Prediction of availability water supply based on area and volume changes of Alluvial sediment at river intake

The biomass power plant in West Borneo uses river water for the cooling process. The riverside area is made into a bay-shaped catchment area before the water entering to the intake area. The alluvial sediment trapped in the catchment area will affect the water supply. In maintaining the availability of water supply in the river intake canal, it is necessary to have information about the area and volume of sediment as time goes on. This study aims to determine the drying height at the time of lowest water, sediment distribution patterns, changes in sediment area, critical depth conditions, and changes in water and sediment volumes between 2019 and 2021. The data used are the position of the sediment surface and the tide height data of 2019, 2020, and 2021. An empirical method from the First Simpson was developed to validate between primary real time and secondary data of sediment area and volume. All data were plotted as the mapping and grinding of contour line. Finally, each plotting and drafting of cross section data was analyzed to calculate the water and sediment volume. In 2019 information was obtained that the available water supply was only 38.18% while in 2021 it was only 33.85% of the safety requirement. Thus, it was more than 50 - 60% of the sediment up to 5.0 m below the MSL ought to be dredged in both 2019 and 2021 to achieve the safety requirements of water supply.