Causes of Urban Floods in India

This topic gets its importance from recent floods in Chennai, Srinagar and other parts of the country. Urban areas are centres of economic activities with have vital infrastructure. Damage to this infrastructure can have a bearing not only on the country but also globally. Major cities such as Mumbai in 2005 and Chennai recently have witnessed loss of life and property, disruption in transport and power and incidence of epidemics. This demands the need for management of urban flooding.

Meteorological Factors

These include rainfall, cyclonic storms, small-scale storms, temperature, snowfall and snowmelt

Hydrological Factors

These include soil moisture level, groundwater level prior to storm, natural surface infiltration rate, presence of impervious cover, channel cross-sectional shape and roughness, presence or absence of over-bank flow, channel network, synchronization of runoffs from various parts of watershed and high tide impeding drainage

Human Factors

The most important human factors are: Land use changes (e.g. surface sealing due to urbanization, deforestation) increase runoff and sedimentation; Occupation of the flood plain and thereby obstructing flows; Inefficiency or non-maintenance of infrastructure; Too efficient drainage of upstream areas increases flood peaks; Climate change effects, magnitude and frequency of precipitation and floods; Urban micro-climate may enforce precipitation events; Sudden release of water from dams located upstream of cities/towns ; Failure to release water from dams resulting in backwater effect; Indiscriminate disposal of solid waste etc.