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The dynamics of suspended sediment involves inherent non-linearity and complexity because of existence of both spatial variability of the basin characteristics and temporal climatic patterns. This complexity, therefore, leads to inaccurate prediction by the conventional sediment rating curve (SRC) and other empirical methods. Over past few decades, artificial neural networks (ANNs) have emerged as one of the advanced modelling techniques capable of addressing inherent non-linearity in the hydrological processes. In the present study, feed-forward back propagation (FFBP) algorithm of ANNs is used to model stage-discharge-suspended sediment relationship for ablation season (May-September) for melt runoff released from Gangotri glacier, one of the largest glaciers in Himalaya. The simulations have been carried out on primary data of suspended sediment concentration (SSC) discharge and stage for ablation season of 11-year period (1999-2009). Combinations of different input vectors ( viz. stage, discharge and SSC) for present and previous days are considered for development of the ANN models and examining the effects of input vectors. Further, based on model performance indices for training and testing phase, a suitable modelling approach with appropriate model input structure is suggested. The conventional SRC method is also used for modelling discharge-sediment relationship and performance of developed models is evaluated by statistical indices, namely; root mean square error (RMSE), mean absolute error (MAE) and coefficient of determination ( R2). Statistically, the performance of ANN-based models is found to be superior as compared to SRC method in terms of the selected performance indices in simulating the daily SSC. The study reveals suitability of ANN approach for simulation and estimation of daily SSC in glacier melt runoff and, therefore, opens new avenues of research for application of hybrid soft computing models in glacier hydrology. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract No great earthquake has occurred in the Garhwal–Kumaun region of NW Himalaya in the past 500 years or more. We report results of continuous GPS measurements from 28 sites from the region to suggest that the convergence rate in this part of the Himalaya is about 18 mm/yr which is leading to strain accumulation in the region. The Main Himalayan Thrust (MHT) in the frontal part of the Himalaya under the Outer and southern Lesser Himalaya is strongly coupled for a width of about 85 km. The midcrustal ramp where earthquakes of Himalayan seismic belt occur, exhibits low coupling. Strong coupling on the MHT beneath the Outer and Lesser Himalaya is homogeneous except in the very shallow updip part of the MHT. Subduction of sediments of the Indo-Gangetic plains or the Delhi Hardwar ridge does not seem to influence coupling. A high rate of strain accumulation, which has continued for more than 500 years on a strongly coupled MHT makes this one of the most earthquake-vulnerable segments of the Himalayan arc. Graphical abstract Highlights • Locking variation on MHT beneath Garhwal Kumaun Himalaya from 28 cGPS measurements. • Long term convergence rate in the region is ∼18 mm/yr. • Strong locking on the MHT beneath the Outer and Lesser Himalaya. • Ramp is in transition from strongly coupled to aseismically slipping MHT. • Strong coupling, high strain rate for >500 yr makes it highly vulnerable segment. [ABSTRACT FROM AUTHOR]

Springs and streams are essential sources of fresh water for the Himalayan population. To global and regional extents, these resources are being severely affected by climate change as well as anthropogenic activities. However, the effects of seismicity also have considerable influence on springs but are negligibly studied in that aspect. Crustal deformation, shaking, and movement of the earth's surface due to an earthquake, can modify the stream flow and water level in wells through consolidation of surficial deposits and development of new fractures. The present study addresses the effect of an earthquake on water springs in a seismically active zone. On 18 September 2011, the Sikkim Himalaya experienced a strong earthquake of magnitude (Mw) 6.9. To assess the impact of this earthquake on hydrology, we studied the springs located in the South Sikkim district, India. Our research indicates that few springs dried up following the Mw 6.9 earthquake in 2011 while some springs discharged at a higher rate than before. The springs which were dried up due to climate change were excluded in this study. Furthermore, our study suggests that in tectonically active mountain ranges, like Himalaya, an earthquake not only causes surficial deformations but also influences the hydrological framework at a regional scale. Therefore, the seismic nature of the terrain should also be considered for spring rejuvenation policies. • Impact of an earthquake on water bodies were studied. • Himalayan springs are sensitive to both climate change as well as earthquakes also. • An earthquake having magnitude Mw ≥ 5 may affect the discharge of a spring. [ABSTRACT FROM AUTHOR]

The Himalayan mountain system to the north of the Indian land mass with arcuate strike of NW-SE for about 2400 km holds one of the largest concentration of glaciers outside the polar regions in its high-altitude regions. Perennial snow and ice-melt from these frozen reservoirs is used in catchments and alluvial plains of the three major Himalayan river systems, i.e. the Indus, Ganga and Brahmaputra for irrigation, hydropower generation, production of bio-resources and fulfilling the domestic water demand. Also, variations in the extent of these glaciers are understood to be a sensitive indicator of climatic variations of the earth system and might have implications on the availability of water resources in the river systems. Therefore, mapping and monitoring of these freshwater resources is required for the planning of water resources and understanding the impact of climatic variations. Thus a study has been carried out to find the change in the extent of Himalayan glaciers during the last decade using IRS LISS III images of 2000/01/ 02 and 2010/11. Two thousand and eighteen glaciers representing climatically diverse terrains in the Himalaya were mapped and monitored. It includes glaciers of Karakoram, Himachal, Zanskar, Uttarakhand, Nepal and Sikkim regions. Among these, 1752 glaciers (86.8%) were observed having stable fronts (no change in the snout position and area of ablation zone), 248 (12.3%) exhibited retreat and 18 (0.9%) of them exhibited advancement of snout. The net loss in 10,250.68 sq. km area of the 2018 glaciers put together was found to be 20.94 sq. km or 0.2% (± 2.5% of 20.94 sq. km). [ABSTRACT FROM AUTHOR]