Search

The water resources carrying capacity (WRCC) is an essential indicator for assessing the ability of water resources to support socioeconomic activities. However, existing studies on WRCC were inadequate in terms of both temporal and spatial resolution, and had not incorporated human activities such as water transfer and storage into their assessment process. In this study, a Soil and Water Assessment Tool (SWAT+) model was employed to examine the spatiotemporal variation of monthly water consumption overload in each subbasin of the Qinhuai River Basin (QRB), a basin that is significantly impacted by human activities, from 2021 to 2023. The water resources were allocated based on the connection among subbasins. Subsequently, a dynamic assessment of the WRCC in each subbasin was conducted before and after allocation using the entropy weighted technique for order preference by similarity to ideal solution (TOPSIS) method. The results show that the intraanual and interannual differences in water resources led to temporal variations of water consumption overload ratio (0.69–1.05) in QRB, while the differences in the water use structure of subbasins led to spatial variations of water consumption overload ratio (0.38–2.54). The water allocation could significantly increase the WRCC in the dry year from 0.43 to 0.47, and all the subbasins with a weak carrying status were improved to moderate, and in general lift the mean WRCC from 0.43 to 0.47. Finally, it is anticipated that the WRCC of QRB will continue to improve in the future under the SSP245 scenario, due to an increase in rainfall and a decrease in population size. This study discovers a finer relationship between human activities and water cycle in both temporal and spatial dimensions, and enhances the WRCC through water allocation, thereby providing a novel perspective on basin water resources management. • SWAT + model simulates human impacts on water distribution effectively. • Emphasizes monthly assessments for better water resources management. • Utilizes dynamic approach to evaluate water resources carrying capacity. • Considers subbasin connectivity for effective water allocation strategies. • Highlights the integration of human activities in resources assessment. [ABSTRACT FROM AUTHOR]

Plastic pollution in river basins poses a significant environmental challenge, particularly in Japan, located in the northwestern North Pacific, often referred to as a hotspot for plastics. This study quantified the annual recovery of anthropogenic plastic litter from riverbanks and water surfaces, utilizing a nationwide cleanup dataset provided by the Japanese Ministry of Land, Infrastructure, Transport and Tourism. The dataset includes the amount of litter recovered through volunteer and administrative cleanup campaigns from 2016 to 2020 in 109 Japanese river basins. Total plastic recovery ranged from 763 to 1177 tons/year, averaging 938 tons/year. Basin-specific recovery was associated with extreme weather events, such as typhoon approaches and heavy rain, which caused significant flood damage in local regions. The estimated annual plastic recovery was an order of magnitude smaller than the previously estimated annual emission of land-based plastic. • Significant plastic pollution challenge in Japanese river basins. • Annual recovery quantified using nationwide cleanup dataset. • Average plastic recovery: 938 tons per year • Moderate correlation with population and cleanup participants • Extreme weather impacts plastic recovery rates. [ABSTRACT FROM AUTHOR]

[Display omitted] • 10 m pixel-based crop development monitorization by NDVI at river basin scale. • Integration of Remote Sensing-based Soil Water Balance and Water Footprint methodologies. • Remote sensing-based estimation of green and blue crop water use and water footprint. • Knowledge generation to water managers by spatially distributed thematic cartography. Since the development of Water Footprint environmental indicator, significant research on blue and green crop water use and the respective water footprint estimations has been published. Such research is commonly approached using different methodologies that leverage tabulated values for crop development characterisation, while studies based on remote sensing data are less abundant, despite crop monitoring using remote sensing-based vegetation indices having demonstrated great capabilities and operability. To help fill this gap, we present a methodology that uses a remote sensing vegetation index time series from Sentinel-2 satellite near infra-red and red spectral bands data to derive basal crop coefficient time series to subsequently be used under the Remote Sensing-based Soil Water Balance approach that follows the globally operative FAO56 procedure. It provides pixel-based temporal and spatially distributed estimations of net irrigation requirements and adjusted crop evapotranspiration, with the aim being to divide up the latter and estimate the remote sensing-based green and blue crop water use and the subsequent green and blue water footprint. This is all done under the Agricultural Water Footprint Assessment framework for a growing crop or tree. This methodology was applied over a large, crop-diverse Spanish river basin district (Júcar) and across two different climatological years (humid vs. dry). Its feasibility was demonstrated by the acceptable behaviour of the remote sensing-based blue crop water use estimation for different herbaceous and woody crops, against the official dataset for irrigation water accounting at two water management scales (of a relative mean absolute error of 15.4 % in the case of the largest water user association and of 17.1 % in the case of the river basin water authorities' own estimations). The proposed approach, which we call Remote Sensing-based Agricultural Water Accounting and Footprint, aims to provide reliable and accurate spatially and temporally distributed thematic cartography about the remote sensing-based blue and green crop water use and water footprint. This information is essential for water managers with the goal of generating transparent and complementary information to incorporate into their own working scales. [ABSTRACT FROM AUTHOR]

Tropical rivers such as the Rio Negro constitute a major portion of the global aquatic flux of dissolved organic carbon (DOC) entering the ocean, but the exact amount, source contributions and fate of terrestrial DOC remain unknown. We investigated the role of valley and upland whitesand ecosystems (WSEs) and terra firme plateaus in forming blackwater tributaries in the Rio Negro basin to develop novel constraints for the terrestrial export of carbon. 5709 molecular markers from ground- and surface waters of two contrasting valley and upland sites feeding Rio Negro tributaries were identified by ultrahigh resolution mass spectrometry (FT-MS), analyzed by multivariate statistics and compared to known Rio Negro markers. In a Principal Coordinates Analysis, valley and upland DOC molecular composition differed by 78% from plateau DOC, which was characterized by reworked, aliphatic and unsaturated N- and S-containing molecules, while valley and upland DOC contained mainly condensed aromatics, aromatics and oxidized unsaturated structures. Valley and upland samples differed by 10% in molecular DOC composition and by their isotopic content (14C of SPE-DOC, 18O and 2H of water) which indicated differences in hydrology and C turnover. Against expectation, markers of widespread whitesand valleys did not emerge as a major source of Rio Negro markers, but specific upland markers did. Pubchem suggested chromene and benzofuran structures as promising candidates for further study. Our findings indicate that the export of molecular markers diverges from expected transport-limited DOC behavior, and thereby opens new avenues for source annotation beyond DOC quantity. Terrestrial DOC from upland whitesand areas is a major source of specific blackwater molecules missing in the regional ecosystem C balance, whereas C export from the whitesand valleys and especially from terra firme plateaus represents mainly recycled and transformed carbon not directly affecting the ecosystem C balance and possibly, the watersheds downstream molecular signature. Our study highlights the potential of high-resolution techniques to constrain carbon balances of ecosystems and landscapes by novel molecular markers. A comparison with other terrestrial DOM datasets indicated molecular similarities with temperate acidic soils and tropical rivers that warrant further analysis of common DOM markers. Implications, limitations, and future challenges are discussed in the light of potential applications of diagnostic molecular links for DOC source annotation and estimation of terrestrial DOM export in the land-to-ocean continuum. [ABSTRACT FROM AUTHOR]

Wastewater treatment plant (WWTP) discharges of microcontaminants negatively impact freshwater streams, underscoring the need for accurately mapping wastewater-derived contamination in water bodies across Europe (EU). In this study, we present a fast and open-source code for a microcontaminants fate and transport (MFT) model, capable of simulating contamination at a high resolution (15 arc second scale) across the EU. The model was developed using the best publicly available hydrological (HydroSHEDS) and sanitation (UWWTD) datasets and was rigorously calibrated, with a goodness of fit of 77.5% as measured by the R 2. Importantly, the model demonstrated the ability to predict wastewater-derived contamination in water bodies, making it a valuable tool for planning the upgrade of WWTPs and improving the ecological condition of freshwater streams in the EU. • A model is developed to simulate wastewater-based contamination in rivers. • Large-scale free hydrologic and sanitation layers are used. • The model is calibrated obtaining an R2 of 77.5%. • The model is open-source and has fast runtimes. [ABSTRACT FROM AUTHOR]

