knowledge about flood frequencies at different
points in a catchment. The classical approach to
obtain design flows is to carry out local or regional
flood frequency analysis using long records of
observed discharge data (e.g. Hosking and Wallis
1997; Stedinger et al. 1993). Other models for
synthetic rainfall generation which can be applied
for derived flood frequency analysis include different disaggregation approaches (Koutsoyiannis
et al. 2003; Lu and Yamamoto 2008; Olsson 1998)
and various re-sampling methods (Bardossy 1998;
Lall and Sharma 1996).
In West Tripura District two rivers, namely,
the Haora River and the Lohar Nala experience
flood and these basins also experience flash
flood. Flow reaches to peak discharge in a few
minutes or a few hours and they often have a
steep bore front (Leopold and Miller 1956;
Renard and Keppel 1966; Sharon 1972; Schick
1988; Hassan 1990; Abrahams et al. 1995; Reid
and Frostick 1997). About 40 percent mouza and
41 percent population of West Tripura District
are severely affected by flood. Piedmont plains
(areas of flash flood) and the alluvial plains cover
about 70 percent of the district out of which 60
percent experiences flood hazard and 55 percent
population are affected which also includes
Agartala, the capital of Tripura. This hazard
causes tremendous loss in terms of property,
standing crops, roads and houses.
15.2 Study Area
West Tripura District extends from 23°40′N to
24°07′N latitude and 91°12′E to 91°32′E longitude (Fig. 15.1). Geologically, the study area
falls under Dupitilla series and Tipam group of
rocks which is characterized by sand rocks.
Surma group and alluvium deposition are also
found in this district. Tropical monsoon type of
climate prevails here. Physiography of the study
area is characterized by (i) hill range, (ii) piedmont slopes and uplands, (iii) terraces and tillas
and (iv) flood plains. In this district (i) reddish
yellow brown sandy soil, (ii) red loam and sandy
loam soils, (iii) younger and older alluvial soils
and (iv) lateritic soils are found. The total
population of this district is 988,192 (30% of the
state) out of which about 189,998 population live
in Agartala, that is, 20 percent of this district and
about 256,930 (26%) population are engaged in
agricultural activities.
15.3 Aims and Objectives
The aim of this research work is to reduce the
flood risk, as well as disaster risk in West Tripura
District. To fulfil this aim, the main objective is
to prepare flood simulation model of West Tripura District for 50 and 100 years return period.
15.4 Materials and Method
In order to carry out this study, Geomatica V
10.1, ArcGIS, MS Excel, Adobe Photoshop,
GPS tool, SOI topographical maps (Ref.
No. 79 M/1, 2, 5, 6, 9, 10, 78 P/8 and 12), Land
sat Imagery (ETM PAN and MSS) (2015) and
Google Earth Imagery (2015) have been used.
Flood simulation map has been prepared
using ArcMap 10.1 and ArcScene 10.1. For this
purpose, digital elevation model, contour map at
1 m interval, rainfall data, water level and flood
inundation data have been considered. In ArcMap, contours at 1 m interval have been generated on DEM which was downloaded from
Bhuban Cartosat website. In ArcScene, 3D map
of West Tripura District has been prepared; flood
inundation data and water level have been
entered in Animation Manager Table, and the
simulation layer, thus generated, has been overlaid on 3D map of West Tripura District. For this
modelling, discharge and water level of the
Haora River for 50 and 100 years return period
have been measured from the flood frequency
curve and rating curve. On the basis of those
water level data, the flood simulation model of
the Haora River for those return periods has been
prepared. In case of the Lohar Nala, no hydrological data was available. Therefore, the flood
simulation model of the Lohar Nala has been
prepared on the basis of collected information on
flood inundation depth and water level.
202
M. Bhowmik and N. Das (Pan)
points in a catchment. The classical approach to
obtain design flows is to carry out local or regional
flood frequency analysis using long records of
observed discharge data (e.g. Hosking and Wallis
1997; Stedinger et al. 1993). Other models for
synthetic rainfall generation which can be applied
for derived flood frequency analysis include different disaggregation approaches (Koutsoyiannis
et al. 2003; Lu and Yamamoto 2008; Olsson 1998)
and various re-sampling methods (Bardossy 1998;
Lall and Sharma 1996).
In West Tripura District two rivers, namely,
the Haora River and the Lohar Nala experience
flood and these basins also experience flash
flood. Flow reaches to peak discharge in a few
minutes or a few hours and they often have a
steep bore front (Leopold and Miller 1956;
Renard and Keppel 1966; Sharon 1972; Schick
1988; Hassan 1990; Abrahams et al. 1995; Reid
and Frostick 1997). About 40 percent mouza and
41 percent population of West Tripura District
are severely affected by flood. Piedmont plains
(areas of flash flood) and the alluvial plains cover
about 70 percent of the district out of which 60
percent experiences flood hazard and 55 percent
population are affected which also includes
Agartala, the capital of Tripura. This hazard
causes tremendous loss in terms of property,
standing crops, roads and houses.
15.2 Study Area
West Tripura District extends from 23°40′N to
24°07′N latitude and 91°12′E to 91°32′E longitude (Fig. 15.1). Geologically, the study area
falls under Dupitilla series and Tipam group of
rocks which is characterized by sand rocks.
Surma group and alluvium deposition are also
found in this district. Tropical monsoon type of
climate prevails here. Physiography of the study
area is characterized by (i) hill range, (ii) piedmont slopes and uplands, (iii) terraces and tillas
and (iv) flood plains. In this district (i) reddish
yellow brown sandy soil, (ii) red loam and sandy
loam soils, (iii) younger and older alluvial soils
and (iv) lateritic soils are found. The total
population of this district is 988,192 (30% of the
state) out of which about 189,998 population live
in Agartala, that is, 20 percent of this district and
about 256,930 (26%) population are engaged in
agricultural activities.
15.3 Aims and Objectives
The aim of this research work is to reduce the
flood risk, as well as disaster risk in West Tripura
District. To fulfil this aim, the main objective is
to prepare flood simulation model of West Tripura District for 50 and 100 years return period.
15.4 Materials and Method
In order to carry out this study, Geomatica V
10.1, ArcGIS, MS Excel, Adobe Photoshop,
GPS tool, SOI topographical maps (Ref.
No. 79 M/1, 2, 5, 6, 9, 10, 78 P/8 and 12), Land
sat Imagery (ETM PAN and MSS) (2015) and
Google Earth Imagery (2015) have been used.
Flood simulation map has been prepared
using ArcMap 10.1 and ArcScene 10.1. For this
purpose, digital elevation model, contour map at
1 m interval, rainfall data, water level and flood
inundation data have been considered. In ArcMap, contours at 1 m interval have been generated on DEM which was downloaded from
Bhuban Cartosat website. In ArcScene, 3D map
of West Tripura District has been prepared; flood
inundation data and water level have been
entered in Animation Manager Table, and the
simulation layer, thus generated, has been overlaid on 3D map of West Tripura District. For this
modelling, discharge and water level of the
Haora River for 50 and 100 years return period
have been measured from the flood frequency
curve and rating curve. On the basis of those
water level data, the flood simulation model of
the Haora River for those return periods has been
prepared. In case of the Lohar Nala, no hydrological data was available. Therefore, the flood
simulation model of the Lohar Nala has been
prepared on the basis of collected information on
flood inundation depth and water level.
202
M. Bhowmik and N. Das (Pan)