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Deriving flow directions for coarse‐resolution (1–4 km) gridded hydrologic modeling
Author(s) -
Reed Seann M.
Publication year - 2003
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2003wr001989
Subject(s) - flow routing , grid , digital elevation model , computer science , radar , flow (mathematics) , ranging , range (aeronautics) , hydrological modelling , resolution (logic) , routing (electronic design automation) , precipitation , remote sensing , tracing , algorithm , meteorology , environmental science , geology , geography , geodesy , mathematics , telecommunications , engineering , artificial intelligence , geotechnical engineering , geometry , climatology , aerospace engineering , operating system , computer network
The National Weather Service Hydrology Laboratory (NWS‐HL) is currently testing a grid‐based distributed hydrologic model at a resolution (4 km) commensurate with operational, radar‐based precipitation products. To implement distributed routing algorithms in this framework, a flow direction must be assigned to each model cell. A new algorithm, referred to as cell outlet tracing with an area threshold (COTAT) has been developed to automatically, accurately, and efficiently assign flow directions to any coarse‐resolution grid cells using information from any higher‐resolution digital elevation model. Although similar to previously published algorithms, this approach offers some advantages. Use of an area threshold allows more control over the tendency for producing diagonal flow directions. Analyses of results at different output resolutions ranging from 300 m to 4000 m indicate that it is possible to choose an area threshold that will produce minimal differences in average network flow lengths across this range of scales. Flow direction grids at a 4 km resolution have been produced for the conterminous United States.