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We adopted a spectral clustering algorithm to divide the document co-citation network of 1,776 papers in the field of Lancang-Mekong water, and 14 clusters were identified. For each cluster, the top-cited references construct the knowledge base, and the most-coverage cities are taken as the research frontier. Three indicators, namely betweenness centrality, citation burstness strength, and Sigma, were used to identify the research outputs with pioneering and transformative value. The changes in the research topics and hotspots are closely related to the planning, construction, and operation progress of hydropower engineering, that affected by the gaming results of all parties. The 2009–2010 is an important time boundary, with the original research hotspots including the impact of upstream reservoirs on the hydrological regime and sediment (Clu#3) and arsenic contamination of groundwater in the Lower Mekong (Clu#4) that obtained periodical achievements and reached consensus to some extent around 2008, and the new research boom turns to the Tonle Sap Lake and flood pulse (Clu#2) in short-term characterized literatures with the highest burstness strength mainly concentrated around 2012.

This paper addresses the doubts regarding the spatial characteristics of the commonly used rules for parallel reservoir system operation. The rules based on aggregation-decomposition determine the system total release first and then assign this release to individual reservoirs, without considering the water demand distribution in the river network. In this paper, a conceptual model for parallel reservoir systems with distributed water demands is proposed. Three specific optimality conditions are derived for determining the optimal analytical solution. A rigorous proof shows that the aggregation-decomposition-based rules are a special case of the derived rules. An efficient algorithm is then developed based on the optimality conditions and shortage allocation index (SAI), in which a larger SAI indicates taking a higher percentage of the system water shortage, as release or storage. Unlike traditional algorithms that modify the violated variables empirically, we propose a criterion in terms of relative deviation indicators to determine the crucial priority of variable modification. This criterion can effectively address constraint violations. The optimal rules along with the solution algorithm are then demonstrated by the operation of a parallel reservoir system in the Shiyang River Basin, China. The results show that the proposed rules and algorithm are more efficient and effective than traditional algorithms and aggregation-decomposition-based rules, especially in dry seasons with more binding constraints.

Building water dissipation (BWD) refers to the change of water into vapour during water use activities in the building. The intention of the work described in this paper was to explore the BWD mechanism and establish a calculation model for BWD. The main research methods included experimental monitoring, a questionnaire survey and data mining. The results of this work showed that the capacity of buildings and the building area determine the type of water dissipation whereas the building population determines the BWD volume. The BWD calculation model was thus built based on two key parameters – building area and building population. Multi-variate regression fitting was used to analyse and study the other factors that influence BWD, such as water consumption, number of floors and so on. Using cluster analysis, 100 sample buildings were divided into different categories. Ordinary least squares regression was used to fit the multi-variate regression for the BWD of sample buildings. The results showed that the classification of buildings by cluster analysis can enhance the fitting effect of multi-variate regression of BWD.

Dissipation of water (evapotranspiration and water vapor conversion in human water use activities) is one of the significant hydrological processes in urban area, which becomes more complicated with rapid urbanization. However, there are few systematic studies on water dissipation problems in urban area, and even the related concepts are unclear. This paper proposed the concept of urban water dissipation (UWD) to describe water vapor conversion in urban areas, and presented analysis on mechanism of UWD based on observing and monitoring experiments. The urban underlying surface was divided into five categories: buildings, paved ground, vegetation, water surface, and soil, in which the buildings have been scarcely discussed in terms of water dissipation. The dissipation of water in buildings plays a more and more important role in the urban water circulation system, as the water supply increases in urban areas. To reveal how much water is dissipated in the buildings, the main water dissipation processes in different kinds of buildings were analyzed, and the quantitative model was proposed. Based on the traditional evapotranspiration models for urban underlying surface and the proposed model for water dissipation in buildings, a new modelling system was built to simulate the total UWD. The new model system reflects the impact of human water use activities on urban water dissipation. It was applied in Xiamen city to simulate the UWD in 2000, 2005, 2010, and 2015. The results show that the UWD intensity increased with the urbanization process in Xiamen urban area in past 15 years. The UWD contribution rate increased for most land use types, except green land. For example, the water dissipation on residential land is the fastest growing one of all land use types, and its contribution rate surpassed that of green land to become the largest contributor in 2010. Because of the interference of strong human activities, the contribution rate of water dissipation on the social side continues increasing. The contribution rate of UWD on the social side was more than 40% in 2015, and it is still increasing.

