Flood Risk and Agriculture

Chapter 7

Abstract

basins

111

1. Introduction

and also to quantify flood risk.

Methodology for Agricultural

Badri Bhakta Shrestha, Hisaya Sawano, Miho Ohara,

this chapter can also be applied in other areas for flood risk assessment.

Keywords: flood damage, agriculture, damage curves, RRI model, Asian river

The impact of floods is becoming greater due to their increasing frequency and scale and the concentration of population and socioeconomic activities in river basins [1]. Developing countries are particularly vulnerable to flood disasters because of limited resources to cope with them. Flood disasters cause serious damage to properties and livelihoods as indicated in Figure 1, which shows the estimated value of flood damage to agriculture and infrastructure and also the number of houses totally or partially damaged by floods in the case of Region III of the Philippines. For the assessment of flood disaster risk and the evaluation of risk mitigation measures, flood risk needs to be quantified as accurately as possible [2]. Flood damage assessment is thus essential for flood management to mitigate risk

Flood damage can be assessed quantitatively based on the analysis of hazard, exposure, and vulnerability. By conducting flood damage assessment, the effectiveness of countermeasures in reducing the intensity of a flood hazard can be quantified by comparing simulated damage before and after the implementation of

This chapter describes a method for assessing flood damage to the agricultural sector, specifically focusing on flood damage to rice crops. The chapter also includes the case studies of flood damage assessment conducted in the Asian river basins, the Pampanga River basin of the Philippines, and the Lower Indus River basin of Pakistan. The assessment was performed by defining flood damage to rice crops as a function of flood depth, duration, and growth stage of rice plants and using depthduration-damage function curves for each growth stage of rice plants. In the case studies, flood characteristics such as flood depth, duration, and distribution were computed using a rainfall-runoff-inundation (RRI) model. Flood damage to rice crops was assessed for the 2011 flood and 100-year flood events in the case of the Pampanga River basin and for the 2010 flood in the case of Lower Indus River basin. The calculated values of agricultural damage were compared with reported data for validation of methodology, and it was found that the calculated damage reasonably agreed with reported data. The rice-crop damage assessment method described in

Flood Damage Assessment

Yusuke Yamazaki and Yoshio Tokunaga
