Recent abnormal tectonic acitity and subsequent earthquakes (12 May'08, 26 Aug'08) in China, Nepal & Tibet support my hypothesis that ongoing tectonic activities influenced the path of Kosi and its divergence point near supoil. River is under the influence of Malda Kishenganj fault on the eastern margin of Monghyr-sharasa ridge. It seems this fault is influenced by the recent China and Tibet earthquakes.
Although water level in the barrgae and rainfall is the cause for floods but rivers tendency yo erode its embankments has been influenced by other factors also. The reason for the sudden changes may be related to the the recent increased tectonic activities in Nepal & China Himalays. Frequency of earthauakes (more than 5 intensity) is observed highest in the last few dwcades.
In that paper i had identified the zones showing diffrent levels of tectonic influence on kosi River shifting. Geophysical data and GIS modeling using and RS images of different years proved that it is shifting its path under the influence of tectonic movements in its catchment area in Himalayas twoards China and Nepal side.
Kosi River changed its path in three main phases due to changes in the spatial position and orientation of its diversion points ( meeting point of three main basement faults). This is the fourth such phase and river will keep on gradually changing its position after that also. The diversion point of Kosi near Birpur has shifted north-eastward and it caused breaches in the East Kosi river south east of Chtara.
There are many ways to control the situation for temporary respite but the fact is that it is a problem that needs long term carefull micro level study study of the factors causing this shift since thousnad of years and then remedial planning by the India and Nepal. Its not that if you can fill the breach in the dam and the problem will be solved forever. The barrage's estimated lifespan of 30 years expired in 1986 but the river's morphology — it was showing a reverse tendency to shift eastward — began changing even earlier. Read the paper for more details.
http://www.gisdevelopment.net/application/geology/geomorphology/geom0002b.htm
In this paper i had identified the zones showing diffrent levels of tectonic influence on kosi River shifting. Geophysical data and GIS modeling using and RS images of different years proved that it is shifting its path under the influence of tectonic movements in its catchment area in Himalayas twoards China and Nepal side.
