In order to study the effect of the construction of the sponge cites on the process of urban water circulation in China, we analyzed the precipitation data from 756 stations across China between 1961 and 2011 and national land-use data in 2014. The spatial distribution characteristics of built-up area and amount of annual average runoff interception in sponge cities were explored in five different zonal scale levels. Assuming that the sponge cities have been built at the national-level construction land and the volume capture ratio of annual runoff is taken as 85%, the amount of annual average runoff interception in sponge cities is 988.58 × 108 m3 during 1961 to 2011 in China, where the annual precipitation is greater than or equal to 400 mm. The cities with more amount of annual average runoff interception are mostly distributed in Beijing-Tianjin-Hebei region, the Yangtze River Delta, and the Pearl River Delta. As to the Haihe River Basin, the annual average amount of surface water resources is 135.69 × 108 m3 between 2005 and 2014, and the amount of annual average runoff interception is 219.58 × 108 m3 from 1961 to 2011. The construction of sponge cities has the greatest impact on the surface water resources in the Haihe River Basin. Taking 80%–85% as the volume capture ratio of annual runoff in sponge cities is not reasonable, which may lead to the irrational exploitation and utilization of regional water and soil resources.

The variability of the relationship between precipitation and runoff is of vital importance to study the characteristics of regional water cycle and water resource management and planning. In this study, in order to explore the relationship between precipitation and runoff of the different hydrological patterns, the analysis of bivariate precipitation and runoff distributions and the simultaneous occurrence probability was analyzed by employing the Archimedean copula, based on the monthly runoff and precipitation data during 1960~2000 in the upper Huai river basin, China. The results indicated that: (I) the study region could be classified into four hydrological patterns, namely the Huai river valley zone, Huaibei plain zone, Huainan mountain zone and Huaibei mountain zone, with Xixian, Zhuanqiao, Meishan and Zhaopingtai as the maximal loading subbasin respectively. (II) There were positive dependence structure between precipitation and runoff in the study area, and the bivariate frequency distributions could be fitted best by the Gumbel-Hougaard copula. (III) The simultaneous occurrence probability of bivariate drought events was remarkable higher than that of corresponding classification of bivariate flood events; besides, the simultaneous occurrence probability of bivariate extreme events was maximum in the Huainan mountain zone, followed by the Huai river valley zone and Huaibei mountain zone, while that was minimum in the Huaibei plain zone. These results would be of essential guiding significance for water resource management and planning, flood and drought control and layout optimization of water conservancy projects in the study region.Water Resour Manage

Hydrologic regime plays an important role in maintaining aquatic ecosystem structures and biogeochemical processes of endorheic salt lakes. Due to joint influences of regional climate change, runoff regulation and water withdrawal, ecological water deficiency has been increasingly prominent in endorheic salt lakes in Northwest China, especially in the Inner Mongolian Plateau. Previous studies mainly focused on establishing and applying methods to determine ecological water levels of lakes, while much less attention was paid to a more important problemhow such water levels could be reached under changed watershed hydrological processes. Solutions of this gap were explored in this study using the Dalinuoer Lake as an example. This lake is a typical endorheic salt lake located in the Inner Mongolian Plateau. It is a critical source to provide important ecological services and economic values for locals. Its ecological water level to maintain the optimum salinity threshold was first calculated by applying a statistical analysis of relationships between the phytoplankton biomass, salinity and water level of the lake. Potential measures to preserve the ecological water level of the lake were subsequently evaluated based on a hydrological process analysis of the watershed. The results indicated that the optimum salinity threshold was 5.7 g/L. This value should be also valid for other endorheic salt lakes in this region. According to a function between the water storage and the mean water depth of this lake, the ecological water level was determined to be 10.28 m with an ecological water deficit of 2.5 Â 10 8 m 3 . A basin water balance analysis using the results proposed measures to maintain a sustainable ecological water level, including controlling local water consumption and infusing ecological water. The results of this study could be extrapolated to other similar conditions to provide guidance for policy-makers, so that better decisions could be hopefully forged to protect ecohydrological processes of endorheic salt lakes in the Mongolian Plateau, as well as other comparable scenarios.

In this study, the supportable maximum GDP/ population and the water poverty status were analyzed using the dual indices calculation model and the water poverty index in the Ecological Economic Zone of Dongting Lake in the different planning level years. The results showed that the supportable maximum GDP and population keep on increasing in the Ecological Economic Zone of Dongting Lake in the planning level years, and that in the Yueyang, Changde and Yiyang was the three maximum. On the other hands, the water poverty status in the Ecological Economic Zone of Dongting Lake was improved in the planning level years since the water conservancy project construction, the incremental water supply and the pollutants abatement. Key words: Water Resource Carrying Capacity; Dual Indices Calculation Model; Water Poverty Index; Ecological Economic Zone of Dongting Lake

No abstract