Understanding biota distribution patterns is essential for ecosystem conservation and restoration. In addition to biogeography, the distribution patterns of aquatic organisms that inhabit rivers vary longitudinally along river networks. Although longitudinal changes in distribution patterns in aquatic organisms along river networks have been studied in single river basins, it is crucial to understand these patterns at a regional ecological scale for broad-scale ecosystem conservation. This study aimed to elucidate the longitudinal distribution patterns of fish fauna and their correlation with environmental factors in several watersheds within the East Setouchi Ecological Region, renowned for its rich freshwater fish diversity in the Japanese archipelago. Data were obtained for 118 species across 10 watersheds and 85 sites, and the surveyed sites were classified into four longitudinal groups based on the similarity of the fish fauna. The lowest group comprised river estuaries, abundant in brackish-water fish, comprising primarily Gobiidae species. In lower watershed areas with low agricultural land and forest cover but high urbanization, all fish species selected as indicators were non-native. Upstream areas with a high percentage of agricultural land featured a mix of native Cyprinidae and non-native species such as Micropterus salmoides and Rhodeus ocellatus ocellatus. The most upstream groups, marked by significantly greater elevations and bed slopes, exclusively comprised native species as indicator species. Analyzing the longitudinal distribution patterns of fish fauna at multiple sites within the same ecological region enabled us to choose endemic fish species as indicators and identify important species for conservation. Additionally, the selection of sites characterized by significant urbanization and strong anthropogenic influences, along with the selection of non-native species as indicators, underscores the urgency of conserving native organisms in these areas, calling for continuous monitoring. [ABSTRACT FROM AUTHOR]

Suspended sediment prediction is essential for wearing awayof soil and sedimentation at time of peakinundation period. Several kinds of neural networks have been projected in preceding papers for applications in hydrological events. This research intelligence focuses on assessment of applicability of Recurrent Neural Network (RNN) and Radial Basis Function Network (RBFN) for forecasting flow on daily basis at gauging station in Mahanadi river basin. Superlative performance is assessed on basis of RMSE, R2 which was attained by the precipitation and antecedent flow as model inputs. Based on performance value RNN gives prominent value as compare to RBFN. In case of RBFN three transfer function Tan-sig, Log-sig, purelin are utilized for evaluating model performance. While Tan-sig function used model gives extent value of R2 that is0.9614 and 0.9843 for training and testing phase respectively. [ABSTRACT FROM AUTHOR]

• Tool for optimal selection and implementation (TSI) of the eco-remediation measures. • TSI supports implementation of mitigation measures on the most critical source areas. • TSI reduces the size of required area and cost of implementing measures. Erosion processes in the watershed and sediment transport cause hydro-morphological changes, eutrophication, and the loss of storage capacity in reservoirs. This study examines the tool for the optimal selection and implementation (TSI) of eco-remediation measures (ERM) in the river basin area to improve water quality and to reduce storage loss in the reservoir in question. The main purpose of this tool is to support decisions and measures taken to correct defined problems and to improve water quality and storage capacity in the watershed while minimising sediment transport. This tool enables the effective and necessary implementation of these measures to the most critical source areas (CSAs). In order to verify its operability, we selected the Ledava reservoir with a transboundary area of 105.25 km2 in NE Slovenia and SE Austria. With the use of the Soil and Water Assessment Tool (SWAT), critical source areas were determined and the effects of eight different scenarios on sediment yield and load transport were simulated. The results showed that CSAs occupy 12% of the watershed and that sediment inflow into the Ledavsko jezero reservoir could be reduced by up to 30%. After determining the CSAs and which measures would be most effective, the implementation plan could be defined. Within this framework, the TSI enabled the selection of effective measures and contributed to the long-term improvement of the ecological status of surface waters required by Water Framework Directive (2000/60/EC), improving the quality of water bodies of all types to safeguard water ecosystems from harmful consequences. [ABSTRACT FROM AUTHOR]

Abstract Within river basins, water resources competition often exists between agricultural, municipal and industrial sectors, particularly in semi-arid regions where surface water and groundwater are managed conjunctively to sustain urban areas and food production. There is a need for physically-based modeling tools to assist with identifying successful water management strategies in these basins. This paper presents an updated version of SWAT-MODFLOW that allows application to large agro-urban river basins in semi-arid regions. Code changes include linkage between MODFLOW pumping cells and SWAT HRUs for groundwater irrigation, joint groundwater and surface water irrigation routines, and the use of MODFLOW-PSB to handle the large array of groundwater sources/sinks that exist in a highly managed river basin. Model performance is demonstrated for the 72,000 km2 South Platte River Basin, Colorado, USA. The model can be used in agro-urban river basins worldwide to assess water resources supply under a variety of scenarios. Highlights • Updated SWAT-MODFLOW code can be used for large agro-urban river basins. • The model includes all major water transfer pathways for managed river basins. • The model links MODFLOW pumping to SWAT groundwater irrigation. • The model is tested in a 72,000 km2 river basin in Colorado, USA. [ABSTRACT FROM AUTHOR]

Highlights • Spatial distribution of δ18O values in river water across the Ganga river Basin. • Upper stretch of river Ganga shows dominance of snow/glacier melt. • Evaporation effect is higher in middle stretch of the river Ganga. • Lower stretch shows high contribution of water from the Himalayan tributaries. • Seasonal control in δ18O values of river water is more in middle than lower stretch. Abstract Knowledge of the spatial distribution of water isotopes in the large river system is useful to comprehend the hydrological processes within the basin. Spatially limited water isotope data in the Ganga river basin (GRB), one of the largest river basins in the world, hinders the understanding of hydrological processes at the basin scale. Therefore to understand the hydrological processes, river water and ground water were collected from the source (Gangotri glacier) to sink (Bay of Bengal) of the river Ganga. The δ18O values of river water vary from −14.9‰ to −6.3‰ with a general enrichment in 18O from source to sink. The δ18O values of ground water are similar to river water only in the middle stretch of the river, indicating higher mixing of these two water sources in the middle stretch. Comparison of the monthly averaged (three years) δ18O values of river water and rain water suggests that temporal variability in the isotopic composition of river water is higher in the middle stretch of the river compared to lower stretch due to lower discharge in the middle stretch. To understand the spatial variability of δ18O values in the GRB, δ18O values of river water were modeled using latitude and elevation as primary predictors. The residuals of the model suggest that in the upper stretch snow/glacier melt control the δ18O values, in the lower stretch Himalayan tributaries control the isotopic composition of the river water and in the middle stretch evaporation dominates which is also supported by δ18O-δD plots of the different water inventories. [ABSTRACT FROM AUTHOR]

Abstract The coastal zones on continental shelves are the main channels for the distribution of fluvial-sourced suspended sediments (SSs). In the current research, the monthly average amount of SS draining into the Caribbean Sea from the Magdalena River in northern Colombia was analyzed to detect nanoparticle (NPs) containing potential hazardous elements (PHEs). The ecological authorities of Colombia claimed that the climate change is the key reason behind land erosion and floods occurred in the last years; therefore, an elaborate understanding of NP dynamics between the Magdalena River body and streambed is an essential issue in SS research. In this work, the NP geochemistry of SS in the Magdalena River estuary was studied from the perspective of water quality controls on SS sorting. The morphologies and the structures of NPs (<100 nm) were examined by field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), and selected area electron diffraction (SAED)/micro-beam diffraction (MBD)/energy dispersive X-ray spectroscopy (EDS) techniques. The average size of NPs was found to be greater than 2 nm and Al, Ti, Fe oxides, and other hazardous elements were also detected in the SS. The obtained data confirmed that these typical categories of NPs caused the occurrence-dependent intensification of a conjugative transmission rate associated with the regulators. The advanced electron beam technique provided a clear insight into SS transportation; therefore, it could be used as an essential instrument for river supervision/dynamics. Graphical abstract Image 1020 Highlights • Colombian Caribbean area showed various degrees of contamination by anthropogenic activities. • Nanoparticles were critical compared with the probable effect level. • Human activities played a dominant role, to human impacts and environmental pollution. [ABSTRACT FROM AUTHOR]

