Retrieval of Landuse and Hydrology-based Parameters from Remote Sensing Satellite Synthetic Aperture Radar Data: The Case of the Volta Lake Basin in Ghana

Abstract

Landuse and hydrology-based information on the Volta Lake Basin have been retrieved from Satellite remote sensing data. The results obtained could be applied in Hydro-Geographical Information System models, such as the TOPMODEL, for water balance studies. Eight Synthetic Aperture Radar Precision Images of the lake area acquired between August 1994 and June 1997 were processed into two sets of multi-temporal images (central and northern portions of the catchment areas, respectively). The images were analysed based on changes in land surface rough-ness, as characterised by the dynamics of the radar (satellite) backscatter coefficient. The first image (Mid-Volta Lake Sub-basin) revealed high variation in vegetation, soil and water surface roughness both in time and space. The lake also showed consistent high surface roughness (> -6.0 dB) in correspondence with seasonal passes of the South-west Monsoon and Northeast Trade Winds. The second image (Upper Volta Lake Sub-basin) demonstrated a more dynamic vegetation and soil surface roughness in relation to intense landuse activities (e.g. burning-induced shifting cultivation, livestock grazing, etc.). Whereas a quantitative relationship between cumulative seasonal rainfall and lake elevation could be established, direct effects of landuse on lake level fluctuation could not be easily deduced.

Journal of Applied Science and Technology (JAST), Vol. 4, Nos. 1 & 2, 1999, pp. 44–58