Trends In Water Resources Research Articles

Assessment of current and future trends in water resources in the Gambia River Basin in a context of climate change

Accurate assessment of water resources at the watershed level is crucial for effective integrated watershed management. While semi-distributed/distributed models require complex structures and large amounts of input data, conceptual models have gained attention as an alternative to watershed modeling. In this paper, the performance of the GR4J conceptual model for runoff simulation in the Gambia watershed at Simenti station is analyzed over the calibration (1981–1990) and validation period (1991–2000 and 2001–2010). The main inputs to conceptual models like GR4J are daily precipitation data and potential evapotranspiration (PET) measured from the same catchment or a nearby location. Calibration of these models is typically performed using the Nash–Sutcliffe daily efficiency with a bias penalty as the objective function. In this case, the GR4J model is calibrated using four optimization parameters. To evaluate the effectiveness of the model's runoff predictions, various statistical measures such as Nash–Sutcliffe efficiency, coefficient of determination, bias, and linear correlation coefficient are calculated. The results obtained in the Gambia watershed at Simenti station indicate satisfactory performance of the GR4J model in terms of forecast accuracy and computational efficiency. The Nash–Sutcliffe (Q) values are 0.623 and 0.711 during the calibration period (1981–1990) and the validation period (1991–2000), respectively. The average annual flow observed during the calibration period is 0.385 mm while it increases with a value of 0.603 mm during the validation period. As for the average flow simulated by the model, it is 0.142 mm during the calibration period (i.e., a delay of 0.142 mm compared to the observed flow), 0.626 mm in the validation period (i.e., an excess of 0.023 mm compared to the observed flow). However, this study is significant because it shows significant changes in all metrics in the watershed sample under different scenarios, especially the SSP245 and SSP585 scenarios over the period 2021–2100. These changes suggest a downward trend in flows, which would pose significant challenges for water management. Therefore, it is clear that sustainable water management would require substantial adaptation measures to cope with these changes.

Evolution Characteristics of Rainfall and Runoff in the Upper Reaches of Zhang River Basin

It is of great significance to study and analyze the surface water resources and their change trend in the groundwater overexploitation area of the North China Plain, which is of great significance to solve the shortage of water resources in the groundwater overexploitation area of the North China Plain, promote the exploitation of groundwater, and realize the sustainable development of water resources. This paper takes Minyou Irrigation District of Handan City, a typical overexploitation area in the North China Plain, as an example. Based on the measured rainfall and runoff data from 1957 to 2020, the Mann–Kendall trend test, cumulative anomaly method, double cumulative curve method, and Morlet wavelet transform were used to analyze and predict the trend of water resources in the irrigation area and the individual contribution of climate change and human activities to runoff change. The results show that the annual rainfall and annual runoff in the irrigation area have a significant downward trend and significant cyclical changes throughout the study period. In 1977, the annual runoff showed a sudden change, and the average contribution rates of climate change and human activities to its change were 40.55% and 59.46%, respectively. In the future (2020–2035), runoff will remain stable and rainfall will show an increasing trend. The research results can provide scientific reference for the development, utilization, and rational allocation of surface water resources in the groundwater overexploitation area of the North China Plain.

Temporal and spatial variation characteristics of surface water area in the Yellow River Basin from 1986 to 2021.

The Yellow River Basin is short of water resources. The dynamic monitoring of surface water area is helpful to clarify the distribution and change trend of water resources in this area. It is of great scientific significance to deeply understand the impacts of climate change and human activities on water resources and ensure the ecological security of the basin. Based on the Google Earth Engine (GEE) cloud platform, we analyzed the spatial variations of surface water area in the Yellow River Basin from 1986 to 2021 by using the mixed index algorithm, and revealed the driving factors of surface water area change in the Yellow River Basin. The results showed that the overall recognition accuracy of the water extraction algorithm based on mixing index was 97.5%. Compared with available water data products, the proposed algorithm can guarantee the integrity of the whole water area to a certain extent. The surface water area in the upper, middle, and lower reaches of the Yellow River Basin was 71.7%, 18.4%, and 9.9% of the total surface water area, respectively. From 1986 to 2021, the surface water area of the basin showed an overall upward trend, with a total increase of 3163.6 km2. The surface water area of the upper, middle, and downstream regions increased by 72.0%, 22.4%, and 5.6%, respectively. The increase of precipitation was the main reason for the increase of water area, with a contribution of 55%. Vegetation restoration and construction of water conservancy projects had increased the water area of the basin. The intensification of human water extraction activity reduced the water area of the basin.

