This study investigates the urbanization of Taihu Basin and its influence on Satellite Pour l’Observation de la Terre (SPOT)-Normalized Difference Vegetation Index (NDVI). The correction model of the Defense Meteorological Satellite Program-Operational Linescan System (DMSP-OLS) of nighttime images was built to extract the dynamics of urban expansion. Tempo-spatial correlations between a vegetation index and nighttime light intensity are discussed to quantitatively assess the urbanization effect. The results show that Taihu Basin is in a period of rapid urbanization. Urban expansion is developing not only surrounding the city center circle but also along the main traffic arteries and rivers, which show a linear expansion resulting in an urban agglomeration. Under the influence of urbanization, the NDVI shows a slight decrease, and there is a significant negative tempo-spatial correlation in the urban areas of the eastern watershed between NDVI and nighttime light intensity, which are predominantly...

Rain-flood utilization refers to transforming some amount of rain or floodwater into ordinary water resources without decreasing flood control standards or damaging the ecological environment of rivers, which have gained widespread attention as it can alleviate water shortages and gain benefits. This paper put forward the evaluation method of rain-flood utilization availability at the distributed watershed scale. Based on the water node, some indices of rain-flood utilization availability had been defined. Then the evaluation method and calculation process were unified. Finally, the status and potential of rain-flood utilization of Hanjiang River Basin were analyzed. The results indicated that the rain-flood resource in the whole basin is 48.9 billion m³, the outflow is 29.9 billion m³, and the actual utilization is about 19.0 billion m³. The current available rain-flood amount and rain-flood utilization potential are 27.7 billion m³ and 11.0 billion m³, and the rain-flood utilization rate is 49.4%. Limited by regulation ability and the rain-flood resources, the current rain-flood utilization has a clear threshold range. The potential utilization objects are mainly for the rainfall process of about 2 to 10 years return period. The application in Hanjiang River Basin offers some practical information for assessing rain-flood utilization scientifically, and the premise for effectively guiding and formulating adaptive countermeasures for water resources management.

The operation of Three Gorges Reservoir (TGR) has changed the hydrological situation of Yangtze River and its connected lakes. Based on the hydrodynamic model, the influence of TGR operation from 2009 to 2014 on the Poyang Lake has been evaluated. It is found that TGR impoundment reduced the discharge of the Yangtze River and the water level of Poyang Lake, brought the decreasing of the backflow phenomenon. Especially in October, the discharge and water level of Hukou station (HKS) decreased by 9.6% and 1.09 m respectively, and this effect could be up to the Kangshan area. Meanwhile, TGR operation has also increased the water level of HKS by 0.1~0.56 m from December to May, which only affected the vicinity of Duchang. In addition, TGR operation also increased the maximum water level of HKS from April to June by 0.1~0.34 m, and that from July to August decreased by 0.22~0.4 m which is beneficial to reducing the flood control risk of Poyang Lake. But TGR impoundment changed the water exchange process between Yangtze River and Poyang Lake, and advanced the dry season, which had a certain impact on the water supply and ecological environment of the lake area.

In order to analyze the potential of rain-flood resources, and to reveal its water-constrained response to further develop the assessment method of rain-flood availability, based on the conceptual model, this paper takes the upper reaches of Hanjiang River (UHRB) as a demonstration area to carry out the assessment of rain-flood availability. According to the constraint factors, analysis of water-constrained response has been conducted. It is found that the average annual rain-flood availability amount during the flood season in UHRB is 17.30 billion m3, and the rain-flood utilization potential is 5.37 billion m3, showing a decreasing trend since the 21st century. Rain-flood utilization is directly constrained by regulation ability and necessary water requirements such as production, living and ecological environment, and there is an obvious non-linear response relationship. Based on scenario assumptions, the iso-curve of rain-flood resources availability and utilization potential that meet the practical needs of water resources utilization could be drawn. The findings enrich the evaluation theory of rain-flood resources and provide technical support for improving the water resources utilization efficiency.