Abstract
The spatial depth distribution of flood inundation, caused by 2015.09 Kanto-Tohoku heavy rainfall, was estimated at the lower part of the Kinu River basin. The presented procedure follows 1) to measure the elevations of flood marks (i.e. flood water levels) with a high spec GPS (at 35 locations in this study), 2) to spatially interpolate the measured water levels and 3) extract the topographic elevation from the interpolated water level. The estimation result suggested that paddy field in the southern part of Joso city had the deepest depths with about 3.8 m, while the average depths in the entire area was estimated to be 1.44 m. Average depths on natural levees (= 0.87 m), typically used for residential areas, was about 50 % smaller than that on other flat areas (= 1.75 m). The presented approach is an efficient method to estimate the spatial distribution of flood water depths over large areas.
