Coupling Hydrodynamic Inundation Modeling with Flood Risk and Economic Loss Analysis Under Land Cover Change

Land-cover change is a major driver of rising flood risk in river catchments, including the Jatiroto Catchment in Lumajang Regency, East Java. Previous studies have mainly examined river flow, land-use impacts on discharge, or erosion separately, with limited integration of spatial inundation modeling, disaster risk, and economic loss assessment. This study addresses this gap through a two-stage framework. First, a two-dimensional flood model was developed for three land cover conditions (1995, 2014, and 2023) and four rainfall return periods (2, 5, 10, and 25 years). Second, the resulting inundation maps were used to assess disaster risk and estimate economic losses across 44 villages in the lower catchment. The model was validated against the 23–24 December 2018 flood event in Rowokangkung and Sidorejo, showing reasonable agreement with field observations. Built-up land increased from 4.0% in 1995 to 15.9% in 2023, accompanied by increased inundation under all return periods. Flood extent was strongly and positively correlated with open land and settlements and strongly and negatively correlated with forest cover. Economic losses increased from IDR 185.3 billion in 1995 to IDR 540.1 billion in 2023, despite a temporary decline in 2014. Inundated area was the strongest predictor of economic loss. Kaliboto Lor, Rowokangkung, and Sidorejo consistently ranked among the highest-risk and highest-loss villages. The integrated framework provides a practical basis for flood mitigation, budget prioritization, and adaptive spatial planning in the Jatiroto Catchment.