One reason for the huge damage done by the floods in our cities is that we have walled our rivers as shown in the pictures of Sabarmati, Gomti and Meethi given alongside. This has led to reduction in the cross section of the river and reduced the ability of the river to carry the flood water. In normal circumstances, a river bed is sloped. So, when the water in the river increases, it spreads and does not immediately overflow the banks and take up the shape of a flood.
The mud riverbanks are home to vegetation which, in turn, supports aquatic life like turtles and fishes. Therefore by making walls on the river banks, we deprive the river of vegetation and also fish. Fishes have the ability to clean up the debris in the water and they indicate the living nature of the water. By making walls we are actually killing the living river water.
We talk for making India a “developed” country. We are following the UK and US in their economic policies. It is also necessary for us to learn from these countries how to revive the urban rivers. Similar walls had been made previously in the Thames River in England as shown in picture below:
The Government recognized the negative impacts of these walls and removed them. This was replaced by a slopy riverbank. At the bottom steel pillars were put into the river banks to give the stability to the river bank. However these pillars not visible from the surface as shown in the picture below.
Above the pillars they placed a coir fibre roll which enabled vegetation to grow. Further, they placed a fibre mat in a sloping manner. The vegetations could grow through the mat. In this manner we can seen that the vegetation has grown back on the Thames in the river as shown in the picture below. At the same time, the slope in the river bank led to increase in the capacity of the river to carry the floods water and it helps prevent floods.
Similar walls had been made on the Menomonee river in Michigan state of the United States as seen in the picture on the left below.
The Government found that this has led to decline in the aesthetic and biotic values of the river. They broke the concrete banks as seen in picture on the right above. Then they restored the natural mud based river banks in a sloping gradient so that the water could spread over a larger area as it increased. They also placed some stones and created reffils and pools in the river bed so that the fish could lay their eggs and rest between the stones. This led to increase in vegetation in Menomonee river and create a huge astethic value for the people living nearby. They made walking paths and picnic areas along the river banks. In this manner they improve the quality of the life of the river as well as the city. They found that 80 houses had to be removed in order to increase area of the river. They persuated these people to move away and demolished those houses and gave that land back to the river. In this manner they restored the river, increase the value of the river and improve the quality of life of city.
We have to take lesson from regeneration of Thames and Menomonee Rive floods in the area. If we have to make our cities at par with those in UK and US, we have to restore at the aesthetic value of the river and rejuvinate the river by improving the fishes and vegetations sorrounded rather then enclosing the river in concrete and killing the same. By removing the vertical walls and making slopy banks we will also increase the flow area of the river and help prevent the floods.