With increasing reports of high-intensity rainfall in short durations leading to urban flooding, concerns are mounting around the world. This has been compounded by factors such as unplanned expansion, encroachment of natural water bodies and an inadequate drainage system.
Understanding Urban Flooding
Urban flooding is described as the inundation of land or property in a built environment, especially in densely populated regions such as cities. It is mainly caused by rainfall that exceeds the capacity of the drainage system. Unlike rural floods, urban floods result not just from heavy rainfall, but also from impromptu urbanisation that escalates flood peaks and volumes up to 1.8 to 8 times and 6 times respectively.
Primary Causes of Urban Flooding
Several elements contribute to the prevalence of urban flooding. Encroachments on drains due to scarcity of land and inflated land prices have given rise to developments in low-lying city areas. In a perfect scenario, natural drains should have been broadened to accommodate higher stormwater flows, however, the contrary often happens with large-scale encroachments resulting in decreased drain capacity and subsequent flooding.
Climate change, too, plays a significant role, increasing frequency of heavy, short duration rainfall leading to more considerable water runoff. Unplanned and sudden release of water from dams or lakes can also cause urban area flooding.
Illegal mining for building construction purposes depletes the natural beds of rivers and lakes, leading to soil erosion and reducing the waterbody’s water retention capacity, thus increasing the speed and scale of water flow.
Implications of Urban Flooding
The consequences of urban flooding are manifold. Loss of life and property is often accompanied by physical injuries either directly due to floods or indirectly due to water-borne diseases spreading during the inundated period.
Environmental damages include trees and plants being washed away during severe flood events and erosion of riverbanks caused by high-speed flood water. Stagnation of stormwater and contamination of drinkable water can lead to various health problems and spread diseases. Loss of shelter and loved ones creates emotional distress and often results in long-lasting psychological trauma.
Government Initiatives to Curtail Urban Flooding
To address and mitigate the issue of urban flooding, governments have put forth several initiatives. These include Jal Shakti Abhiyan (JSA), Amrit Sarovar Mission, Atal Bhujal Yojana, Atal Mission for Rejuvenation and Urban Transformation (AMRUT) 2.0, Model Building Bye Laws (MBBL), 2016, and Standard Operating Procedures (SoPs) on Urban Flooding by the Ministry of Housing and Urban Affairs.
Sustainable Solutions Moving Forward
Moving forward, implementation of sustainable urban planning practices that focus on green spaces, retention ponds, and permeable surfaces to manage stormwater are essential. Construction in flood-prone areas should be avoided and natural drainage systems preserved.
Investments need to be made in upgrading and expanding drainage infrastructure, including natural drains, stormwater channels, and flood-control systems. Regular maintenance and cleaning of these drains will ensure effective water flow.
Identification and mapping of flood-prone areas and development of appropriate floodplain management strategies could significantly reduce the risk of flooding. Improved early warning systems to alert residents about imminent floods are also crucial, as timely warnings can assist in evacuations and preparations.
