Reservoirs play an important role in the development and management of water resources in Indonesia, especially in meeting the needs of water for irrigation, raw water, power generation, as well as flood control, tourism and other water benefits. reservoir stopped functioning namely sedimentation. To overcome this, it is necessary to have a more accurate prediction of reservoir sedimentation for the planning, operation and maintenance of dams and reservoirs in Indonesia.
This consideration then prompted Abror Reseda to address this issue in his dissertation entitled ‘Development of a Sedimentation Prediction Protocol in Indonesian Reservoirs.’ So far, the Dead Storage capacity of a reservoir in a dam is designed based on the erosion value of the reservoir’s water storage area per year. without taking into account changes in land use and the dynamics of rainfall and the distribution of sediment transport scattered at the bottom of the reservoir.
The development of reservoir sedimentation prediction protocols is needed to produce more accurate predictions of reservoir sedimentation by field conditions and can accommodate the limited hydraulic data on reservoirs in Indonesia. The implementation of the development of reservoir sedimentation prediction protocols can provide a better perspective in the field of reservoir planning, operation and maintenance.
“The case study in this protocol uses the Wonogiri Reservoir. Even though each catchment has different hydrological and geomorphological characteristics, the Wonogiri Reservoir can represent the condition of catchments in Indonesia’s reservoirs. The Wonogiri Reservoir also represents the limited availability of long-term water discharge data. The limited availability of long-term water discharge data is experienced by almost all reservoirs in Indonesia,” said Abror.
Furthermore, Abror explained that the Wonogiri Reservoir has had bathymetric data for several years. The data is used for clarification and validation of simulation results. This is difficult to find in other reservoirs in Indonesia. In protocol development research, the steps take a long time so only case studies on one dam are possible.
This protocol simulation begins by predicting annual land erosion in the Wonogiri Reservoir catchment for a long period from 1993 to 2019. This protocol consists of 4 stages consisting of long-term land erosion prediction, long-term sediment transport discharge modelling, reservoir sediment transport modelling spatially and temporally, and prediction of reservoir sedimentation in the future.
Sediment transport discharge was modelled from predictions of annual land erosion and hydrographs which were modelled using the FJ Mock method and validated with the results of reservoir sediment measurements in the field. While reservoir sediment transport is modelled spatially and temporally using MIKE software. This simulation then generates the volume of sediment in the reservoir every unit of time-based on indications from changes in reservoir bottom elevation and validated by bathymetry in the field. From these results, the predicted results of the reservoir sedimentation volume are 146 million m2 for the next 50 years using the modular regression method.
“This protocol widely introduces mathematical models of reservoir sediment transport spatially and predicts the volume of sediment distribution at the bottom of the reservoir in the future using a modular regression method whose results are more accurate than previous studies. In the future, this protocol is expected to contribute to predicting the sediment of reservoirs in Indonesia,” said Prof. Dr. Heri Hermansyah, S.T., M.Eng., IPU., Dean of the UI Faculty of Engineering.
A research dissertation on the development of reservoir sedimentation protocols succeeded in bringing Abror Reseda to a doctorate on March 31, 2023. Abror was listed as the 67th doctoral graduate of the Civil Engineering Department and the 499th doctorate from the Faculty of Engineering, Universitas Indonesia. Prof. Dr. Ir. Yanuar, M.Eng., M.Sc with promoter Prof. Dr. ing. Ir. Dwita Sutjiningsih, Dipl. HE and co-promoter Prof. Dr. Ir. Setyo Sarwanto Moersidik, DEA. While the examiner team consisted of Ayomi Dita Rarasati, S.T., M.T., Ph.D; Prof. Dr. Ir. Suripin, M. Eng; Dr. Nyoman Suwartha, S.T., M.T., M.Agr; Dr. Eng. Mochamad Adhiraga Pratama, S.T., M.T .; and Dr. Evi Anggraheni, S.T., M.T.
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Faculty of Engineering, Universitas Indonesia