Analysis of changing trend of water resources and water environment quality in china from 2009 to 2019

Based on the statistical analysis of China Water Resources Bulletin, China environmental situation Bulletin and national environmental statistics yearbook during 2008-2019, we summarized the water resources and water environment quality of seven major basins, and the proportion, main pollutants and change trend of various types of water quality are discussed. Meanwhile, wastewater discharge and pollution discharge are also analyzed. The results show that in the recent years, the overall water environment quality in China is improving, but the overall water environment quality is still not optimistic. Water resources are not only the basis for human survival and development, but also a strategic resource for the development of the national economy. According to the <<World Water Development Report 2018>> issued by the United Nations, the current global water demand is increasing at a rate of 1% per year. This demand will continue to increase, and my country's water resources are even scarcer, and the per capita consumption is only 1/4 of the global average. In the face of this situation, understanding the state and changing trends of my country's water resources and water environment, and putting forward targeted resource conservation and pollution control measures are of great significance to alleviating the problem of my country's water shortage.

Characteristics and Driving Mechanism of Water Resources Trend Change in Hanjiang River Basin.

Studying the historical and future trends of water resources in a basin and explaining the causes of water resource changes is very important, which is key to the management of water resources in a basin. The Hanjiang River Basin is an important water supply source for southwestern Fujian and eastern Guangdong, but it has an uneven spatial and temporal distribution of water resources and an outstanding conflict between supply and demand. In this study, the SWAT model was used to simulate the conditions of the Hanjiang River Basin in the last 50 years, using long time series climate data to study the characteristics and driving mechanism of water resources trend change. The results show that the water resources in the basin have not increased significantly in the last 50 years, but evapotranspiration has increased significantly. The forecast results for water resources in the future are reduced. The water resource changes in the basin have been unevenly distributed in the last 50 years. Climate change has been the main factor in total water resource change in the basin, while the difference in water resource change trends within the basin is caused by land use. The key reason for the decrease in water resources in the Hanjiang River Basin is the significant increase in evapotranspiration due to the significant increase in temperature. If this situation continues, the available water resources in the basin will continue to decline. In fact, many basins around the world are currently likely to have such problems, such as the 2022 summer drought in the Danube River Basin in Europe and the Yangtze River Basin in China, so this article is informative and representative of future water resources management in the basin.

Prediction of water resources change trend in the Three Gorges Reservoir Area under future climate change

In this study, the water intake module and the confluence module were added to the Community Land Model version 4.5 (CLM 4.5), forming the Community Land Model-Dualistic Water Cycle (CLM-DWC) model (land surface hydrological model). It solved the problem that the influence of human activities was not considered in the existing hydrological coupling simulation process, which so as to the inaccuracy of the simulation process. The CLM-DWC model was driven by the average results of five Global Climate Models (GCMs) ensemble to form the “atmosphere-land-hydrology” fully coupled model to predict the temporal and spatial variation trends of water resources in the Three Gorges Reservoir Area (TGRA) from 2021 to 2050 under Representative Concentration Pathway (RCP) 2.6, RCP4.5 and RCP8.5. In the future scenarios, in terms of spatial distribution, the runoff, surface water and groundwater all indicated the high at the belly of the reservoir and low at the head and tail of the reservoir, which were in good consistency with the baseline period. In terms of intra-annual distribution and inter-annual variability, runoff depth increases by 20.8 mm at RCP4.5 compared with the baseline period, and it tended to decrease under RCP2.6 and RCP8.5. At the same time, under the three scenarios, the average increase of surface water was 3.44 %, groundwater decreases by an average of 11.72 %. Accurately predicting the change trend of water resources in the TGRA under climate change has great significance for future water resources management and planning in the reservoir area.

