Estimation of Unit Flood Discharge for Various Land Use Types with a Focus on Urbanization

Manabu Segawa,Keiji Takase,Toshisuke Maruyama

doi:10.4236/ojmh.2016.64016

Abstract

We proposed unit flood discharge model that defined as the discharge into end-order (smallest) drainage canals. The discharge acts an important role for estimating regional flooding by big rainfall events which leading roughly estimation of flood discharge associated with land use changes as urbanization. In some areas of Japan, increased urbanization with insufficient drainage canal capacity has led to increasingly frequent flooding and flood damage. The aim of this study was to investigate the effect of urbanization on unit flood discharge using a runoff model for the Tedori River alluvial fan area, Japan. The discharge was studied as collecting runoff from paddy fields, upland crop fields, and residential lots. A runoff model for various land use types in the study area was developed using actual and physical properties of the runoff sites, and parameters for paddy fields. The model was tested using 54 big events and inputted those. The maximum total runoff ratio among different land use types was observed for residential lots, and the ratio remained relatively constant across different flood events. The minimum total runoff ratio was observed for irrigated paddy fields. There was a positive relationship between the total runoff ratio and total precipitation for all land use types. Whereas, the relationship between the peak runoff ratio and peak precipitation was variable. The runoff analysis was carried out using 60-min and 10-min precipitation data. For agricultural land, data for both intervals produced similar results.

Highlights

The discharge acts an important role for estimating regional flooding by big rainfall events which leading roughly estimation of flood discharge associated with land use changes as urbanization
We proposed the unit flood discharge concept as a measure of flooding discharge potential to investigate the impact of urbanization on flooding and flood damage
The previous research on runoff analysis of agricultural land is limited in to conceptual model rather than physical model, but the proposed model is basing on physical properties of agricultural land including depression storage

Summary

Introduction

M. Segawa et al 196 frequent flood events and flood damage, primarily as a result of insufficient drainage canal capacity. Segawa et al 196 frequent flood events and flood damage, primarily as a result of insufficient drainage canal capacity This phenomenon of increased flood discharge likely reflects the widespread change in land use from paddy fields and upland crop fields to residential areas. Yomota and Miura [5] studied flood discharge from paddy fields and upland crop fields under rotational use. To assist with flood prevention planning, Senge et al [6] developed a runoff simulation model and investigated the peak discharge ratio for the rotational use of paddy fields and upland crop fields

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Conclusion