NUMERICAL MODEL OF SEDIMENTATION AND WATER QUALITY IN KERINCI LAKE

Abstract

A study of Kerinci Lake in the Province of Jambi, Sumatera Island of Indonesia, is conducted
to formulate future actions to conserve the area. The purpose of the study is to investigate the distribution of
four parameters [total suspended sediment (TSS), biochemical oxygen demand (BOD), dissolved oxygen
(DO), and phosphate]. The study includes field measurements and a numerical model, resulting in a time
series of spatial distributions of the hydro-environmental parameters mentioned. The numerical model is
driven by discharges from six rivers and generated using a Surface-water Modeling System (called SMS).
SMS consists of modules RMA2 for flow modeling, RMA4 for contaminant transport modeling, and SED2D
for sedimentation modeling. The result of RMA2 shows an acceptable agreement with the water level and
current velocity field measurement data. The model is then developed into a sedimentation and water quality
model using SED2D and RMA4, resulting in a yearly change of the investigated parameters. The results
show that Tebing Tinggi River outlet has the biggest yearly bed change of around 0.3 m, caused by the high
TSS value in the river. The water quality model shows that the BOD, DO, and phosphate concentrations of
Merao River outlet are as expected as it has significantly bigger discharges than the other rivers. It is
recommended that local authorities provide wastewater treatment facilities, particularly in Merao River, to
maintain the sustainability of Kerinci Lake.