Flood Management in Built Environment
Climate change has been one of the major environmental issues that is being discussed in the world with many consulting engineers and environmental specialists cautioning about its impact on livelihood. One of the major consequences of climate change is the increasing frequency of flood across the globe, which creates another major problem that is Flood Management in built environment.
According to the National Disaster Management Authority, 40 million hectares (Mha) of India’s total area is prone to floods, which is alarmingly high. Consulting engineers in India affiliated to the Consulting Engineers Association of India (CEAI) have conducted many thought provoking studies on flood management and risk management measures.
Implementation of effective flood management techniques is imperative in India, considering the mass population of the country, which could be affected by the ghastly impact of floods. Massive loss of human life, destruction of property, public infrastructure due to floods can all lead to a major economic imbalance. This is especially in built up areas where important infrastructure like power plants, roads, hospitals, constitutional buildings etc. could be destroyed.
Causes of Flood:
1. Unplanned development in urban areas
Unplanned urbanization is often triggered by the increase in migration from the rural to the urban areas without any planning and structural development. The unregulated and unplanned construction then has led to the overburdening of the drainage infrastructure. Moreover, the flattening of terrain and conveniently altering the natural drainage routes by the property builders or public agencies in the urban areas have also increased the flood risks by damaging the drainage systems.
2. Inefficient water drainage systems
Mentioned by the World Health Organization as well as by Dr. H. Kazmi in his research paper, a poor drainage system can be the principal cause of floods. The underground drainage structures in urban areas are years old with inadequate structural facilities. These systems are flood prone since there are insufficient water retention areas with no functional capacity. This is also due to the unplanned construction of bridges, road, railways, canals etc. that hampers the flow of water causing a major interference in the drainage system.
3. Higher precipitation in a shorter duration
History states that one of the major causes of floods was the high intensity precipitation in a short duration that led to the destruction of many. The excessive rainfall has exceeded the capacities of the local infrastructural systems leading to massive flooding. For instance, the example by S K Mazumder regarding the Kedarnath town which was washed out due to a Glacial Outburst Flood in the year 2013 resulting in the death of nearly 3000 people in the Mandakini River.
4. Inadequate flood control structures
Consulting engineer Ronald Gomeseria from the CEAI, through his research has thrown light on how sewer backflow from the municipal system affects the environment adversely. The cause of the floods could originate at a very micro level, such as there being no provision for oil, grease or wet waste traps in kitchens and garages. He also mentions the impact of demographic changes, namely increase in population density.
Flood Control Management Techniques:
When it comes to flood management, we can either focus on how we can predict them and what measures to carry out in order to deal with such disasters or we can build solutions in order to prevent floods.
1. Involvement of administrative bodies
A case study based research paper by Mousumi Ghosh, Pradip Kalbar and Shubhankar Karmarkar titled, “Managing the Unmanageable: A Flood Modeler’s Perspective,” explains how the local administrative bodies need to incorporate technology and use more scientific methods.
Local bodies should also carry out timely assessments of the structures built in the flood prone areas and maintain them. In addition, the general public needs to be educated about the calamitous conditions to enhance preparedness and disaster management strategies.
2. Building of sump pumps
Taking into consideration the natural climate change calamities such as excessive rainfall, building these sump pumps reduces the risk of flooding. On the other hand, in a flood prone area, it is recommended to have these pumps to carry the rainwater to a surface groundwater manhole. These pumps are used to remove the excessive collected water from the sump basin or house basements and are usually hard wired directly into the electrical system of a home or a building.
3. A combination of flood management strategies
Dr. H A Kazmi had discussed a set of best mixes of strategies to be implement for risk management. There are three basic characteristics which determine the strategies which can be implied during a flood situation – the climate, the socio-economic conditions of a region and the basin characteristics.
WMO has developed a table which briefly explains four strategies and the options for those.
- To reduce flooding
Building dams and reservoirs, channel improvements and high flow diversions can have a positive impact on a region.
- To reduce damage
Constant development of policies, building and designing flood proof facilities, flood proofing and constant flood forecasting.
- To reduce the impacts of flooding
Preparing for the disastrous situation, basic education on this topic, post flood recovery plans and signing up for flood insurance
- Preserving the natural resources of flood plains
Regulating and zoning the floodplain on a timely basis.
History suggests that damages due to floods in India have considerably increased since 2000. If effective measures, whether structural or non-structural, are not implemented, the economy will continue to suffer due to such events.
Members of the CEAI have conducted studies on how risks from floods can be mitigated, by analysis and forecast of natural disasters. The consulting engineers’ study also explains in detail the various techniques to prevent damage from floods which have been discussed in this article. Flood management is thus a very important issue that needs to be addressed in order to cope with the impact of the natural calamity.