A Multi-Directional Flow Path Mapping Method Using Digital Elevation Models

摘要

Digital elevation models (DEM) are extensively used in hydrological analysis to obtain distributed hydrological attributes and the flow direction. Flow direction is not only used for channel network determination but also to obtain distributed hydrological attributes such as specific catchments. Demerits are consistently hindering hydrologists despite the ease of using DEM with several existing methods to obtain flow direction. A new multidirectional method of assigning flow directions based on flow tendency is proposed in this paper. This method assigns flow direction toward multiple downstream cells by evaluating the flow tendencies of 8 triangular facets inside a 9 grid-cell’s window. Iterative search of continuous pits and flats are also embedded inside. Multiple higher flow tendencies are included on the basis of their rank from the maximum, which has made it possible to trace significant parts of off-peak wet zones. This method is named as Ranked Flow Tendency (RAFT) method. A storage function method is used to simulate the water movement taking the DEM of Kamishiiba Reservoir Site (210 km2) as the case. The results of RAFT method are compared against the conventional D8 method and modified D8 method for flow networks. The proposed RAFT method has yielded better flow path simulation. The RAFT method has displayed promising ability to trace the reservoir sites as well. This method shows its better ability to involve more cells at off-peak wet region in flow routing