Morphometric analysis of hillslope evolution in the Kadisha River Basin based on archived aerial photographs

Abstract

The morphometric analysis of hillslope evolution, using the traditional method of interpreting archived aerial photographs, requires both considerable time and subjectivity. It is well-established that the Structure from Motion (SfM) approach, a photogrammetric method producing high resolution Digital Surface Models (DSM), is more effective. This study aims to determine how hillslope evolution in the upper basin of Kadisha watershed can be better analysed for an accurate morphometric analysis. It investigates and validates the influence of the applied Morphometric Slope Index (MSI) on morphology, depth, and erosion volume, as well as the processes of the computed pre-erosion surfaces in GIS environment. To enable testing the hypothesis that the characteristics of drainage networks are highly affected by the MSI, the following drainage network parameters were quantified in the thirty-two sub-basins: MSI, Drainage Density (D d ), average slope (ASL), depth, and eroded volume (V). Correlation between morphometric features and erosion was identified to reveal the mechanism of hillslope evolution. The results largely support what was hypothesized: MSI was useful in capturing single slope morphometric characteristics in sub-basins. The process revealed that pre-erosion MSI is a desired slope morphometry indicator and a hillslope evolution predictor in the study area.