Studying Bankline Migration of the Lower Pra Basin using Remote Sensing and GIS

Abstract

The study investigated bank erosion and accretion of the lower section of the Pra River of Ghana using a topographical map of 1974 and satellite imagery of 2007, 2015, and 2018 which was augmented by field observation and key informant interviews. Bankline changes due to erosion and accretion and the total volumetric change in river channel were measured using Remote Sensing and Geographic Information System approaches. The study showed that erosion was more pronounced in both the right and left bank as compared to accretion. The study revealed that bank width area of the lower basin of Pra River increased by 50.7 m² from 16.2 m² in 1974 to 66.9 m² in 2018 eroding large portions of land along the right and left banks of the river. In general, the number of erosional spots in selected cross sections exceeded that of deposition. Erosion took place in 13 spots out of 20 spots constituting 65% with a rate ranging between 0.2 and 3.4 m/year. This research showed the value of channel morphological analysis as it brought to the fore, a quantitative perspective to bank erosion and accretion processes of fluvial systems.