Evaluation of the sand trap performance of the Pengasih weir during the operational period

Sedimentation is the main trigger in reducing the capacity of the irrigation channel. The weir is equipped with a sand trap, to withstand the volume of sediments originating from the upstream area, some of which enter the irrigation intake. The sand trap is designed with sufficient width and sloping energy slope, allowing sediment to settle. The Pengasih Weir, located in Kulonprogo Regency, is one of the weirs that is equipped with a sand trap building. The Pengasih Weir and the sand trap were built-in 1972. With the development of current conditions, it is necessary to evaluate the performance of the sand trap of The Pengasih Weir. In this study, the evaluation of sand trap performance is reviewed during the operational (settling) period. The result showed that the Meyer-Peter Muller formula can be used as an approach in the calculation of the amount of sediment transport and also to estimate the settled volume. It is recommended to flush the sand trap in between 184.922 days. The average value of trap efficiency was 0.89. It can be concluded that the Pegasih Weir sand trap design still has good performance in settling the sediment inflow.