Water, Volume 14, Issue 16 (August-2 2022) – 139 articles

Eutrophication caused by excessive total nitrogen (TN) and total phosphorus (TP) emissions is of wide concern for society at large. Studies have revealed certain relationships among land use, TN, and TP. However, the relationships among land use compound topographic position, TP, and TN have seldom been studied. Therefore, the objectives of this paper are to construct optimal zoning of land use and reduce the nutrient load of lakes. Spearman correlation and redundancy analyses were used to reveal the relationship between land use comprehensive topographic position and TN and TP in the lakes of Guizhou Plateau. The results show that the nutritional state of the research area is medium. The trophic level index (TLI) value and TN concentration were high during flood periods, while TP concentration was high in dry periods. The TN concentration in the tributaries was higher than that in the reservoir area. Construction land and valley were the sources of the pollution, whereas forest land and gentle slope were the sink. According to the ”source–sink” effect, once the optimal zoning of land use is completed, the governance of urban land pollution governed areas should be strengthened next. This paper can provide decision support for water environment management and sustainable development decision-making. Full article

Monitoring water quality is critical for mitigating risks to human health and the environment. It is also essential for ensuring high quality water-based and water-dependent products and services. The monitoring and detection of chemical contamination are often based around a small set of parameters or substances. Conventional monitoring often involves the collection of water samples in the field and subsequent analyses in the laboratory. Such strategies are expensive, time consuming, and focused on a narrow set of potential risks. They also induce a significant time delay between a contamination event and a possible reactive measure. Here, we developed a real-time monitoring system based on Artificial Intelligence (AI) for field deployable sensors. We used data obtained from full-scan UV-spec and fluorescence sensors for validation in this study. This multi-sensor system consists of (a) anomaly detection that uses multivariate statistical methods to detect any anomalous state in an aqueous environment and (b) anomaly identification, using Machine Learning (ML) to classify the anomaly into one of the a priori known categories. For a proof of concept, we tested this methodology on a supply of municipal drinking water and a few representative organic chemical contaminants applied in a laboratory-controlled environment. The outcomes confirm the ability for the multi-sensor system to detect and identify changes in water quality due to incidences of chemical contamination. The method may be applied to numerous other areas where water quality should be measured online and in real time, such as in surface-water, urban runoff, or food and industrial process water. Full article

The lack of sidewalls in a spillway leads to lateral expansion of the flow and, consequently, a non-uniform transversal flow rate distribution along the chute. The present work shows the velocity field measured in a physical model of a 1 V:0.8 H steeply sloping stepped spillway without sidewalls. An application of a Bubble Image Velocimetry (BIV) technique in the self-aerated region is shown, using air bubbles entrained into the flow downstream of the inception point as tracers. The results indicate that, for small dimensionless discharges and sufficiently downstream of the point of inception, the free-surface velocity compares relatively well with the corresponding air–water interfacial velocity previously obtained with a double-tip fiber optical probe in the same facility. In turn, the velocity profiles along the normal to the pseudo-bottom, far downstream of the inception point, are reasonably in agreement with the air–water interfacial velocity profiles in the inner part of the skimming flow, with the largest differences being verified in the upper skimming flow region near the free-surface. Full article

Producers of drinking water (DW) occasionally require chemical identification of new or unexpected contamination, e.g., caused by an incident. The state-of-the-art technique for the identification of organic compounds is High-Resolution Mass Spectrometry (HRMS). The ability to discover unexpected compounds at low concentrations in any sample by HRMS is facilitated by comparison to non-contaminated reference samples. Samples of raw and drinking water were collected regularly over one whole year from six Swedish drinking water treatment plants (DWTPs). The samples were analyzed by LC-HRMS together with spiked samples mimicking an incident. This setup enabled evaluation of the significance of having access to a collection of matrix-matched reference samples. The main variation in the organic compound profile in the data set was explained by the uniqueness of the raw water and purification steps in the individual DWTPs. Seasonal variations were also significant but subordinate. This subject was further explored by the analysis of drinking water sampled once from 90 of the 1750 Swedish DWTPs, where a similarity between DW originating from rock aquifers was observed. No other significant correlation between samples was observed—e.g., other types of raw water, which types of purification steps were involved, or which additives or process chemicals were added—which could aid in the selection of relevant reference samples. The conclusion from the study is that it would be imperative for the DWTPs to have access to their individual reference samples for use in the investigation of an incident. A library of such reference samples, e.g., collected monthly and covering the last 12 months, could be stored and used together with a fresh “suspected sample” for non-target HRMS investigations as described. Full article

