Impacts of precipitation variability on urban hydrology: cases of Ahmedabad and Surat
Student name: Mr Harsh Shah
Guide: Dr Prateek Sharma
Year of completion: 2013
Host Organisation: CEPT University, Ahmedabad
Supervisor (Host Organisation): Prof Tushar Bose
Abstract: The precipitation variability is a common term as it has made the whole world familiar with the
impacts as well as causes of variability. The study aims to the see relationships and the effects of
the variability on some of the components of Urban Hydrology, such as runoff and storm water
accumulation. It is of a deeper significance as we know urbanisation leads to changes in the
natural drainage altering the land use patterns. We are trying to measure the impacts of those
changes on various runoff scenarios as well as the relation of the induced variability with the
extreme events. The study also tries to map the flood affected zone with the use of software HEC
RAS and its extensions, a buffer area is predicted in cases of various extreme events. The study
so formed concentrates on the relationships between various aspects of Urban Hydrology and
the precipitation variability. The variability under the study boundaries were not quantified but
just the presence of the variability was checked and the impacts in terms of change in the long
term average rainfall were computed, Extreme events were observed. Further, the land use land
cover changes were observed over a span of urbanisation and they were then used for
quantification of various runoff scenarios. The model HEC RAS was used to form a buffer at
various peak discharges giving us vulnerable areas for our calculations of the peak discharge.
The back calculations were applied forming a buffer of 200 m and 500 m of the nearby low lying
areas and finally a pilot model was devised for the authorities to check whether the system is
efficiently functioning or not and some suggestive measures for increasing capacity has also
been discussed.
Keywords: Precipitation Variability, Urban Hydrology, Land Use Patterns, Runoff & HEC RAS
