Digital Elevation Model Extraction and Correction of Hilly River Channel Network in Pi-Shi-Hang Irrigation District, China

This research focuses on river and canal systems extraction in hilly irrigation areas. It aims to improve extraction precision and correct the DEM. Given the significance and challenges, the hilly area of the Pi-Shi-Hang Irrigation District is selected as the study area. The study integrates water systems with channels uses with 12.5 m DEM data for 2018 from Pi-Shi-Hang Irrigation District. The key working areas are determined through slope analysis. Based on ArcGIS 10.8.2, the elevation of the raster at the inflection points in the problem area is lowered by 3 m. ArcSWAT 2012_10.8.26 is used to construct a complete water network structure and to search for an appropriate threshold for the water system in the Pi-Shi-Hang Irrigation District. It is based on integrating three key features: water system density, tributary development coefficient, and water system connectivity. Research results derived in this paper show that the chosen thresholds of 50 hectares for the Yangtze River system and 150–200 hectares for the Huai River system can more accurately reflect the characteristics of the water system in this region. Moreover, the corrected and optimized DEM has remarkably enhanced the accuracy of extracting the river channel network in hilly areas, thus supplying more precise basic data for related field applications.