Abstract Quantification of hydrological components in-terms of surface runoff, stream flow and evapotranspiration is important and useful in planning and management of water resources across the river basin, including downstream delta regions. River deltas water availability; management and related disaster risk are largely influenced by the hydrological state of upstream river basins. The paper presents the results of hydrological modelling (SWAT) based long-term water balance components in river basins draining into selected delta Districts of Eastern India. Mahanadi, Brahmani-Baitarani river basins and Hooghly river and adjacent small river basins are considered. The long-term water balance components of Mahanadi and Brahmani-Baitarani river basins are similar and significantly different in Hooghly river and adjacent small river basins. The runoff coefficient is significantly higher in Hooghly river and adjacent small river basins at 0.39 compared to other two river basins (0.247 & 0.256). The evapotranspiration component is relatively low in Hooghly river and adjacent small river basins with smaller range of long-term variation. The time-series model outputs brought out the basin-specific hydrological response variations in low and high rainfall years such as changes in fraction of evapotranspiration and surface runoff. Mahanadi and Brahmani-Baitarani river basins exhibit large inter-annual variation in evapotranspiration, surface runoff fractions. The developed hydrological modelling framework is capable of incorporating future climate data and to predict the basin-scale future water availability, demand, use and to bring out resulting water scenarios that would impact river deltas in-terms of their exposure towards water related adversities, such as drought and flood. Graphical abstract Unlabelled Image Highlights • River delta's water resources are influenced by upstream hydrological conditions. • Hydrological response is influenced by terrain and meteorological conditions. • Contrasting hydrological behavior during low and high rainfall conditions • Preceding year conditions are influencing following years hydrological response. • Useful to simulate future climate periods water related adversaries [ABSTRACT FROM AUTHOR]

Abstract There is a growing need to better understand and communicate multi-dimensional river ecosystem processes and properties at the catchment scale for both scientific research and integrated catchment management. Data visualisation is believed as a very useful approach to support this need. However, there is a lack of visualisation applications tailored for river ecosystems, especially for visualising both river environmental data and their spatial and topological relations. To fill up the gap, this paper introduces an R package rivervis, which has been developed as a free, easy-to-use and efficient visualisation solution for river ecosystems. This novel tool is able to visualise riverine data in a compact and comparable way, with retaining the river network topology and reflecting real distance between sites of interest. The rivervis package visualises variables according to their measurement types – either quantitative or qualitative/semi-quantitative data. This type-based principle makes the package applicable for a wide range of scenarios with data in forms of index values, condition gradings and categories. By producing topological river network diagrams, the package helps to understand the functioning and interconnections of riverine ecosystem at the catchment scale, especially the longitudinal upstream-downstream and tributary-mainstream connectivity and relationships. It can also be used to study the associations between biological communities, physical conditions and anthropogenic activities. The Ballinderry River Basin in the UK, as a data-rich river basin with a reasonable complex river network, is used to demonstrate the rationale, functions and capabilities of the R-package. Highlights • Meet the demand for tailored river visualisation tools for research and management. • Introduce a novel R package to visualise both river data and river network topology. • Help study longitudinal relations and connectivity of rivers at the catchment scale. • Apply a type-based visualisation principle which applies to most data scenarios. [ABSTRACT FROM AUTHOR]

Highlights • This article explores convergences between the concept of scale in human and physical geography. • It examines Brazil's exertion of hydro-hegemonic power in South America. • It contributes to assessments of water politics in South America via a production of scale approach. • The article analyses the array of social interactions to produce hydropolitical scales. Abstract This article analyses the production of scale in the La Plata River Basin and Guarani Aquifer System within regional hydropolitics in South America. We argue that different political and ecological scales acquire prominence according to the national political goals at stake, reproducing multi-scalar politics within and beyond South America. To support this argument, this article presents a literature review on the concept of scale in geography that explores the production of, and interaction among scales. The article then takes a historical approach to the evolving scales associated with the cases of the La Plata River Basin and Guarani Aquifer System to show how Brazil exerts hydropolitical regional hegemony through the construction of infrastructure and signing of agreements and treaties. Rather than a simple case of conflict or cooperation over water resources, these episodes represent a continuum of political interactions engendered by specific political goals and involving different social actors. [ABSTRACT FROM AUTHOR]

Developing and implementing water quality models that utilize sophisticated processes and plenty data in large river basins can be a challenging task. Factors such as sampling design, prediction at unsampled sites, and derivation of new spatial information in monitoring studies can restrict the methodologies applicable to water quality modeling. In recent years, spatial stream network (SSN) models, incorporating hydrologic distance and topological data structures, have emerged as a novel approach for predicting water quality in extensive study areas. These models have integrated conventional geostatistical methodologies and have demonstrated their effectiveness in analyzing water quality within large river basins. In this study, we aimed to investigate the feasibility of using SSN to predict alkalinity through a comparative analysis of two distinct river basins in Türkiye. We evaluated the prediction performance of SSN and the spatial characterization of the basins using spatial data sets as model components. The models are based on moving-average (MA) functions and constructed by evaluating alkalinity observations at 90 locations in Kucuk Menderes River Basin and 224 locations in the Coruh River Basin, using torgegram, correlogram, principal component analysis, and exhaustive search algorithm for covariate selection. In this research, we evaluated the optimal combination of covariates obtained from 20 different variables within the context of five spatial data set classes: topography, geology, climate, land use, and anthropology. The outcomes of the model indicate that impact of anthropogenic activities on autocorrelation based on hydrologic distance, impact of spatial covariates on variance, and root mean square prediction error (RMSPE) values of the predictions in Kucuk Menderes are more effective than those in the Coruh. The findings from the model predictions show that modeling water quality on stream network scale by using topological relationships and autocorrelation based on hydrologic distance can be recommended for rivers affected by complex and detailed processes. • A novel geostatistical approach for the prediction of water quality in large-scale basins was applied. • Stream Network Models (SSN) consider river topology and spatial autocorrelation. • The spatial covariates of the models supported the characteristics of the distinct river basins. • Alkalinity predictions demonstrated that the SSN models were feasible and effective. [ABSTRACT FROM AUTHOR]

To assess the quality of a water environment, an in-depth analysis of temporal patterns of contaminant concentrations in water body should be carried out based on unbiased water quality datasets. In this study, we developed a modified log-linear model to account for non-stationary seasonal variations of contaminant concentrations over multiple periods. The model was applied to analyze temporal changes of the Ammonia Nitrogen (AN) concentration at Middle Reaches of Huaihe River (MRHR) and two major tributaries, Shaying River (SR) and Guo River (GR). The modified model outperformed the original models and fitted the data well with Pearson correlation coefficients ranging from 0.67 to 0.86. Temporal patterns of AN concentrations, loads and sources were identified from 1998 to 2015 in connection to the implementation of Five-Year Plans (FYPs, policies for controlling water pollution) in the Huaihe River Basin (HRB). The results show that the AN concentration experienced a significant decrease. Since FYPs focused on controlling AN point sources, the proportion of AN loads derived from point sources decreased from 48–86% to 1–17% in the MRHR and from 66–92% to 2–56% in the SR and GR. However, rebounds of AN concentration occurred in the first year of each FYP period possibly due to discontinuity of the policy implementation over the transition between two consecutive FYPs. High AN concentration anomalies were found in flood seasons, related to pollution discharge beyond limits and/or irrational regulation of sluices. These results have implications for future pollution control policies in the HRB, particularly, the need to reduce the upper limits of contaminant loads for flood seasons, continuity of the policies implementation, reduction of non-point source pollution, rational sluice regulation and integrated pollution prevention programs. The developed model and approach are applicable to other polluted river basins to facilitate water quality assessment and evaluation of pollution control policies. [ABSTRACT FROM AUTHOR]

