August 19, 2016

The Root Cause of Unprecedented River Rise

A station hospital in Yesagyo located near the confluence of the Ayeyawady and Chindwin rivers is submerged on 3rd August 2016. Photo: Pe Tun Zaw
A station hospital in Yesagyo located near the confluence of the Ayeyawady and Chindwin rivers is submerged on 3rd August 2016. Photo: Pe Tun Zaw

The monsoon had not fully reached its peak yet, but most parts of the country, which lie along the paths of the major rivers, namely: the Ayeyarwady, Chindwin, Dotehtawady, Ngawun, Sittaung and Bago rivers are being seriously inundated. The most noteworthy is the news of the level of the Ayeyardy River at Nyaung Oo, which had been recorded as the highest in fifty years.
Some may call these natural disasters, but from my point of view, these are in reality the consequences of humans’ disregards for the environments. Humans had abused the eco-system by over-exploitations of its resources, especially the trees and forests. One may be curious,
what those had to do with the flooding. Of course they have plenty to do with it. The depletion of the trees and hence the forests is the root cause of the flooding.
It is common knowledge that the trees absorbs the rain water and stored them so that they could thrive. Thus, if there are no trees to absorb the rain water, where would they go? I don’t think it would be necessary for me to say that they would drain off to the lower levels. In doing so they would drag the loose top soils and gravels along. Also the absence of trees or forests make the top soils more vulnerable to erosions, as there are no tree roots to retain them in place.
These loose soils and gravels brought down by the rain water are deposited into the rivers and streams. This process give rise to a situation called silting. The silting causes the river to become shallow as the silts and gravels raise the level of the river bed. Thus, during the monsoons, the rain water draining into the rivers and streams caused them to overflow into the low-lying areas, or in other words the floodplains grow wider. When there are heavy rainfalls, and if the floodplains cannot be contained by dykes or embankments built along the banks of the major rivers, the flooding would occur.
So, what caused the depletion of the forests? The wild fires, started by thunderbolts, human negligences or intentional cases of arson, slash and burn agricultural practices, minings, industrializations, development projects and last but not least, the over-extractions of timber, legally or otherwise, should be held accountable. Apart from the wild fires caused by the thunderbolts, which can be blamed on the nature, other causes are man-made, which should be preventable.
As the trees also play a major role in the control of carbon emissions that are causing the global warming, which is behind the climate changes that are plaguing the whole world with extreme high temperatures and freak weather conditions, more trees should be grown. The reforestations and conservations of whatever forests remain should also be systematically carried out. In due course of time, when all the barren hills and mountains due to deforestations are reforested, the soil erosions and silting would be reduced. That condition, combined with the systematic river trainings and regular dredging would deepen the rivers would retract the floodplains and also facilitate the rapid draining of the rivers into the sea. This would, hopefully, prevent and mitigate devastating floods to a certain extent in the future.
Last year, immediately after the unprecedent flooding that affected over a million people and damages and losses were great, I had contributed an article titled “What Triggered the Unprecedented Flood?” (15/08/2015 GNLM). In that article I had discussed, at length, the causes of flooding, deforestations and the necessity to ban logging to prevent the forests from further depletions and the importance of reforestations. Recent news of the banning of loggings is a very positive step in the right direction to conserve our forests.
Again in June of this year, in an article titled “Have We Overcome the Severest El Nino?”(24/06/2016 GNLM), I had ventured to predict that this year’s flooding would be more severe than that of the last year’s. By the look of it, my predictions may be right, which I have been wishing to be proven wrong. Last year’s flooding was made severe by the heavy rains brought on by the cyclone Komen. However, although it was not associated with a cyclone, but just a depression in the Bay of Bengal, we are getting heavy rainfalls that caused the present floods, which I presume to be the works of the severe El Nino or may be the La Nina weather condition, that is expected to follow in its wake, had a hand in it too.
Whatever the reasons may be, we should be prepared for the worst and hope for the best. Fortunately the number of people affected by the floods this year is far less than that of last year. The response to prevent and mitigate the effects of the floods  are also timely in most places and so the losses are not as great as last year.
According to the latest media reports, the water level of the Ayeyarwady River at Mandalay had receded a few inches. However, the water in the Taungthamann lake, home of the world famous U Pein bridge, would still be a problem. In the old days, before the bund road was built across the southern part of the lake as a bypass for traffics to reach the Mandalay-Yangon highway directly from the Ava bridge, the water from the rising Ayeyarwady and the Dotehtawady rivers could rapidly fill and easily empty the lake. As there are lack of enough and adequate floodgates along that road, it had turned into a large reservoir. During the floods, the water had overflowed the high bund road, making the filling faster. However, it is only natural, in such situations, that the receding of the water level there would take some time.
We should be vigilant and be prepared for more flooding. As the present flood is caused by the second rise of the three regular river rises in our country, we should be expecting for another one before the monsoon is out. From the past experiences, the last of the three river rises are seldom as high as the two preceding rises.
However, if there should be a cyclone coinciding with the third river rise, there could be severe flooding again. Thus, I would like to caution the farmers not to be in much hurry to sow paddy again, if the first batch had been swept away by the floods. Otherwise, if the next river rise should destroy the second crop, they would be left empty-handed.


Related posts

Translate »