Estimation of flash flood loss level in Banjaririgasi Village, Lebakgedong Sub-district, Lebak Regency, Banten

The flash flood that occurred at Lebak Regency on January 1st, 2020, has caused around 30 villages in 6 sub-districts area were affected. The most affected area among 30 villages was Banjaririgasi Village. The research of estimating flood damage in Banjaririgasi Village was based on damage data, also based on the location of the village itself that located at the upper Ciberang Hulu river basin which has sloping topography. The goal of this research was to determine the physical characteristics of flash flood inundated area based on two-parameter: slope steepness and elevation difference from the river, and to estimate the amount of economic loss caused by flash floods. The estimation was obtained by overlaying the inundation map and land use map, then calculate the area of affected land use, and compared to the economic exposure value of each type of land use. Results showed that the inundated area of the flash flood in Banjaririgasi Village has physical characteristics: it has low slope steepness categorized as flat to gently slope (0-15 % sloping), and low elevation difference (5-10 m) from the river. Total economic loss caused by flash flood in Banjaririgasi Village estimated at around IDR 71,539,847,517.00, with the highest damage was IDR 59,415,832,341.00 from the damaged/destroyed government facility, and the lowest damage was IDR 59,457,216.00 from damaged forestry. The highest land use inundated area was paddy field with 25 ha inundated area, and the lowest was forestry with 0.41 ha.