Dechlorane related compounds (DRCs), including Dechlorane Plus ( syn -DP and anti -DP), Dechlorane-601, -602, -603 and Chlordene Plus (CP), constitute a group of polychlorinated flame retardants (FRs) that are still of industrial use. In particular, DRCs have been detected in various environmental matrices and in different aquatic and terrestrial biota, thus exhibiting bioaccumulation and biomagnification potentials. The present study aimed at producing first occurrence data of a range of DRCs in Silurus spp. samples from different rivers located in France. Determination was carried out by gas chromatography high-resolution mass spectrometry after a sample clean-up based on a multilayer silica column and gel permeation chromatography. The concentration of monitored ΣDRCs ranged from 1.58 to 408 pg g −1 wet weight (54–11100 pg g −1 lipid weight). The fractional abundance of syn - and anti -DP stereoisomers was similar to that reported by other studies with an average equal to 0.60. Dec-601 was not detected in any sample. Detection frequencies ranged between 34 and 100% for other DRCs. Investigated correlations between DRCs and polychlorobiphenyls (PCBs) suggest a link with lipid content but independent contamination sources. [ABSTRACT FROM AUTHOR]

Investigating the coupling relationship between water environment and social economy is the hot issue in the sustainability study of river basin. Ganjiang River is the largest tributary of Poyang Lake watershed in China. Based on the social economic and water environment status quo in Ganjiang River basin from 1999 to 2016, this research builds the coupling coordinate model, and uses this model to analyze the coupling degree and coordinate degree between the social economic development and the water environmental quality by constructing evaluate formulate, comprehensive utilization of principal component analysis method and coupling model. The results indicate that for the time node of 2006, the period from 1999 to 2006 is the social economic lag phase and the period from 2007 to 2016 is the water environment lag phase; in the Ganjiang River basin, the coupling degree and the coordinate degree between social economy and water environment are not ideal from 1999 to 2016. If this basin continues the existing development speed, the pressure of water environment brought by the social and economic development will become very huge in the next years. [ABSTRACT FROM AUTHOR]

The planning, management, governance, and ecological protection of a river basin are becoming more and more important, which needs a great support of water resources data both spatial and attribute data. According to the characteristics of these data, a suitable thematic water resources spatial database management system (WRSDBMS) in river basin is proposed to manage these data integrally. In the thematic system, an extensible data model conforming to water resources data is proposed with the synthesization of traditional structured database system and unstructured spatial data management system. In the extendable data model, client/server structure is used, an extended model of Oracle is used to manage both spatial data and property data, and the spatial database engine is used to import/export spatial data to/from Oracle. The WRSDBMS system is finally used for water resources data management of Hanjiang river basin. It is clearly seen that the system is efficient and reasonable in integrated management of spatial and attribute data. And it may provide a strong support for the scientific management of the river basin. [ABSTRACT FROM AUTHOR]

Vegetation response to flooding across large dryland areas such as Australia's Murray Darling Basin (MDB) is not understood synoptically and with locally relevant detail. We filled this knowledge gap by quantifying vegetation dynamics, defined here as greening and browning due to changing chlorophyll content and leaf area index, in response to flooding and rainfall across the floodplains of the entire MDB. We quantified vegetation and flooding dynamics using the same data source, namely 26 years of high resolution, wall-to-wall satellite data, in a top down statistical modeling approach, where we controlled for rainfall. Our time series (1986–2011) covered a period of extreme hydroclimatic variability, including the South East Australian Millennium Drought, thus providing a research opportunity to investigate how the relationship between vegetation and flooding changed during wet and dry periods. Our results showed that besides rainfall, flooding plays a key role in driving floodplain vegetation dynamics, yet the role of flooding varied across the MDB floodplains. We quantified a change in the relationship of how vegetation responds to rainfall and flooding with an unprecedented level of spatial detail. The change in the relationships coincided primarily with the onset of the Millennium Drought, yet local and regional differences in the timing of the change did occur, suggesting that the beginning of the Millennium Drought did not impact all floodplain areas at the same time. Our synoptic while locally relevant quantification of the changing response of vegetation to rainfall and flooding is a first step to help underpin Australia's investment into environmental water allocations. [ABSTRACT FROM AUTHOR]

This work aims to assess how Pleistocene glaciations modeled the landscape in the upper Senguer River basin and its relationship to current watershed features (drainage surface and fluvial hydrological regime). During the Pleistocene six glacial lobes developed in the upper basin of the Senguer River localized east of the Andean range in southern Argentinean Patagonia between 43° 36’ - 46° 27′ S. To describe the topography and hydrology, map the geomorphology, and propose an evolution of the study area during the Pleistocene we employed multitemporal Landsat images, national geological sheets and a mosaic of the digital elevation model (Shuttle Radar Topography Mission) along with fieldwork. The main conclusion is that until the Middle Pleistocene, the drainage divide of the Senguer River basin was located to the west of its current limits and its rivers drained the meltwater of the glaciers during interglacial periods. However, processes of drainage inversion and drainage surface reduction occurred in the headwater of most rivers of the basin during the Late Pleistocene. Those processes were favored by a relative shorter glacial extension during LGM and the dam effect produced by the moraines of the Post GPG I and III glaciations. Thus, since the Late Pleistocene, the headwaters of several rivers in the basin have been reduced, and the moraines corresponding to the Middle Pleistocene glaciations currently divide the watersheds that drain towards the Senguer River from those that flow west towards the Pacific Ocean. [ABSTRACT FROM AUTHOR]

This study includes three methods having considerable differences with each other and with experimental observations, because the sediment measures have certain limits. The equations relating to sediment transport are used in estimating sediment load. In the present study, black box models, ANN (Artificial Neural Network) are used for the simulation of the suspended sediment load. Hence, models which give the lowest RMSE and highest R 2 are considered to be the best model for this study. The lowest values of RMSE based on normalized data for Feed forward back propagation, Cascade forward back propagation and neural network fitting are 0.00873, 0.00834 and 0.01193 respectively. The corresponding values of R 2 are 0.9304, 0.9713 and 0.9831 respectively for the cited MSE. The study shows Neural Network Fitting model is superior to the other models. However, a drawback of neural network fitting is that it produces few negative estimates, which is not at all tolerable in the field of estimation of sediment load and hence these models are not crowned in this study. [ABSTRACT FROM AUTHOR]

The Gravity Recovery And Climate Experiment (GRACE) satellite mission provides time-variable gravity fields that are commonly used to study regional and global terrestrial total water storage (TWS) changes. These estimates are superimposed by different error sources such as the north–south stripes in the spatial domain and spectral/spatial leakage errors, which should be reduced before use in hydrological applications. Although different filtering methods have been developed to mitigate these errors, their performances are known to vary between regions. In this study, a Kernel Fourier Integration (KeFIn) filter is proposed, which can significantly decrease leakage errors over (small) river basins through a two-step post-processing algorithm. The first step mitigates the measurement noise and the aliasing of unmodelled high-frequency mass variations, and the second step contains an efficient kernel to decrease the leakage errors. To evaluate its performance, the KeFIn filter is compared with commonly used filters based on (i) basin/gridded scaling factors and (ii) ordinary basin averaging kernels. Two test scenarios are considered that include synthetic data with properties similar to GRACE TWS estimates within 43 globally distributed river basins of various sizes and application of the filters on real GRACE data. The KeFIn filter is assessed against water flux observations through the water balance equations as well as in-situ measurements. Results of both tests indicate a remarkable improvement after applying the KeFIn filter with leakage errors reduced in 34 out of the 43 assessed river basins and an average improvement of about 23.38% in leakage error reduction compared to other filters applied in this study. [ABSTRACT FROM AUTHOR]

