DefinePK

Abstract

The Sumampa stream is located in the Municipal capital of Mampong-Ashanti in the forest-savannah agro-ecological zone of the Ashanti Region in Ghana. The study investigated the changes in the flashiness of the Sumampa stream as a result of increasing human activities in the catchment by assessing the stream’s pathlength and Richards-Baker’s new flashiness Index (R-B Index), annual and decadal variation in the flashiness Index using daily flow data from 1985 to 2009. The daily flow data was generated from the stream’s daily stage data using the stream’s rating curve developed by the Department of Hydrology, Kumasi, Ghana. The landuse change scenarios and the rainfall trend coupled with 43.8% of catchment land on 5-10^o slope represent a potentially high erosion risk and an important factor to influence flashiness in a fast expanding urban catchment. The stream R-B Index dropped by 12.15% and the flow pathlength by 13.89% in 2000-2009 decade. The total decadal stream discharge also decreased by 35.22% in the 2000-2009 decade. The daily stream flow hydrograph shows a decrease in the stream’s flashiness between 1989 and 2006 after which it increased above the mean period flashiness index. The increase in R-B Index after 2006 was due to rapid expansion and rehabilitation of urban facilities and is regulated by a sharp increase in agricultural activities for livelihood.