Surface Runoff Responses to Rainfall Variability over the Bida Basin, Nigeria

Abstract

Information on annual, seasonal, monthly and daily rainfall variation is desirable for planning operation and management of water resource projects as this gives an insight into river flow regimes.  A surface runoff response to rainfall variation in The Bida River Basin was investigated.  The River Basin has an area extent of about 7,540 km².  The research utilizes rainfall data for a period of 30 years (1980 – 2009) mean, standard deviation, coefficient of variation and linear regression are used in the analysis. Results indicate that the rainfall pattern is generally in the form of alternating dry and wet years, and characterized by strong seasonality which is reflected in the surface runoff. Declining trend in rainfall over the years has been observed during the study period and is also reflected in the overall decline in runoff leading to variability in annual flow regimes. Therefore, attention should be focused on development of networking of continuous observation and monitoring of hydrometeorological variables and also control of environmental factors that influence the hydrology of the Bida Basin.

Keywords: Rainfall, Runoff, Landscape, Streamflow, Seasonality