Mass balance of Dokriani Glacier, Central Himalaya: a model in response to climate fluctuation and debris cover

Abstract

In this thesis, study on the Dokriani Glacier concentrates as a long term monitoring and understanding of the glacier ice mass variability in the central Himalaya. Glacier was assessed for length/area change and mass balance variation for resolving the relationship between atmospheric variability and geometry of glacier. A well established ground based glaciological method was opted for assessing the glacier’s surface mass gain and loss on the basis of annual as well as decadal scale. Annual balance is presented with the annual accumulation and annual ablation. The study described the results of the annual balance, mass balance gradient and epiglacial morphological changes observed during first decade of 21st century (2007/08-2012/13) and also compared with the previous observations of 1990s (1992/93-1999/2000). A way forward, the study investigated the characteristic difference between accumulation-area ratio (AAR), annual averaged AAR (AARn) and balance budget AAR (AAR0), an analysed the current state (αd=AAR-AAR0/AAR0) of the Dokriani Glacier and other (eight) Indian Himalayan glaciers lies in different climatic zone. To understand the distribution and characteristics of glaciers mass balance, a review of four decades mass balance of the Indian Himalayan glaciers was discussed. In addition, an overview of the glacier mass balance records by glaciological, geodetic, hydrological and accumulation-area ratio (AAR) and specific mass balance relationship methods in the Indian Himalaya since 1970s was also done. It suggests that since 1970s onwards the mass balance measurements by glaciological methods have been conducted for 10 glaciers in the western Himalaya, 4 glaciers in the central Himalaya and 1 glacier in the eastern Himalaya. Hydrological mass balance has been conducted only on Siachen Glacier from 1987 to 1991. Geodetic method has been attempted for the Lahaul-Spiti region for a short time span during 1999-2011 and Hindu Kush–Karakoram–Himalaya region (HKKH) from 2003 to 2008. Few studies based on substitute methods like AAR and specific mass balance relationship has also been estimated glacier mass balance for few basins. The present review compared in-situ specific mass balance data series with modelled mass balance derived from AAR and specific balance. AAR0 and ELA0 based on available in-situ AAR and specific mass balance data series was also revised for the Indian Himalayan glaciers. In general, in-situ specific and cumulative specific mass balance observed over different regions of the Indian Himalayan glaciers shows mostly negative mass balance years with a few positive ones during 1974-2012. On a regional level, the geodetic mass balance studies suggest that on the whole western, the central, and the eastern Himalaya experienced vast thinning during the last decade (2000s). Conversely, Karakoram region showed slight mass gain during similar period.