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Groundwater exploitations in semi‐arid regions result in significant declines of groundwater levels and streamflow and even trigger seasonal streamflow drying up, which may bring adverse impacts on riparian ecosystems. It is critical to explore future streamflow changes caused by variable climate scenarios and groundwater exploitation intensities; however, a comprehensive assessment of the streamflow drying up frequency remains lacking. Furthermore, the thresholds of controlling factors beyond which streamflow drying up occurs have rarely been explored. Here we develop an integrated surface water‐groundwater model for the Taoer River Basin (TRB), a typical semi‐arid watershed in northeast China. We apply the model to multiple future scenarios to reveal the frequency of potential streamflow drying up and explore the thresholds of controlling factors of streamflow drying up based on a decision tree method. We find that the groundwater level in the lower region of the TRB (LTRB) is hard to recover to the riverbed elevation and the streamflow drying up frequency is still high unless the groundwater exploitation is reduced by 50%. However, this leads to a competition between the ecological and economic objectives. Our results also show that the streamflow drying up frequency in the LTRB is very sensitive to the upstream water inflow that can be regulated through the reservoir operation or inter‐basin water diversion, indicating the importance of a basin scale strategic management. The findings of this paper can help policy makers sustainably exploit water resources in semi‐arid regions. [ABSTRACT FROM AUTHOR]

With the development of rapid industrialization, urbanization, and modernization, water resources have been facing a series of increasingly severe problems in China, especially in urban areas. However, the absence of an effective, scientific evaluation method may lead to a lack of awareness of sustainable water usage. Thus, this paper focuses on performance analysis for regional sustainable water use in China. First, the sustainable water management (SWM) efficiency is defined, and then, six indicators are selected to construct an evaluation index system. Given that experts are usually not completely rational in practice, we need to take the effect of the experts' nonrationality into consideration when evaluating the SWM efficiency. In view of the indicators' uncertainty and fuzziness, and the experts' nonrationality, the hesitant fuzzy TODIM (HF‐TODIM; TODIM is an acronym in Portuguese for interactive multicriteria decision making) method, which can capture the influence of the experts' psychological factors on the evaluation results, is used to evaluate the SWM efficiency. Furthermore, the assessment method is applied to some sample regions in Tuojiang River Basin. Based on the calculated results, some findings and implications for the SWM efficiency in the sample regions are analyzed. Finally, the applied results using the proposed method are compared with the results derived using the HF‐TOPSIS (hesitant fuzzy technique for order preference by similarity to an ideal solution in hesitant fuzzy environment) method. Through the comparative analysis, we conclude that the HF‐TOPSIS method does not take the experts' psychological factors into consideration, but the HF‐TODIM method can avoid this issue and is very useful for the evaluation of the regional SWM efficiency. [ABSTRACT FROM AUTHOR]

Acquiring freshwater resources is a necessary component of sustainable human settlement subject to increasing pressure from population and climate changes. This sometimes scarce resource primarily comes from rivers, and international river basins ( IRBs), where watersheds and watercourses cross political boundaries, are often spaces of great political tension and conflict worldwide. Such conflict potential has garnered interest from a wide range of research communities, and each emphasises public access to hydrologic data as integral to successful international management of IRBs. However; these hydrologic data, especially measurements of river flow rate, are often closely guarded state secrets. Satellites have been cited as a key technology set to challenge this data monopoly that have yet been unable to calculate river flow rate without some form of guarded ancillary data. Now, at-many-stations hydraulic geometry ( AMHG) offers a means of circumventing data limitations without any a priori information, and the forthcoming NASA/ CNES Surface Water and Ocean Topography ( SWOT) satellite also promises to estimate flow rates solely from its novel measurements following launch. In this paper, we explore how these newly available estimates of river flow rate could reconfigure water-management and interstate relations in IRBs, and demonstrate AMHG, for two cases: the Ganges- Brahmaputra and Mekong. For these basins we find that satellite flow rate retrievals will likely reinforce and favour state-level negotiations of water resource governance. Also, satellite flow retrievals can have the direct, concrete effect of improving hydrologic understanding of the upstream Ganges- Brahmaputra, a sorely needed advance that will positively benefit millions of Bangladeshis and affect state-level interactions between India, China, and Bangladesh. Finally, we avoid offering prescriptive water management solutions for each case, as local stakeholders will ultimately determine if and how such satellite retrievals will be used. [ABSTRACT FROM AUTHOR]

