Imphal flood crisis management
WL Hangsing *
Heavy flooding in Imphal on March 31 2017 :: Pix - Shankar Khangembam
In Imphnl there are two kinds of floods dcpcnding on the location of rainfall. One, whenever there is a heavy downpour, occurnng in the Imphal plains with duration of a day or two, and the other when it rains heavily in the surrounding hills in the catchment areas of the rivers flowing Into the valley.
In the first case due to the fact that the river embankments are higher than the inhabited areas the rainwater has nowhere to flow out and resultantly flood the compounds and entrance roads and thoroughfares of the 'leikais' and eventually even into the homes.
The only short-term (and the quickest) solution in this situation is to employ big and powerful high volume, low lift pumps to pump out the flood waters from the 'leikais' into the rivers over the embankments . This solution will last only as long as the rivers do not overflow and breach their embankments.
The encroachment on pockets of storm water collection areas all over the valley, which were low lying areas or 'paats' and which have now been filled up or converted into fishery ponds through the years is another matter to be considered. This trend became more serious with the increase in population and the resultant pressure on land.
The two 'pukhris' in front of Sanjenthong Officers Quarters is a case in point. In the sixties and seventies, these low lying areas used to be kept empty and dry during the winter months and when the monsoon months came they used to function as collection points for the excess water from the surrounding habitations and inundation of the inhabited area was avoided.
Now that these flood control mechanisms have been converted into fishery ponds, even an overnight rainfall in Imphal would inundate the compound of these habitations. The long term strategy would be to revive these storm water collection areas.
The second type of flood occurs due to sustained rainfall in the hills more particularly in the catchment area of rivers flowing into the valley – like Nambul, Imphal, Iril and Thoubal rivers Heavy rainfall in the hills causes the rivers to rise in spate and flow at high speed.
The flow of the rivers abruptly slows down as they hit the valley and this causes the rivers to overflow their embankments. Thus there is severe inundation of Inhabited areas and this causes large scale destruction of paddy fields and homestead lands.
The long term solution is to go for large scale plantation, of trees preferably of local varieties in the catchment area of the rivers. However since this will take a long gestation period, for an immediate effect we should go in for construction of micro checked dams which are semi permeable with locally available materials.
Hundreds of these dams should be built in the upper reaches of the tributaries of the main rivers. These check dams will slow down the run-off of water to the rivers and overflowing of the rivers in the valley will be averted.
We may prepare a concept paper for the treatment of Nambul river first, observe the results and accordingly go for the remaining rivers.
* WL Hangsing wrote this article for The Sangai Express
The writer is Additional Chief Secretary, IFCD
This article was posted on April 04, 2017.
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