Based on satellite images of the Kedarnath area pre and post the disaster on June 16-17, the Uttarakhand Space Application Centre has pointed out that the Chaurabari lake at the base of the glacier of that name overflowed after being saturated by heavy rains.
The water from the lake used to flow in two streams down the valley before the disaster but after the disaster it was noted that water from the saturated lake had flowed down forming a third stream.
According to the USAC report, comparing old photographs of 1882 along with recent photographs and satellite images shows that there was tremendous growth in infrastructure during the last few decades along with a
proportionate increase in pilgrim numbers. It was observed that antecedent rainfall saturated the area, causing the water to exceed the lake capacity which was one of the reasons for activation of landslide and flash flood in the area.
Pre- and post-temporal satellite data shows that the Chaurabari lake near the snout of Chaurabati glacier above Kedarnath is seasonal with heavy rainfall and snow cover in the area raising the water level of the lake which triggered the streams and lakes to overflow by saturating the moraines.
The velocity of debris flow was very high due to high gradient slope from Kedarnath to Rambada and Gaurikund exacerbating damage and washing out about 80 per cent of the pedestrian route between Kedarnath and Gaurikund. Viewing the interpretation of pre and post satellite data makes it clear that the Vasuki Tal lake had no role in this devastation.
Based on analysis of the satellite images, USAC director MM Kimothi said that there is need for detailed investigation of the disaster-hit area for evaluation of the actual damage and causes of this devastation and the future rehabilitation planning of Kedarnath and downstream of the Mandakini valley.