STUDY ON RIVER MANAGEMENT CONSIDERING THE TRENDS IN VEGETATION ZONE BY UTILIZING LP DATA

The discharge capacity of Kumozu River has evidently declined due to the sandbars development caused by vegetation growth on sandbars. By continuous monitoring the areas of sand deposit since 2013 and utilizing laser profiling (LP) data, it is now possible to accurately estimate the sandbar size (volume and area) and the vegetation distribution. In order to specify the area of growing sandbars from the viewpoint of river management, we have developed a method for grasping the vegetation density and distribution by utilizing LP data, and determining the variable-permeability coefficient with considering of vegetation height. The proposed variable-permeability coefficient is applied to riverbed variation analysis model from August 2014 historic flood. By comparing the analysis results and monitoring records, it was found that reproducibility improves with respect to riverbed variation height and the sediment volume. In addition, as a result of the sensitivity analysis on the relation between vegetation density and sandbar volume, the clear indication of vegetation density promoting sandbar deposition was found. The proposed method aims to contribute to predicting the area of deposition for efficient and effective river management.