Delivery in water markets is generally operated by agencies through channel systems, which imposes physical and institutional market constraints. Many water markets allow water users to post selling and buying requests on a board. However, water users may not be able to choose efficiently when the information (including the constraints) becomes complex. This study proposes an innovative two-phase model to address this problem based on practical experience in China. The first phase seeks and determines the optimal assignment that maximizes the incremental improvement of the system's social welfare according to the bids and asks in the water market. The second phase sets appropriate prices under constraints. Applying this model to China's Xiying Irrigation District shows that it can improve social welfare more than the current pool exchange method can. Within the second phase, we evaluate three objective functions (minimum variance, threshold-based balance, and two-sided balance), which represent different managerial goals. The threshold-based balance function should be preferred by most users, while the two-sided balance should be preferred by players who post extreme prices.

Multiple stakeholders in transboundary river basins would benefit from cooperation, but how and why stakeholders can achieve this cooperation remains difficult to determine. This paper prop...

Agricultural irrigation accounts for the largest proportion of freshwater use worldwide, and canal automation potentially improves conveyance efficiency in irrigation canal systems. In this...

Confronted with diverse water management schemes, policymakers in arid basins face difficulty in choosing a particular scheme due to a lack of appropriate tools to estimate possible physica...

Water rights management modeling was considered the useful measure to ensure efficient water resources allocation and to avoid intensifying conflicts over water rights. Regarding to the two major patterns of water rights across the world, namely, quantitative water rights (QWR) and duration-based water rights (DWR), the corresponding measures are fastidious. Since QWR was established to set water entitlements instead of DWR in Heihe River Basin, China, the disability of usual DWR tool, managing water diversion by water intakes closing (WIC) during a certain period, has arisen increasingly. The historical data also reflected the low reliability of DWR in allocating water resources quantitatively without modeling guidelines. Aimed at the challenge, a modeling framework and a mixed integer optimization model (MIOM) combing QWR objectives and DWR tools were developed, by which the optimal schemes in Pareto frontier were found to improve the water intake on/off events, including WIC stages, duration days, and starting date through long term series probability analysis and historical data. Results showed that the reliability of DWR allocation was enhanced and WIC duration was reduced significantly compared with current regulation. Scenario analyses indicated that MIOM was powerful for assisting DWR tool to manage QWR and the proposed framework was able to manage water rights efficiently in comparable basins.

An accurate estimation of water resources dynamics is crucial for proper management of both agriculture and the local ecology, particularly in semi-arid regions. Imperfections in model physics, uncertainties in model land parameters and meteorological data, as well as the human impact on land changes often limit the accuracy of hydrological models in estimating water storages. To mitigate this problem, this study investigated the assimilation of Terrestrial Water Storage (TWS) estimates derived from the Gravity Recovery And Climate Experiment (GRACE) data using an Ensemble Kalman Filter (EnKF) approach. The region considered was the Hexi Corridor of Northern China. The hydrological model used for the analysis was PCR-GLOBWB, driven by satellite-based forcing data from April 2002 to December 2010. In this study, EnKF 3D scheme, which accounts for the GRACE spatially-correlated errors, was used. The correlated errors were propagated from the full error variance-covariance matrices provided as a part of the GRACE data product. The impact of the GRACE Data Assimilation (DA) scheme was evaluated in terms of the TWS, as well as individual hydrological storage estimates. The capability of GRACE DA to adjust the storage level was apparent not only for the entire TWS but also for the groundwater component, which had annual amplitude, phase, and long-term trend estimates closer to the GRACE observations. This study also assessed the benefits of taking into account correlations of errors in GRACE-based estimates. The assessment was carried out by comparing the EnKF results, with and without taking into account error correlations, with the in situ groundwater data from 5 well sites and the in situ streamflow data from two river gauges. On average, the experiments showed that GRACE DA improved the accuracy of groundwater storage estimates by as much as 25 %. The inclusion of error correlations provided an equal or greater improvement in the estimates. No significant benefits of GRACE DA were observed in terms of streamflow estimates, which reflect a limited spatial and temporal resolution of GRACE observations. Results from the 9-year long GRACE DA study were used to assess the status of water resources over the Hexi Corridor. Areally-averaged values revealed that TWS, soil moisture, and groundwater storages over the region decreased with an average rate of approximately 0.2, 0.1, and 0.1 cm/yr in terms of equivalent water heights, respectively. A substantial decline in TWS (approximately −0.4 cm/yr) was seen over the Shiyang River Basin in particular, and the reduction mostly occurred in the groundwater layer. An investigation of the relationship between water resources and agriculture suggested that groundwater consumption required to maintain the growing period in this specific basin was likely the cause of the groundwater depletion.

