Mass Balance Modeling On Glaciers In Urumqi River Basin,Northwest China

Xinjiang uygur autonomous region("Xinjiang" for short)is localed in the northwestern China,the central part of Asia with more than 20,000 glaciers developed in.The glaciers in Xinjiang play an significant role as a constituent of water resources and in runoff regulation.Previous studies indicated that those glaciers in Xinjiang are extremely sensitive to climate change.In past decades,along with global warming,glaciers in Xinjiang experienced dramatic ablation and retreat,which gave birth to rapid changes in the spatial and temporal distribution of local water resources and in the water cycle processes.In this case,the dynamic evolution of glacial melting becomes a hot-point problem in Xinjiang.Glacier mass balance,the difference between accumulation and ablation at the glacier surface,is the direct reflection of local climate regime.Meanwhile,mass balance links glacier with atmosphere/hydrology.In the context of global warming,the content of glacier mass balance and the strategy to study it have been altered.This thesis makes mass balance modeling as entry point,reviewing the observational methods of mass balance,the history of mass balance studies and the schemes of mass balance models.The simple energy balance model(sEBM)is utilized to simulate the mass balance of Urumqi Glacier No.1(UG1)and 128 glaciers in Urumqi River Basin(URB).The results indicate:(1)the difference of equalibrium line altitude(ELA)of east and west branch of UG1 is decreasing these years,indicating that the influence of topograph on mass balance declines along with the rising of air temperature.(2)Degree day model can be used to depict the characteristic of mass balance along elevation,but not the local features.Additionally,the Degree-Day Factors are spatially and temporally variable,thus Degree Day Model with fixed Degree-Day Factors is not applicable in watershed scale.(3)sEBM can be used in watershed scale.(4)Most glaciers in URB experienced intensive melting during 2001-2005.The annual wastage of solid water accounted for 2.5-5.3%of current glacial water storage.Mass balance of very limited glaciers in URB was positive.Those glaciers were quite small in size and supplied limited contribution to local water resources conservation.(5)Glaciers in URB was sensitive to air temperature change.In details,loC rise in air temperature would lead to>100%increase in solid water wastage.The problems in this study:(1)DEM and glacier profiles data of different time were used;(2)no verification on the simulated mass balance in watershed scale was made,would lead to extra error to the modeling results.