Abstract The study of the hydrological characteristics of a river is an important aspect in order to study the spatial variations and flow dynamicity of the river. The geomorphic signatures of the river can be indirectly assessed with the help of its hydrological character at a specific river stretch. The Subarnarekha river eastern India, traverses over varied geomorphology and this variation can be related to the hydrological signals, it leaves behind, at different reaches. A detailed statistical analysis throws light on the flooding character of the river which was done through flow histograms, yearly variations of water levels, river regime, recession curve analysis and rating curves. The study reports two specific findings. Firstly, the flow regimes are experiencing a change and there is a decline in the quantity of water flowing in the river in the present compared to the past. Secondly, there is a spatial variation in the flow patterns that are experienced by the different hydrological stations located in the different reaches of the river. The plateau region stations are experiencing high magnitude low frequency floods whereas the alluvial floodplains are experiencing low magnitude high frequency events.
 
Keywords: Hydrograph, regime, recession curve, rating curve, water level, flood

Abstract The large temperature variability of nightly mean temperatures in 30 to 80 km altitude range is investigated using 15 years of lidar data from the year 1998 to 2012 over a low latitude station Gadanki, India (13.5o N, 79.2o E). The monthly mean values are compared with the coincident SABER temperature data obtained in a grid encompassing latitudes 08–18°N and longitudes 74–84°E during years 2002-2012 (i.e., 11 years). The comparison between the lidar and SABER measurements reveals a reasonable agreement with the standard deviation of the temperature difference ~1.5 K at 50 km and ~3 K at 70 km altitudes. To understand the physics of variability noted in the temperature data, abest-fit analysis is used.This reveals the presence of Semi-Annual Oscillation (SAO), Annual Oscillation (AO), Quasi-Biennial Oscillation (QBO), El Niño Southern Oscillation (ENSO), Solar Cycle Influence, and a residual secular trend. The residual trend shows a warming at 30-40 km altitudes and cooling between 40 and 80 km. The underlying physics of these oscillations are explained with the present knowledge of atmospheric forcings.
 
Keywords: Temperature, SAO, QBO, ENSO, Trends

Abstract In hard rock granitic terrains groundwater availability has become a major geo-environmental and socio-economic issue. Groundwater recharge& draft are the two key factors in water balancing studies, especially in the semi-arid, granitic terrains of Southern India. Considering these issues and ever changing dynamics of groundwater resources, a micro level watershed wise groundwater draft estimation studies have been taken by integrating both Geohydrological, surface and sub-surface components as input variables, thus creating a knowledge guided geo-mathematical model. The outputs obtained from the knowledge guided geo-mathematical model are used and validated with field conditions. It was observed that the estimated groundwater draft falls within the acceptable range. The results of the present study and knowledge guided geo-mathematical model can serve as guidelines for planning future studies in similar geological provinces in order to ensure groundwater draft measurement, dependable water supply, and sustainable groundwater utilization on a long-term basis for sustainable scenario development.
 
   Keywords: Water balance, Semi-arid environment, knowledge guided geomathematical model, Groundwater Management plan

Abstract Seismic hazard evaluation and disaster mitigation is a very challenging task and needs a detailed description of the seismic sources within the region which includes the location, depth of earthquake and surface or local magnitude. We applied different analytical techniques to study data generated from two important domains– Earthquake–seismicity catalogs for seismic vulnerability assessment using seismic vulnerability assessment ofthe seismotectonic zone of North-East India and IndoMyanmar region. The seismogenic behaviour observed by the recent strain energy release from 2015 to June, 2016 has been studied for identification of the geo-tectonic blocks in North-East India. In the proposed work, the strain energy release and rupture patterns is highlighted using iso-strain release maps and contour plot analysis. The former part of the data is used as learning samples to quantitatively predict the error associated with the focal depth of the earthquake in the spatial basin. The results of this simulation approachis found to characterize the imminent earthquake occurrence using back propagation network model that has strong nonlinear approximation capability which reflects the non-linear relationship between the associated depth. The error between the prediction results and the measured values is small, which can be used for identification of cluster patterns.
 
Keywords: Geo-Tectonic block, Seismicity, Strain Energy, Iso-Strain