Mass media are important sources of information about water issues that significantly influence civil life. This paper presents a content analysis approach to contextualize the water issues reporting of the People's Daily. The intent of our approach is to uncover the reporting pattern of water issues and the relationship between government policies and their news reports. Using the newspaper with the second widest circulation in China, the content analysis approach reveals that the document frequency of water issues had shown a flat trend since the 1970s. Water-related articles were given more significance by providing additional front pages. The results suggest that newspapers have been focusing more on the recreational function and protection of water since the 1980s. The results also show that there was a relative shortage of coverage on certain types of water-related central government documents. Lacking persistence was another feature of policy propaganda. These factors could work against public engagement in water issues and undermine the public's understanding of and confidence in water management measures. We believe these results could help water resource managers to interpret media content of water issues and improve the propaganda of their policies, which would contribute to better administration of water resources.

This study develops a new approach to quantitatively identify the most important determinants of urban water use. The approach is based on a data mining model called genetic programming (GP), which automatically optimizes the structure of the function and parameters simultaneously. With historical urban water use as the target, the GP model identifies the most relevant factors for 47 cities in northern China. Compared with conventional regressive models, the GP model performs better than the double-log model. The Nash–Sutcliffe model efficiency coefficient (NSE) of the GP model is 0.87, while the NSE of the double-log model is 0.79. According to the results of the case study, urban water use is determined by both socio-economic and natural variables. Total population, service industry indicators, green land area, housing area, water price, and rainfall are the most significant determinants of urban water use. Among them, total population, service industry indicators, and green land area clearly have posit...

River flow that is characterized by variability requires commensurate flexibility in allocating water so that water users are able to plan their activities and respond accordingly. An indicator-based assessment method is proposed in this study to evaluate the flexibility of water allocation, based on a concept that a flexible water allocation regime provides greater opportunity for users to freely decide individual water use and leads to more variability and diversity for water consumption among the users. This is demonstrated by using historical water-use data and applying the assessment method in three river basins with different water allocation regimes. These allocation regimes include the seasonal and volumetric water allocation system in the Yellow River of China, duration-based water allocation in Northwestern China, and capacity sharing in southern Queensland in the northern Murray Darling Basin of Australia. Historical water-use variability and diversity are defined and assessed. The result shows that water allocation flexibility varies across the different water entitlement regimes. Duration-based water allocation, a type of allocation that provides the highest degree of water-use autonomy, is ranked as the most flexible regime. Seasonal water allocation, which has the highest level of centralized regulation, shows the lowest flexibility. The proposed indicator based assessment method would be useful for evaluating the flexibility of policy options for water allocation. This could be helpful for improving the capability of water allocation regimes to cope with the changing environment and improving the effectiveness of water allocation systems.

Water cycles exist in all processes of water resources utilization, including water-saving irrigation. Due to the complex water cycle process of irrigation, the ecological effects and safety of large-scale water-saving irrigation have received increasing attention. This paper analyzed both the positive and negative ecological effects of water-saving irrigation and the scale effects from the plant-scale to the watershed-scale. Based on the Vensim and GMS (Groundwater Modeling System) models, a quantitative evaluation method of ecological safety of large-scale water-saving irrigation was proposed. The case study in Changma Irrigation District in the arid inland river basin of Northwest China showed that the ecological safety of large-scale water-saving irrigation was sensitive to the combination of water source condition, water distribution technology and water-saving irrigation technology in field. In terms of the positive effects, large-scale water-saving irrigation can reduce the percolation loss of irrigation water, increase the environment water flow for the downstream, and slow down the salinity accumulation. As for the negative effects, large-scale water-saving irrigation could reduce the groundwater recharge, decrease the environment water supply in local farmland, and cut down the soil salinity leakage. The research results have positive significance for guiding the sustainable development of water-saving irrigation and conservation of ecosystem in an arid inland river basin.

In China, the allocation of water rights in river basins is customarily determined by annual mean volumes of water resources. However, seasonal variability of water availability should be considered for an effective and flexible allocation policy. This paper summarizes a framework for seasonal water allocation. It proposes a modified rule for seasonal water allocation on the basis of the traditional rule used in China and introduces a risk analysis model to assess the performance improvement of the proposed rule when dealing with hydrologic variability in the context of a water rights system. The framework and models were applied to the Shiyang River Basin, Gansu Province, China, and they indicated that seasonally allocated water under the modified rule is more stable and has a lower risk for water use than a rule based on annual mean volumes. This leads to more reliable supplies over the seasons and could provide an effective method for water rights operation in the Shiyang River Basin. It also p...

