Vulnerability assessment of flood-affected locations of Bangalore by using multi-criteria evaluation

Abstract

ABSTRACT: The large-scale land conversions to urban impervious surfaces, loss of lakes and occupation of floodplains, have resulted in many problems like urban heat island, depletion of the ground water and more importantly flash floods. The impervious surfaces of urbanization led to accelerated run-off and reduced recharge. Currently, around 280 locations are vulnerable to flash floods in the Bangalore city of India. The dumping of solid waste, laying of cables in the channels, under-potential culverts and allotment of the floodplain for housing purposes has developed vulnerability to frequent flooding. Increased urbanization with intensified vertical growth of the city has led to the liquid waste disposal along the storm water drains making the run-off models unpredictable. The breach of lake embankments and overflowing lakes at the initial monsoon rains is the popular phenomenon as the lakes are silted and saturated with sewage. Efforts of revival of some lakes and desilting storm water drains have not improved the overall circumstance. Floods are reported even in short rainfall of 30 mm per hour. Adoption of the dual piping system to carry the wastewater and the rainwater would make restoration more meaningful. Multiple criteria evaluation of spatial layers in GIS environs provides a better assessment of vulnerable flash flood regions. For strategic plans, results from this investigation intuit in building a self-sufficient eco-friendly sustainable smart city that conserves the rainwater and avoid flooding in low-lying regions. The outcomes of the study guide in developing proper structures to the present urban situation, thereby implementing sustainable alternative development.