Drainage Network Definition for Low Resolution DEM Obtained from Drainage Network Extracted from High Resolution DEM Using Upscaling Processes

Abstract

Drainage network is basic information for developing applications involving surface and underground water resources. The determination of good quality drainage network can be extracted from altimetry grids with high or at least medium resolution. They can be used for studies in small and large watersheds. When the target is a large watershed, high and medium resolutions are not adequate. The grid resolution should be decreased and consequently the drainage network must be extracted for this new resolution. This mapping can be done in two ways. The first possibility is to extract the drainage network from the new grid altimetry. The second one is to define the new drainage network from the original drainage. In this work, the second possibility was implemented to provide the best quality drainage. The method called Priority First Search—PFS used by TerraHidro for extracting drainage from Shuttle Radar Topography Mission (SRTM) with 90 m of horizontal resolution, is described. The Upscaling process, responsible to convert high resolution drainage network to low resolution drainage network, is detailed and results are presented to show the effectiveness of the Upscaling process contained in TerraHidro. The distributed hydrologic models employed in underground waters using in many cases the network of surface drainage as basic information.