ablation zone of the Gangotri glacier is covered by a thick pile of supraglacial moraines and is characterized by several ice sections, melting into pools of supraglacial lakes. Because of subsidence and the fast degenerating nature of the glacier, its centre is full of supraglacial lakes. In this part of higher Himalaya, glacial melt-water dominates the fluvial system. The total ice cover is approximately 200 km² and has about 20 km³ of ice in volume. Tributaries This glacier has three main tributaries, namely Raktvarn (15.90 km), Chaturangi (including Kalaxsyfeyfrfkdfndini bamak) (22.45 km) and Kirti (11.05 km) and more than 18 smaller tributary glaciers The Raktvarn system contains 7 tributary glaciers; among them Thelu, Swetvarn, Nilambar and Pilapani are important. Similarly the Seeta, Suralaya and Vasuki are the major tributaries which make up the Chaturangi system, while the Kirti system is made up of only three tributary glaciers. Besides these three major tributary systems, some other tributary glaciers of this area drain directly into the Gangotri glacier; among them Swachand, Miandi, Sumeru and Ghanohim are important. Four other glaciers, Maitri, Meru, Bhrigupanth and Manda drain into the river Bhagirathi. The total glacierized area of the catchment is 258.56 km², out of which the Gangotri system comprises 109.03 km², followed by Chaturangi (72.91 km²), Raktvarn (45.34 km²) and Kirti (31.28 km²). The remaining four glaciers contain 29.41 km² of glacierized area; among them maximum contribution is Bhirgupanth glacier (14.95 km²). Retreat NASA, in conjunction with scientists from United States Geological Survey (USGS) and the National Snow and Ice Data Center (NSIDC), is developing a global inventory of all the world's glaciers to help researchers track each glacier's history. According to them, the Gangotri glacier, currently 30.2 km long and between 0.5 and 2.5 km wide, is one of the largest in the Himalayas. This glacier has been constantly receding since measurements began in 1780. Data for 61 years (1936–96) showed the total recession of Gangotri glacier as 1147 m, with an average rate of 19 m per year. However over the last 25 years into the 21st century it has retreated more than 850 meters (34 meters per year), and 76 meters between 1996 and 1999 (25 meters per year) See also List of glaciers Gomukh Bara Shigri Notes References Bali, R., Awasthi, D.D. and Tiwari, N.K.2003 Neotectonic control on the geomorphic evolution of the Gangotri Glacier Valley, Garhwal Himalaya, Gondwana Research,