Estimation of Surface Siltation Rate in Tagwai Reservoir, Minna, Niger State, Nigeria

Abstract

This study examines the level of sediment deposit in the reservoir by estimating the reduction in surface area of the reservoir. In achieving these, a traverse survey was run through the bank the dam using TC 1201 Leica Total Station and its accessories from three set of control points namely; CSN 239,CSN 240 and CSN 241. Coordinates of the control points were given in three dimension (x,y,z) and hence the perimeter of the reservoir was obtained using Microsoft excel and surfer8 software in year 2010. Five years interval was chosen for estimation; therefore, a digitized spot5 satellite image of the reservoir was acquired for the year 2005. The perimeter area of the reservoir plotted from the field data in 2010 was superimposed on the digitized satellite image for 2005. The two areas measured 356ha and 340ha respectively. The result of the perimeter traverse revealed that about 3.7% of the surface area of the reservoir has been taken over by sediment deposit. The reduction is attributed to the environmental impact and long time morphological changes of the natural water. It is also as a result of particles transported through the runoff that entered the reservoir which is a function of watershed characteristics. Its effect is that, it present hazard to navigation, changes water stage and ground water condition. With this, vegetation growth around the bank of the reservoir, continuous monitoring of the sediment yield, conservation and erosion control is recommended.