Urban Floods in Bharat: As Bharat moves towards the climax of transition from a predominantly rural to urban society, urbanization has become an underlying factor for development and often acts as a major driver of economic growth. It is estimated that by the year 2030, 40.76% of the country’s population will be residing in urban areas.
However, the urban planning system has also not developed at the same pace with which urbanization and technological progress are developing. Unplanned development and climate change are causing many catastrophic events including urban flooding, which need serious attention.
Thousands of houses were submerged in the floods of the year 2020 in Hyderabad. The Chennai floods of 2015 are a reminder of how rapidly urbanization is making cities more prone to urban floods. At present, Bangalore has witnessed several incidents of similar floods during the monsoon season.
What is Urban Flood?
Urban flooding is the submergence of land or property in a built environment, especially in densely populated areas such as cities, which often occurs when waterlogging due to rainfall overwhelms the capacity of its drainage systems.
Unlike rural floods (caused by heavy rains in a flat or low lying area), urban floods arise not only because of high rainfall but also because of unplanned urbanization that:
- Increases the flood peaks from 1.8 to 8 times,
- Increases flood volume up to 6 times.
Major Causes of Urban Floods in Bharat
Encroachment of Drainage Channels:
Due to rising land prices in Bharatn cities and towns and lack of land in the main city, new development works are taking place in low-lying areas, usually through encroachment of lakes, wetlands and river banks etc. Used to be.
Ideally it should have widened the natural effluents (such as road widening with increasing traffic) to accommodate the high inflow of storm water.
But the situation is opposite where instead of widening these natural drainage systems, they have been encroached on a large scale. As a result their runoff capacity is reduced, leading to flood conditions.
Climate change has worsened the situation leading to extreme weather events. Climate change has led to an increase in the frequency of heavy rainfall in the following periods, resulting in high water runoff.
NASA studies indicate that the effect of urban heat islands or ‘urban heat islands’ also increases rainfall in urban areas, which then leads to flooding.
Whenever rain-laden clouds pass over an urban heat island, the warm air from there pushes them up, resulting in highly localized rainfall that can sometimes be of high intensity.
Unplanned Tourism Activities:
Water bodies have long been used as an attraction for tourism development. Water bodies that play a role in reducing runoff speed are being diverted from rivers and lakes to sustain tourism activities.
The dumping of non-biodegradable substances into rivers and lakes during religious and cultural activities reduces the water quality. These suspended particles and pollutants pose a health risk to cities in the event of floods.
For example, the Ashtamudi lake in Kollam, Kerala has become polluted due to oil spills from boats.
Release of Water from Dams Without Warning:
Unplanned and sudden release of water from dams and lakes also causes floods in urban areas, where people are not given enough time for any action.
For example, Chennai was flooded in 2015 due to release of water from Chembarambakkam lake.
Illegal Mining Activities:
Illegal mining of river sand and quartzite for use in building construction destroys the natural bed of rivers and lakes.
This causes soil erosion and reduces the water holding capacity of the water body thereby increasing the speed and scale of water flow.
For example, Jaisamand Lake – Jodhpur, Kaveri River – Tamil Nadu.
Effects of Urban Floods
Damage To Life and Property:
Urban floods often cause loss of life and physical trauma. This is due to the direct impact of floods or the transmission of waterborne diseases during the flood period.
Urban floods cause many local effects such as structural damage to buildings, property, crops. In addition, it causes water supply, sewerage, power and transmission lines, communication, traffic-road and railways, and infrastructure disruptions.
During extreme flood events, fast-flowing flood waters wash away vegetation and cause erosion of coastal areas.
Impact on animal and human health: Water logging and contamination of drinking water in local areas lead to various health problems which can also lead to epidemic situation.
The accumulation of sewage and solid waste in and around homes also spreads many diseases.
Loss of home and relatives adversely affects the mental health of those trapped in floods. The recovery process in case of such incidents is a cumbersome and time-consuming process which often leads to long lasting psychological trauma.
Way of Solution
Developing Blue-Green Infrastructure:
Blue-Green Infrastructure is an effective way to provide a sustainable natural solution to urban and climate-related challenges.
Water management and development of sound infrastructure should be equally emphasized to create a more pleasant, less stressful environment.
Along with this, it should be ensured that every building in the city has provision for rainwater harvesting as an integral part of the building utility.
Blue-green refers to water bodies in infrastructure such as the Nile and reservoirs, while green refers to trees, parks and gardens.
Flood Vulnerability Mapping:
Through the analysis of topography and historical data of floods at the urban level, vulnerable areas can be identified.
Maintaining records of all water bodies and wetlands at the city and village level will be equally important for flood survival, resilience and resilience.
Effective Water-shed Management:
Construction of flood-walls, construction of high platforms along flood prone river valleys, periodic cleaning and deepening of drainage channels are some of the measures that should be taken in the entire river basin rather than in urban areas alone. should be adopted.
Bioswales can be built along the roads so that rain water from the roads flows towards them and goes down.
In addition, the catchment areas of water bodies should be well maintained and free from encroachment and pollution; Thus the passage of water should be kept free from obstructions.
Disaster Resilient Public Utility:
Public establishments like hospitals and schools and basic services like food, water, health and sanitation should be made disaster resilient.
They should be installed or repositioned in such a way that they are able to function without any hindrance during floods.
Sensitization and Rehabilitation:
Awareness should be created about flood preparedness and mitigation measures along with response drills.
Residents need to be made aware of the risks associated with illegal construction along the banks of drains and water bodies. The government should also consider shifting the poor to other areas.
It is necessary to create an integrated flood control implementation agency at the city level, which includes city administrative officials, doctors, police, firefighters, NGOs and other emergency service providers.
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