Wonogiri Reservoir Sedimentation as Influenced by Change of Catchment Characteristics

Abstract

The rate of erosion and sedimentation of Wonogiri Reservoir is higher than planned, so that the reservoir storage capacity decreases rapidly. The sedimentation problem of Wonogiri Reservoir has reached the critical condition where reducing the sediment entering the reservoir is no longer effective that caused sedimentation had reached the intake structure. This paper presents the result of studies on the dynamics of the Wonogiri Reservoir sedimentation. Series of data on monitoring reservoir bed dynamics have been used to analyze the sedimentation rate and series of bathymetry map have been used to discuss the deposition pattern. Evacuation of the sediment from the reservoir has been carried out in 2003 by means of dredging. The dynamics of the reservoir sedimentation during 1993, 2004, 2005, and 2011 are performed, and the results show that in 2011 the total reservoir capacity remains 67% whereas the dead storage capacity remains 50% of the initial capacity. The comparison of the aforesaid dynamics with the change in catchment characteristic is discussed and suggests necessity of integrated countermasures on both catchment and reservoir management.