Problems and trends in water resources use in the Russian-Kazakhstan transboundary region

This article considers the trends in use of water resources of transboundary rivers in the adjacent regions of Russia and Kazakhstan. The problems of transboundary water use in the river basins of the Ural and the Irtysh in the Russian-Kazakh region as well as the influence of economic activity in China are outlined. Among the regions under study, we identified those areas of the three countries whose water economy depends on the transboundary rivers of neighbouring regions or significantly regulates the hydrological regime of these rivers. To study and calculate water use trends, data on the water use from 2010 to 2019 was used. The structural specifics of water use are shown and the ratio of water consumption to available renewable water resources for the regions of Russia, Kazakhstan and the Xinjiang-Uygur Autonomous Region of China is determined. General trends and differences in water use in the water sectors of the transboundary river basins of the Ural and Irtysh have been identified.

An Analysis on the Trend of Sustainable Utilization of Water Resources in Dongying City, China

Dongying City is located in the northeast of Shandong Province and is the central city of the Yellow River Delta. It has abundant oil and gas resources, vast saline-alkali land area, and saline brine as the main groundwater. Therefore, freshwater resources are poor, as there is a contradiction in the water supply and its demand. Judging the trend of sustainable utilization of water resources in Dongying City has an important role in promoting the local conservation and exploitation of water resources, recycling water resources, and undermining the contradiction between supply and demand of urban water resources. In this paper, 21 indicators have been selected to build the index system for judging the sustainable utilization of water resources. In addition, the DPSIR model is used to evaluate the sustainable utilization trend of water resources in Dongying City from 2005 through 2017. On the other hand, the GM (1, 1) model is considered to predict the sustainable potential-utilization of water resources in Dongying City from 2019 through 2025. The results demonstrated that the sustainable utilization of water resources in Dongying City shows an increasing trend from 2005 to 2017, So that the highest and lowest values are in 2017 and 2005, respectively. In addition, the sustainable potential-utilization of water resources in Dongying City may indicate a continuous upward trend from 2019 through 2025. Rainfall, runoff of the Yellow River and water resources per capita are the main factors affecting the sustainable utilization of water resources. According to the continuous improvement of residents' awareness of water saving and water-saving level, the development and exploitation of water resources will be more and more reasonable.

Knowledge map of Yellow River Basin’s water resources based on literature analysis

The Yellow River Basin (YRB) is an important economic zone in China. The issue of water ecology has attached widely attention by scholars and society. This paper systematically reviewed the status, hotspots and development tendency on water resources research in the YRB based on the China National Knowledge Infrastructure (CNKI) database from 1992 to 2019. The SATI4.0 was used to analyze the annual publication, journal sources and keywords. High-frequency keywords were extracted, and software including NetDraw, SPSS and CiteSpace were used to analyze the co-occurring keywords, clustering and research frontier. Results showed that: (1) The number of published papers had increased before 2005 and decreased after it. The quantity of paper has increased sharply since 2018, indicating that the research has a new direction. (2) The source of journals mainly concentrated on basic subjects and hydraulic engineering. (3) The cluster analysis shows that hydrologic features, water management and protection and the water rights system are hotspots. (4) The result of research frontier indicates that sensitivity, ecological protection and high-quality development of water resources have ample research perspectives. It is general trend to combine the scientific methods with traditional methods. The results are conducive to systematically understand research advances and trends of water resources under changing environment, thereby promoting the construction of ecological civilization in the YRB.

Future trends of water resources and influences on agriculture in China.

