Landforms Classification of Wadi Al-Mujib Basin in Jordan, based on Topographic Position Index (TPI), and the production of a flood forecasting map

Abstract

The main target of this study is to classify the landforms of wadi Al-Mujib Canyon, as considered one of the main wadi draining towards the Dead Sea. Based on Topographic Position Index (TPI), and depend upon Shuttle Radar Topography Mission (SRTM) data for preparing digital elevation model (DEM) which is available with 30*30 m ground resolution. By using the TPI, the landforms were classified into both Slope Position index and landform types. Landform categories were generated by combined two TPI grids at different scales (neighborhoods: (a 1km radius and 2km radius). TPI defended as: algorithms of Weiss and Jenness used to measure the topographic slope positions and automated landform classifications. TPI values are depended upon the cell size, type, elevation, and the standard deviation (SD) of TPI. By using TPI, the study area classified into slope position index with 6 classes; Valley, Lower slope, Flat slope, Model Slope, Upper Slope, Ridge, and the Landform categories with 10 classes are as follows; canyons / deeply incised streams, middle slopes, drainage, shallow valley, upland drainage, head water, u-shaped valleys, Plains, open slope, upper slope, local ridges, hills in valleys, midslope ridges, small hills in plain, and mountain tops, high ridge. Canyons / deeply incised streams, valley and ridge were forming the majority of landforms patterns, forming about 78.5% of all six landforms classes and the tenth-landform categories. Landforms pattern have strong relationship with the natural hazards including flash floods; thus about 37% from the total of the study area facing high risk of flooding.