Flooding Rivers in India -Why?
We know that the areas classified as flood-prone-defined as area affected by overflowing rivers (not areas submerged because of heavy rains)-has progressively increased over the past decades. It was 25 million hectares (mha) in 1960, which went up to 40
mha in 1978 and by the mid-1980s an estimated 58 mha was flood affected. But importantly, over these years the area under floods increased each year even though average rainfall levels did not increase. In other words, we were doing something wrong in the
way we manage the spate of water so that rivers would overflow each season.
The answer is not difficult to find. In flood-prone areas-from the flood plains of the mighty Himalayan rivers to many other smaller watersheds-the overflow of the river brought fertile silt and recharged groundwater so the next crop was bountiful.
But over the years, we learnt not to live with floods. We built over the wetlands, we filled up the streams that dispersed and then carried the water of the rivers and we built habitations in lowlands which were bound to be inundated. We cut down our forests,
which would to some extent have mitigated the intensity of the flood by impeding the flow of water. All in all, we have become more vulnerable to annual floods.
The current floods are all that, and much more. In recent years, the flood fury has intensified because of the changing intensity of rainfall. The deluge comes more frequently because of the sheer fury of incessant rain, which has nowhere to go. Just last
week torrential rain in villages of Andhra Pradesh and Karnataka killed over 60 people. We know that climate change models had predicted extreme rain events. Is there a connection here?
We know that dam authorities maintain high reservoir levels because of the uncertainty of rains. We also know that when there are intense bursts of rain and levels of water rise to an extent that could endanger the dam, the gates are opened and the water rushes
out. If this flow of water is combined with even more rain in the region, then a deluge becomes inevitable. We know that variability in our rainfall is increasing at the sub-regional level. What then will this mean for the management of our reservoirs in the
future? The question is do we understand the phenomenon of floods?
We don’t. We have no mechanism to be informed of the changing intensity of rainfall; of the increased inflow into our reservoirs and of the water released by dam authorities. The fact is that today’s floods are a double tragedy: of mismanagement of our land
and water combined with mismanagement of science and data.
This mismanagement is criminal. Let’s at least know that.
Source: Editorial by Sunita Narain
http://www.downtoearth.org.in/cover_nl.asp?mode=2