Water resources are indispensable for all social-economic activities and ecosystem functions. In addition, changes in water resources have great significance for agricultural production. This paper uses five global climate models from CMIP5 to evaluate the future spatiotemporal variation in water resources in China under four RCP scenarios. The results show that the available precipitation significantly decreases due to evapotranspiration. Comparing the four RCP scenarios, the national average of the available precipitation is the highest under the RCP 2.6 and 4.5 scenarios, followed by that under the RCP 8.5 scenario. In terms of spatial distribution, the amount of available precipitation shows a decreasing trend from southeast to northwest. Regarding temporal changes, the available precipitation under RCP 8.5 exhibits a trend of first increasing and then decreasing, while the available precipitation under the RCP 6.0 scenario exhibits a trend of first decreasing and then increasing. Under the RCP 2.6 and 4.5 scenarios, the available precipitation increases, and the RCP 4.5 scenario has a higher rate of increase than that of RCP 2.6. In the context of climate change, changes in water resources and temperature cause widespread increases in potential agricultural productivity around Hu’s line, especially in southwestern China. However, the potential agricultural productivity decreases in a large area of southeastern China. Hu’s line has a partial breakthrough in the locking of agriculture, mainly in eastern Tibet, western Sichuan, northern Yunnan and northwestern Inner Mongolia. The results provide a reference for the management and deployment of future water resources and can aid in agricultural production in China.

Assessment of impacts of utilization on water resources in the basin of trans-boundary Red river system

The Red river system is the large trans-boundary river system, there has been no united system of hydrology stations as well as integrated plan for the water use and management in the whole basin. The trend of water resources change in the Red river system basin has been assessed on the basic of statistic analyses of data observed during the studies, especially in the time when the exploitation of water resources has been intensified for the multisectoral development. This paper shows some of the results from considerations of the water use in the highlands that is influential in water resources in the Red river system basin and the planned reservoirs which are built in the basin of Red river system. The results include the assessment of the state and trend of water resources in the Red river system basin, the trend of water level lowering in the lowlands and its impacts.

An Assessment of Water Resources in the Taiwan Strait Island Using the Water Poverty Index

Water resources are a very important issue in the Global Risk 2015 published by the World Economic Forum. The research objective of this study was to construct a Water Poverty Index (WPI) for islands. The empirical scope of this study was based on Kinmen Island in the Taiwan Strait, which has very scarce water resources. Kinmen has a dry climate with low rainfall and high evaporation. Therefore, the Kinmen area is long-term dependent on groundwater resources and faces serious water resource problems. This study used the WPI to examine various issues related to water resources. In addition, this study selected several main indicators and performed time series calculations to examine the future trends of water resources in Kinmen. The results show that the overall water resources of Kinmen are scarce. To ensure sustainable development of water resources in Kinmen, policies to improve water scarcity, such as water resource development, water storage improvement, and groundwater control, should be researched. The research results of this study can be used as a reference for government agencies in formulating and revising water resources to achieve the sustainable development of island-type water resources.

Assessment of multi-model climate projections of water resources over South America CORDEX domain

Future climate projections focusing on precipitation and water resource trends over South America (SA) are investigated using two ensembles. One of them is composed of three global climate models (GCMs), and the other of eight regional climate models (RCMs) from the Coordinated Regional Climate Downscaling Experiment (CORDEX). The present (1970–2005) and the future (2006–2100) climate trends are analyzed for representative pathway scenarios 4.5 (RCP4.5) and 8.5 (RCP8.5). For the most pessimistic scenario (RCP8.5), trends in water resources are assessed considering the terrestrial branch of the hydrologic cycle by analyzing the precipitation minus evapotranspiration (P-ET). For the present climate, RCMs added value to the GCMs in simulating more realistic precipitation fields in several regions. GCMs and RCMs project, in general, the same precipitation change signal for the end of the 21st century over SA, which is stronger in RCP8.5 than in RCP4.5. For RCP8.5 in most regions, GCMs and RCMs ensembles have the same precipitation trend signal, but a great spread between the ensemble members, which is greater in austral summer than winter, can be noted. In winter a negative trend in rainfall in most members and regions predominates. At the end of the 21st century, relative changes in rainfall in RCP8.5 are in the range of +14% (over northeastern Brazil in summer) to − 36% (over the Andes Mountains in winter). In RCP8.5, the ensembles project an increase in air temperature with a similar magnitude, while in RCP4.5 the trends are weaker. For air temperature, there is small spread between members, and the positive trend is statistically significant for all ensemble members in the RCP8.5 scenario. In terms of water resources, on an annual scale, for RCP8.5 the RCM ensemble projects a larger area with wetter conditions in the future than GCMs. Regionally, it is expected a decrease in water availability in the Amazon basin and an increase over northeast Brazil and southeast SA during the summer. In other regions (northern Amazon, the Andes Mountains and Patagonia) the ensembles indicate drier conditions in the future winter, except in southern Amazon. It is expected that such information could be useful for devising adaptation and mitigation policies due to climate change over the SA.

