Flood mitigation

By:Mudassar Rehan(B.ARCH/1003/08)Alain Ekka (B.ARCH/1011/08)Md.Azizullah(B.ARCH/1033/08)

Flood mitigation involves managing the effects of flooding, such as redirecting flood run-off, rather than trying to prevent it altogether. It is management of people, through measures such as evacuation and dry/wet proofing properties.

Floods are water covering previously dry area.A flood is a very large amount of water that has overflowed from a source such as a river, lake, and ocean. They can also have overflowed a broken pipe onto a previously dry area. The damages after a flood is harsh because everything or parts of things will be under water and the effects of a flood can kill many people.

Flooding occurs in a wide variety of settings:

Riverine flooding

Coastal zone flooding with wave actionHigh, saturated ground water

Back up flooding from rivers, creeks, drainage basins

Dams and levees breaking

Clogged culverts causing water back upBack flow from sewer lines

Downhill sheet flow after a heavy rain or snow melt

Roof drainage into the house

Flooding conditions can be:

Shallow to deep water

Short warning time

High or low flow velocities

Long or short duration

High rates of rise and fall

Wave action

Debris potential

Hazardous materials in the water

Low-point water entry in the house

Let the Flood Plain be a Flood Plain

Nutrient rich soils settle out in the flood plain not in the stream

The easiest way to mitigate flood damage is to let the flood plain act as a flood plain. When there is more water in the stream than it can hold, the water spreads out in the flood plain. As the water recedes, the water in the flood plain works it’s way slowly back to the river. This is the natural function of flood plains. If we try to force the river to stay within the banks during a flood, the stream cuts down and bank erosion gets worse.

Allow the flood plain to be a flood plain and do not build houses, businesses or industries in the flood plain we end up with less mess, less flood damage and less water pollution.

Less MessLess Damage

Less Water Pollution

Flood Mitigation in the Watershed

Reduce:•Flood Frequency•Intensity

•Increase Retention•Increase Infiltration

Reduce Pollution

Retain Water in Watershed

Pond

Sediment settles out

Storm Water Retention Basin

Sunlight kills pathogens

Retain Water in Watershed

Sediment settles out

Sunlight kills pathogens

Plants capture nutrients

Let The Water Soak In

Terraces

Keeps sediment and phosphorus in the field

Cover crops

Nitrogen held in plants

Permanent grass

Keeps sediment and phosphorus in the field

Rain Gardens

Bio swales

Water evaporated through plants

Nitrogen held in plants

Pervious Pavement

Less pollution washes off pavement

Green Roofs

Water evaporated through plants

Conclusion

As we work to:

Reduce flood frequency & intensity

Reduce damages from flooding

Hold more rain water in the watershed

Let the flood plain be a flood plain

Improve water quality

Thank you!!!