Investigating subtidal friction and mass transport is pivotal for examining subtidal dynamics in tidal rivers. Although the behavior of subtidal friction and transport has been discussed in recent years, most studies have been conducted on tidal rivers that are affected by high amounts of river runoff. The aim of this study is to offer an initial understanding of the spatial and temporal behaviors of subtidal friction and subtidal flux in a tidal river channel with limited river runoff. This study utilized the frequency domain and theoretical decomposition analyses to determine the dominant tidal and subtidal mechanisms. Frequency domain analysis indicated the dominance of semidiurnal and diurnal tides in the observed tidal river channel. The rate of energy transfer owing to shallow water interaction was found to be stronger for the current velocity than for the water elevation. Decomposition analysis showed that subtidal friction and flux in a low-discharge tidal river channel were largely influenced by subtidal flow-induced subtidal friction and Eulerian return flux, respectively. The key findings of this study are as follows: (i) the limited amount of river runoff (4–20 m³/s) leads to the vertical variability of subtidal friction contributions from subtidal flow and subtidal-tidal interaction, as well as Eulerian return flux, and (ii) the vertical variability of the aforementioned terms can be associated with the existence of influential longitudinal subtidal density gradients along the tidal river. We believe that these findings advance our understanding of subtidal dynamics in tidal river systems, particularly those with limited discharge. Full article

Human activities have altered global nutrient cycling and have significantly changed marine systems. This is evidenced by the significant changes in nitrogen and phosphorus availability. The Maowei Sea (MWS) is the largest oyster culture bay in southwest China. From August 2018 to May 2019, the spatial and temporal nutrient concentrations and fluxes in MWS using system-wide scale seasonal data were assessed from river estuaries and adjacent coastal waters. The annual average concentrations of total nitrogen (TN) and total phosphorus (TP) in the three estuaries of Maolingjiang River (MLJR), Dalanjiang River (DLJR) and Qinjiang River (QJR) were 3.00 mg/L and 0.183 mg/L, respectively. Therein, the highest TN and TP concentrations were in DLJR, the lowest TN concentration was in MLJR, and the lowest TP concentration was in QJR. DIN and DIP were the main forms of TN and TP, accounting for 80.9% and 59.4%, respectively. The main form of DIN in MLJR and QJR was NO₃⁻, accounting for 86.8% and 84.4%, respectively, while the main form of DIN in DLJR was NH₄⁺, accounting for 55.9%. The annual flux of pollutants discharged into MWS from the three estuaries is 10,409.52 t for TN and 556.21 t for TP. The month with the largest contribution to the annual load was July, accounting for 29.2% and 24.2% of TN and TP, respectively, and the fluxes of TN and TP were significantly different among the three seasons (p < 0.05). The annual average concentrations in the surface waters of the MWS were 1.07 mg/L for TN and 0.129 mg/L for TP, and there were significant differences (p < 0.05) in the concentrations of TN and TP among the three seasons. The annual average N/P ratios of the river water and seawater were 43 and 18, respectively, which were higher than the Redfield ratio (N/P = 16), indicating that the growth of phytoplankton in MWS may be limited by phosphorus. Eutrophication owing to nutrient pollution in the three estuaries may be persistent in adjacent coastal waters, and land–ocean integrated mitigation measures should be taken to effectively improve the water quality in the river estuary and coastal water. Full article

A comprehensive compilation of long-term data records about the dynamics of nutrient migration and availability in the Kinneret epilimnion was statistically evaluated. A replacement of Peridinium spp. domination by cyanobacteria in Lake Kinneret (Israel) was documented. Nitrogen outsourcing is a significant factor within the Kinneret ecosystem structure. Part of the Kinneret watershed, the Hula Valley, which was covered by a shallow lake and swampy wetlands was drained. The result was the conversion of the nitrogen supply, as ammonium and organic forms, into nitrate. Nevertheless, nutrients supplied from aquaculture (fish ponds) and raw sewage partly compensated for the ammonium deficiency. After sewage removal and fish pond restrictions (the early 1990s), the majority of nitrogen migration became nitrate, dependent on climate conditions (rainfall, river discharges). The preference for ammonium by the bloom-forming Peridinium spp. caused a reduction in the efficiency of nitrogen utilization and cyanobacteria replaced phytoplankton for domination. Full article

The Gully Land Consolidation (GLC) project, aiming to create land for agriculture on the Loess Plateau, heavily interfered with the underlying surface and thus affected the hydrological process. The purpose of this study was to investigate the effects of the GLC on the surface runoff and peak flow rates of watershed on the Loess Plateau under different rainfall events and hydrological years. A GIS-based Soil Conservation Service Curve Number (SCS-CN) model was used. The results showed that GLC reduced the mean event surface runoff by 6.2–24.7%, and the reducing efficiency was the highest under light rain events. GLC also decreased annual surface runoff, and the reducing efficiency was 12.04% (normal year) > 7.63% (wet year) > 4.45% (dry year). In addition, GLC decreased the peak flow rate of the watershed by 8.1–30.2% and prolonged the time to peak flow rate. The efficiency of GLC in reducing the peak flow rate was higher under light rain events than that under extraordinary storm events. The reason for the decrease in runoff and peak flow rate after GLC was that the GLC decreased the slope gradient and hydrological connectivity of the watershed. The results will provide guidance for the application of GLC on the Loess Plateau and watershed management for similar regions. Full article

