Leaky dams

Leaky dams are a flooding prevention measure, moderating the flow of water downstream. Barriers are added to a stream/river to prevent soil and silt escaping and allowing water to escape at a slower rate.

With the regular flooding of settlements in the UK, a rethink on flood risk management was initiated. One of the proposals put forward was containing flood waters at source to prevent large volumes of water flowing downstream causing soil erosion and flooding of properties.

A variety of solutions was put forward including using naturally occurring composting materials in path of flow to hold valuable fertile silt and dam up waters over many small dams. A leaky dam was added to the arsenal of flood prevention tools. This type of structure is what nature uses for similar events. Logs from fallen trees are placed at intervals down the stream acting as a barrier, holding the silt and small debris back and allowing just the water that overflows the structure to continue the course of the stream.

The area surrounding the leaky dams have many benefits including better quality of water to life behind the barrier, prevention of soil erosion, available nutrients for wildlife, stabilisation of river banks, spawning ground for aquatic life, rooting habitat, place of nesting birds, areas of growth for microbes, algae and fungi, efficient temporary storage of water and a slow release of water into surrounding area.

After a heavy downpour , soil, gravel, silt and valuable nutrients are lost when the rains wash away the top soil. This animation of a side view of a mountain embankment shows how bad soil management contributes to tonnes of topsoil ending up in flood areas and river beds. It costs a fortune to collect the soil from river beds, estuaries and river mouths, decontaminate, transport and physically replace the reclaimed sand.

Theses are types of barriers used by organisations in UK to prevent soil erosion and flooding downstream.

The following are possible approaches:

Barriertypes

More vegatation is able to be supported behind the barrier due to the higher level of nutrients captured from debri and silt.

Aquatic life is able to populate and continue to multiply with limited inventions.

This method shows better results.

nature in the event of a natural felling.

Water isn't dammed up as much with this method but valuable silt is

still filtered and not lost downstream.

Aquatic life can move between barriers and continue upstream.

This method is favoured by environmental groups who claim that

it closely resembles nature.

Surrounding vegetation is able to absorb more water and nutrients from standing body of water rather than a flowing one

The larger the tree, the better the root growth, the more more water is absorbed and the more soil is held together.

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Wikipedia