The Okhla Bird Sanctuary wetlands are part of the natural wealth of Delhi, a city on the banks of the river Yamuna. One of the most productive ecosystems of the world, wetlands contribute to reducing disaster risk by serving as natural protective barriers or buffers, mitigating hazard impacts.
But the wetlands on the corridor of Yamuna are rapidly diminishing due to human induced activities and are today one of the most threatened ecosystems, with the pressure for conversion of wetlands for developmental purposes growing exponentially every single day.
A rivers playground stolen
Floods are not new to Delhi. In 1978, the capital witnessed one of the worst ever flood, and when 130 villages and 25 urban colonies in Delhi were submerged in water. In 2010, when the September rainfall was 180% more than the normal and water levels in Yamuna crossed the danger mark, destructive floods again hit the city. The river water was further squeezed as a chunk of the floodplain, size of the Commonwealth Games Village, was no longer available for it as it was for centuries. And so, the floods again created havoc.
Today, urban floods are a regular nuisance. Heavy rains are not only to blame. The entire river bed in the west, between the ring road and the stream, has been swallowed up in the name of construction and development. Instead of the open land, it now hosts a thermal power plant, politicians and leaders samadhis and the Millenium bus depot. Encroachment, uncontrolled siltation, weed infestation and uncontrolled discharge of effluents and wastewater, have made the floodplains even more vulnerable.
No place to run
Ponds have disappeared under newly made bridges and flyovers; and unplanned and erratic urbanisation has altered the drainage characteristics of natural catchments. Concretised areas don’t allow water to seep in, increasing the volume of surface runoff. The existing drains, already choked with indiscriminate solid waste disposal, are unable to cope with this extra heavy load. Both of these, inadequate drainage and uncontrolled development, are a major reason for urban floods, a perennial occurrence in the city today.
Why the wetland matters
The floodplains of the river Yamuna, more than 90 sq. km area, boasts of forests, agricultural fields, settlements, lakes and ponds, besides an array of floral and faunal diversity. And it also has the capacity to hold 2 billion cubic meters of water. The maximum width of the floodplain is observed near Okhla, where the Bird Sanctuary, a rich biodiversity habitat exists.
The wetland and the availability of water near Okhla throughout the year helps maintain minimum water level required for functioning of the floodplain. The surplus water during monsoon percolates down, and helps control floods and also maintain moisture regimes during lean periods. Bio accumulation of key nutrients in floodplain also helps to reduce pollution stress.
Besides these, it provides ecosystem services like groundwater recharge, excess water storage, disease regulation, carbon sequestration, shelter belt and thermal regulation in the hot summers. A source of livelihood, water and fish, the wetlands support recreational and educational activities too.
The fertile floodplain supports vegetable farming, horticulture and floriculture, ensuring a regular income for the communities living here. For the city, it helps in disaster risk reduction by addressing hazards such as drought, floods and epidemics, and reducing its vulnerability.
Thus these wetlands ecosystems provide various tangible and intangible benefits both to the urban society and other associated dependent ecosystems, on a sustainable basis. And integration of ecosystem services of these very wetlands in the DRR framework can work as a strategy to reduce exposure and vulnerability, and enhance livelihood capacities as well as resilience of the city.
This blog is based on an excerpt from ‘Urban Resilience and Sustainability through Peri-Urban Ecosystems: Integrating Climate Change Adaptation and Disaster Risk Reduction’, a Process Guidance and Training Handbook, published by the Gorakhpur Environmental Action Group (GEAG), supported under the ACCCRN initiative of The Rockefeller Foundation.
Image source: Wikimedia Commons