risk of flood. In 2015 a high intensity of rainfall of 40 cm occurred within an hour,
resulting in vast damage to properties in the city that was mainly caused by LULC
and climate change patterns in the city (Suriya and Mudgal 2012).
International Level
Hafr Al-Batin City
Hafr Al-Batin city, located in the northeastern part of Saudi Arabia, was put in
danger from floods that caused serious damage to public and private properties. The
city is located in the dry valley of Wadi Al-Batin, part of Wadi Al-Rummah, where
three valleys meet, which causes more city flooding during intense rain with short
duration of rainfall. The estimated average rainfall in the basin was about 125 mm,
and recently maximum rainfall events generated flood water flow from the valleys
toward the city. In this study, HEC-HMS and HEC-RAS models were used to
simulate flood occurrence in the city. The average flow depth occurred during this
study period were 3.02 m, 3.26 m, 3.45 m, 3.76 m, 4.04 m, and 4.34 m for the
simulated 2-, 5-, 10-, 25-, 50-, and 100-year design floods, respectively. Flood
hazard maps are also generated to identify the areas within the city with high risk
of flooding (Aliani et al. 2019).
Dhaka City
The greatest flood that had occurred in Greater Dhaka in Bangladesh in the year 1998
was studied by using synthetic aperture data (SAR) with GIS. Flood frequency and
floodwater depth were calculated by SAR data for generation of flood hazard maps.
The flood hazard maps were created by a ranking matrix with land cover, geomorphic units, and elevation data as GIS components. From the results it was observed
that the major portion of Greater Dhaka is subject to very high hazard zones whereas
only a small portion is not exposed to the potential flood hazard. The proposed flood
hazard maps are useful for mitigation of the lives of people and property of Dhaka
city (Dewan and Makoto 2006).
Ho Chi Minh City, Vietnam
Rapid and unplanned urbanization combined with climate change has increased the
chance of flood risk in Ho Chi Minch city, Vietnam. Remote sensing data with a GIS
tool are integrated with a hydrologic model to identify flood risk in the city. In this
study, a Quick bird image was used to generate LULC maps; US Soil Conservation
Service Technique Release 55 (SCS TR-55) is used for generating a rainfall–runoff
model. The digital elevation data (DEM) and GIS were used to analyze tidal floods.
3 Flood Risk Assessment for a Medium Size City Using Geospatial Techniques with. . .
51
resulting in vast damage to properties in the city that was mainly caused by LULC
and climate change patterns in the city (Suriya and Mudgal 2012).
International Level
Hafr Al-Batin City
Hafr Al-Batin city, located in the northeastern part of Saudi Arabia, was put in
danger from floods that caused serious damage to public and private properties. The
city is located in the dry valley of Wadi Al-Batin, part of Wadi Al-Rummah, where
three valleys meet, which causes more city flooding during intense rain with short
duration of rainfall. The estimated average rainfall in the basin was about 125 mm,
and recently maximum rainfall events generated flood water flow from the valleys
toward the city. In this study, HEC-HMS and HEC-RAS models were used to
simulate flood occurrence in the city. The average flow depth occurred during this
study period were 3.02 m, 3.26 m, 3.45 m, 3.76 m, 4.04 m, and 4.34 m for the
simulated 2-, 5-, 10-, 25-, 50-, and 100-year design floods, respectively. Flood
hazard maps are also generated to identify the areas within the city with high risk
of flooding (Aliani et al. 2019).
Dhaka City
The greatest flood that had occurred in Greater Dhaka in Bangladesh in the year 1998
was studied by using synthetic aperture data (SAR) with GIS. Flood frequency and
floodwater depth were calculated by SAR data for generation of flood hazard maps.
The flood hazard maps were created by a ranking matrix with land cover, geomorphic units, and elevation data as GIS components. From the results it was observed
that the major portion of Greater Dhaka is subject to very high hazard zones whereas
only a small portion is not exposed to the potential flood hazard. The proposed flood
hazard maps are useful for mitigation of the lives of people and property of Dhaka
city (Dewan and Makoto 2006).
Ho Chi Minh City, Vietnam
Rapid and unplanned urbanization combined with climate change has increased the
chance of flood risk in Ho Chi Minch city, Vietnam. Remote sensing data with a GIS
tool are integrated with a hydrologic model to identify flood risk in the city. In this
study, a Quick bird image was used to generate LULC maps; US Soil Conservation
Service Technique Release 55 (SCS TR-55) is used for generating a rainfall–runoff
model. The digital elevation data (DEM) and GIS were used to analyze tidal floods.
3 Flood Risk Assessment for a Medium Size City Using Geospatial Techniques with. . .
51