Rainwater Harvesting - A Potential Safety Net for Water Security in Ghana

Water is an important medium for many activities including water for consumptive and non-consumptive purposes. Lack of water quality and quantity does not only hampers socio-economic development but affects agricultural productivity, sustainable development, sanitation, health, industrial development and the ecosystem. The advent of climate change is known to affect water flow, increases dry season spells and drought, and influences reservoirs or deep groundwater wells thus worsening the precarious water situation in Africa. About 1.7 billion of the world population lives in water scarce regions and this is projected to grow to about 300% or 5 billion by 2025 especially in Africa. In Ghana, population growth, pollution of river bodies, high evapotranspiration, erratic rainfall pattern and environmental degradation among others have affected water availability and use. These challenges will therefore require a deliberate water harvesting, integrated water management and conservation, water use efficiency and capacity building to withstand the dwindling trend of water resources in the country. This paper therefore seeks to inform policy makers, stakeholders, institutions responsible for water resources management among others to consider water harvesting as a potential solution to the many challenges including water shortages, floods, and land degradation. The article was carried out through extensive review of literature, official reports and policy documents. It shows the need to adopt appropriate techniques for rainwater harvesting to address the perennial water scarcity in the country.

Development of a New Quantile-Based Method for the Assessment of Regional Water Resources in a Highly-Regulated River Basin

In this paper, we present a study of assessing regional water resources in a highly regulated river basin, the Dee river basin in the UK. The aims of this study include: 1) to address the issue of hydrological simulations for regulated river catchments; 2) to develop a new method revealing the trends of water resources for different scenarios (e.g. dry and wet) and 3) to facilitate water resources assessment under both climate change impacts and regulations. We use the SWAT model to model the hydrological process of the river basin with carefully designed configurations to isolate the impact from the water use regulations and practice. The spatially-distributed model simulations are then analysed with the quantile regression method to reveal the spatial and temporal patterns of regional water resources. The results show that this approach excels in presenting distributed, spatially focused trend information for extremely dry and wet scenarios, which can well address the needs of practitioners and decision-makers in dealing with long-term planning and climate change impact. The representation of the management practice in the modelling process helps identify the impact from both climate change and necessary regulatory practices, and as such lays a foundation for further study on how various management practices can mitigate the impact from other sources such as those from climate change. The novelty of the study lies in three aspects: 1) it devises a new way of isolating and representing management practice in the hydrological modelling process for regulated river basins; 2) it integrates the QR technique to study spatial-temporal trends of catchment water yield in a distributed fashion, for wet and dry scenarios instead of the mean; 3) the combination of the methods are able to reveal the impacts from various sources as well as their interactions with catchment water resources.

