Determination of factors influencing recession of Himalayan glaciers in context of Supraglacial Lakes
Student name: Ms Florencia Matina Tuladhar
Guide: Dr Chander Kumar Singh
Year of completion: 2015
Host Organisation: International Centre for Integrated Mountain Development (ICIMOD), Lalitpur- Nepal
Supervisor (Host Organisation): Mr Samjwal Ratna Bajracharya
Abstract: Climate change has been adversely affecting glacier dynamics causing glaciers to advance and retreat worldwide. In the long term, this impacts freshwater availability for downstream inhabitants; in the short term, this accelerates expansion of glacial lakes leading to potential glacial lake outburst floods (GLOF). Existing studies have primarily recognized temperature as the leading factor causing glacier retreat. However, detailed studies that have investigated effect of other factors like presence of debris cover, slope, contact with water bodies is still lacking. This research, thus, is an attempt to explore the role of supraglacial lakes in retreat of debris-covered glaciers since these lakes are present only in debris-covered glaciers. Hence, the objectives are to detect interannual variation in supraglacial lake area of debris-covered glaciers in Dudh Koshi basin and to test the hypothesis that supraglacial lakes plays significant role on glacier retreat.
Delineation of supraglacial lakes at five year interval was done using Google Earth Pro to assess interannual variation in lake area. Slope, elevation and change in supraglacial lake area were predictors influencing decadal average area change of glaciers. Multiple linear regression yielded two models, first model used elevation and slope and second used change in supraglacial lake area as the additional predictor. The second model had a higher coefficient of determination (R square) and Adjusted R-square values of 99% and 96 % respectively. Subsequently, the test statistics from ANOVA results were compared to test the hypothesis. Moreover, the RMSE of second model was also lesser than the first one. Hence, both statistical results confirmed that change in area of supraglacial lakes was an important factor that determines overall recession of debris-covered glaciers. Nevertheless, use of higher spatial and temporal resolution data should be incorporated in future to ensure robust outcomes. Therefore, this research can bolster overall understanding of glacier and glacial lake dynamics to enhance future predictions of climate change models.
Keywords: Supraglacial Lake, Recession, Debris glaciers, Multiple Linear Regression, Interannual variation
