Improvements in large‐scale drainage networks derived from digital elevation models

This paper presents an improved algorithm for deriving drainage networks for coarse‐gridded distributed hydrological models based on relatively fine resolution digital elevation models. The proposed algorithm aims to reproduce actual drainage networks more closely when applied in regions with meandering rivers running in parallel and for cell sizes of the order of 10 kilometers. To achieve this goal, the COTAT algorithm of Reed (2003) was improved, introducing another parameter related to the minimum upstream flow path into the cell besides the area threshold. The proposed algorithm was tested by applying it to the catchments of the rivers Tapajos (530,000 km2) and Grande (145,000 km2) in South America. Results show that drainage networks are generally improved by the proposed algorithm, needing only minor manual corrections.