Evolution and Trend of Water Resources in Qinghai-Tibet Plateau

Evolution and Trend of Water Resources in Qinghai-Tibet Plateau

Analysis on the evolution trend of water resources and water environment in Xiangjiang River basin

According to the daily flow data collected by three representative hydrological stations in the Xiangjiang River basin which are the Guiyang station in the upstream section, the Hengshan station in the midstream section, and the Xiangtan station in the downstream section, and the water environment data collected from the Hunan Water Resources Bulletin, Mann-Kendal method was used to analyze the changes of the annual average flow of the Xiangjiang River basin in the past 20 years as well as the variation of water environment quality in the whole year, flood season and non-flood season. Based on these analysis, the evolution trend of water resources and water environment in the Xiangjiang River basin is further forecasted. The results show that the annual runoff of the upper reaches of the Xiangjiang River basin tends to be stable, and the runoff of the middle and lower reaches is decreasing. The water quality of the Xiangjiang River basin got deteriorated from 1996 to 2010. A sudden change occurred around 2012, and the water quality of the basin gradually improved.

Water resources of Ukraine in the XXI century under climate change scenarios (RCP4.5 AND RCP8.5)

Data of climate change scenarios RCP8.5 and RCP4.5 (Representative Concentration Pathways) were used. They were proposed for consideration in the Fifth Report of Intergovernmental Panel on Climate Change. Average long-term annual flow values using meteorological data (air temperature and precipitation) from the scenarios for the period 2011-2050 were calculated. 84 points (grid nodes) uniformly distributed on the territory of Ukraine were studied. The calculations were made based on the model "climate-runoff", developed in Odessa State Environmental University. Projection of changes in water resources was given by comparing the calculation results in the past (before 1989) and in the future (2011-2050). The major trends in water resources of Ukraine were established. It is shown that by the middle of the XXI century reducing of water resources is expected on the plain territory of Ukraine (70% in the southeast). In the geographical zone of the Ukrainian Carpathians, especially in the Tisa river basin, its stability or growth is possible. Analysis of changes in the ratio of moisture and heat resources showed that climate aridity will be intensify and the insufficient moisture zone and the semiarid zone will be widen.

Comprehensive evaluation of multiple methods for assessing water resources variability of a lake–river system under the changing environment

Abstract The inherent regularities of hydrological processes will not be stationary under the changing environment, making the evaluation of hydrological characteristics and trend forecasting face great uncertainty. Based on the observed streamflow series in the Poyang Lake catchment during the period 1960–2013, this study investigated the evolution characteristics and future trend of water resources. The extracted trend component by wavelet decomposition and the reliability of trend forecasting by rescaled range analysis (R/S analysis) were verified and assessed by a non-parametric statistical test. Results indicate a change point at 1995 when the trend of annual streamflows across the catchment changed. Periodic components indicated that the lake basin seems to enter into an increasing process under inter-decadal scale, while decreasing under inter-annual scale in the near future. R/S analysis revealed that annual streamflow series of most stations in Poyang Lake show ‘weaker’ or ‘very weak’ persistence. For the whole study period, Hurst exponents of most stations are less than 0.5 (0.224–0.339), therefore, opposite from the increasing trend of historical series, decreasing trend is forecasted for the basin. However, due to the effect of intensified human activities in the Fuhe sub-basin, the reliability of R/S analysis on trend forecasting is disturbed at Lijiadu station.

Estimation of future water resources of Xiangjiang River Basin with VIC model under multiple climate scenarios

Variation trends of water resources in the Xiangjiang River Basin over the coming decades have been investigated using the variable infiltration capacity (VIC) model and 14 general circulation models' (GCMs') projections under the representative concentration pathway (RCP4.5) scenario. Results show that the Xiangjiang River Basin will probably experience temperature rises during the period from 2021 to 2050, with precipitation decrease in the 2020s and increase in the 2030s. The VIC model performs well for monthly discharge simulations with better performance for hydrometric stations on the main stream of the Xiangjiang River than for tributary catchments. The simulated annual discharges are significantly correlated to the recorded annual discharges for all the eight selected target stations. The Xiangjiang River Basin may experience water shortages induced by climate change. Annual water resources of the Xiangjiang River Basin over the period from 2021 to 2050 are projected to decrease by 2.76% on average within the range from −7.81% to 7.40%. It is essential to consider the potential impact of climate change on water resources in future planning for sustainable utilization of water resources.