Microplastic particles are of concern to aquatic environments because their size enables them to be easily ingested by animals and they may become vectors of potentially harmful chemicals. This study focused on understanding the impact of plastic size and plastic types on adsorption and adsorption kinetics of commonly found contaminants of emerging concern (CECs). We exposed macro- and micro-sized polyethylene (PE), polystyrene (PS), and polyvinyl chloride (PVC) to six CECs: diclofenac (DCF), atenolol (ATN), ibuprofen (IBU), 4-acetamidophenol (ACE), bisphenol A (BPA), and 2-mercaptobenzothiazole (MBT). Our results showed that the pseudo-first order model described the adsorption kinetics better than the pseudo-second order model. The rate of adsorption ACE onto macro-PS was the fastest rate of adsorption for all CECs and microplastics evaluated. Generally, the mass fraction of CECs sorbed at equilibrium did not depend on the size of the plastic and chemical hydrophobicity. With a relatively low K_ow among the CECs studied here, ACE had the most mass fraction sorbed onto all the plastics in this study. DCF was also consistently sorbed onto all the plastics. The mechanism van der Waals interaction may have dominated in all the adsorptions in this study, but π-π interaction could also be a major mechanism in the adsorption of DCF, IBP, and ACE. Fast adsorption of ATN, IBP, and ACE may occur during wastewater treatment, but slow adsorption may still continue in the wastewater effluent. Our study highlights an ecotoxicological concern for plastics being a vector of commonly found CECs that are not highly hydrophobic. Full article

Inorganic nitrogen (N) is an important element for eutrophication and harmful algal bloom (HAB) formation. However, the roles of inorganic N in HAB outbreaks are still unclear. Here, we compared the affinities and abilities for inorganic N uptake and assimilation among three typical bloom-forming algae in the East China Sea (ECS), Skeletonema costatum, Prorocentrum donghaiense and Alexandrium pacificum by investigating the uptake and enzymatic (nitrate reductase (NR) and glutamine synthetase (GS) kinetics for nitrate and ammonia. The K_s of nitrate and ammonium in S. costatum was lower than those in P. donghaiense and A. pacificum. The NR activity of S. costatum and P. donghaiense exhibited a positive relationship with the nitrate concentration, and NR activity of S. costatum was nearly 4-fold higher than that of P. donghaiense at high nitrate concentration. However, the NR activity of A. pacificum could not be detected. The GS activity of three species decreased with the increase of ammonium concentrations, and the highest GS activity was detected in A. pacificum. S. costatum presented the highest affinity for nitrate and ammonium, followed by P. donghaiense and A. pacificum. Moreover, P. donghaiense exhibited the highest affinity for intracellular ammonium. Our results characterized the differences in inorganic nitrogen uptake among the three typical bloom-forming algae, which may contribute to the formation of blooms in the coastal waters of the ECS. Full article

In the Venetian lagoon, the storm surge barriers (Mo.S.E. system) are crucial to prevent urban flooding during extreme stormy events. The inlet closures have some cascading effects on the hydrodynamics and sediment transports of this shallow tidal environment. The present study aims at investigating the effects of the Mo.S.E. closure on the wind-wave propagation inside the lagoon. In situ wave data were collected to establish a unique dataset of measurements recorded in front of San Marco square between July 2020 and December 2021, i.e., partially during the COVID-19 pandemic. Ten storm events were analyzed in terms of significant wave heights and simultaneous wind characteristics. This dataset allowed for validating a spectral wave model (SWAN) applied to the whole lagoon. The results show that the floodgate closures, which induce an artificial reduction of water levels, influence significant wave heights H_S, which decrease on average by 22% compared to non-regulated conditions, but in the shallower areas (for example tidal flats and salt marshes), the predicted decrease is on average 48%. Consequently, the analysis suggests that the Mo.S.E. closures are expected to induce modifications in the wave overtopping, wave loads and lagoon morphodynamics. Full article

Water is one of the most important natural resources and is widely used around the globe for various purposes. In fact, the agricultural sector consumes 70% of the world’s accessible water, of which about 60% is wasted. Thus, it needs to be managed scientifically and efficiently to maximize food production to meet the requirements of an ever-increasing population. There is a lack of information on water requirements of crops and irrigation scheduling concerning the Shaheed Benazirabad district, Pakistan. Thus, the present study was conducted to determine the irrigation water requirements (IWR) and irrigation scheduling for the major crops in the Shaheed Benazirabad district, Sindh, Pakistan, using agro-climatic data and the CROPWAT model. Agro-climatic data such as rainfall, maximum and minimum temperature, sunshine hours, humidity, and wind speed were obtained from the NASA website, CLIMWAT 2.0, and world weather However, data about studied crops and soils were obtained from FAO (Food and Agriculture Organization). Analysis revealed that the IWRs per irrigation round for the four major crops—sugarcane, banana, cotton, and wheat—were as 3108.0 mm, 1768.5 mm, 1655.7 mm, and 402.5 mm, respectively. It was observed the IWRs are more sensitive in the hot season because of high temperatures and low relative humidity, and vice versa in the cold season. The use of scientific tools such as CROPWAT is recommended to assess IWRs with a high degree of accuracy and to compute irrigation scheduling. Accordingly, the study results will be helpful for improving food production and supervision of water resources. Full article

