Rivers breaching banks every year during periods of heavy rain cause losses to human communities. Ideally the human communities should not live on a floodplain, but few have that luxury in developing countries. So, is it feasible to increase the drainage network for a river, by digging canals that can be used for irrigation and diversion of excess water in periods of high flow, while the gates to these articially dug canals are closed when flows are low?
Dear Amartya,
Reforestation and Crop Rotation can be a solution. But reforestation is an inexpensive but slow process, and depends on combination of the upland landuse area.
Flood Warning Systems is another way that includes a number of rain gauges located in areas where high amounts of rainfall can be sampled, in conjunction with the data generated by properly located stream gauge stations. Flood Warning system is designed to make available the maximum lead time for the evacuation of those people and their property likely to be affected by a flood.
Dear Amartya,
Reforestation and Crop Rotation can be a solution. But reforestation is an inexpensive but slow process, and depends on combination of the upland landuse area.
Flood Warning Systems is another way that includes a number of rain gauges located in areas where high amounts of rainfall can be sampled, in conjunction with the data generated by properly located stream gauge stations. Flood Warning system is designed to make available the maximum lead time for the evacuation of those people and their property likely to be affected by a flood.
Hi Amartya
At present solution lies in: 1. strengthening embankments, 2. controlling water level by constructing flood water pumping stations at suitable places, 3. deepening channels, 4. controlling the land use patterns alongside the river. These could save the riparian ecosystem. Planting trees like mangroves could also be taken up at selective sites. However, its an ecologically sensitive issue and needs thorough research before setting up any of these as plantation/irrigation or construction of structures or diversion of the river flow may hamper the natural flow of a river, its circulation, sediment deposition patterns etc., which may affect the river as well as the riparian ecosystem in general.
have a look
http://planassam.info/Economic_Survey_Assam_2010-11/Economic%20Survey_Chapter-7_FLOOD%20AND%20FLOOD%20CONTROL%20MEASURES.pdf
I don't think there is a straight forward answer to this question because a lot of the expectations are strongly dependent on the land-use patterns in the region and government policies. If the region is not a farming community, irrigation of crops will not be a desirable venture.
Seasonally functional canals also seems like an exotic option. I believe the river flow already has a flow path and a destination towards the sea or ocean, thus dredging and regular desilting of rivers so that the rivers can accommodate more water during the high rains is a simpler and more direct solution.
Re-directing the water flow inland may cause more problems.
Thank you Raouf, Dola and Azubuike for sharing your perspectives so clearly. Yes, the periodic deepening / dredging of channels is probably the best way, along with reforestation or maintaining a forested watershed, or at the very minimum, maintaining riparian vegetation along streambanks. I also agree that diggng more channels can create other problems like altering the water table and introducing new species to areas.
Natural Flood Management techniques would be ideal for your situation. Using the natural environment to control flooding is an idea that's been around for a while but only recently these techniques have been put into wide spread use. Scotlands leading the way on these techniques there use has been written into law.
Check out
http://www.dundee.ac.uk/water/research/eddlestonwater/
In many places floods are caused by man's mismanagement of the land through deforestation and intensive cultivation which has led to serious soil erosion and the decreased ability of the soil to retain water. In these areas flood control is implemented through reforestation and efficient methods of soil management such as contour ploughing and crop rotation.
Thanks Craig, a very positive heartening step in Scotland ! Also thanks Azubuike, yes, the challenge is to implement these solutions, that typically requires communities that cooperate with each other to do so.
I think canals cost too much and difficult to maintain. Maybe strengthening the banks and riparian areas with vegetation would reduce flow and harm to humans would reduce.
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