Drought Effect on Water Management and Limnology of Kainji Lake, Nigeria

Abstract

The paper defines drought comprehensively after Havens (1954). It then reviewed the works of Nedeco & Balfour Beatty (1961) and Abiodun (1974). The former studied the two types of inflows (white & black floods) into the Kainji Lake and the correlation between rainfall and run-off in the river Niger basin prior to the formation of the lake; while the later studied the effect of drought on the performance of the Kainji Hydroelectric scheme and made recommendations on steps for combating drought. This present paper shows the effect of drought on rainfall, the inflows into the lake, water management techniques, water transparency, and plankton life in the lake by comparing data obtained in a drought-free year with those of a drought year.The data on total annual rainfall indicate a deficit of 46% during the drought year. This deficit affected the inflowsinto the lake such that the peaks of the two floods were 32% and 18% lower respectively than those of the drought-free year. This drought further affected the normal management operation of the lake water for hydroelectric production and extended the exchange ratio for the lake to 2:1 in contrast to a ratio of 4:1 in the drought-free year. In the drought year water transparency was generally lower and the 1% level of light penetration in the lake was nearer the surface. These affected the abundance of plankton life in the lake during the drought year.