Evaluation method of rain–flood resource utilization availability and its application in the Hanjiang River Basin

Abstract 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 has 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 were defined. Then the evaluation method and calculation process were unified. Finally, the status and potential of the 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, current rain–flood utilization has a clear threshold range. The potential utilization objects are mainly for a rainfall process of about two to ten 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.