the evolution of the episodes across the continent, separate analyses were performed for two spatial domains: Central Europe and the Mediterranean region. These regions were defined according to the 5th Intergovernmental Panel on Climate Change Assessment Report. For both regions, this drought episode was most severe from 1980 to 2015, according to the one-month Standardised Precipitation Evapotranspiration Index (SPEI-1) analysis, which was conducted using monthly precipitation and potential evapotranspiration data from the Climate Research Unit. Analyses of precipitation, potential evapotranspiration, pressure velocity at 500 hPa, and vertically integrated moisture flux were conducted to characterise the anomalous patterns over the regions during the event. A Lagrangian approach was then applied in order to investigate possible continental-scale changes in the moisture supply over the Central European and Mediterranean regions during 2003. This approach is based on the FLEXible PARTicle (FLEXPART) dispersion model, integrated with data from the European Centre for Medium-Range Weather Forecasts (ECMWF): the ECMWF Re-Analysis ERA-Interim. The results indicate that anomalous subsidence, increased evapotranspiration, and reduced precipitation predominated over both regions during the episode. The most intense reduction in the moisture supply over Central Europe was registered for the Mediterranean Sea (MDS) and the Central European region, while for the Mediterranean region, most intense reduction in the moisture supply was observed in the MDS and—in minor-scale—Gibraltar regions. Full article
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Open AccessArticle Meteorological Driving Mechanisms and Human Impacts of the February 1979 Extreme Hydro-Geomorphological Event in Western Iberia
Water 2018, 10(4), 454; https://doi.org/10.3390/w10040454
Received: 12 March 2018 / Revised: 4 April 2018 / Accepted: 5 April 2018 / Published: 10 April 2018
Cited by 1 | PDF Full-text (31663 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The large number of floods and landslides that occurred on 5–16 February 1979 in Portugal was a major hydro-geomorphologic extreme event according to the DISASTER database in terms of number of displaced people. The February 1979 event is the top ranked episode in
[...] Read more.
The large number of floods and landslides that occurred on 5–16 February 1979 in Portugal was a major hydro-geomorphologic extreme event according to the DISASTER database in terms of number of displaced people. The February 1979 event is the top ranked episode in terms of the total number of evacuated people (4244), displaced people (14,322) and also on the number of days of event duration (12 days) for the period 1865–2015. In this event, 62 damaging floods and five damaging landslides causing eight fatalities were recorded in Portugal. This event was driven by an unusually intense atmospheric forcing mechanism acting at different time scales. Despite the intense magnitude and the widespread impact on the population, this event has not been studied in detail. In this study, we show that the precipitation period of February 1979 had produced several multi-day accumulated precipitation events over the Portuguese continental territory, ranking among the top 10 events observed between 1950–2008. Additionally, most of the precipitation from this event occured in days in which atmospheric circulation was dominated by “wet” circulation weather types (CWTs), namely, cyclonic (C), west (W) or southwest (SW) types. Full article
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Open AccessArticle Return Level Estimation of Extreme Rainfall over the Iberian Peninsula: Comparison of Methods
Water 2018, 10(2), 179; https://doi.org/10.3390/w10020179
Received: 30 November 2017 / Revised: 29 January 2018 / Accepted: 2 February 2018 / Published: 9 February 2018
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Abstract
Different ways to estimate future return levels (RLs) for extreme rainfall, based on extreme value theory (EVT), are described and applied to the Iberian Peninsula (IP). The study was done for an ensemble of high quality rainfall time series observed in the IP
[...] Read more.
Different ways to estimate future return levels (RLs) for extreme rainfall, based on extreme value theory (EVT), are described and applied to the Iberian Peninsula (IP). The study was done for an ensemble of high quality rainfall time series observed in the IP during the period 1961–2010. Two approaches, peaks-over-threshold (POT) and block maxima (BM) with the generalized extreme value (GEV) distribution, were compared in order to identify which is the more appropriate for the estimation of RLs. For the first approach, which identifies trends in the parameters of the asymptotic distributions of extremes, both all-days and rainy-days-only datasets were considered because a major fraction of values of daily rainfall over the IP is zero. For the second approach, rainy-days-only data were considered showing how the mean, variance and number of rainy days evolve. The 20-year RLs expected for 2020 were estimated using these methods for three seasons: autumn, spring and winter. The GEV is less reliable than the POT because fixed blocks lead to the selection of non-extreme values. Future RLs obtained with the POT are greater than those estimated with the GEV, mainly because some gauges show significant positive trends for the number of rainy days. Autumn, rather than winter, is currently the season with the heaviest rainfall for some regions. Full article
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Open AccessArticle Land Use Change over the Amazon Forest and Its Impact on the Local Climate
Water 2018, 10(2), 149; https://doi.org/10.3390/w10020149
Received: 7 November 2017 / Revised: 19 January 2018 / Accepted: 22 January 2018 / Published: 3 February 2018
Cited by 3 | PDF Full-text (1998 KB) | HTML Full-text | XML Full-text
Abstract
One of the most important anthropogenic influences on climate is land use change (LUC). In particular, the Amazon (AMZ) basin is a highly vulnerable area to climate change due to substantial modifications of the hydroclimatology of the region expected as a result of
[...] Read more.
One of the most important anthropogenic influences on climate is land use change (LUC). In particular, the Amazon (AMZ) basin is a highly vulnerable area to climate change due to substantial modifications of the hydroclimatology of the region expected as a result of LUC. However, both the magnitude of these changes and the physical process underlying this scenario are still uncertain. This work aims to analyze the simulated Amazon deforestation and its impacts on local mean climate. We used the Common Land Model (CLM) version 4.5 coupled with the Regional Climate Model (RegCM4) over the Coordinated Regional Climate Downscaling Experiment (CORDEX) South America domain. We performed one simulation with the RegCM4 default land cover map (CTRL) and one simulation under a scenario of deforestation (LUC), i.e., replacing broadleaf evergreen trees with C3 grass over the Amazon basin. Both simulations were driven by ERA Interim reanalysis from 1979 to 2009. The climate change signal due to AMZ deforestation was evaluated by comparing the climatology of CTRL with LUC. Concerning the temperature, the deforested areas are about 2 °C warmer compared to the CTRL experiment, which contributes to decrease the surface pressure. Higher air temperature is associated with a decrease of the latent heat flux and an increase of the sensible heat flux over the deforested areas. AMZ deforestation induces a dipole pattern response in the precipitation over the region: a reduction over the west (about 7.9%) and an increase over the east (about 8.3%). Analyzing the water balance in the atmospheric column over the AMZ basin, the results show that under the deforestation scenario the land surface processes play an important role and drive the precipitation in the western AMZ; on the other hand, on the east side, the large scale circulation drives the precipitation change signal. Dipole patterns over scenarios of deforestation in the Amazon was also found by other authors, but the precipitation decrease on the west side was never fully explained. Using budget equations, this work highlights the physical processes that control the climate in the Amazon basin under a deforestation scenario. Full article
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