Water quality monitoring is important for the management of freshwater resources in river basins. Allocation of monitoring stations is the first step in the design of a water quality network. For this task, planning objectives are identified and a Multi-Objective Artificial Bee Colony-based optimization algorithm is designed and implemented in a Geographic Information System framework. Specifically, the number of stations is minimized in a range of values at the same time that the detection of lower compliance areas, the affected population and the relative importance of the river stretches are maximized. The estimation of pollutant parameters such as Biochemical Oxygen Demand, Faecal Coliform Bacteria or Total Dissolved Solids is performed by using the WorldQual model. This allows to objectively allocate monitoring stations to rivers where no real measurements are available, and thus it is especially relevant to allocate water quality stations for the first time. This approach has been tested on the Great Fish River basin (South Africa), finding networks improving the values of the objective functions between 22.22% and 47.83% with respect to the ones of the current network. Moreover, the solution analysis provides insightful and valuable information to the decision maker. [ABSTRACT FROM AUTHOR]

The metal(loid) pollution still is a great concern due to the effects from urbanization and industrialization. While, the health risks from the toxic metal(loid)s could decrease if strict pollution control measures were adopted. However, few studies to date investigate the health risks of heavy metal(loid)s in a systematic river basin for the dependent residents, after taking pollution control measures. Thus, the contents of metal(loid)s (Cu, Pb, Zn, Cd, Mn, As) in surface water along a typical river basin were investigated in this study, and the potential non-carcinogenic and carcinogenic health risks posed to the residents were assessed. Although the soluble contents of Cu, Pb, Zn and Cd exceeded the respective thresholds in two sites located downstream the mine area, they were greatly decreased in comparison with previous contamination levels, and the soluble concentrations of all the metal(loid)s were within the relevant thresholds in the sites far away from the mining area. Moreover, the closer to the mining area, the higher the pollution levels of metal(loid)s. The total hazard index for non-carcinogenic risks of metal(loid)s were basically lower than the threshold (1) for the local population. Whereas, although the content of metal(loid)s were low (such as As), they could pose relative higher non-carcinogenic health risks. The result illustrated that pollution levels, toxicity of the contaminants and exposure behavior patterns all could contribute to the potential detrimental health risks. Additionally, the non-carcinogenic and carcinogenic risks from ingestion exposure were ∼2–∼4 orders of magnitude higher than those from dermal contact. The total carcinogenic risks were basically lower than the maximum tolerable levels (1.0 × 10 −4 ), indicating carcinogenic risks from most areas of the river could also be accepted. Among different population groups, heavy metal(loid)s posed relative higher non-carcinogenic and carcinogenic risks to the children in 0–5 years old. Fortunately, the surface water in most area of this basin is safe in usage for the local population and the health risks were basically acceptable in case exposed to the target metal(loid)s, after the river basin was in the charge of strict pollution control measures. [ABSTRACT FROM AUTHOR]

This article examines the 2011 flood in Thailand, with an emphasis on the Chao Phraya River Basin, and analyzes the existing plans and measures relevant to the flood risk management of the country. It also highlights some deficiencies in current practices, and suggests improvements using a strategic flood risk management framework. The results indicate that the flood risk management of Thailand is ineffective and needs to shift from a passive response (that relies mainly on structural measures and emergency responses during a flood event) to a progressive response that emphasizes non-structural measures (e.g., land use planning, building and development controls, regulations, etc.) and participatory collaboration among government agencies and stakeholders (people, public, and private agencies in the affected areas). Further studies about flood insurance for the agricultural sector and about socioeconomic levels and perceptions in the flood risks of the target communities are also recommended. These can improve financial resilience to flood risk and the effectiveness of the relevant plan implementations. [ABSTRACT FROM AUTHOR]

As the effects of global warming on climate have a wide spatial variability, regional studies of temporal climate trends are critical. This study investigates the effect of global warming on temperature and precipitation trends in the Yellow, Yangtze and Pearl River basins (the Three Basins) of China over the past 58 years (1956–2013). Over this time period, the mean warming rate in the Three Basins (0.22 °C/10 yr) was close to that for the global land surface (0.21 °C/10 yr). However, the warming rate showed high spatial variability across the study region, ranging from 0.05 °C/10 yr to 0.49 °C/10 yr. These rates tend to increase with latitude and elevation and toward very large cities (e.g., Shanghai). The warming rate in the Three Basins varied by season, it was lower in summer (0.14 °C/10 yr) and higher in winter (0.29 °C/10 yr). In spite of the warming trend, no statistically significant increase or decrease in precipitation was found for the Three Basins over the past 58 years. [ABSTRACT FROM AUTHOR]

Classic (polybromodiphenyl ethers, PBDEs) and emerging halogenated flame retardants (HFRs) such as decabromodiphenyl ethane (DBDPE) and halogenated norbornenes, as well as organophosphate flame retardants (OPFRs) were analysed in 52 sediments and 27 fish samples from three European river basins, namely the Evrotas (Greece), the Adige (Italy) and the Sava (Slovenia, Croatia, Bosnia and Herzegovina and Serbia). This is the first time that FR levels have been reported in these three European river basins. The highest contamination was found in the Adige and Sava rivers, whereas lower values were obtained for the Evrotas. The levels in sediment samples ranged between 0.25 and 34.0 ng/g dw, and between 0.31 and 549 ng/g dw, for HFRs and OPFRs respectively. As regards levels in fish, concentrations ranged between 9.32 and 461 ng/g lw and between 14.4 and 650 ng/g lw, for HFRs and OPFRs, respectively. Thus, whereas OPFR values were higher in sediments, similar concentrations (in the Evrotas) and even lower concentrations than HFRs (Sava) were found for OPFRs in the fish samples, indicating the lower bioaccumulation potential of OPFRs. Biota to sediment accumulation factors (BSAFs) were calculated and higher values were obtained for HFRs compared to those assessed for OPFRs. [ABSTRACT FROM AUTHOR]

Ecological vulnerability assessment is a key approach to adaptation to and mitigation of environmental degradation. To assess the ecological vulnerability of Yinma River Basin in cold mountain region of China, the ecological vulnerability index (EVI) model was established based on the integrated system dynamic (SD) model and driving force-pressure-state-impact-response-management (DPSIRM) framework. Using multi-sources data including meteorological, remote sensing, basic geographical, sample and socio-economic data, the values of EVI were calculated. The assessment results indicated that the overall ecosystem vulnerability conditions in the study area experienced a degenerating trend. The extremely, heavily and moderately vulnerable zones were mainly distributed in the north-central and southwest parts of the basin. The slightly and lightly vulnerable areas were distributed in the southeast part of the basin. For the distribution of ecological vulnerability grades, in administrative regions, the high rate of slightly vulnerable level and light vulnerable level appeared in Shuangyang district and Panshi city while the largest area rate of moderately, heavily and extremely vulnerable level were distributed in Dehui city, Nongan county, Jiutai district and Yitong county. The study demonstrated that the SD model could efficiently reflect the dynamic mechanism of the basin ecological vulnerability and the results gained closely reflected the reality of the study area. [ABSTRACT FROM AUTHOR]