The management and monitoring of the quality of water resources in the Mekelle area are challenging, due to both geogenic and anthropogenic impacts. The extent of these impacts and the sources of pollution in this area have not been thoroughly investigated. In this article, a mapping of water resources vulnerability was carried out using the DRASTIC method and a modified DRASTIC vulnerability map was produced. Single-parameter and map-removal sensitivity analyses were performed on the relevant rates and weights. A final DRASTIC vulnerability index, varying from 54 to 140, was divided into four vulnerability classes: low (225.7 km²), medium (302.8 km²), high (307.2 km²), and very high (187.6 km²); the values in the parentheses indicate the corresponding areal coverage of each class. Similarly, a modified DRASTIC vulnerability index, ranging from 91 to 192, was divided into four vulnerability classes: low (166.4 km²), medium (266.8 km²), high (338.0 km²), and very high (252.2 km²) Nitrates were used to validate both models. in which moderate positive correlations (with Pearson’s correlation coefficient, r) of 0.681 and 0.702 were calculated for the DRASTIC and modified DRASTIC indices, respectively. A comparison of the two maps showed that significant sources of pollution are located in areas with high to very high vulnerability. The results of this research work can be used for the protection and monitoring of groundwater resources in the Mekelle area. Full article

Membrane fouling has attracted a lot of attention in the membrane separation field. Herein, we selected the homogeneous-reinforced polyvinylidene fluoride (HMR-PVDF) and heterogeneous-reinforced polyvinylidene fluoride (HTR-PVDF) hollow fiber membranes to investigate the fouling mechanism of membranes in membrane bioreactor (MBR) systems. The filtration models, membrane adsorption experiment, and membrane resistance distribution after a long or short time operation were assessed to compare their antifouling properties in order to verify the optimal membrane. The outer surface, shown by an SEM observation of the HMR-PVDF and HTR-PVDF membranes, was rough and smooth, respectively. Moreover, the HMR-PVDF membranes had a higher adsorption capacity than the HTR-PVDF membranes when an equilibrium state was almost 2.81 times that of the original membrane resistance. A cleaning method (mainly physical and chemical) was utilized to illustrate the operational stability of the membranes. In summary, the HMR-PVDF hollow fiber membrane presented better antifouling properties than the HTR-PVDF membranes, which was conducive to industrial implementation. Full article

Cutting fluids (CFs) are chemical liquids or aqueous emulsions of mineral (or synthetic) oil widely used in metal-machining processes. They contain toxic organic compounds and petroleum products, and spent CFs contain numerous small metal particles derived from the processing of metal workpieces. The iron fine particles (IFPs) in CFs can diminish the quality and precision of machine products. Machining industries purchase large amounts of CFs, which they must treat appropriately and from which they must remove the IFPs; therefore, cost-effective ways to treat spent CFs are needed. In this study, we evaluated the effectiveness of collecting and separating the IFPs and treating organic matter in spent CFs using microbubbles (MiBs). We found that numerous IFPs with sizes of ~1 μm were suspended in spent CFs and that they could be very effectively removed by bubbling with MiBs and skimming the surface of the CFs. The lifetime of the CFs could be doubled via this treatment. The cost for treating spent CFs using MiBs was 12% lower than the cost of traditional treatment. These results strongly suggest that bubbling with MiBs is a cost-effective and eco-friendly way to treat spent CFs. Full article

Shallow groundwater is often exposed to multiple sources of pollution that can make it unsuitable for certain uses. Complete hydrogeochemical studies are necessary for the better management of these resources. Well water samples were collected on the extent of Karfiguéla paddy field for physico-chemical parameters, such as pH, EC, TDS, Na⁺, Ca²⁺, Mg²⁺, K⁺, NH4⁺, NO₃⁻, NO₂⁻, SO₄²⁻, CO₃²⁻, Cl⁻, and HCO₃⁻, and metallic trace elements analyses as a case study. Due to the alluvial nature of aquifer deposits and the short residence time of groundwater, physical parameters and ion concentrations are low and within the recommended guideline values for irrigation water of the Food and Agriculture Organization (FAO) of the United Nations. However, Cd presents concentrations above 10 µg/L, the limit recommended by the FAO, while NO₃⁻ presents a slight to moderate risk. Piper and Stiff diagrams showed two types of water, Ca·Mg·HCO₃ and Ca·Mg·SO₄·Cl. Saturation indices revealed the under mineralization of natural minerals. Gibbs and bivariate diagrams, correlations and factorial analyses indicated that groundwater mineralization is mainly controlled by anthropogenic agricultural activities (60.05%), calcite and magnesite alteration (15.01%) and CO₂ dissolution process (9.05%). Irrigation water suitability parameters, such as sodium adsorption ratio (SAR), sodium percentage (%Na), potential salinity (PS), the Kelly ratio (KR), residual sodium carbonate (RSC) and irrigation coefficient (Ka), confirmed that the shallow groundwater is 100% good for irrigation, while NO₃⁻ and permeability index (PI) indicated that it is permissible. However, according to magnesium hazard (MH), the groundwater is 100% unsuitable for irrigation and could lead to soil alkalinity. Full article

