07 Aug Monsoon River Floods : Need for Water Resources Management
Every Monsoon some or the other region of India gets flooded. Its an annual recurrence, afflicting some part of our country, either alternately or every year, like in case of Assam. As soon as the flood waters invade our lives, so do messages and articles on how Climate Change and disregard to the river’s flood lines have led to this situation. Urbanization and encroachments may lead to higher run-offs, causing flash floods in cities. But the riverine floods that we experience are a whole different matter.
Blaming the monsoon floods on Climate Change is a futile exercise. If it were so, India wouldn’t have shown occurrence of floods in earlier time periods. Climate Change, may have increased the instances of abnormal weather patterns, so that the recurrence of an abnormal monsoon is more frequent. So, if floods also happened before, but were not as devastating, there has to be some significant difference between now and then.
The one significant difference between the good old days (when rivers were not encroached upon and climate change was not a prominent issue) and today. Today, most rivers have dams. And ts quite ironic, because, dams are often built as engineering solutions to control floods.
The purpose of dams is two-fold. They are built to allow storage and control supply of water during the non-monsoon period of the year and they produce electricity. These two are very important requirements because of which cities thrive and farmers can have irrigated lands. The larger objective of any dam is to ensure a resonably equitable water supply. This happens by capturing rain in high rainfall areas and distributing it to less rainfall areas. In many parts of the world, multiple dams also help control floods, link different tributaries through a network of canals that ensures an equitable water supply to all the regions of a region or a country. The Colorado river-Canal network system is a very good example of how this massive river, fed directly by the glaciers (like the Ganges), is able to supply relatively large quantum of water to desert locations of Arizona and California.
Today, when a river, with a dam in its upper reaches, floods, it is primarily due to two reasons. One, the amount of rainfall for a period far exceeds the ‘normal’ that is expected during that period. This ‘normal’ is decided upon empirical data going back hundreds of years. Second, the dam storage capacity is not designed to absorb the ‘excess rainfall’ . Whether it was Kerala floods last year or Kolhapur floods this year, the actual rainfall, by itself, did not cause the floods. Flash floods due to high runoffs may be there, but these are local and less devastating. River flooding occurred because of the release of the waters from the upper dams. That too, because this water was not allowed to be released periodically, but was released in large quantum at one time.
Every government, considering that the dams have to ensure an adequate water supply for the year round, is going to wait for the dams to get full before it can start thinking of releasing water. Even the citizens of cities like Pune, Mumbai and Kolhapur, will object if the dam waters are released before the dam is full. It will signal a definite water scarcity situation in the summers in the preceding year. Once the dams are full and the rains do not abate, water has to be released in a large quantum at a single point in time. So essentially, this manually released water leads to floods and devastation. Not Climate Change or river encroachments. During a flood, the river encroachments get submerged and are the victims of a flood, rather than its cause.
So primarily, the problem is in the management of water in the reservoirs and prediction of monsoons. If, for example, an excess rainfall is predicted accurately, governments can release smaller quantities of water during the pre-monsoon or early monsoon days and ensure that the dams do not have to release vast quantities, causing floods. Similarly, if mechanisms can be employed to divert the reservoir waters to other storage devices or canals that link to other rivers, systematic water management can ensure that flooding will not occur. Successful river-canal networks across the world have achieved this.
Many countries, including Asian countries like Thailand are doing this successfully. This water resources management and accurate monsoon prediction makes it possible to have controlled floods during the monsoons, adequate water supply during rest of the year and minimum water flows in the river all throughout, thereby maintaining the health of riverine systems. A flowing river, will also ensure that encroachments will be kept to a minimum. A superb example of this is Rio Grande project in Arizona, which managed to create a beautiful riverfront for the university town of Tempe (where Arizona State University is located), while controlling the water and the city’s water supply, when Colorado discharges water downstream.
A very good article about the issue of annual floods in India was published last year after the Kerala floods by Mathew Abraham (https://www.thehindu.com/opinion/op-ed/how-dams-can-control-floods/article24794603.ece). It is, with this background, that I feel, that the new Ministry of JalShakti can play a significant role, in bringing together, under one umbrella, all the decision making units related to water storage, water supply and irrigation. There needs to be a more coherent approach, an annual mechanism, to control water resources. This is particularly important for a monsoon fed country like India, where a 3 month long rainy season leads to very fast removal of a fresh water to the seas.
If we, however, continue to bark up a wrong tree and do not identify the correct problems and provide appropriate solutions, every year articles like mine and Abraham’s will flash and die away, while the floods will continue to wreak havoc and cause devastation in India.