Riparian ecosystems are amongst the most vulnerable ecosystems of the world. The natural gradients and increasing human perturbations under these ecosystems can be explored for understanding the soil carbon (C) dynamics, especially soil carbon dioxide (CO 2 ) efflux. However, studies on soil CO 2 efflux and its governing variables under different land uses of dry tropical riparian ecosystems are limited. Therefore, the present study aimed (1) to assess the impact of riparian land use on soil CO 2 efflux, and (2) to identify the key drivers of soil CO 2 efflux along the river Ganga, Varanasi, India. The riparian land uses taken in this study were moist sandy flat (MSF), uncultivated sandy land (USL) and cultivated sandy land (CSL) depending upon their slope and distance from river body to upland, respectively. Soil CO 2 efflux and other soil biophysical properties were measured at 54 locations distributed in six sites having these land uses, in dry season of 2014–15. Soil biophysical properties considered in this study were soil organic C, soil moisture, bulk density, porosity, fine particles, microbial biomass C and soil pH. Riparian land uses were found to have significant impact over soil CO 2 efflux with a respective increase of 222, 424 and 63%, for MSF to USL, MSF to CSL, and USL to CSL land use transitions ( P < 0.01), respectively. Similarly, the regulators of soil CO 2 efflux varied with the land uses. It showed strong positive correlation with soil organic C (r = 0.81), fine particles (r = 0.64) and porosity (r = 0.61), whereas negative correlation with soil moisture (r = 0.61) and bulk density (r = 0.62) for overall dataset. However, soil organic C, fine particles, microbial biomass C and soil pH at MSF; soil organic C and microbial biomass C at USL; and soil moisture, porosity and microbial biomass C at CSL land uses were observed to regulate soil CO 2 efflux. The findings revealed that riparian land uses have significant control over soil CO 2 efflux and its biophysical regulators which have relative control over it. Soil organic C, soil moisture, fine particles, porosity and microbial biomass C were identified as prevalent regulators of soil CO 2 efflux under dry seasons. Overall, the results indicate that the biophysical variables in addition to human interferences (CSL land use) have pronounced regulation over soil CO 2 efflux in dry tropical riparian ecosystems. [ABSTRACT FROM AUTHOR]

Report cards are an increasingly popular method for summarising and communicating relative environmental performance and ecosystem health, including in aquatic environments. They are usually underpinned by an Ecosystem Health Index (EHI) that combines various individual indicators to produce an overall ecosystem health “score”. As a result of public water quality concerns, an integrated means of monitoring and reporting on aquatic ecosystem health was needed for the Fitzroy Basin in central Queensland, Australia. The Fitzroy Partnership for River Health was formed to address this need, and developed an EHI and report card for the Basin using existing monitoring data collected from various third parties including regulated companies operations and government. At 142,000 square kilometres, the Fitzroy Basin is the largest catchment draining to the World Heritage Listed Great Barrier Reef. The Fitzroy Basin provides an example of how to deliver an effective aquatic ecosystem health reporting system in a large and complex river basin. We describe the methodology used to develop an adaptive EHI for the Fitzroy Basin that addresses variability, complexity and scale issues associated with reporting across large areas. As well, we report how to manage the design and reporting stages given limitations in data collection and scientific understanding. [ABSTRACT FROM AUTHOR]

Drought as a complex natural hazard encompassing comprehensive information on the occurrence and development of drought using a single variable alone is difficult. In the present study, a composite multivariate drought index (CMDI) was developed based on a copula combining three univariate drought indices (standardized precipitation index [SPI], standardized runoff index [SRI], and water storage deficit index [WSDI]) and four timescales (monthly, quarterly, semi-annually, and annually). The new index combines information on terrestrial water storage, precipitation, and runoff to capture drought comprehensively. Based on the CMDI, drought trends and characteristics were assessed for 10 major basins in China from 2003 to 2020 using the seasonal Mann–Kendall test and the run theory. The results showed that the developed CMDI 1) integrated meteorological and hydrological drought information using the SPI, SRI, and WSDI; 2) captured overall drought development more completely and frequently than traditional drought indices; and 3) monitored an increasing trend of drought in the Qinghai-Tibet Plateau and North China Plain, in addition to a more substantial drought in northern China than in southern China. [Display omitted] • We developed Combined Multivariate Drought Index (CMDI). • CMDI monitors drought from multiple time scales and factors. • CMDI allows robust and reliable drought characterization. [ABSTRACT FROM AUTHOR]

• Process-based model was extended to link with plastic debris model in entire Japan. • Model simulated point and diffuse sources are transported from land to ocean. • Total flux varies according to micro-plastic removal and plastic density. • Plastics discharge to ocean intensively during rainfall seasons. • Methodology is powerful to take measures to reduce plastic input to ocean. Plastic contamination has been receiving considerable attention during the last few decades. Although some models could simulate transport and fate of plastic debris in freshwater systems, complete model for the whole picture of plastic dynamics on basin scale has yet to be established. In the present study, the authors extended process-based eco-hydrology models, NICE (National Integrated Catchment-based Eco-hydrology) and NICE-BGC (BioGeochemical Cycle), to link them with plastic debris model, and applied to all of the 109 first-class (class A) river basins throughout Japan. New model included advection, dispersion, diffusion, settling, dissolution and deterioration due to light and temperature. These processes could help to evaluate effect of mismanaged plastic waste (MPW) and point sources (tyres, personal care products, dust, and laundry) on spatio-temporal dynamics of macro- and micro-plastics there. The model showed simulated hydrologic cycle was generally in good agreement with observed one. In contrast, simulated value of annual-averaged nutrient transports was overestimated in comparison with observed value averaged over non-flood periods. Sensitivity analysis of micro-plastic transport to various factors also implied effects of degradation would not be negligible under some conditions. Generally, large amounts of plastic flowed out of some limited rivers (Tone, Kiso, Yodo, and Ara Rivers) with a large proportion of macro-plastic flux in comparison with micro-plastic flux. Further, scenario analysis quantified the total plastic flux varied according to efficiency of micro-plastic removal in wastewater treatment plants (WWTP) and density of plastic, and was estimated as within the range 1,100 – 3,500 ton/yr, relatively similar to that of existing values. It was also clarified only a limited proportion of plastics discharged onto land flow out into the ocean intensively during rainfall seasons. These results help to quantify impacts of plastic waste on biosphere, and may aid development of solutions and measures to reduce plastic input to the ocean. [Display omitted] [ABSTRACT FROM AUTHOR]

Nitrogen (N) retention sensu lato refers to all processes preventing new reactive nitrogen brought into watersheds through agricultural or industrial activities to be exported by river systems to the sea. Although such processes protect marine systems from the threat of eutrophication and anoxia, they raise other environmental issues, including the acidification of soils, the emission of ammonia and greenhouse gases, and the pollution of aquifers. Despite these implications, the factors involved in N retention are still poorly controlled, particularly in arid and semi-arid systems. The present study evaluates the N fluxes of 38 catchments in the Iberian Peninsula with contrasting climatic characteristics (temperate and Mediterranean), land uses, and water management practices. This diversity allows addressing the contribution of physical and socioecological factors in N retention, and more specifically, exploring the relation between N retention and water regulation. We hypothesise that the extreme flow regulation implemented in the Mediterranean enhances the high N retention values associated with arid and semi-arid regions. The results show that reservoirs and irrigation channels account for > 50% of the variability in N retention values, and above a certain regulation threshold, N retention peaks to values > 85–90%. Future climate projections forecast a decrease in rainfall and an increase in agricultural intensification and irrigation practices in many world regions, most notably in arid and semi-arid areas. Increased water demand will likely lead to greater flow regulation, and the situation in many areas may resemble that of Iberian Mediterranean catchments. High N retention and the associated environmental risks must therefore be considered and adequately addressed. [ABSTRACT FROM AUTHOR]