The soil freeze–thaw phenomenon is one of the most outstanding characteristics of the soil in Heilongjiang Province. Quantitative analysis of the characteristics of changes in key variables of the soil freeze–thaw processes is of great scientific importance for understanding climate change, as well as ecological and hydrological processes. Based on the daily surface temperature and air temperature data in Heilongjiang Province for the past 50 years, the spatial–temporal distribution characteristics of key variables and their correlations with air temperature and latitude in the freeze–thaw process of soil were analyzed using linear regression, the Mann–Kendall test, the local thin disk smooth spline function interpolation method, and correlation analysis; additionally, the spatial–temporal distribution of key variables and the changes in the surface temperature during the freeze–thaw process are discussed under different vegetation types. The results show that there is a trend of delayed freezing and early melting of key variables of the soil freeze–thaw process from north to south. From 1971 to 2019 a, the freezing start date (FSD) was delayed at a rate of 1.66 d/10 a, the freezing end date (FED) advanced at a rate of 3.17 d/10 a, and the freezing days (FD) were shortened at a rate of 4.79 d/10 a; with each 1 °C increase in temperature, the FSD was delayed by about 1.6 d, the FED was advanced by about 3 d, and the FD was shortened by about 4.6 d; with each 1° increase in latitude, the FSD was delayed by about 2.6 d, the FED was advanced by about 2.8 d, and the FD was shortened by about 5.6 d. The spatial variation in key variables of the soil freeze–thaw process under the same vegetation cover was closely related to latitude and altitude, where the lower the latitude and altitude, the more obvious the variation trend; among them, the interannual variation trend of key variables of soil freeze–thaw under meadow cover was the most obvious, which varied by 9.65, 16.86, and 26.51 d, respectively. In addition, the trends of ground temperature under different vegetation types were generally consistent, with the longest period of unstable freeze–thaw and the shortest period of stable freeze in coniferous forests, compared to the shortest period of unstable freeze–thaw and the longest period of stable freeze in meadows. The results of the study are important for our understanding of soil freeze–thaw processes and changes in Heilongjiang Province, as well as the evolution of high-latitude permafrost; they also promote further exploration of the impact of soil freeze–thaw on agricultural production and climate change. Full article

Policies for promoting sustainable development of dam projects in the world have always been an argument due to the negative impacts on ecosystems. How to improve the efficiency of identifying the impacts and main indicators in the environmental impact assessment (EIA) process and post environmental impact assessment (PEIA) process is a common topic. Since the rapid dam construction in the past decades, most dam projects in China have turned to operation period. In order to identify the main impacts and provide scientific bases for the decision-making process, we optimized and applied the decision-support prototype (DSP) toolkit on the cascade dam projects on the Yangtze River. Through the optimization of the module and tools, the modified DSP was more applicable for China’s dams. Though the modified DSP cannot replace large-scale assessments for dam projects, it would assist the EIA and PEIA process by identifying the most relevant environmental concerns and knowledge gaps at early stages of negotiation, so that more attention can be focused on subsequent studies and evaluative processes. On the other hand, some new limitations were found in our practice. In response to the limitations, we propose several suggestions: (1) SBQ: to introduce a factor to balance the proportion evaluation result of new developed dams and existing dams in the study; (2) SBQ: to consider more about interactions between cascade dam projects and their impacts on different spatial scales; (3) EEM, extend the parameters for generating EEM from dams in areas outside of the U.S. Full article

