witnessed loss of life and property, disruption in transport and power, and the
incidence of epidemics. In this literature study, flood modeling studies adopted for
various major cities nationally and internationally are discussed, and a suitable
methodology for developing flood modeling studies in a medium size city is
recommended.
Case Studies in India
Mumbai
Zope et al. (2016) analyzed LULC changes and their effects on urban floods in the
expanding urban catchment of the Oshiwara River in Mumbai, India. In this study,
LULC change was determined for the years 1996, 2001, and 2009 by acquired
topographic and satellite images. The analysis proved that LULC change between
the years 1966 and 2001 was much slower that that between the years 2001 and
2009, when it was observed to be rather rapid. The results obtained between 1966
and 2009 proved that there was a 74.84% increase in the built-up area and a 42.8%
decrease of open space in response to urbanization. The effects of LULC on the flood
hydrograph for various return periods were evaluated using the HEC-HMS model. It
was noted that over the past 43 years, the increase in peak runoff and volume was
3.0% and 4.45%, respectively, for the 100-year return period. The results also
reported that increase in intensity of rainfall with short span and the lower return
period had a maximum peak discharge and volume of runoff when compared to
higher return periods for changing land use conditions.
Guwahati
A flood hazard map for a 100-year return period was developed for Guwahati city,
and hazard ranks identified the areas susceptible to flood inundation in the city This
study quantifies the reason for flood risk and identifies the parameters responsible for
peak runoff. From the analysis it is identified that LULC and microclimate change
are among the factors responsible for runoff changes in the city. The LULC and their
influence on surface runoff were analyzed for the years 2006 and 2011. Almost
46.5% of the city was inundated. The flood risk was found to increase from 2006 to
2011 because of increased imperviousness. For reducing peak discharge, it is
recommended to adopt a detention pond that reduces almost 43% of inundated
area in the city. Thus, detention ponds were found to be effective in reducing the
effect of urban flood, and hence can be proposed as a suitable measure for flood
management (Sahoo and Sreeja 2017).
3 Flood Risk Assessment for a Medium Size City Using Geospatial Techniques with. . .
49
incidence of epidemics. In this literature study, flood modeling studies adopted for
various major cities nationally and internationally are discussed, and a suitable
methodology for developing flood modeling studies in a medium size city is
recommended.
Case Studies in India
Mumbai
Zope et al. (2016) analyzed LULC changes and their effects on urban floods in the
expanding urban catchment of the Oshiwara River in Mumbai, India. In this study,
LULC change was determined for the years 1996, 2001, and 2009 by acquired
topographic and satellite images. The analysis proved that LULC change between
the years 1966 and 2001 was much slower that that between the years 2001 and
2009, when it was observed to be rather rapid. The results obtained between 1966
and 2009 proved that there was a 74.84% increase in the built-up area and a 42.8%
decrease of open space in response to urbanization. The effects of LULC on the flood
hydrograph for various return periods were evaluated using the HEC-HMS model. It
was noted that over the past 43 years, the increase in peak runoff and volume was
3.0% and 4.45%, respectively, for the 100-year return period. The results also
reported that increase in intensity of rainfall with short span and the lower return
period had a maximum peak discharge and volume of runoff when compared to
higher return periods for changing land use conditions.
Guwahati
A flood hazard map for a 100-year return period was developed for Guwahati city,
and hazard ranks identified the areas susceptible to flood inundation in the city This
study quantifies the reason for flood risk and identifies the parameters responsible for
peak runoff. From the analysis it is identified that LULC and microclimate change
are among the factors responsible for runoff changes in the city. The LULC and their
influence on surface runoff were analyzed for the years 2006 and 2011. Almost
46.5% of the city was inundated. The flood risk was found to increase from 2006 to
2011 because of increased imperviousness. For reducing peak discharge, it is
recommended to adopt a detention pond that reduces almost 43% of inundated
area in the city. Thus, detention ponds were found to be effective in reducing the
effect of urban flood, and hence can be proposed as a suitable measure for flood
management (Sahoo and Sreeja 2017).
3 Flood Risk Assessment for a Medium Size City Using Geospatial Techniques with. . .
49