Thursday, June 13, 2024
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Flooding in the City: A study report

Kumaresh Subramanian

Flooding is a natural incidence which is caused by continuous heavy rain.  This means low-lying areas at risk and may flood quickly before it begins to get to higher ground. If it is one inch of rain per hour will also cause flooding. As you all know recently, Bengaluru has received the highest amount of rain similarly as it has got in August since 1890.
Recently several areas including Koramangala, ST Bed Layout, HSR Layout, Electronic city, KR Market, Shantinagar, Wilson Garden, Ulsoor, Vivek Nagar, Old Airport Road etc., have been inundated with almost knee-level water on the streets leaving residents stranded in their homes. Services like water supply, electricity, milk supply and newspapers are disrupted and people struggled and suffered as a result. In addition to this flooding brings lot of diseased and infections including dengue, chikankunya, fever etc., Sometimes insects and snakes make their way to the area and cause a lot of havoc. Eventually, our Bangalore drainage system is not up to the mark so it’s very likely that 2 or 3 days of heavy rain will also flood and paralyse the city now a day.
Actually, frankly speaking that if we are living in Bengaluru, that means we are living in one of the safest places on earth in terms of natural calamity, because our Bangalore city is on high ground and it is not on the coastal side like Chennai or Mumbai.
Once upon a time our Bangalore city was known for garden city and lakes, but now it is known for information technology and job opportunities. The rapid growth in the IT sector in the city demanded rapid growth in housing, infrastructure, transportation etc. As housing and infrastructure were supplied with least care for planning, the city has grown totally unplanned. The growth patterns of the city will shed more light on the flood vulnerability too. Of course, the population has also increased rapidly.
Effects of Flooding:
The effects of floods are disappointing. Many times floods can destroy everything. Houses can be torn off their foundation because the water has made its structure weaker, tar can be seen pulled off road causing major potholes, lots of trees have the possibility of being ripped out. They harm human, animal and plant life, disruption of all transport and communication, services like water supply, electricity, milk supply and newspapers are disrupted. Flooding brings lot of diseased and infections including dengue, chikankunya, fever etc. Water has to be pumped out of flooded areas. When floods occur, there is a large amount of water that runs over the ground.
What causes flood:
Each time there are more rains than the drainage system can take, there can be floods. Sometimes, there is heavy rain for a very short period that result in floods. Most floods in city are caused due to heavy rainfall, lack of lakes, silting of surface water bodies, population pressure, deforestation, encroachment of storm water drains, poor water and sewerage management, loss of wetland and vegetation, Flatten Roads, Poor Interconnections between Primary, Secondary and tertiary drainage, Blocked or collapsed gullies, gutters, pipes, sewers, culverts or ditches, Some areas where hard surfaces such as roads and concrete do not let the water drain away into the ground. This leads to surface overflow and can often overwhelm local drainage systems leading to flood. Due to blockage of road side gutter pipes, the secondary drainage is unable to receive the entire volume of rain water that needs to be disposed. Encroachment of floodplains, obstruction of sewer pipes, manholes, dumped construction material and solid waste have also blocked the system and cause floods.
Which areas are more likely to flood / where do flood occurs:
Any plain low-lying area adjacent a primary drainage, lake is also more likely to have floods anytime when the water level rises. Generally, these areas may be like lost lakes bed / tank bed areas and encroached drains. Otherwise, coastal areas are the most susceptible to flooding; however, it is only possible for flooding to occur in areas with unusually long periods of heavy rainfall.
Management & Mitigation of Floods:
Floods are natural processes that sometimes become natural disasters. By improving our understanding of how floods happen, and planning for their inevitable occurrence, we can prevent and protect much of the damage caused by floods in our area.
n If an area is likely to floods, houses should be constructed on raised platforms.
n Frequent regular check and maintenance of primary, secondary drainage is definitely required to prevent flooding.
n Concerned authorities to check the depth of the primary drainage and increase the depth if required to control the overflow of flood.
n Flood relief camp need to be setup
n Sand bags are made and placed in strategic areas to retain floodwaters.
n Remove silt at the earliest and build a wall to prevent flooding
n Construction of Parallel Storm Water Drain is required to manage the flood.
n It’s also important to make sure to keep your gutters clean, repair any gutter leaks, and check regularly to see that they drain properly.
n All drainage should be mapped and the surrounding areas appropriately prepared for floods
n Buy flood insurance if available
n Check out, if any rainwater from other areas was pooling into our areas, if found try to block or divert it to other side.
Conclusion & Recommendation:
Flooding is one of the most frequently and severe disasters in our city. It often occurs rapidly and causes many damages to the local communities. Based on findings, it is recommended that the flood control management is compulsory required to reduce the flood. That means to say flood disasters are natural, so we cannot control floods completely, but with the help of some management techniques, preparedness and spreading awareness among the people we can reduce the impact the flood disaster. Whenever a flood occurs, most important of all, it demands a good coordination among various departments including BBMP, BWSSB, BESCOM, Police, Fire & Safety, Home Guards, Armed Forces (in case of necessity), etc., to manage the floods in the city. It is necessary to have a good monitoring system in order to have a good storm water management system. Koramangala is lacking in terms of planning, engineering, remodeling of primary and secondary drain, flood fighting awareness should be given, flood management like drainage improvement in up-gradation.
Thus, diversion of flood has to be looked in. Also, all primary drains have to be desilted on timely basis and encroachments needs to be taken care.

*The writer is an Executive Committee Member of Koramangala 4th Block Residents’ Welfare Association

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