Mapping the spatial changes in Lake Volta using multitemporal remote sensing approach: Fid-Bau Portal

Mapping the spatial changes in Lake Volta using multitemporal remote sensing approach

Ghansah, Benjamin / Asare, Yaw M. / Tchao, Eric T. / Forkuo, Eric K.

Lake Volta is the world's largest man‐made lake by surface area, and the fourth largest by water volume. Located completely within Ghana, it has a surface area of about 8502 km² (3283 square miles). Like many other lakes on the African continent, Lake Volta is a major natural resource for Ghana, storing water for the operation of the hydroelectric dam, water supply for domestic, agricultural and industrial purposes, habitat for diverse aquatic species, an avenue for recreational activities, means of navigation between the north and south parts of the country, and a climate modulator for the tropical region. The lake has experienced variable water level and surface area changes attributable to climate change and excessive water abstractions. Using histogram thresholding techniques, this study produced binary images and vector maps of the lake. Spatial extent mapping of the lake using Landsat TM 1990, ETM + 2000 and ETM + 2007 images indicated the lake experienced both increased and decreased surface area changes during the study period. The lake's surface area varied by about 197 km² between 1990 and 2007, with the water level fluctuating between ±7 m. Factors thought to be contributing to these changes include human factors (regulated flows, deforestation, increased water abstractions and pollution) as well as natural phenomenon (climate change, water run‐off and subsequent sediment transport).