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CAUSES OF FLOODS

CAUSES OF FLOODS. DEFORESTATION . What is River Flooding?.

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CAUSES OF FLOODS

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  1. CAUSES OF FLOODS DEFORESTATION

  2. What is River Flooding? All of the water that flows down a river comes from rain or melting snow. Sometimes after heavy rain or a rapid snow melt , there may be too much water for the river to hold . The river will then overflow its banks and spread out across the land on either side of its channel. This is called RIVER FLOODING.

  3. What Causes A River to Flood? Usually when it rains, most water simply soaks into the ground and there is little chance of flooding. If , however ,the water is unable to soak into the ground , it will stay on the surface and quickly flow downhill into a river. This is when floods are most common. Some rivers are more at risk from flooding than others.

  4. DEFORESTATION

  5. What is Deforestation? Deforestation refers to clearing of vegetation from the surface of the earth(mainly on steep slopes). Man’s interference of hillsides includes the removal of trees for: • Cultivation • Lumbering • Settlements • For fuel

  6. What is the causes of Deforestation? Deforestation occurs for many different reasons, mainly as a result of the following: • Urban Sprawl-the expansion of the urban society on rural areas. • Agriculture-farmers clear forests to provide more room for planting or grazing animals by cutting down trees and burning them. • Lumbering/Logging Operations-trees are cut down for export , to make paper products , fuel and for wood during logging operations. • Housing/Infrastructure & Industrial Purposes-forests are being cut down to build houses and for infrastructure to support them . Deforestation facilitates industrial activity such as quarrying and mining. • Accidental Fires-may be caused by peasant farmers clearing land and burning of sugarcane or unwanted trees or bush. • Squatting-people who do not own land may clear a forested area to build houses or for small scale farming.

  7. Why We NeedTrees? The forest canopy (the treetops) and root systems provide natural filters for the water we use from lakes and rivers. When it rains the forest canopy intercepts and re-distributes precipitation that can cause flooding and erosion, the wearing away of topsoil. Some of the precipitation flows down the trunks as stemflow, the rest percolates through the branches and foliage as throughfall. Trees increase the ability of the land to store water.The forest floor can hold as much as five times its weight in water and a tree contains water in its roots, trunk, stems, and leaves. Because of all this stored moisture, forests help to maintain an even flow of water in rivers and streams in times of flood or drought. The roots of the trees and other vegetation hold the soil in place and control erosion from wind and rain, preventing flooding and clouding of streams and rivers.

  8. Results of Deforestation: • A quick run off • The carrying of extra sediments to the river’s course • The raising of the valley floor by its sediment deposition • Consequently, the over flowing of its banks,thus creating flooding.

  9. Deforestation Causes Flooding. When steep hillsides slopes are bare of trees, due to shifting cultivation practices, flash flooding often occurs , consequently swelling or increasing river volumes. The water holding structure of soil is reduced. The removal of trees along stream banks contributes directly to increased water velocity. Much water is held by leaf litter and this is released slowly to the soil. Leaves, roots and vines reduce the flow of water downhill. The removal of the trees allows the water to flow freely downhill resulting in flooding in low areas.

  10. Deforestation Causes Flooding

  11. DEFORESTATION CAUSES FLOODING. BEFORE RAINFALL AFTER RAINFALL

  12. Pictures Of Deforestation.

  13. An Example of a Flood caused due to Deforestation , Locally. Flood in Port-of-Spain Trinidad (not sure of cause) Date November 18th 2008 Floods take toll on T&TStill reeling from the effects of Monday’s heavy rains and flooding, Port-of-Spain suffered another major blow yesterday as several disasters, natural and otherwise, shut down vehicular and pedestrian movement in and around the capital city.DistressThousands stranded as massive floods, landslides cripple East-West CorridorCity Gate shuts downPort-of-Spain came to a standstill yesterday as thousands of commuters were stranded while making their way into and out of the capital city because of muddy waters that flooded major streets.Commuters gridlockedIncessant rains over the past few days, coupled with yesterday’s inclement weather resulted in flooding, landslides and left students marooned at a primary school in Bourg Mulatresse.Bridge collapsesIt was stress for motorists heading west and east along the Churchill Roosevelt Highway yesterday as the collapse of the B 1/12 bridge at Macoya caused them to be caught in hours of traffic yesterday morning. The situation had worsened by afternoon as heavy showers caused flooding in several parts of the east-west corridor.

  14. Example of Floods caused by Deforestation in the Caribbean.

  15. Examples of floods caused due to Deforestation, Internationally.

  16. FINALLY!!! • FINALLY!!!!!

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