The study using different satellite data and topographic maps since 1977 and available reports shows remarkable retreat of glaciers due to climate change in the Poiqu basin in Xixiabangma area – a common basin between China and Nepal. Poiqu River in the downstream in Nepal is named SunKoshi-BhoteKoshi.
At present, there are about 150 glaciers covering 11 percent of area within Poiqu basin in China. The study reveals that about five percent of the glaciers from the entire basin have vanished since the last three decade. As a result of glaciers re treat, glacial lakes are growing in alarming rate. Some of the glaciers , such as the valley glaciers with IDs 5O191B0029 (mother glacier of LumuChimi glacial lake) and 5O191C0009 (mother glacier of Gangxi Co glacial lake) on the eastern slope of the Xixiabangma decreased by about 0.055 km2 and 0.059 km2 in area and retreated around 45 metres and 68 metres in length respectively per year since 1977. Similarly the analysis on the five valley glaciers on the northern slope of the Laptshegang Mountain had also shown the glacier shrunk by average of 0.028 km2 in area and retreated about 20 metres per year.
Some of the lakes, such as LumuChimi and GangxiCo lakes have grown almost double in size. Nine glacial lakes pose potential threat of glacial lake outburst floods (GLOF) which most often have devastating effects on local people and the surrounding environment. Such GLOF events may damage existing infrastructure such as hydropower and roads, and agriculture land in the downstream to the lower riparian country. There is need for regional cooperation for exchange of scientific information and to carry out detailed field investigation in the area to evaluate the possible damage in downstream area. Early Warning Systems (EWS) at the potential dangerous lakes and downstream areas are necessary to minimize and mitigate the effects of such natural disasters.
