4.2 Lower Indus River basin of Pakistan

Figure 14 shows the location of the Lower Indus River basin in Pakistan. The area of the study basin is about 700,375 km2 . The global land-cover data of GLCNMO were used to extract paddy fields, and Figure 15(a) shows the paddy

Figure 14. Study area of the lower Indus River basin in Pakistan.

[19] were used in the calculation. About 11.3% of the total paddy-field area in the basin was damaged during this flood event. Figure 12 compares the calculated ricecrop damage with the reported data for five municipalities in the basin. The calculated results reasonably agreed with the reported damage, although some difference was found in the case of Candaba Municipality. This discrepancy between the calculated and reported damage can be attributed to a variety of reasons, for exam-

Comparison of calculated value of rice-crop damage with reported data for five municipalities during the flood

Calculated maximum flood inundation depth using the RRI model and estimated flood damage to rice crop by

Figure 13 shows the calculated maximum flood inundation depth and flood damage to rice crop for a 100-year flood. The damaged paddy fields and value of rice-crop damage in the case of a 100-year flood were 67,655 ha and 2248.3 million

ple, accuracy of topographical and land-cover data.

from 26 September to 4 October 2011. Reported data source: [19, 20].

Figure 11.

Figure 12.

122

the flood event from 26 September to 4 October 2011.

Recent Advances in Flood Risk Management

Figure 15.

Paddy field in the study area and cropping calendar for wet-season rice crop.

fields in the Lower Indus study area. The paddy fields in the area are about 8.62 million ha (12.3% of the study basin area). Figure 15(b) shows the wet-season rice cultivation calendar in the study area, which was prepared based on FAO [21]. The wet-season rice cultivation period in the basin is from June to October.

The flood hazard was analyzed using the RRI Model for the August 2010 flood. DEM, flow accumulation, and flow direction data downloaded from the HydroSHEDS were used for the analysis. Since the study basin area is quite large, flood hazard simulation was conducted using a 60 arc-second grid size (approximately 1.8 km). In the RRI Model simulation, the observed river discharge boundary conditions at Tarbela and Kabul were defined, and recorded rainfall was also considered. The details of calibration and validation of the RRI Model can be found in Sayama et al. [10].

Figure 16 shows the calculated maximum flood inundation depth and estimated flood damage to rice crop during the August 2010 flood event. The values of the farm gate price equal to 17.5 Rs/kg [22] and the rice yield equal to 2641 kg/ha, obtained from the Directorate of Agriculture Extension Sindh, Hyderabad, were used in the calculation. The damage curve for the maturity stage was used according to the cropping calendar and the duration of the growth stage. The calculated flood inundation areas with a flood inundation depth greater than 0.5 m and the damaged rice-field areas were found to be 1,611,252 ha and 662,580 ha, respectively. About 7.6% of the paddy-field area was damaged during the August 2010 flood. The total estimated flood damage to rice crop in the basin was found to be 19.72 billion Rs (Pakistani Rupees), while the reported damage was 21.17 billion Rs. The calculated damage values were also compared with the reported data for four provinces (Figure 17). The comparison results show that the calculated damage values reasonably agreed with the reported data. The results show that rice crops were severely damaged by flooding in Sindh and Punjab provinces.

5. Conclusions

2010 flood. Reported data source: [22].

Figure 17.

125

Figure 16.

Indus River basin.

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

The method for assessing flood damage to rice crop with case studies in the Asian river basins was discussed. The results of flood damage assessment in the Pampanga River basin of the Philippines and the Lower Indus River basin of Pakistan were also presented in this paper. The calculated values of rice-crop damage were compared with reported data. The comparison results show that the values of calculated damage reasonably agreed with the reported damage values. The ricecrop damage estimation method presented in this paper can be easily applied to estimate damage for future flood events and can also be applied to other river basins

Comparison of calculated value of rice-crop damage with reported data for four provinces during the August

Calculated maximum flood inundation depth and rice-crop damage during the August 2010 flood in the lower

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

#### Figure 16.

fields in the Lower Indus study area. The paddy fields in the area are about 8.62 million ha (12.3% of the study basin area). Figure 15(b) shows the wet-season rice cultivation calendar in the study area, which was prepared based on FAO [21]. The

The flood hazard was analyzed using the RRI Model for the August 2010 flood.

Figure 16 shows the calculated maximum flood inundation depth and estimated flood damage to rice crop during the August 2010 flood event. The values of the farm gate price equal to 17.5 Rs/kg [22] and the rice yield equal to 2641 kg/ha, obtained from the Directorate of Agriculture Extension Sindh, Hyderabad, were used in the calculation. The damage curve for the maturity stage was used according to the cropping calendar and the duration of the growth stage. The calculated flood inundation areas with a flood inundation depth greater than 0.5 m and the damaged rice-field areas were found to be 1,611,252 ha and 662,580 ha, respectively. About 7.6% of the paddy-field area was damaged during the August 2010 flood. The total estimated flood damage to rice crop in the basin was found to be 19.72 billion Rs (Pakistani Rupees), while the reported damage was 21.17 billion Rs. The calculated damage values were also compared with the reported data for four provinces (Figure 17). The comparison results show that the calculated damage values reasonably agreed with the reported data. The results show that rice crops were

HydroSHEDS were used for the analysis. Since the study basin area is quite large, flood hazard simulation was conducted using a 60 arc-second grid size (approximately 1.8 km). In the RRI Model simulation, the observed river discharge boundary conditions at Tarbela and Kabul were defined, and recorded rainfall was also considered. The details of calibration and validation of the RRI Model can be found

wet-season rice cultivation period in the basin is from June to October.

Paddy field in the study area and cropping calendar for wet-season rice crop.

Recent Advances in Flood Risk Management

DEM, flow accumulation, and flow direction data downloaded from the

severely damaged by flooding in Sindh and Punjab provinces.

in Sayama et al. [10].

124

Figure 15.

Calculated maximum flood inundation depth and rice-crop damage during the August 2010 flood in the lower Indus River basin.

#### Figure 17.

Comparison of calculated value of rice-crop damage with reported data for four provinces during the August 2010 flood. Reported data source: [22].

### 5. Conclusions

The method for assessing flood damage to rice crop with case studies in the Asian river basins was discussed. The results of flood damage assessment in the Pampanga River basin of the Philippines and the Lower Indus River basin of Pakistan were also presented in this paper. The calculated values of rice-crop damage were compared with reported data. The comparison results show that the values of calculated damage reasonably agreed with the reported damage values. The ricecrop damage estimation method presented in this paper can be easily applied to estimate damage for future flood events and can also be applied to other river basins for flood risk assessment. The method was also introduced to the related organizations in several developing countries of Asia such as the Philippines, Indonesia, Cambodia, Thailand, and Myanmar. The results of flood damage provide a basis to identify areas at risk, and these results can be useful for planners, developers, policy makers, and decision-makers to establish policies required for flood damage reduction. The results may also be useful for them to implement flood mitigation actions including agricultural land-use regulations while taking into account the risk areas of rice-crop damage and adaptation measures.

The accuracy of flood disaster risk assessment can be further improved by considering the following points:


Author details

Yoshio Tokunaga1,2

127

the auspices of UNESCO, Tsukuba, Japan

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

provided the original work is properly cited.

2 Public Works Research Institute (PWRI), Tsukuba, Japan

\*Address all correspondence to: shrestha@pwri.go.jp

Badri Bhakta Shrestha1,2\*, Hisaya Sawano1,2, Miho Ohara1,2, Yusuke Yamazaki2 and

1 International Centre for Water Hazard and Risk Management (ICHARM) under

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,
