KAJIAN MODEL HIDRAULIK KANTONG LUMPUR BENDUNG COLO KABUPATEN SUKOHARJO

Abstract

Wonogiri Dam has been operated for many years, and has been shallowed due to sedimentation. The sedimentation material almost reaches the base elevation of dam intake (the limit of dead storage). This condition gives impact to the sedimentation rate at West Colo Weir and East Colo Weir intake. The solution of this condition has been done by constructing sedimentation channel in West Colo Weir as well as in East Colo Weir. In order to achieve maximum result in planning, it is required to carry out a hydraulic modelling test for sedimentation channel by constructing a model from Colo Weir with charasteristic adjustment between model and prototype in the field. In this experiment, the model scale is nh = nl = 20 for the implementation in the laboratory, which will be compared with the scale-making process and comparison between sediment in the field and sediment in the model. There are some model hydraulic test carried out in this research, such as similarity test, movable model test, and modification test. Based on the result of model test, there is an important thing should be considered, i.e., the variation of channel flushing in East Colo would be optimum if being done by doing this way : if channel 1 and 4 are flushed, channel 2 and 3 must be closed or on the contrary for discharge 0,6 Qn, ; and flushing being done simultaenously for full discharge. Whereas, in West Colo, flushing can be done in the half of right channel first or half of left channel first. There are also some changes compared with the initial design, such as change on base floor before irrigation gate and add a gatewall in front of flushing gate. The flushing result is satisfied, with average capacity about 90% flushed-sediment.