The cities are continuously experiencing extreme flooding events which requires attention and proper solution before it gets converted to a deadly disaster. URBAN FLOODING is a chronic process which is caused due because the city landscapes fail yo absorb or manage the rainfall. Urban Flooding is separate and different from coastal and riverine flooding and are more frequent and localized.
What is Urban Flooding ?
Urban Flooding is the flooding happening in urban areas due to excessive runoff in urban areas and because the runoff doesn’t get managed properly. This phenomenon can be caused during heavy rainfalls as well as in small amount of rainfall. Even small amount of rain can deteriorate or cause flooding due to inadequate infrastructure and actions taken by neighborhood or city to manage the storm water, especially in impoverished, neglected and socio-economic isolated urban communities. Urban flooding has three components: (i) caused by rainfall; (ii) falls on impervious surfaces; and (iii) increases the level of local storm water drainage capacity. These components along with heavy rainfall or precipitation, climate change, outdated drainage infrastructure and storm water management infrastructures and increased urbanization can cause major challenge and disaster in urban areas. Urban Flooding is caused due to the climate change and extreme weather conditions of the cities. The phenomenon becomes more and more frequent and common in urban areas these days. While untimely heave rains can be seen as a consequence of climate change, the urban flooding can be seen as the consequence of unplanned urbanization.
Urban Flooding in India
The rate of urban flooding has been increasing in India and it is severely affecting the major cities. Some of the most disastrous urban flooding were found in Mumbai (2005), Kolkata (2007), Delhi (2009), Bangalore (2015) and Hyderabad (2020) the most recent doubt. Flooding in India is mostly found in its peak in monsoons seasons and many times when the storm surges at coastal cities urban flooding is caused. There are many other causes of urban flooding also, like failure to release water from dams, increasing proportion of built up area etc. In addition to these causes, Urban Heat Island effect has also resulted in an increase in rainfall over urban areas. Global climate changes results in extreme weather patterns and increased incidences of heavy rainfall occurring over shorter periods of time. This phenomenon is also increasing sea level and threatening all the coastal cities.
Factors behind Urban Flooding
There are number of factors behind the phenomenon and some of the major factors behind this phenomenon are
- Inadequate Drainage Facilities: There are many cities in the country who are relying on age old drainage systems which are efficient in carrying the rainfall when heave rainfall happens. These drains don’t have adequate capacity for carrying them.
- Alteration of Natural Drains: Cities have been built and developed by flattening the natural terrain and altering and manipulating the natural drainage routes.
- Increasing Imperviousness and Reducing Seepage: With increasing urbanization, the proportion of impervious areas is also increasing. With this the seepage of rainwater decreases and leads to flooding.
- Encroachment over Natural Spaces: The developments are encroaching the green spaces, water bodies, open spaces etc. which are natural areas and have the ability to seep water.
With the increasing rate of urbanization the capacity of natural drains has decreases and results in flooding. Improper solid waste disposal and dumping of construction debris into the drains which also contributes significantly to the reduction in capacity of the natural drains. This problem will keep on increasing with increasing population because the demand of living spaces and infrastructures are met by encroaching over floodplains and green spaces. Hence, it is important to manage and regulate the developmental works taking place in the city.