ANALISIS PERILAKU EROSI PADA DASAR SUNGAI BAGIAN HILIR BANGUNAN GROUNDSILL

Abstract

Local scour is the erosion of soil at the riverbed, often occurring due to changes in
flow type that become concentrated, influenced by river morphology or the presence
of structures within the river. The hydraulic jump caused by flood discharge at the
groundsill structure of the Gung River leads to local scour downstream of the
structure. Insufficient mitigation of local scour downstream of the groundsill can
result in long-term damage to the structure itself. This study was conducted to
analyze the potential scour depth using empirical methods and modeling with HECRAS
software. The analysis considers rainfall data over the past five years in the
Gung River Watershed (DAS) and soil particle diameters obtained from soil
investigations in 2022. The analysis of scour depth, taking into account a 50-year
rainfall event and followed by flood discharge analysis for a 50-year return period
(Q50), yielded a design discharge for analyzing local scour depth using the Lacey
method, with a depth of 7.95 m. Through modeling with HEC-RAS version 6.5, the
resulting local scour depth was found to be 8.2 m.