Flood are natural disasters affecting the crops, livestock, infrastructure and human beings. Floods occur when water bodies like rivers carry more amount of water than their capacities and when this additional water cannot be drained in a proper manner. Floods are not a recent phenomenon, it have been occurring since ages. However, today the destruction caused by floods is immense because of increased population density and spread of people in every part of the country.
Types of Floods in India
Floods in India are not restricted to any one place. There are several different kinds of flood, and each one bears a different impact in terms of how it occurs, the damage it causes, and how it is forecasted. In this section we will discuss about the different types of flood.
(Surge Flood) It occurs in areas that lie on the coast of a sea, ocean, or other large body of open water. It is typically the result of extreme tidal conditions caused by severe weather. Eastern coast of India is vulnerable to thi type of floods due to frequent cyclonic activities. Further, rising sea level due to climate change can put many coastal cities of the world at risk of being over run by sea water.
(River Flood) It occurs when excessive rainfall over an extended period of time causes a river to exceed its capacity. It can also be caused by heavy snow melt and glacial level outburst. The damage from a river flood can be widespread as the overflow affects smaller rivers downstream, often causing dams and dikes to break. This type of flood usually occurs in Himalayan rivers and cause massive destruction including landslides.
(Surface Flood) It is caused when heavy rainfall creates a flood event independent of an overflowing water body. It can happen in any urban area even higher elevation areas that lies above coastal and river floodplains.
Apart from these, floods may also be caused due to upsurge in groundwater and outburst of drain and sewer.
Major Flood Prone Areas of India
The major flood prone regions in India according to National Commission on comprises of Ganga river basin which includes state of Uttar Pradesh, North Bihar and West Bengal. The heavy rainfall and huge siltation makes flood yearly affair in Brahmaputra river system also. The inadequate surface drainage which causes inundation and water-logging over vast areas is the main cause of floods in North-Western part of India.
Cloudburst and torrential rainfall have caused flood in Uttarakhand and Kashmir. The small rivers of Kerala, originating in Western ghats and flowing to the Arabian sea, cause considerable damage when in spate. The deltaic region of the Mahanadi, the Godavari, the Krishna and the Kaveri suffer from occasional floods wing to the large scale silting and consequent change in the river course.
Causes of Flood
Flood are caused by natural, ecological or anthropogenic factors either individually as a combined result. Earthquake, landslide and cloudburst are among other causes of flood. Man made causes include collapse of dams, embankments inefficient sewerage system in cities. The various causes of floods in India are as follows
• Rainfall of about 15cm or more in single day, sometimes are beyond the carrying capacity of the river causes the spilling of river over natural banks. West coast of Western Ghats, Assam and Sub-Himalayan West Bengal and Indo-gangetic plains faces flood due to heavy precipitation almost every year.
• The Himalayan rivers carry a lot of silt with them due to erosive action of the rivers. Because of the amount of silt carried by the rivers, the level of river bed rises and the water carrying capacity of the rivers gets reduced. This causes floods in the nearby areas of hill slopes. The water level in river rises because of greater run off. Floods in Western ghats, Shiwaliks and Chotanagpur plateau region occurs due to this reason.
•Excessive sand mining comes at a huge cost to the river and those living around it. Excessive sand mining can alter the river bed, force the river to change its course, erode banks and lead to flooding. It also destroys the habitat of aquatic animals and micro-organisms besides affecting groundwater recharge.
•In the flat terrain especially in plain areas, rivers have tendency to meander or change the course within a specific boundary. Because of this, frequent flood occurs in lower reaches of Ganga and Brahmaputra rivers.
•Tropical cyclone accompanied by strong winds, huge torrential rain and high tidal bores causes inundation of Eastern coastal regions of India. Floods due to cyclone are common in the East coasts of Tamil Nadu, Andhra Pradesh, Odisha and West Bengal
• In coastal areas sea tides deposit silt in the river mouths and discharge channels leading to steady deterioration of their discharge capacity, it causes floods in taic areas of India.
•Due to inadequate drainage, floods have occurred in Punjab, Haryana and Western UP. After introduction of irrigation in these areas, the sub-soil water table rises fast leading to widespread flooding.
Being a natural phenomenon, the total elimination or con 1 of floods is neithe possible nor economically viable. Hence, flood ontrol measures aim at a reasonable degree of protection against flood dama, at economic co in the section we will discuss various control measures of flood adopted by covernment and citizens.
• For controlling the flood, the government has constructed many dams and authorities which includes Damodar Valley Corporation for Damodar river, Narmada Control Authority for Narmada river, Hirakund dam on Mahanadi, ukai dam on the Tapi and the Bhakra dam across Sutlej. The Central Water Commission and National Flood Control Board in partnership with the Nation Disaster Management Authority (NDMA) has taken many steps for flood control.
• Among other structural measures, flood embankments, flood banks and levees have been constructed all along the major rivers, so that excess water in the channel does not cause havoc in nearby areas.
• Surface water drainage congestion due to inadequacy of natural or manmade drainage channels results in flooding in many areas. In this regard governme has started many drainage improvements programs.
• Diverting all or a part of the discharge into a natural or artificially constructe channel, lying within or in some cases outside the flood plains is a useful means of lowering water levels in the river to control the flood. The flood spill channel skirting Srinagar city and the Supplementary Drain in Delhi ar examples of diverting excess water to prevent flooding of the urbanised areas
•Among the non-structural measures which strive to keep people away from flood waters, the flood-plain zoning and flood proofing have been adopted by the government. These are non-structural changes, adjustments or additions to reduce and prevent flood. Similarly, India Meteorological Department (IMD) issues flood forecasting and warning which are of immense help in relocation of the vulnerable section of population.
• Watershed management measures such as developing the vegetative cover i.e. afforestation and conservation of soil cover in conjunction with structural work like check dams, detention basins etc. serve as an effective measures in reducir flood peaks and controlling the suddenness of the runoff. Government under National green mission aims at massive afforestation all along the channels o major rivers. Further many watershed developments projects have been taken up under MGNREGAwhich will eventually help in controlling the flood.
However, more efforts by the government and proper implementation of the warious policies it has made is required to control the situation of flood. Apart from that, the human induced reasons needs to be controlled. Proper planning and control mechanism should be put in place for the meteorological and geographical factors
The occurrence of floods every year results in the loss of GDP to the country as precious lives are lost due to floods. Therefore, flood control and management is essential today, for which both government and private sectors efforts are needed with organisational efforts , individual awareness and participation to strengthen the infrastructure will prove beneficial in this direction.
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