Encroachments and urban development have choked the Mithi river in Mumbai which caused the massive floods in the region in July 2005 which affected the whole city and surrounding areas of Mumbai.
Now the flood-prone zone around the Oshiwara river, which runs from the Sanjay Gandhi National Park down to Malad creek, has also expanded in the past half decade for similar reasons including rapid urban growth.
A new study from IIT Bombay includes another flood hazard in the area. “Between 1966-2009, there was a 74.84% increase in built-up area in the catchment zone of the Oshiwara river,” suggests the study.
The research focused on the pace of urban growth was greater after 2001—around 31% increase in built-up area in the eight years between 2001-2009 compared with 43.5% in the 35 years between 1966 and 2001.
In the same four-decade period, open spaces in the catchment zone reduced by 42.8% and water bodies by 62%.
The increased built-up area has been accompanied by a rise in the extent of flood inundation, with the downstream part of the catchment zone more vulnerable than upstream, found IIT researchers P E Zope, T I Eldho and V Jothiprakash.
The area in the highly hazardous zone increased by 64.29% while that falling in less hazardous one declined by 32%, shows the analysis. The total flood-hazard area increased by 22.3%, says the researchers.