Slaughterhouse wastewater (SHWW) has a great potential to generate biomethane energy when subjected to anaerobic digestion (AD). Nonetheless, the process is susceptible and prone to failure because of slow hydrolysis and the production of inhibitory compounds. Accordingly, to address this deficiency, anaerobic co-digestion (ACoD) is used to improve the treatment efficiency of the monodigestion of this high-strength waste and thereby increase methane production. The current investigation utilized the biochemical methane potential (BMP) test to assess the treatment performance of co-digested SHWW with sugar press mud (SPM) for improving biomethane energy recovery. It was established that the ACoD of SHWW with SPM increased methane (CH₄) yield, enhanced organic matter removal efficiency and improved process stability, while also presenting synergistic effects. The anaerobic monodigestion (AMoD) of SHWW (100SHWW: 0SPM) showed a higher CH₄ yield (348.40 CH₄/g VS) compared with SPM (198.2 mL CH₄/g VS). The 80% SPM: 20% SHWW mix ratio showed the optimum results with regard to organic matter removal efficiency (67%) and CH₄ yield (478.40 mL CH₄/g VS), with increments of 27% and 59% compared with AMoD of SHWW and SPM, respectively. However, it is also possible to achieve 5% and 46% CH₄ yield increases under a 40% SPM: 60% SHWW mix proportion in comparison to the AMoD of SHWW and SPM, respectively. Furthermore, kinetic analysis of the study using a modified Gompertz model revealed that the CH₄ production rate increased while the lag time decreased. The synergistic effects observed in this study demonstrate that incorporating SPM into the substrate ratios investigated can improve the AD of the SHWW. In fact, this represents the environmental and economic benefits of successfully implementing this alternative solution. Bioenergy recovery could also be used to supplement the country’s energy supply. This would help to increase the use of cleaner energy sources in electricity generation and heating applications, reducing the greenhouse gas effect. Full article

Precipitation nowcasting predicts the future rainfall intensity in local areas in a brief time that impacts directly on human life. In this paper, we express the precipitation nowcasting as a spatiotemporal sequence prediction problem. Predictive learning for a spatiotemporal sequence aims to construct a model of natural spatiotemporal processes to predict the future frames based on historical frames. The spatiotemporal process is an abstraction of some of the spatial things in nature that change with time, and they usually do not change very dramatically. To simplify the model and facilitate the training, we considered that the spatiotemporal process satisfies the generalized Markov properties. The natural spatiotemporal processes are nonlinear and non-stationary in many aspects. The processes are not satisfied with the first-order Markov properties when making predictions, such as the nonlinear movement, expansion, dissipation, and intensity enhancement of echoes. To describe such complex spatiotemporal variations, higher-order Markov models need to be used for the modeling. However, many of the previous models for spatiotemporal prediction constructed were based on first-order Markov properties, losing information on the higher-order variations. Thus, we propose a recurrent neural network which satisfies the multi-order Markov properties to create more accurate spatiotemporal predictions. In this network, the core component is the memory cell structure of the gated attention mechanism, which combines the current input information, extracts the historical state that best matches the existing input from the historical multi-period memory information, and then predicts the future. Through this principle of the gated attention, we could extract the historical state information that is richer and deeper to predict the future and more accurately describe the changing characteristics of motion. The experiments show that our GARNN network captures the spatiotemporal characteristics better and obtains excellent results in the precipitation forecasting with radar echoes. Full article

The catalytic capability of original carbon nitride (CN) is limited by a small specific surface area and high electron–hole recombination rate. In this study, WO₃-loaded porous carbon nanosheets (MCA-CN/WO₃) were synthesized by thermal treatment with melamine, cyanuric acid and WCl₆. The MCA-CN/WO₃ could degrade 98% of the methylene blue (MB) within 30 min in the photo-Fenton-like process, displaying better catalytic activity than the original CN (30%), pure MCA-CN (63%) and original CN/WO₃ (87%). The results of photoluminescence and electrochemical impedance spectroscopy demonstrated that the Z-scheme heterojunction of MCA-CN/WO₃ inhibited the recombination of electrons and holes. In addition, the porous nanosheet structure accelerated the electron transfer and provided abundant active sites for MB degradation. A radical quenching experiment indicated that the Z-scheme heterojunction facilitated the decomposition of H₂O₂ to produce ¹O₂ for MB degradation. The possible degradation pathways of MB were proposed. Full article

How to better harmonize the relationship between humans and rivers is a global issue of widespread concern at home and abroad, and science-based and integrated evaluation of rivers themselves is crucial to river management. Based on Maslow’s hierarchy of needs and according to the World Happiness Report and the 2030 Agenda for Sustainable Development, this paper argues that a happy river is a river that can maintain its own health, support high-quality economic and social development in the river basin and the region, reflect harmony between humans and water, and give people in the river basin a high sense of security and the ability to gain and satisfaction. This paper also analyzes happy rivers at five levels, including water security, water resources, water environment, water ecology, and water culture, and develops the River Happiness Index (RHI) and its indicator system, as well as assesses the overall river happiness in China’s 10 first-grade water resource zones. The results show that China’s RHI is at a medium level, with flood control capacity at a near-good level. On the grounds of the RHI evaluation results, the paper puts forward targeted measures for river basin governance, and provides a systematic solution to national river protection and governance. Full article