In a rapidly changing water resources system, dynamic models based on the notion of systems thinking can serve as useful analytical tools for scientists and policy-makers to study changes in key system variables over time. In this paper, an integrated system dynamics simulation model was developed using a system dynamics modelling approach to examine the feedback processes and interaction between the population, the water resource, and the agricultural production sub-sectors of the Volta River Basin in West Africa. The objective of the model is to provide a learning tool for policy-makers to improve their understanding of the long-term dynamic behaviour of the basin, and as a decision support tool for exploring plausible policy scenarios necessary for sustainable water resource management and agricultural development. Structural and behavioural pattern tests, and statistical test were used to evaluate and validate the performance of the model. The results showed that the simulated outputs agreed well with the observed reality of the system. A sensitivity analysis also indicated that the model is reliable and robust to uncertainties in the major parameters. Results of the business as usual scenario showed that total population, agricultural, domestic, and industrial water demands will continue to increase over the simulated period. Besides business as usual, three additional policy scenarios were simulated to assess their impact on water demands, crop yield, and net-farm income. These were the development of the water infrastructure (scenario 1), cropland expansion (scenario 2) and dry conditions (scenario 3). The results showed that scenario 1 would provide the maximum benefit to people living in the basin. Overall, the model results could help inform planning and investment decisions within the basin to enhance food security, livelihoods development, socio-economic growth, and sustainable management of natural resources. [ABSTRACT FROM AUTHOR]

The method used to calculate ecological compensation remains an important but difficult issue in current studies of ecological compensation. In this study, we used the ecological compensation method to examine the natural, social, and economic interactions between ecological and economic systems at the administrative level and between upstream and downstream areas in a river basin, with the aim of capacity control in the total amount of pollutants discharged. We used the information entropy method to build the total pollutant allocation model, in which we included a range of indexes that reflected regional heterogeneity in factors such as population, economic structure, production level, pollution control, and the water environment. The relationship between the capital invested and the quantity of pollutants discharged was used to calculate the unit value of the pollutants, from which we constructed a quantitative model of ecological compensation standard for river basin water environment based on total pollutants control. We used the Xiao Honghe River Basin, China, as a case study, and calculated the ecological compensation values of the water environment from 2008 to 2012 with chemical oxygen demand (COD) as the main pollution evaluation index. From the upper to lower reaches, the compensation value gradually decreased while it gradually increased in terms of time scale. This study provides a valid approach that can be applied to develop a long-term effective mechanism for protecting river basin ecology and improving the system of ecological compensation in river basins. [ABSTRACT FROM AUTHOR]

This study examined the river sediment transport characteristics of the Ping River basin, which is one of the major river basins in Thailand. River surveys of the Ping River were carried out nine times between 2011 and 2013. Survey data included river cross sections, flow velocities, suspended sediment concentration, and bed load transport in the river. Analyzes of these data indicated that suspended transport rates in the Ping River during normal flow conditions in 2012-2013 ranged between 107 and 9,562 metric tons/day (mt/d), but increased to 35,300 mt/d during high flooding conditions (Thailand's Great Flood of 2011). The rate of bed load transport was 1,401 mt/d during the Flood of 2011. However, the measured bed load in 2012-2013 varied between 0 and 482 mt/d. The bed-to-suspended load ratio in the Ping River fluctuated in the broad range of 0-2.0. Estimates of total sediment transport in the Ping River were made using some of the classic equations from the hydrologic literature. The results obtained from the different methods show that the Laursen-Copeland formula gives the best estimate of total sediment transport rate of the Ping River compared to other methods. Results from this study also reveal that the Bhumibol Dam, constructed in 1964, has had a significant effect on suspended sediment load reduction downstream of the dam. [ABSTRACT FROM AUTHOR]

Seasonally continuous long-term information on surface water and flooding extent over subcontinental scales is critical for quantifying spatiotemporal changes in surface water dynamics. We used seasonally continuous Landsat TM/ETM + data and generic random forest-based models to synoptically map the extent and dynamics of surface water and flooding (1986–2011) over the Murray–Darling Basin (MDB). The MDB is a large semi-arid basin with competing demands for water that has recently experienced one of the most severe droughts in the southeast of Australia. We used a stratified random probability sampling design with 500 sample pixels each observed across time to assess the accuracy of the surface water maps. We further developed models to map flooded forest at a riparian site that experienced severe tree dieback. Water indices and bands 5 and 6 were among the top 10 explanatory variables most important for mapping surface water. Surface water extent per season per year showed high inter-annual and seasonal variability, with low extent and variability during the Millennium Drought (1999–2009). Accuracy assessment yielded an overall classification accuracy of 99.9% (± 0.02% standard error) with 87% (± 3%) and 96% (± 2%) producer's and user's accuracy of water, respectively. User's and producer's accuracies of water were higher for Landsat 7 than Landsat 5 data. Both producer's and user's accuracies of water were lower in wet years compared to dry years. The approach presented here can be further developed for global application and is relevant to areas with competing water demands. Quantifying the uncertainty of the accuracy assessment and providing an unbiased accuracy estimate are imperative steps when remotely sensed products are intended to be used for follow on applications. [ABSTRACT FROM AUTHOR]

We apply a linear regression mixed effects model to explore the influence of landscape factors on nitrate-N concentrations in a coastal watershed of Portugal. Landscape composition and configuration metrics, together with variables assessing the physical characteristics of the study area, were used. The analysis was performed using seasonal data from the years 2001 and 2006. The seasonal influence was included as a random effect to account for temporal correlations. Together, the fixed and the random factors explain 78% of the variance, whereas the fixed factors alone explain 10%. Urban, slope, elevation and aggregation index of urban class contribute to the differences found in the NO 3 − -N concentrations. Urban has the weakest effect, whereas slope and elevation show a conditioned negative effect on nitrate-N. The effect of slope gets stronger for higher standard deviations of elevation and the effect of the standard deviation of elevation, measuring the variation of elevation within a sub-watershed, gets stronger for steeper slopes. Of the configuration class level metrics included in the analysis, only aggregation index of urban played a significant role in the final model, and it revealed to be related to urban percentage. The influence of landscape configuration metrics, though observed by others, was not obvious in this study. Future analysis evaluating the effect of metrics selection could be performed. [ABSTRACT FROM AUTHOR]

Excess salt loading from watershed landscapes into river systems acts as a chemical stressor in water bodies and can have significant impacts on downstream water quality. High salinity threatens sustainable crop production globally and is especially prevalent in semi-arid and arid regions. However, relatively little research has been conducted to evaluate salt movement and loadings in natural, high-desert catchments in the face of climate change and extreme climate events. In this study, we use the watershed model SWAT and a newly developed salinity module to simulate the mass transport of 8 major salt ions, SO 4 2−, Cl−, CO 3 2−, HCO 3 −, Ca2+, Na+, Mg2+, and K+, in the soil-aquifer-stream system of the Purgatoire River Watershed (PRW) (Colorado, USA, 8935 km2) via major hydrologic pathways (surface runoff, percolation, recharge, soil lateral flow, groundwater upflux, groundwater discharge) and quantify changes in predicted salt loads with possible future increasing storm intensity. The PRW is susceptible to high salt transport due to high topographic slopes, dry climatic conditions, and sparse vegetation, and loads to the Arkansas River, a major source of irrigation water in the Arkansas River Basin. From study results we conclude that 99% of salt in the Purgatoire River originates from subsurface water pathways (soil lateral flow, groundwater flow), composed primarily of SO 4 2−, Ca2+, and HCO 3 −. If intensity of large storms increases by 5% and 35%, the total salt mass exported from the watershed increases by 12% and 73%, respectively, indicating large influxes of legacy salt from the soil-aquifer system. For baseline and storm intensity scenarios, the PRW contributes significant salt loads to agricultural regions via the Arkansas River, highlighting the need for basin-wide salt management strategies to include upland desert regions. We expect these results, and associated consequences for salt management, to be similar for other upland desert catchments worldwide. • SWAT model is used to quantify salt ion loadings in a high-desert watershed. • Method is applied to the Purgatoire River Watershed (8935 km2), Colorado, USA. • Approximately 99% of salt in the Purgatoire River is sourced from the subsurface. • The Purgatoire River contributes significant salt mass to downstream regions. • Salt loading via groundwater discharge increases with increasing storm intensity. [ABSTRACT FROM AUTHOR]

