Spatial-temporal estimation of evapotranspiration over Black Volta of West Africa

Evapotranspiration is an important component necessary for ensuring efficient management of water resources for every river basin. The Bui Hydroelectric Plant completed early 2014 to provide electricity for the people of Ghana is located within the Black Volta River Basin of West Africa. With the construction of this plant and related developments, there is a need for attention to be paid to the conservation of water resources within this basin. This paper therefore assesses the spatial temporal behaviour of evapotranspiration within the basin from 2001 to 2013 and compares this with the average monthly rainfall estimates from 1983 to 2012. The assessment shows that the average monthly evapotranspiration is within 0 to 150 mm/month for the period assessed. However, significant variation exists between the years with a highly erratic pattern observed. The pattern of the rainfall indicates that the upstream portion of the basin receives lower rainfall compared to the downstream portion of the basin. This pattern is consistent with the overall variation of the evapotranspiration within the basin. This spatial-temporal behaviour is an important factor that needs to be considered by all stakeholders given the anticipated land-use changes expected within the basin coupled with likely future increases in temperatures resulting from climate change.   Key words: Evapotranspiration, moderate resolution imaging spectroradiometer 16 (MODIS16), satellite application facility (SAF), Tropical Applications of Meteorology using SATellite (TAMSAT) rainfall, Bui Hydroelectric plant.