Modelling fine-grained sediment transport in the Mahakam land-sea continuum, Indonesia

SLIM is an unstructured mesh, finite element model of environmental and geophysical fluid flows, which is being improved to simulate fine-grained sediment transport in riverine and marine water systems. A 2D depth-averaged version of the model is applied to the Mahakam Delta (Borneo, Indonesia), the adjacent ocean, and three lakes in the central part of the Mahakam River catchment. The 2D code is coupled to a 1D section-averaged model for the Mahakam River and four tributaries. The coupled 2D/1D model is mainly aimed at simulating fine-grained sediment transport in the riverine and marine water continuum of the Mahakam River system. Using the observations of suspended sediment concentration (SSC) at five locations in the computational domain, the modelling parameters are first determined in a calibration step, for a given period of time. A validation step is then performed using data related to another period of time. It is concluded that the coupled 2D/1D model reproduces very well the observed suspended sediment distribution within the delta. The spatial distribution of sediment concentration in the delta and its temporal variation are also discussed.