Inventorying And Spatial Distribution Of Rock Glaciers In The Yarlung Zangbo River Basin

The Yarlung Zangbo River Basin is an important water source area and a frequent area of geological disasters in China,where a large number of permafrost are distributed Rock glacier as a special type of periglacial geomorphology in permafrost regions,the melting of the internal ice may be an important source of water supply in the basin under the background of global warming.At the same time,the gradual increase of loose deposits in the tongue area will increase the risk of debris flow,which may be an important disaster-causing factor in the future of the cryosphere.Therefore,the potential ice volume and understanding of the rock glaciers in the basin are estimated.The spatial distribution characteristics of rock glaciers have great practical needs.In view of this,using the high-resolution remote sensing image provided by Google Earth,the distribution information of rock glaciers in the Yarlung Zangbo River basin can be identified by manual interpretation through the unique texture features of rock glaciers combined with the slope information extracted by SRTM.The first inventory of rock glaciers in the Yarlung Zangbo River Basin is made by batch extraction of various attribute parameters of rock glaciers using ARCGIS software and python program.Based on the results of the inventory of rock glaciers,the following conclusions are preliminarily drawn:(1)There are 370 rock glaciers in the basin,covering a total area of 75.55 km2,with an average elevation of 5135 m,an average slope of 12 degrees,an average area of 0.16 km2,an average length of 737 m and an average width of 188m.Located in Luoza Xiongqu River Basin(14,3.70 km2),Xiba Xiaqu River Basin(63,8.65 km2),Yamzho Lake Basin(9,1.05 km2),Nianchu River Basin(70,17.13 km2),Doxiong Zangbo River Basin(54.5.60 km2)and Lhasa River Basin(160,40.42km2),respectively.(2)In terms of spatial distribution,the most developed rock glaciers are in the middle part of the basin(238),followed by the western part(120),and the least in the eastern part,with only 13 rock glaciers.There are 217 rock glaciers on the north bank and 156 on the South bank.In terms of type characteristics,there are 266 intact rock glaciers(including ice),104 relict rock glaciers(not including ice),198 moraine-type rock glaciers(evolved from glaciers),172 talus-type rock glaciers(evolved from talus),268 tongue-shaped rock glaciers(length-width ratio greater than 1),and only 2 lobate-shaped rock glaciers(length-width ratio less than 1).(3)The minimum elevation at the front(MEF)of intact rock glaciers in the basin is higher than that of relict rock glaciers(98%).The distribution of intact rock glaciers coincides with the areas with high probability of occurrence of permafrost in the Permafrost Zonation Index map,which indicates that the distribution of rock glaciers has certain reference significance for the mapping of permafrost.(4)Two empirical formulas established by White(1973)and Brenning(2005)were used to estimate the average ice volume of rock glaciers in the basin.The results show that the ice volume of rock glaciers in the basin are 2.20 km3,the highest in the Lhasa River Basin(1.11 km3)and the lowest in the Yamzho Lake Basin(0.01 km3).It shows that with the accelerated melting of glaciers,rock glaciers may be an important source of runoff recharge in the future.