Although viscous sediment environments along the coast strongly attenuate waves, the attenuation dynamics and physical mechanism governing the attenuation process remain relatively unknown. Extremely complex interactions between muddy seabed have become increasingly important for wave evolution studies pertaining to coastal areas. The coastal protection function of mangroves was confirmed during the 2004 South Asian tsunami. Nevertheless, most research has been limited to macro-qualitative analyses, including those on variations in the transmission coefficient K_t and reflection coefficient K_r, and subsequent comparisons. However, determining the micro-physical characteristics is challenging, similar to coastal vegetation analyses with respect to mangrove vegetation characteristics. This study aims to quantify the attenuation difference in the wave energy owing to the coastal vegetation structure, under different layout conditions and combinations. Particle image velocimetry (PIV) technology is used to explore the variations in the velocity field and velocity distribution during the interaction process and calculate the wave-induced kinetic energy before and after setting up the vegetation structure. The research results emphasize that the resistance and frictional effects generated by vegetation are inversely proportional to the size of the stem, and the variation of kinetic energy determined from the velocity distribution and the thickness of the vegetation stem is mainly due to the larger frictional resistance of dense vegetation, relative to the fast flow velocity above the vegetation. Different vegetation heights slightly affect the short-period waves; however, the impact on energy reduction was smaller. For long-period waves, vegetation height significantly reduces wave kinetic energy. Full article

In the arid areas of Northwest China, especially in the Tianshan Mountains, the scarcity of meteorological stations has brought some challenges in collecting accurate information to describe the spatial distribution of precipitation. In this study, the applicability of TRMM3B42, GPM IMERG, and MSWEP V2.2 in different regions of Tianshan Mountain is comprehensively evaluated by using ten statistical indicators, three classification indicators, and variation coefficients at different time–space scales, and the mechanism of accuracy difference of precipitation products is discussed. The results show that: (1) On the annual and monthly scales, the correlation between GPM and measured precipitation is the highest, and the ability of three precipitation products to capture precipitation in the wet season is stronger than that in the dry season; (2) On the daily scale, TRMM has the highest ability to estimate the frequency of light rain events, and MSWEP has the highest ability to monitor extreme precipitation events; (3) On the spatial scale, GPM has the highest fitting degree with the spatial distribution of precipitation in Tianshan Mountains, MSWEP is the closest to the precipitation differentiation pattern in Tianshan Mountains; (4) The three satellite products generally perform best in low and middle longitude regions and middle elevation regions. This study provides a reference for the selection of grid precipitation datasets for hydrometeorological simulation in northwest arid areas and also provides a basis for multi-source data assimilation and fusion. Full article

The literature on irrigated agriculture is primarily concerned with irrigation techniques, irrigation water-use efficiency, and crop yields. How human and non-human agents co-shape(d) irrigation landscapes through their activities and how these actions impact long-term developments are less well studied. In this study, we aim to (1) explore interactions between human and non-human agents in an irrigation system; (2) model the realistic operation of an irrigation system in an agent-based model environment, and; (3) study how short-term irrigation management actions create long-term irrigation system patterns. An agent-based model (ABM) was used to build our Irrigation-Related Agent-Based Model (IRABM). We implemented various scenarios, combining different irrigation control methods (time versus water demand), different river discharges, varied gate capacities, and several water allocation strategies. These scenarios result in different yields, which we analyse on the levels of individual farmer, canal, and system. Demand control gives better yields under conditions of sufficient water availability, whereas time control copes better with water deficiency. As expected, barley (Hordeum vulgare, Poaceae) yields generally increase when irrigation time and/or river discharge increase. The effect of gate capacity is visible with yields not changing linearly with changing gate capacities, but showing threshold behaviour. With the findings and analysis, we conclude that IRABM provides a new perspective on modelling the human-water system, as non-human model agents can create the dynamics that realistic irrigation systems show as well. Moreover, this type of modelling approach has a large potential to be theoretically and empirically used to explore the interactions between irrigation-related agents and understand how these interactions create water and yields patterns. Furthermore, the developed user-interface model allows non-technical stakeholders to participate and play a role in modelling work. Full article

Given that the two institutional arrangements of government regulation and market allocation cannot effectively solve the conflict between individual and collective interests in the process of water pollution control, this work presents a useful attempt on the third institutional arrangement of environmental governance—social governance—to overcome the dilemma. Based on common pool resource theory and multi-person prisoner game analysis framework, it incorporates environmental damage function, spatial network structure, and strategy update based on a learning mechanism into the analysis framework. In addition, it constructs a set of spatial cooperative evolution game models of basin water pollution social governance, so as to test the guarantee effect of the spontaneous collective action conditions of basin polluters on the long-term survival of the new system. This work adopts the Monte Carlo numerical simulation method to conduct the simulation experiment research. The experimental results show it is possible to successfully form collective actions entirely dependent on emitters, which yet requires a large initial scale of cooperation, that is, a majority of the emitter group autonomously abides by credible commitments. In this process, transparent full information and active organizational mobilization have a positive effect on the collective action development. The organic combination can better guide emitters to abide by credible commitments to achieve the optimal collective interests. The study results can provide a theoretical and practical reference for the social governance mechanism at a large-scale basin. Full article