Analytical optimal hedging rules are derived for two-objective reservoir operation based on the characteristics of economic and multilevel environmental water demands. This approach is employed to balance current and future economic and environmental water demands using a two-period model. According to the marginal values of utilities, the derived three-step hedging rule curves (THRCs) consist of three steps and six stages. The Huaihe River basin of China is taken as an example to regress the THRCs from a two-objective optimization model. Results show that the derived THRCs can be regressed from the optimal release decision, thereby confirming the derivations and theoretical analysis. The shapes of the THRCs are sensitive to the weight parameters of the objectives and capture the core concern of multiobjective reservoir operation. The THRCs tend to widen and flatten the stages with increasing storage capacity, which implies more water storage and more consideration for future demands.

A water market is an effective way to increase water-use benefits. A preliminary market for irrigation water trading among villages has emerged in the arid area of northwestern China since 2008. This study conducts a quantitative evaluation of the water market at the Xiying irrigation district of the Shiyang River Basin in western China. Network analysis method is employed to assess trading activity and market centrality. The characters of case water market are compared with that of the United States and Australia to discuss the foundations and barriers for developing a mature water market in China. Results show that the case water market in China is undeveloped and is highly regulated by local government although water transactions continuously occur among villages for years. Insufficient incentives and high transaction cost are the key barriers in further developing the market. The indicators proposed in this study for market network analysis are useful for quantitatively evaluating the characte...

Pubic water rights allocation, in which water resources are allocated to users administratively as shared public property, is an effective and powerful policy for water resource management. Dozens of public water right allocation systems have been established in China since 1998 without any unified standard across the country. An indicator-based assessment approach, based on equity, efficiency and sustainability, is proposed in this study to evaluate the performance of public water rights allocation systems in China in a quantitative way. The approach was applied in 11 river basins of China in which water rights have been defined. The results show that the performance of the allocation systems depends on the spatial density and exploitation ratio of the water resources. The performance of allocated water rights systems is better in river basins with greater resource densities and smaller water exploitation ratios. This assessment approach is very useful for evaluating policy options for public water rights allocation with appropriate consideration of the local conditions of the river basins.

The assessment of surface water resources (SWRs) in the semi-arid Yongding River Basin is vital as the basin has been in a continuous state of serious water shortage over the last 20 years. In this study, the first version of the geomorphology-based hydrological model (GBHM) has been applied to the basin over a long period of time (1956–2000) as part of an SWR assessment. This was done by simulating the natural hydrological processes in the basin. The model was first evaluated at 18 stream gauges during the period from 1990 to 1992 to evaluate both the daily streamflows and the annual SWRs using the land use data for 1990. The model was further validated in 2000 with the annual SWRs at seven major stream gauges. Second, the verified model was used in a 45-year simulation to estimate the annual SWRs for the basin from 1956 to 2000 using the 1990 land use data. An empirical correlation between the annual precipitation and the annual SWRs was developed for the basin. Spatial distribution of the long-term mean runoff coefficients for all 177 sub-basins was also achieved. Third, an additional 10-year (1991–2000) simulation was performed with the 2000 land use data to investigate the impact of land use changes from 1990 to 2000 on the long-term annual SWRs. The results suggest that the 10-year land use changes have led to a decrease of 8·3 × 107 m3 (7·9% of total) for the 10-year mean annual SWRs in the simulation. To our knowledge, this work is the first attempt to assess the long-term SWRs and the impact of land use change in the semi-arid Yongding River Basin using a semi-distributed hillslope hydrological model. Copyright © 2010 John Wiley & Sons, Ltd.

The planning and management of water resources in the Shiyang River basin, China require a tool for assessing the impact of groundwater and stream use on water supply reliabilities and improving many environment-related problems such as soil desertification induced by recent water-related human activities. A coupled model, integrating rule-based lumped surface water model and distributed three-dimensional groundwater flow model, has been established to investigate surface water and groundwater management scenarios that may be designed to restore the deteriorated ecological environment of the downstream portion of the Shiyang River basin. More than 66% of the water level among 24 observation wells have simulation error less than 1·0 m. The overall trend of the temporal changes of simulated and observed surface runoff at the Caiqi gauging station remains almost the same. The calibration was considered satisfactory. Initial frameworks for water allocation, including agricultural water-saving projects, water diversion within the basin and inter-basin water transfer, reducing agricultural irrigation area and surface water use instead of groundwater exploitation at the downstream were figured out that would provide a rational use of water resources throughout the whole basin. Sixteen scenarios were modelled to find out the most appropriate management strategies. The results showed that in the two selected management options, the groundwater budget at the Minqin basin was about 1·4 × 108 m3/a and the ecological environment would be improved significantly, but the deficit existed at the Wuwei basin and the number was about 0·8 × 108 m3/a. Water demand for domestic, industry and urban green area would be met in the next 30 years, but the water shortage for meeting the demand of agricultural water use in the Shiyang River basin was about 2·2 × 108 m3/a. It is suggested that more inter-basin water transfer should be required to obtain sustainable water resource use in the Shiyang River basin. Copyright © 2009 John Wiley & Sons, Ltd.