As the world embraced Artificial Light at Night (ALAN) and its numerous benefits, the transforming nocturnal environment witnessed the negative impacts of this contaminant of emerging concern, and its consequent Light Pollution, on the fitness and populations of numerous organisms. Over the decades, India's unbridled population growth and rapid urbanization have accelerated the use of ALAN yet research on light pollution, in India, as a potential biodiversity threat remains almost untapped. The present study utilized nighttime light data from the Visible and Infrared Imaging Radiation Suite Day-Night Band (VIIRS DNB) to investigate the spatio-temporal trends of ALAN across India's major river basins, emphasizing on critical riparian habitats. The study also aimed to identify the significant effects on night-time brightness in these habitats. Our findings indicated the year, riparian fauna group and presence within and near protected areas as significant determinants of light pollution in the riparian habitats of species of conservation concern. Light pollution was observed to grow in these habitats from the year 2012 to 2020. Higher radiance, in general, were observed for habitats near conurbations, airports, ports and docks, petroleum refineries, thermal power plants, and nuclear power stations. Otter and Turtle habitats had higher night-time brightness than other groups. The significant increase of ALAN within a span of eight years is concerning, particularly for the critically endangered gharial, which was observed to inhabit predominantly darker habitats. This, along with the gaps in our knowledge regarding the effects of ALAN on these species, urgently warrants a better understanding of its effects in riparian ecosystems. We have highlighted research gaps on ALAN from India's perspective and suggest that national biodiversity programs should evaluate ALAN as a potential biodiversity threat to limit its expansion in critical riparian ecosystems. • A first account of Light Pollution (LP) and factors impacting its level in major Indian River basins. • LP has grown significantly in Indian riparian habitats from 2012 to 2020. • Habitats in protected areas have grown brighter with significant effect of year. • The year, species group and protected area had significant effect on LP. • Major sources include conurbation, airports, petroleum refineries and power plants. [ABSTRACT FROM AUTHOR]

Summary In this study, we aimed to assess the population status of bleak ( Alburnus spp.) over the Western Balkan Peninsula in terms of its sustainable use. A second objective was to determine key factors important for fishery management planning. Two different basins, continental (the Danube Basin and the Sava River sub-basin) and marine (the Adriatic and the Aegean Sea Basins) were examined. A sustainability assessment and factor analysis were conducted using the adjusted ESHIPPOfishing model, extended with additional socio-economic sub-elements, and the categorical principal components analysis (CATPCA), respectively. The results of the assessment revealed the bleak populations in the Danube Basin and the Sava River sub-basin to be highly sustainable. The population characteristics with abiotic and biotic factors were responsible for this status, while the influence of socio-economic factors was insignificant. The sustainability status of the bleak populations of the Mediterranean basin varied, with the populations from Ohrid and Skadar Lakes showing a high and those from Prespa and Dojran Lakes a medium status. Socio-economic factors with traditional fishing were the most important for the Mediterranean bleak populations. [ABSTRACT FROM AUTHOR]

There is a growing pressure of human activities on natural habitats, which leads to biodiversity losses. To mitigate the impact of human activities, environmental policies are developed and implemented, but their effects are commonly not well understood because of the lack of tools to predict the effects of conservation policies on habitat quality and/or diversity. We present a straightforward model for the simultaneous assessment of terrestrial and aquatic habitat quality in river basins as a function of land use and anthropogenic threats to habitat that could be applied under different management scenarios to help understand the trade-offs of conservation actions. We modify the InVEST model for the assessment of terrestrial habitat quality and extend it to freshwater habitats. We assess the reliability of the model in a severely impaired basin by comparing modeled results to observed terrestrial and aquatic biodiversity data. Estimated habitat quality is significantly correlated with observed terrestrial vascular plant richness ( R 2 = 0.76) and diversity of aquatic macroinvertebrates ( R 2 = 0.34), as well as with ecosystem functions such as in-stream phosphorus retention ( R 2 = 0.45). After that, we analyze different scenarios to assess the suitability of the model to inform changes in habitat quality under different conservation strategies. We believe that the developed model can be useful to assess potential levels of biodiversity, and to support conservation planning given its capacity to forecast the effects of management actions in river basins. [ABSTRACT FROM AUTHOR]

The increasing resolution of Digital Elevation Models (DEMs) and the development of drainage network extraction algorithms make it possible to develop high-resolution drainage networks for large river basins. These vector networks contain massive numbers of river reaches with associated geographical features, including topological connections and topographical parameters. These features create challenges for efficient map display and data management. Of particular interest are the requirements of data management for multi-scale hydrological simulations using multi-resolution river networks. In this paper, a hierarchical pyramid method is proposed, which generates coarsened vector drainage networks from the originals iteratively. The method is based on the Horton–Strahler's (H–S) order schema. At each coarsening step, the river reaches with the lowest H–S order are pruned, and their related sub-basins are merged. At the same time, the topological connections and topographical parameters of each coarsened drainage network are inherited from the former level using formulas that are presented in this study. The method was applied to the original drainage networks of a watershed in the Huangfuchuan River basin extracted from a 1-m-resolution airborne LiDAR DEM and applied to the full Yangtze River basin in China, which was extracted from a 30-m-resolution ASTER GDEM. In addition, a map-display and parameter-query web service was published for the Mississippi River basin, and its data were extracted from the 30-m-resolution ASTER GDEM. The results presented in this study indicate that the developed method can effectively manage and display massive amounts of drainage network data and can facilitate multi-scale hydrological simulations. [ABSTRACT FROM AUTHOR]

In order to achieve the integrated river basin management in the arid and rapid developing region, the Heihe River Basin (HRB) in Northwestern China, one of critical river basins were selected as a representative example, while the Murray–Darling Basin (MDB) in Australia and the Colorado River Basin (CRB) in the USA were selected for comparative analysis in this paper. Firstly, the comparable characters and hydrological contexts of these three watersheds were introduced in this paper. Then, based on comparative studies on the river basin challenges in terms of the drought, intensive irrigation, and rapid industrialization, the hydrological background of the MDB, the CRB and the HRB was presented. Subsequently, the river management strategies were compared in three aspects: water allocation, water organizations, and water act and scientific projects. Finally, we proposed recommendations for integrated river basin management for the HRB: (1) Water allocation strategies should be based on laws and markets on the whole basin; (2) Public participation should be stressed by the channels between governance organizations and local communities; (3) Scientific research should be integrated into river management to understand the interactions between the human and nature. [ABSTRACT FROM AUTHOR]

Summary A hydroeconomic optimization approach is used to guide water management in a Chinese river basin with the objectives of meeting water quantity and water quality constraints, in line with the China 2011 No. 1 Policy Document and 2015 Ten-point Water Plan. The proposed modeling framework couples water quantity and water quality management and minimizes the total costs over a planning period assuming stochastic future runoff. The outcome includes cost-optimal reservoir releases, groundwater pumping, water allocation, wastewater treatments and water curtailments. The optimization model uses a variant of stochastic dynamic programming known as the water value method. Nonlinearity arising from the water quality constraints is handled with an effective hybrid method combining genetic algorithms and linear programming. Untreated pollutant loads are represented by biochemical oxygen demand (BOD), and the resulting minimum dissolved oxygen (DO) concentration is computed with the Streeter–Phelps equation and constrained to match Chinese water quality targets. The baseline water scarcity and operational costs are estimated to 15.6 billion CNY/year. Compliance to water quality grade III causes a relatively low increase to 16.4 billion CNY/year. Dilution plays an important role and increases the share of surface water allocations to users situated furthest downstream in the system. The modeling framework generates decision rules that result in the economically efficient strategy for complying with both water quantity and water quality constraints. [ABSTRACT FROM AUTHOR]