and daily rainfall data. The HSG, LULC, and CN maps were developed for each
basin in the study area. From the analysis it was noted that the study area was
delineated into 40 watersheds and the weighted CN for the city is 92. The rainfall–
runoff analysis shows that the area has a high and very high daily runoff of 35–50
and >50 mm, respectively (Radwan et al. 2018).
The major cities in India and in the world have experienced loss of life, property,
disturbance in transport, and the incidence of epidemics as results of floods. Therefore, the lesson learnt from these major cities is decided to be to adopt some of the
parameters for developing flood modeling in these medium size cities, using measures such as management of land use practices, climate risk, and proper maintenance of urban drainage structures. From the various literature reviews, it was
observed that almost all flood modeling studies are done only for major and coastal
urban cities globally and nationally. Very few limited studies were conducted in an
integrated flood modeling approach and for medium size cities.
In this study, an integrated approach of hydrologic and hydraulic modeling with
Arc GIS is adopted. The hydrologic and hydraulic modeling used in this study is
HEC-HMS and HEC-RAS. The integrated flood modeling approach is adopted to
develop a regional model for generating floodplain and flood hazard maps. The
changes in LULC for different years and their impact on urban runoff are studied.
Floodplain and flood hazard maps for different return periods are generated for
various LULC changes.
The current study considers the development of integrated flood modeling for
Koraiyar River basin passing through a medium size city, Tiruchirappalli city, in
India. The study approaches the integrated flood modeling approach for the Koraiyar
River basin by temporal and spatial data collection. Temporal data such as daily
rainfall data are collected and analyzed by frequency distribution methods. The
spatial data of remote sensing images of Landsat images classifies LULC changes
and the DEM data address stream network classification and basin delineation. The
LULC maps with the HSG map are imported to the hydrologic model HEC-HMS for
generating peak discharge. The generated peak discharge is incorporated into the
hydraulic model HEC-RAS to generate flood depths for different return periods.
Motivation of the Present Chapter
In recent years the severity of floods has increased in all cities in India. The most
prominent cities that are frequently affected by floods are Mumbai, Bengaluru,
Hyderabad, and Chennai. After the 2015 floods in Chennai, it is necessary to develop
flood modeling for all developing cities in India to provide sufficient warning and
flood forecasting systems. In India, flood modeling studies so far have focused on
megacities and minimal studies have been done for a basin that passes through a
medium size city. No integrated flood modeling studies have yet been done for the
Koraiyar basin selected for this study.
54
S. Natarajan and N. Radhakrishnan
basin in the study area. From the analysis it was noted that the study area was
delineated into 40 watersheds and the weighted CN for the city is 92. The rainfall–
runoff analysis shows that the area has a high and very high daily runoff of 35–50
and >50 mm, respectively (Radwan et al. 2018).
The major cities in India and in the world have experienced loss of life, property,
disturbance in transport, and the incidence of epidemics as results of floods. Therefore, the lesson learnt from these major cities is decided to be to adopt some of the
parameters for developing flood modeling in these medium size cities, using measures such as management of land use practices, climate risk, and proper maintenance of urban drainage structures. From the various literature reviews, it was
observed that almost all flood modeling studies are done only for major and coastal
urban cities globally and nationally. Very few limited studies were conducted in an
integrated flood modeling approach and for medium size cities.
In this study, an integrated approach of hydrologic and hydraulic modeling with
Arc GIS is adopted. The hydrologic and hydraulic modeling used in this study is
HEC-HMS and HEC-RAS. The integrated flood modeling approach is adopted to
develop a regional model for generating floodplain and flood hazard maps. The
changes in LULC for different years and their impact on urban runoff are studied.
Floodplain and flood hazard maps for different return periods are generated for
various LULC changes.
The current study considers the development of integrated flood modeling for
Koraiyar River basin passing through a medium size city, Tiruchirappalli city, in
India. The study approaches the integrated flood modeling approach for the Koraiyar
River basin by temporal and spatial data collection. Temporal data such as daily
rainfall data are collected and analyzed by frequency distribution methods. The
spatial data of remote sensing images of Landsat images classifies LULC changes
and the DEM data address stream network classification and basin delineation. The
LULC maps with the HSG map are imported to the hydrologic model HEC-HMS for
generating peak discharge. The generated peak discharge is incorporated into the
hydraulic model HEC-RAS to generate flood depths for different return periods.
Motivation of the Present Chapter
In recent years the severity of floods has increased in all cities in India. The most
prominent cities that are frequently affected by floods are Mumbai, Bengaluru,
Hyderabad, and Chennai. After the 2015 floods in Chennai, it is necessary to develop
flood modeling for all developing cities in India to provide sufficient warning and
flood forecasting systems. In India, flood modeling studies so far have focused on
megacities and minimal studies have been done for a basin that passes through a
medium size city. No integrated flood modeling studies have yet been done for the
Koraiyar basin selected for this study.
54
S. Natarajan and N. Radhakrishnan