Revegetation programmes aim to avoid land degradation, control soil erosion, reduce floods, and improve ecological conditions. China has planted billions of trees over the past 20 years. However, little is known about the effectiveness of this artificial revegetation and its consequences on China's national conservation policies and changes in biophysical factors at the county level. Here we use satellite time series data and develop a new metric, the revegetation index (RVI), that quickly monitors revegetation and its long‐term changes. We found that the number of regions where the Grain to Green Program (GTGP) was successfully implemented was only about 55.8% of the areas of GTGP implementation. Surprisingly, we provide observational evidence that the implementation of the GTGP can decrease soil erosion and drought, and increase water availability, but revegetation in the Yangtze River basin (YRB) in China has a limited impact on soil erosion, water, and drought. In particular, for revegetation between 1999 and 2016, indicating that a previous assessment by the Government revealed as official statistics may have overestimated the effects of the ecological restoration practices. [ABSTRACT FROM AUTHOR]

The water ecological environment problem in water resources management of river basins mainly lies in the incoordination between the utilization and protection of water resources among different regions. Ecological compensation, therefore, is needed in order to solve this problem. The measurement of reasonable compensation standard plays a vitally important role in the successful establishment of ecological compensation. In this study, a four‐level compensation standard called 'minimum‐basic‐complete‐maximum' (MBCM) is proposed, which is based on the calculation of direct cost, the equalization of essential public service for water, opportunity loss and the comprehensive benefit of water ecological environment protection in the source region. MBCM method provides a multi‐level platform for the establishment of the compensation mechanism, which enables different departments to know their respective costs and benefits clearly. The Sanjiangyuan region (SR) in China is chosen as the study area. The results show that (1) the minimum compensation standard for the SR is 300 million RMB per year; (2) the basic compensation standard is 1.7 billion RMB per year; (3) the complete compensation standard is about 3.75 billion RMB per year; (4) the maximum compensation standard creates the total economic value of 181.6 billion RMB for the downstream water output. The proposed MBCM four‐level compensation standard can also be applied to other river source regions. [ABSTRACT FROM AUTHOR]

Investigating the changes in streamflow regimes in response to various influencing factors contributes to our understanding of the mechanisms of hydrological processes in different watersheds and to water resource management strategies. This study examined streamflow regime changes by applying the indicators of hydrologic alteration method and eco‐flow metrics to daily runoff data (1965–2016) from the Sandu, Hulu and Dali Rivers on the Chinese Loess Plateau, and then determined their responses to terracing, afforestation and damming. The Budyko water balance equation and the double mass curve method were used to separate the impacts of climate change and human activities on the mean discharge changes. The results showed that the terraced and dammed watersheds exhibited significant decreases in annual runoff. All hydrologic metrics indicated that the highest degree of hydrologic alteration was in the Sandu River watershed (terraced), where the monthly and extreme flows reduced significantly. In contrast, the annual eco‐deficit increased significantly, indicating the highest reduction in streamflow among the three watersheds. The regulation of dams and reservoirs in the Dali River watershed has altered the flow regime, and obvious decreases in the maximum flow and slight increases in the minimum flow and baseflow indices were observed. In the Hulu River watershed (afforested), the monthly flow and extreme flows decreased slightly and were categorized as low‐degree alteration, indicating that the long‐term delayed effects of afforestation on hydrological processes. The magnitude of the eco‐flow metrics varied with the alteration of annual precipitation. Climate change contributed 67.47% to the runoff reduction in the Hulu River watershed, while human activities played predominant roles in reducing runoff in the Sandu and Dali River watersheds. The findings revealed distinct patterns and causes of streamflow regime alteration due to different conservation measures, emphasizing the need to optimize the spatial allocation of measures to control soil erosion and utilize water resources on the Loess Plateau. [ABSTRACT FROM AUTHOR]

Understanding the dominant causes of streamflow alteration and effects of the current water diversion scheme is beneficial for sustainable management of water resources in an arid area. This study presents a quantitative attribution of the run‐off changes between headstreams and mainstream from 1960 to 2015 using the Choudhury–Yang equation and evaluates the effects of 18 times of ecological water conveyance in the lower reaches of the Tarim River Basin (TRB). Our results suggest that climate change was the primary determinant of increase of the streamflow in the headstreams from 2000 to 2015. While in the mainstream, human activities played a dominant role in deduction in the streamflow with the contribution of 54.8–355.6%. Eighteen episodes of ecological water conveyance have a positive effect on rising groundwater level and are highly related to seed falling time of Shrub and Perennial herbaceous and Annual herbaceous except for Arbor. It indicates that restoring the long‐term drying of the lower reaches through continuous water conveyance is feasible, although the existing programme has not restored the entire riparian system. Our study suggests that it is necessary to adopt an integrated approach for water resources allocation rather than relying on a single tributary contribution in the TRB. [ABSTRACT FROM AUTHOR]

