1. Introduction

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 and also to quantify flood 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

Figure 1.

Agricultural, infrastructure, and house damage due to the past floods in Region III of the Philippines [Data source: Office of Civil Defense, Region III, Philippines].

monetary values [5, 7, 8]. Figure 2 shows the categorization of damage with some

Direct damage is damage caused by direct physical contact of floodwaters [5, 8], such as flood damage to buildings and residential properties; losses of crops, livestock, and human lives; immediate health impacts; and losses of ecological goods. Indirect flood damage is damage which is not directly due to flood exposure but mainly caused by disruption of physical and economic linkages and other losses, such as loss of production at flood-affected factories and companies and costs of

Tangible damage is damage which can be easily specified in monetary values, such as damage to buildings, residential properties, assets, and agricultural crops and loss of production. Intangible damage is damage which cannot be specified in monetary values, such as casualties, health impacts, and damage to ecological goods

Flood risk and damage assessment are essential for flood risk management. The main purpose of flood damage assessment is to identify areas at risk where mitigation actions are necessary. This chapter describes a grid-based method for flood damage assessment considering three major factors of risk: hazard, exposure, and vulnerability. Flood damage assessment starts with the identification of the target area and items exposed to a flood hazard using the results of flood hazard simulation and moves on to the evaluation of damage that might occur to exposed items because of the vulnerability of each item. Figure 3 shows the estimation process of agricultural flood damage assessment. Flood damage can be assessed by combining knowledge of a flood hazard and an item exposed to the flood with vulnerability. Flood characteristics such as flood depth and duration can be simulated using a

examples.

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Figure 2.

2.1 Direct and indirect damage

Categorization of flood damage [5, 6, 8, 9].

Methodology for Agricultural Flood Damage Assessment DOI: http://dx.doi.org/10.5772/intechopen.81011

traffic disruption and emergency services [5, 6–8].

and to all kind of goods and services [5, 7, 8].

3.1 Framework of flood damage assessment

3. Method for agricultural damage assessment

2.2 Tangible and intangible damage

countermeasures. The quantification of the effectiveness of countermeasures is also essential in cost-benefit analysis to assess the effectiveness of preventive investment. For flood damage assessment, flood damage functions are generally derived from past flood damage data by relating flood characteristics, such as flood depth and flood duration, with damage [3]. Shrestha et al. [3] pointed out that past flood hazards and damage data and their relationships are very important for the development of an appropriate method as well as for validation of calculated results. In many countries, especially in developing countries where past damage data are very limited, more efforts should be made to improve a flood damage assessment method. Effort should also be focused on the collection of flood damage data for the development of damage curves, model validation, and adaptation of approaches [4]. It is thus essential to develop appropriate flood damage estimation methods for planning mitigation measures and preparedness activities in order to reduce flood damage in the future.

For flood damage assessment, numerous studies have focused mainly on flood damage to the residential, infrastructure, and industrial sectors, while less attention has focused on the agricultural sector [5, 6]. However, the agricultural sector is a major source of income in many developing countries in Asia and thus likely to play a major role in new flood management policies [6]. On the other hand, when a flood occurs, the agricultural sector of many developing countries is severely affected by flooding (Figure 1). Therefore, an appropriate methodology for assessing flood damage to the agricultural sector is essential. This chapter describes a method for assessing flood damage to the agricultural sector, specifically focused on flood damage to rice crops. Flood damage to rice crops is defined as a function of flood depth, duration, and growth stage of rice plants. The case studies of flood damage assessment in the river basins of Asia such as the Pampanga River basin of the Philippines and the Lower Indus River basin of Pakistan are discussed.

### 2. Categorization of flood damage

Flood damage refers to varieties of destruction and losses caused by flooding [7, 8], for example, harmful effects on humans; damage to buildings, residential properties, and other types of infrastructure; impact on lifeline and other public services; and losses of agricultural and industrial production [5, 7]. Flood damage is typically categorized as direct and indirect damage and further categorized as tangible and intangible damage depending on whether damage can be assessed in

Methodology for Agricultural Flood Damage Assessment DOI: http://dx.doi.org/10.5772/intechopen.81011

Figure 2.

countermeasures. The quantification of the effectiveness of countermeasures is also essential in cost-benefit analysis to assess the effectiveness of preventive investment. For flood damage assessment, flood damage functions are generally derived from past flood damage data by relating flood characteristics, such as flood depth and flood duration, with damage [3]. Shrestha et al. [3] pointed out that past flood hazards and damage data and their relationships are very important for the development of an appropriate method as well as for validation of calculated results. In many countries, especially in developing countries where past damage data are very limited, more efforts should be made to improve a flood damage assessment method. Effort should also be focused on the collection of flood damage data for the development of damage curves, model validation, and adaptation of approaches [4]. It is thus essential to develop appropriate flood damage estimation methods for planning mitigation measures and preparedness activities in order to reduce flood damage in the

Agricultural, infrastructure, and house damage due to the past floods in Region III of the Philippines [Data

For flood damage assessment, numerous studies have focused mainly on flood damage to the residential, infrastructure, and industrial sectors, while less attention has focused on the agricultural sector [5, 6]. However, the agricultural sector is a major source of income in many developing countries in Asia and thus likely to play a major role in new flood management policies [6]. On the other hand, when a flood occurs, the agricultural sector of many developing countries is severely affected by flooding (Figure 1). Therefore, an appropriate methodology for assessing flood damage to the agricultural sector is essential. This chapter describes a method for assessing flood damage to the agricultural sector, specifically focused on flood damage to rice crops. Flood damage to rice crops is defined as a function of flood depth, duration, and growth stage of rice plants. The case studies of flood damage assessment in the river basins of Asia such as the Pampanga River basin of the

Philippines and the Lower Indus River basin of Pakistan are discussed.

Flood damage refers to varieties of destruction and losses caused by flooding [7, 8], for example, harmful effects on humans; damage to buildings, residential properties, and other types of infrastructure; impact on lifeline and other public services; and losses of agricultural and industrial production [5, 7]. Flood damage is typically categorized as direct and indirect damage and further categorized as tangible and intangible damage depending on whether damage can be assessed in

2. Categorization of flood damage

future.

112

Figure 1.

source: Office of Civil Defense, Region III, Philippines].

Recent Advances in Flood Risk Management

Categorization of flood damage [5, 6, 8, 9].

monetary values [5, 7, 8]. Figure 2 shows the categorization of damage with some examples.
