Uttarakhand disaster was result of extreme rains and haphazard development: The National Institute of Disaster Management (NIDM), in one of its first reports on the Uttarakhand floods, has blamed climatic conditions combined with haphazard human intervention in the hills for the disaster. The abnormally high amount of rain (more than 400 per cent) in the hill state was caused by the fusion of Westerlies with the monsoonal cloud system. Heavy precipitation swelled rivers, both in the upstream as well as downstream areas. Besides the rain water, a huge quantity of water was probably released from melting of ice and glaciers due to high temperatures during the month of May and June. The water not only filled up the lakes and rivers that overflowed but also may have caused breaching of moraine dammed lakes in the upper reaches of the valley, particularly during the late evening on June 16 and on June 17, killing about several hundred persons; thousands went missing and about 100,000 pilgrims were trapped. The Alaknanda river and the Mandakini, both tributaries of the Ganga), occupied their flood ways and started flowing along the old courses where habitations were built over time (when the river had abandoned this course and shifted its path to the east side). Thus, the rivers destroyed the buildings and other infrastructure that came in its way. The geomorphological study of the area indicates that the surface slopes consist mostly of glacial, fluvio-glacial, or fluvial materials, which are mostly unconsolidated and loose in nature. The drainage studies indicate a migratory or shifting nature of the river systems that causes aggradations on the concave end of the river and degradation or toe erosion on the convex part of the river. Due to morphological setting of the area, the river has high sinuosity and hence, high level of erosive capacity, especially when it is loaded with sediments (the erosive power of river with sediments is almost square of the erosive power without sediments).