Satellite derived bathymetry of Kainji Dam

Abstract

Satellite-Derived Bathymetry (SDB) has emerged as a cost-effective and efficient technique for mapping shallow water bodies. This study investigated the application of SDB using Landsat 8 imagery for Kainji Dam (in Borgu local government area of Niger State), a deep-water reservoir. The methodology involved radiometric correction, Top of Atmosphere (TOA) reflectance, floating, and low-pass filtering to enhance image quality. Land-water separation and application of the Stumpf algorithm implemented using the band ratio technique, enabled bathymetric mapping. Validation using 35, 75, and 150 in-situ points varying from 1m to 71m depth revealed an optimal R2 value of 0.4 with 35 points, indicating moderate accuracy. The results showed a depth range of approximately 30 meters with 27.92 meters being the deepest result from SDB, highlighting SDB's potential for mapping shallow to moderate depths. However, the study exposed limitations in using Landsat 8 imagery for deep water bathymetry, as it failed to accurately capture depths beyond 30 meters threshold. This limitation is attributed to the sensor's spectral and spatial resolution. Future research will focus on developing an algorithm for deep water SDB using high-resolution satellite imagery. This study contributes to the understanding of SDB's potential and limitations in freshwater environments, emphasizing the need for sensor-specific evaluations and algorithm development.