Floods often cause damage to homes and businesses if they are in the natural flood plains of rivers. In the , industry experts estimate that wet basements can lower property values by 10—25 percent and are cited among the top reasons for not purchasing a home. Intangible damages do not have a monetary value. In many areas, this sediment helps replenish valuable topsoil components to agricultural lands and can keep the elevation of a land mass above sea level. Roads, railways, tramlines and bus services may be affected or completely closed in serious floods and often sections of road and supporting infrastructure such as traffic lights and signage can be washed away or damaged.
Rivers that flow slowly carry water, sand and silt. Effective flood channel geometry may be changed by growth of vegetation, accumulation of ice or debris, or construction of bridges, buildings, or levees within the flood channel. Consequently the country experienced tragedy of flood in 1987, 1988, 1998, 2004 and 2007. Dozens of villages were inundated when rain pushed the rivers of northwestern over their banks in early October 2005. Flood controls, such as dams, can be built and maintained over time to try to reduce the occurrence and severity of floods as well. Although many processes are well understood at a point or for a small area, others are poorly understood at all scales, and process interactions under normal or extreme climatic conditions may be unknown. Damage to roads and transport infrastructure may make it difficult to mobilize aid to those affected or to provide emergency health treatment.
These enormous waves cause an enormous amount of destruction when they come into contact with a landmass and cause catastrophic flooding. Heavy floods can be so disastrous that infrastructure is washed away, people and animals drown, and people can be stranded for long periods. Estuarine and coastal Flooding in is commonly caused by a combination of sea tidal surges caused by and low , and they may be exacerbated by high upstream river flow. We take great pride in claiming how far India has come since independence and yet, when it comes to Assam, the nation simply seems to take the damages as a fact of life and everything carries on as usual, once the flood recedes. Lack of Commitment and Vision There has been very low investment made to address the problem of perennial flooding in Assam.
As a result, the rising limb of the becomes ever quicker as the flood moves downstream, until the flow rate is so great that the depletion by wetting soil becomes insignificant. Water is one of our most precious commodities. Tangible damages can be directly calculated by their economic value. Each topic presents distinct yet related questions with varying scope and scale in time, space, and the people involved. The increase in flow may be the result of sustained rainfall, rapid snow melt, , or. The deadly flood resulted from a thunderstorm over part of the drainage basin, where steep, bare rock slopes are common and the thin soil was already saturated.
The country receives large amounts of water passing through it by two major rivers the Ganges and Brahmaputra converging with tributaries on the huge delta formed from silt deposited by the same rivers as they entered the sea. India records most of its rainfall in the monsoon season. In alpine regions reservoirs are built to hold back water and control the flow of small rivers. Flooding is typically caused when rivers, lakes and streams overflow, but heavy and sustained rains may produce flash floods even in dry regions and areas where bodies of water are scarce. They build up their own beds, making them higher than the land around them. Main impacts of floods As floodwaters spread they can threaten lives, inundate properties and businesses, destroy belongings, damage vital infrastructure and prevent access to essential public services.
In broader sense, flood can be classified in two types as: natural flood and catastrophic flood. Before the Mississippi and associated rivers were controlled in levees in southern Louisiana, the rivers would frequently spill their banks. These services may be limited during and following floods, which can greatly impact on the community which relies upon them. This will work best when local people are made stakeholders in finding localized solutions based on local topography. Recovers natural fish stock: Flood can provide fresh water, waste, nutrients and larva to the wetlands.
Rivers should be mapped and the surrounding areas appropriately prepared for floods. Some researchers have mentioned the storage effect in urban areas with transportation corridors created by. These impacts can cause great emotional stress and financial loss to farmers. Elevation of flowing water is controlled by the geometry of the flow channel and, especially, by depth of channel, speed of flow and amount of sediments in it Flow channel restrictions like bridges and canyons tend to control water elevation above the restriction. Ground water becomes scarce and this leads to droughts. Some communities have characteristics which make them more vulnerable, including high proportions of aged residents and culturally and linguistically diverse communities who may not have local knowledge and access to messages about the risk of flood. Although flood can be devastating to the people, it has always been an essential part of nature's renewal process, providing many long-term positive effects as the following: Revives ground water: Many countries like Bangladesh depend on ground water and underground aquifers for fresh water.
More than 675 metres of culverts underneath the streets of Penrith were replaced and a 76,000m³ flood storage reservoir — the equivalent of 30 Olympic sized swimming pools — was constructed upstream to hold back flood water. Shelters are set up for people who are left homeless. The soil will continuously lose groundwater by the process of and transpiration. Coincidence Extreme flood events often result from coincidence such as unusually intense, warm rainfall melting heavy snow pack, producing channel obstructions from floating ice, and releasing small impoundments like dams. Several studies have looked into the flow patterns and redistribution in streets during storm events and the implication on flood modelling. Dust clouds will restrict the amount of light available to plants and animals, resulting in less food and more lives being lost. Special boats pick up people who are trapped on roofs or on the upper floors of buildings.
They destroy houses and buildings, and carry soil away from valuable farming land. Floods have both positive and negative consequences Floods are very important for natural environments. Factors that may affect the frequency and severity of flooding include climate and precipitation, elevation and surrounding terrain as well as the volume of land area located in or near a watershed. Heavy rains and landslides in India cause as much as 58 per cent of all disaster loss in the country. Most precipitation records are based on a measured depth of water received within a fixed time interval. Emergency services can also make provisions to have enough resources available ahead of time to respond to emergencies as they occur. Finally, flooding can have social impacts on a community causing sporting events and festivals to be cancelled.
Flood water may be contaminated or polluted. It is already disrupting vital supply lines to American forces in Afghanistan. Coincident events may cause extensive flooding to be more frequent than anticipated from considering only precipitation runoff flowing within unobstructed drainage channels. In 2011 a tsunami struck Japan, leaving more than 10,000 people unaccounted for in one coastal town alone. High temperatures can also cause flooding when it causes ice caps and snow to melt quickly.