Semi-automating the calculation of catchment scale geomorphic controls on river diversity using publically available datasets

Abstract

The global availability of Digital Elevation Models (DEMs) has enabled rapid, catchment scale geomorphic analysis of river systems. In this paper, we present a semi-automated GIS approach to quickly and accurately extract catchment scale geomorphic controls: slope, gross stream power and valley bottom width, and import bed material texture data along a drainage network. To enable rapid applicability of this approach, we provide the workflow for calculating elevation, slope, contributing catchment area and gross stream power embedded within ArcGIS toolkit, ArcGIS ModelBuilder and Python script as supplementary data. We also present an approach for disaggregating the drainage network and deciding the most appropriate reach length over which to calculate slope based on catchment topography. We demonstrate the importance of investigating DEM quality prior to use, strategic selection of the flow accumulation algorithm, and validation of the drainage network output using aerial imagery.