Flexibility in power systems is the potential to increase or decrease generation relative to scheduled generation or when most valuable. Increased penetration of variable renewable energy sources such as wind and solar increases the need for flexibility. Conventional hydropower plants are an important source of flexibility due to their ability to shut down and start generation units at short notice. However, there are not metrics or standards for hydropower managers to measure or quantify the potential flexibility of their systems. This novel study identifies key hydro system characteristics—physical and operational factors as well as the power markets—that, in our experience with real hydro systems, affect flexibility. A realistic but fictional system is analyzed that includes operating policies, deployment of reserves, physical aspects such as size of reservoirs, network configuration and power markets. The system is first modeled per “business as usual” operating rules to maximize total economic value of generation. The flexibility analysis measures the generation that can be increased or decreased in a single day by either maximizing the total on-peak generation in the upward direction or minimizing the total nadir generation in the downward direction. Results show the effects of each factor on both upward and downward flexibility. Full article

Monitoring drinking water quality is essential to protect people’s health and wellbeing. In the United States, the Safe Drinking Water Information System (SDWIS) database records the occurrence of a drinking water violation regulation in public water systems. A notable shortcoming of SDWIS is the lack of the contaminant concentration level about the allowable maximum contaminant threshold. In this study, we take advantage of both the SDWIS violation database and the contaminants sampling database at the state level to examine the drinking water quality of all kinds of drinking water systems in detail. We obtained sampling data (i.e., the concentration level of contaminants) of public water systems (PWSs) in Tennessee and explored the statistical distribution of contaminant concentration data in relation to the enforceable maximum regulatory contaminant level). We use both SDWIS violation records and actual concentrations of contaminants from the sampling data to study the factors that influence the drinking water quality of PWSs. We find that different types of violations were more frequent in (1) specific geological regions, (2) counties with PWSs that serve a larger population (10,000 to 100,000 people), and (3) places with abundant surface water, such as near a lake or major river. Additionally, the distribution of measured concentrations for many contaminants was not smooth but was punctuated by discontinuities at selected levels, such as at 50% of the maximum contaminant level. Such anomalies in the sampling data do not indicate violations, but more investigation is needed to determine the reasons behind the punctuated changes. Full article

Middle Eastern, North African countries (MENA), and Central Asian countries are considered the countries most facing water and food scarcity. The current water exploitation indicates that a few countries are overexploiting their water resources and using the fossil water available. This study reviews each country’s renewable water resources volume and evaluates the resources available to expand the agricultural area. Different scenarios are considered, using both irrigated and rainfed farming options, for concluding the most sustainable farming method in each country. Different scenarios are considered using irrigated and rainfed farming options to recommend the most sustainable farming method for each country. Results show that the countries in the MENA and Central Asia can be divided into three main categories: (1) Countries whose expansion of agricultural area can only be applied by using fossil water resources (Bahrain, Egypt, Kuwait, Libya, Qatar, Saudi Arabia, Turkmenistan, United Arab Emirates, and Uzbekistan); (2) Countries where the agricultural area can be expanded to a certain limit, by sustainably using both irrigated and rainfed farming (Afghanistan, Algeria, Iran, Palestine, Jordan, Kazakhstan, Morocco, Oman, Syria, Tajikistan, Tunisia, and Yemen); (3) Countries that have enough renewable water resources to farm all their agricultural area (Lebanon, Iraq, Turkey, and Kyrgyzstan). However, the aim of this study and its results are only to assess the renewable water resources available to sustain the increased agricultural water demand by setting aside other agricultural factors that constrain the sector. Full article

Since the hydraulic jump off a tidal bore in the Kampar Estuary has never been well-described, real-time measurements of hydraulic jump properties are crucial to understanding the tidal bore characteristics. This study aims to determine the real-time properties of a tidal bore generation, hydraulic jump, and transport mechanism in the Kampar River estuary. Tidal harmonic and range are analyzed using least-square-based tidal modeling. The tidal bore height and turbulent velocity records based on ADCP surveys in the estuary and upstream area are used to determine the hydraulic jump properties. Furthermore, an acoustic-based approach is also employed to quantify the suspended sediment concentration and flux during the passage of the bore. Kampar Estuary is predominated by semidiurnal co-tidal components (M2 and S2), where, based on the phase lag magnitude, it is categorized as an ebb-dominant estuary. This finding is proven by the more intense and prolonged ebb phases, especially during spring tidal conditions where the tidal range reaches 4 m. Of particular concern, the tidal bore height declines by 1.5 m every 20 km upstream with an erratic turbulent velocity. A sudden increase in transverse and vertical velocity during the passage of bore (ranging from −0.9 to 0.2 m/s) reflects the potency of sediment resuspension in the surrounding river edge marked by the significant increase in suspended sediment flux of about 3.7 times larger than at the end of the ebb tide. However, long-term measurement and regular bathymetry surveys are crucial to monitor the tidal bore behavior and morpho-dynamics in the Kampar River estuary. Full article