Modeling interactions between tides, storm surges, and river discharges in the Kapuas River delta

Abstract. The Kapuas River delta is a unique estuary system on the western coast of island Borneo, Indonesia. Its hydrodynamics are driven by an interplay between storm surges, tides, and river discharges. These interactions likely to be exacerbated global warming, leading more frequent compound flooding in area. mechanisms driving events remain, however, poorly known. Here we attempt fill this gap assessing discharges, surges how they can drive inundation over riverbanks, particularly within Pontianak, main city along River. We simulated these using multi-scale hydrodynamic model SLIM (Second-generation Louvain-la-Neuve Ice-ocean Model). Our correctly reproduces River's its with tides surge from Karimata Strait. considered several extreme-scenario test cases evaluate impact tide–storm–discharge maximum water level profile mouth upstream part river. Based profiles, divide stream into three zones, i.e., tidally dominated region (from about 30 km upstream), transition 150 river-dominated (beyond upstream). Thus, local management define proper mitigation for handling hazards riverbanks zoning category. also successfully reproduced event which occurred 29 December 2018. For event, wind-generated appeared dominant trigger.