Restored annual streamflow ( Qr) and measured daily streamflow of the Chaohe watershed located in northern China and associated long-term climate and land use/cover data were used to explore the effects of land use/cover change and climate variability on the streamflow during 1961-2009. There were no significant changes in annual precipitation ( P) and potential evapotranspiration, whereas Qr decreased significantly by 0.81 mm/yr ( p < 0.001) over the study period with a change point in 1999. We used 1961-1998 as the baseline period ( BP) and 1999-2009 the change period ( CP). The mean Qr during the CP decreased by 39.4 mm compared with that in the BP. From 1979 to 2009, the grassland area declined by 69.6%, and the forest and shrublands increased by 105.4 and 73.1%, respectively. The land use/cover change and climate variability contributed for 58.4 and 41.6% reduction in mean annual Qr, respectively. Compared with the BP, median and high flows in the CP decreased by 38.8 and up to 75.5%, respectively. The study concludes that large-scale ecological restoration and watershed management in northern China has greatly decreased water yield and reduced high flows due to the improved land cover by afforestation leading to higher water loss through evapotranspiration. At a large watershed scale, land use/cover change could play as much of an important role as climate variability on water resources. [ABSTRACT FROM AUTHOR]

The long-term hydrological response to reforestation is critical to regional water management, especially in areas where large-scale reforestation has been practiced. In this study, we investigated the long-term hydrological response to reforestation in the 579 km2 basin in southeastern China through ground-based monitoring of water yield, sedimentation, vegetation cover and climate in the basin. The vegetation dynamics were also examined by remote sensing data (MSS, Landsat and AVHRR NDVI). We found that forest cover increased 23% or 13 593 ha from 1975 to 2002. Meanwhile, annual water yield decreased 86-88 mm from 1971-1983 (i.e. pre-reforestation) to 1984-2009 (i.e. post-reforestation). These decreases were significant statistically according to both regression and double mass analyses. Time series analysis demonstrated that there was a clear decline in annual sediment yield and an increase in annual evapotranspiration (ET) over the period from 1971 to 2009. We concluded that reforestation could significantly reduce annual water yield and sediment yield in the basin because of the forest cover change and forest growth. This conclusion is consistent with findings from widely paired-watershed studies and literatures published on the impact of reforestation in large watersheds. Our results also have important strategic implications and provide insight into more sustainable forest management practices for the future. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Systematic uncertainty analysis (UA) has rarely been conducted for integrated modeling of surface water-groundwater (SW-GW) systems, which is subject to significant uncertainty, especially at a large basin scale. The main objective of this study was to explore an innovative framework in which a systematic UA can be effectively and efficiently performed for integrated SW-GW models of large river basins and to illuminate how process understanding, model calibration, data collection, and management can benefit from such a systematic UA. The framework is based on the computationally efficient Probabilistic Collocation Method (PCM) linked with a complex simulation model. The applicability and advantages of the framework were evaluated and validated through an integrated SW-GW model for the Zhangye Basin in the middle Heihe River Basin, northwest China. The framework for systematic UA allows for a holistic assessment of the modeling uncertainty, yielding valuable insights into the hydrological processes, model structure, data deficit, and potential effectiveness of management. The study shows that, under the complex SW-GW interactions, the modeling uncertainty has great spatial and temporal variabilities and is highly output-dependent. Overall, this study confirms that a systematic UA should play a critical role in integrated SW-GW modeling of large river basins, and the PCM-based approach is a promising option to fulfill this role. [ABSTRACT FROM AUTHOR]

