Flood Mitigation:

Floods are an overflow of water that occurs during heavy rains, by ocean waves reaching the shore, when snow melts too quickly, at the time when dams or levees break. These can occur with a few inches of water or cover cities; They can last minutes, hours, or span days, weeks, or longer.

However, the main risk of a major flood arises from a situation where the basin area is previously saturated, and a rain event causes excess water to run off the saturated soil surface. Factors such as rainfall, vegetation cover, soil texture and slope together represent the potential for runoff.

In order to mitigate floods, soil retention and protection works, slope and hillside control, reforestation and drainage works to stabilize slopes can be carried out. Channel stabilization works refer to the use of staggered dams built on the tributaries to stabilize the slopes of the channels and slopes, reducing the energy of the flow to transport the sediments. Control and retention works consist of dams to capture and store the solid wastes, which are usually built in the gorge of the torrent or in its main tributaries. Also included in this group are sedimentation ponds that serve the same purpose and are built in alluvial fans when there are sufficient spaces for depositing sediments

Conveyance works are used to guide and conduct flows from dams or storage ponds to a safe discharge site. They consist of channelization, levees and berms, drop structures, and dissipation works.[1] The following are examples.

Some recommendations to guide flood mitigation projects include:

• Preserve the watercourse in the highest possible natural state;


• Develop the capacity of the sub-basin as a representative element of the natural environment, to articulate natural, cultural and symbolic values;


• Avoid the occupation of margins, flood plains and other vacant floodplains, through the application of restriction measures, in which the treatment of open space plays a relevant role;


• Generate quality river landscape projects, with continuity throughout the course, from rural areas through urban areas, and up to its mouth at the riparian edge, by improving water quality and assigning compatible activities.

WaterProof analyzes how investing in watersheds can help intercept rainfall, decrease surface flow, and increase the travel time of river water, reducing the magnitude of the flood peak. Reducing the size of peak flood flows can mitigate the impact on infrastructure and private property and reduce the risk to human life. In other words, investment in natural capital can play a key role in retaining water in the landscape and reducing flood peaks; however, the impact of the activities will decrease as storm size increases.

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