Abstract
Watershed delimitation is very important in flood control management. The traditional sub-watersheds delimitated by a filling digital elevation model (DEM) may change the real sink area, such that it may not be the best choice in studies sensitive to sub-watershed storage. This paper proposes a dynamical watershed delimitation method using a no-fill DEM and precipitation. It considers a closed sink area containing cells that fully flow into a large special cell, which can flow out when its water level is “higher than outlet”. We took Wuhan City as a study area and defined the precipitation in return periods of 1, 5, 20, or 100 years to derive the sub-watersheds. It is found that, in the four delimitations, the ratio of isolated basic units which could not flow outside were 27%, 9%, 5%, and 1%, respectively, as the precipitation increased. The results show that the provided method satisfies the assumption that the sink area might overflow with increased precipitation. The sub-watershed delimitated by the proposed method has higher correlation with the distribution of waterlogging points than those delimitated according to the D8 algorithm. These findings indicate that the proposed method can derive reasonable sub-watershed delimitation and that it may be helpful in the practice of urban flood control management.
Highlights
China has recently suffered serious flooding and waterlogging threats
In this paper, we propose a watershed delimitation method through the concept of in this paper, we propose a watershed delimitation method through the concept of multiple flow directions and “source flood” analysis, where the sink area can flow out when its water multiple flow directions and “source flood” analysis, where the sink area can flow out when its water level is high enough to reach the outlet
The areas of 90% of the basic units are less than 770
Summary
Delimitating by No-Fill Digital Elevation Model and Defined Precipitation: A Case Study of Wuhan, China. Hongping Zhang 1 , Xinwen Cheng 1,2, *, Lei Jin 2 , Dong Zhao 3 , Tianjing Feng 1 and. Received: 26 December 2019; Accepted: 8 February 2020; Published: 11 February 2020
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