Ji, Yuhe, Liding Chen, and Ranhao Sun, 2012. Temporal and Spatial Variability of Water Supply Stress in the Haihe River Basin, Northern China. Journal of the American Water Resources Association (JAWRA) 48(5): 999-1007. DOI: 10.1111/j.1752-1688.2012.00671.x Abstract: Water resources are becoming increasingly stressed under the influence of climate change and population growth in the Haihe River Basin, Northern China. Assessing the temporal and spatial variability of water supply stress is urgently needed to mitigate water crisis caused by water resource reallocation. Water supply and use data were compiled for the time period of 1998-2003 in this synthesis study. The Water Supply Stress Index (WSSI) as defined as Water Demand/Water Supply was used to quantitate whether water supply could meet the demand of human activities across the study region. We found a large spatial gradient of water supply stress in the study region, being much higher in the eastern subbasins (ranging from 2.56 to 4.31) than the west subbasins (ranging from 0.56 to 1.92). The eastern plain region not only suffered more serious water supply stress but also had a much higher interannual variability than the western hilly region. The uneven spatial distribution of water supply stress might result from the distribution of land use, population, and climate. Future climate change and rapid economic development are likely to aggravate the existing water crisis in the study region. [ABSTRACT FROM AUTHOR]

The effect of forests on annual water yield is an unresolved central issue in forest hydrology despite years of study. There has been a particular shortage of research in the mountains of arid inland river basins. In the present study, we examined the effects of forests on hydrology using data on precipitation, evaporation, canopy interception, transpiration, and runoff from 1994 to 2008 for the Pailugou catchment of northwestern China's Qilian Mountains. We modelled the water balance to assess the contribution of different vegetation types to annual water yield. In our study area, Picea crassifolia forest covered 38·5% of the catchment area, but contributed little to annual water yield. For an annual average precipitation of 407·1 mm (from 2003 to 2008) at an elevation of 2700 m, the runoff depth from the forest was 11·6 mm, accounting for only 3·5% of total annual water yield of the catchment. For an annual average precipitation of 374·1 mm (from 1994 to 2002), the runoff depth from the forest was − 14·3 mm (i.e. 5·9% of total annual water yield of the catchment was consumed to sustain tree growth). This has significant implications, because forests are increasingly being planted in the Qilian Mountains, and this may decrease the downstream water supply. Thus, the relationship between the forest and water yield must be better understood to permit the establishment of an appropriate regional level of forest cover. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Sustainable water resource developments require reservoir operations that provide environmental flows (e-flows) to support the downstream riverine ecosystem by minimizing the degree of hydrologic alteration under given water supply constraints. The effective management of e-flows below dams was explored by combining three e-flow management strategies for 'normal,' wet, and dry year situations, delivering a range of e-flow regimes for different reservoir storage levels and different natural flow (reservoir inflow) conditions. We combined these into a single combined e-flow strategy and coupled this with reservoir operating rule curves to form a reservoir operating approach that optimized e-flow provision under given water supply constraints. We also explored constraints imposed by the dam's valve release capacity. To investigate the capability of the approach to minimize the degree of hydrologic alteration downstream from a reservoir, we presented a case study of the Tanghe Reservoir in China's Tang river basin. The approach triggered a preferred e-flow strategy when the reservoir water level was high to better maintain the ecological functions within downstream riverine ecosystems, a basic e-flow strategy when the water level was low to reduce the water supply risk, and an acceptable strategy under intermediate conditions. The approach effectively balanced human and ecosystem needs and demonstrated the minimum levels of flow regime alteration achievable within the regulated river. [ABSTRACT FROM AUTHOR]

The article offers information on the description of a hydrological model that considers the five categories of land use. It states that the verification and calibration model were executed at two independent watersheds which include Tangnaihai and Lushi in China. Moreover, the results suggest only a small change in evapotranspiration, yet a marked decreased in precipitation, which was important in all analysed areas excluding the Lanzhou-Toudaoguai inter-watershed area.

Estimating the amount of irrigation water is challenging at the catchment scale because of the difficulties in direct measurement and interactions between the flow components. The objectives of the study were to characterize the catchment flows in an agricultural catchment with an irrigation system in subtropical China and to estimate catchment irrigation flow using hydrograph analysis methods. A weighting model and multiple regression models were established to estimate catchment irrigation outflow according to the hydrographs of the inflows and outflows of the catchment. The multiple regression models took into consideration the drainage time of base flow, resulting in better estimation on an event and annual basis. Using the MR-6d method, the estimated irrigation outflows amounted to 3700 mm, 2600 mm and 2760 mm during 2001, 2002 and 2003 respectively, which covered 70%, 60% and 64% respectively of the total catchment outflows in the corresponding years. [ABSTRACT FROM AUTHOR]