Sediment load characteristics of a proglacial stream of Siachen Glacier and the erosion rate in Nubra valley in the Karakoram Himalayas, India

This paper discusses the results of studies on sediment transport and the erosion rate in the Nubra river carried out in hydrological years from 1986 to 1991.Discharge data of proglacial stream of the Siachen Glacier shows seasonal variation ranging from 0.26×106 m3 d−1 in the beginning of the ablation season to about 23×106 m3 d−1 in the peak ablation season. Suspended sediment mass in the Nubra River varies from 0.01 kg m−3 s−1 in the beginning of the ablation season to about 2–3 kg m−3 s−1 at its peak. A relationship is developed between daily suspended sediment transport and daily discharge. The total sediment load calculated from the data varies from 296 to 1287 tons km−2 (of the glacier basin area) per year. The erosion rate calculated from total sediment load which includes suspended sediment and bedload varies from 0.11 to 0.46 mm year−1.The erosion rates in the Nubra basin are much lower than the Hunza basin in Western Karakoram Himalayas (1.8 mm year−1) which may be due to its geological setting consisting of highly erosion resistant rocks like diorites, grano-diorites, granites and granite-gniesses. Tectonic upliftment and high relief give rise to comparatively higher erosion rates in Karakoram Himalayas.