Unified water flow regulation has been implemented in the Yellow River, Hei River and Tarim River in China since 1999 as a result of institutional reforms. It has been one of the most important water resources management practices in China during recent years and has generated significant impacts. Based on the data of such an experiment in the Yellow River during 1999 to 2004, a “with-without” scenario analysis method is employed in the paper to evaluate the economic and hydrological impacts of regulation through a holistic model coupling economic water use and hydrologic cycle applied to the study basin. The results show that about 2.5% of GDP was increased every year and the Flow Cutoff Events were avoided as a result of the unified water flow regulation.

Surface water and groundwater in the Heihe river basin of China are interconnected and the pattern of water resources exploitation has a direct effect on the interaction of groundwater and surface water, especially on a downstream oasis. A threedimensional groundwater flow simulation model with eight model layers was established to simulate the regional groundwater flow in the multilayered aquifer system and the interaction among the rivers, springs, and groundwater. The model was calibrated not only with historical water levels but also with the investigated baseflow and spring flux. The simulation results of the numerical model match reasonably well with the observed groundwater levels, baseflow to rivers, and spring flux. The numerical simulation also demonstrates that the hydraulic connection between the river and the aquifers has transferred from the coupling to decoupling at some reaches. It is suggested that there is a vital need to reduce groundwater withdrawal and to rationalize the use of both groundwater and surface water in order to maintain sustainable development in the study area. Copyright  2007 John Wiley & Sons, Ltd.

Long-term changes in reservoir inflow due to climate change and human interferences have caused doubts on the assumption of hydrologic stationarity in reservoir design and operation. Incorporating uncertain predictions that consider nonstationarity into an adaptive reservoir operation is a promising strategy for handling the challenges that result from nonstationarity. This study proposes rules for multistage optimal hedging operations that incorporate uncertain inflow predictions for large reservoirs with multiyear flow regulation capacities. Three specific rules for determining the optimal numerical solution are derived. A solution algorithm is then developed based on the optimality conditions and the three rules. The optimal hedging rules and the solution algorithm are applied to the Miyun Reservoir in China, which exhibited a statistically significant decline in reservoir inflow trend from 1957 to 2009, to determine an annual operating schedule from 1996 to 2009. Nonstationary inflows are pred...

[1] This paper discusses the optimality conditions for standard operation policy (SOP) and hedging rule (HR) for a two-stage reservoir operation problem using a consistent theoretical framework. The effects of three typical constraints, i.e., mass balance, nonnegative release, and storage constraints under both certain and uncertain conditions are analyzed. When all nonnegative constraints and storage constraints are unbinding, HR results in optimal reservoir operation following the marginal benefit (MB) principle (the MB is equal over current and future stages. However, if any of those constraints are binding, SOP results in the optimal solution, except in some special cases which need to carry over water in the current stage to the future stage, when extreme drought is certain and a higher marginal utility exists for the second stage. Furthermore, uncertainty complicates the effects of the various constraints. A higher uncertainty level in the future makes HR more favorable as water needs to be reserved to defend against the risk caused by uncertainty. Using the derived optimality conditions, an algorithm for solving a numerical model is developed and tested with the Miyun Reservoir in China.

This paper presents an integrated water resources optimisation (IWRO) model that was developed to manage the conjunctive use of surface and groundwater resources. The IWRO model utilises a genetic algorithm approach in which a surface water systems simulation model and a finite-difference groundwater model are used as evaluation functions. The objective is to achieve equitable water allocation within environmental sustainability constraints. The approach was evaluated through application to the irrigation systems in the Shiyang River basin (SRB) in Gansu province, China. The SRB has been under severe water stress and was experiencing a rapid decline in groundwater levels. Results produced with the IWRO model are compared with those of a previously existing simulation model of the basin for a business-as-usual scenario. The IWRO model produces an equitable water allocation that is sustainable.