S. P. Aggarwal

Snow physical parameters estimation using space-based Synthetic Aperture Radar

This study has been done using Polarimetric Synthetic Aperture Radar (SAR) data to estimate the snow physical properties (snow wetness and snow density), inManali sub-basin of Himachal Pradesh, India. The SAR data used are of Radarsat-2 (RS2) and Environmental Satellite, Advanced Synthetic Aperture Radar (ASAR). SAR-based inversion models were implemented in Mathematica and MATLAB, and have been used for finding out wet and dry snow dielectric constant, snow wetness and snow density. The SAR-based inversion models were implemented separately for fully polarimetric RS2 and dual polarimetric ASAR Alternate Polarization System datasets. Masks for forest, built area, layover and shadow were considered in estimating snow parameters. The overall accuracy in terms of R 2 value comes out to be 0.86 for snow wetness and 0.84–0.72 for snow density based on the ground truth data for subset area of Manali sub-basin of Beas river up to Manali.

Investigation of scale dependence and geomorphic stages of evolution through hypsometric analysis: a case study of Sirsa basin, western Himalaya, India

Hypsometric analysis is an important tool to identify and justify the erosional status, erosional processes, geologic and tectonic influences, and stage of landscape development of a basin. In this study, scale dependence of hypsometric integral (Ea) and hypsometric curve parameters were derived and analysed for various order sub-basins of Sirsa river. Here, Ea of higher order sub-basins are quite scale dependent and controlled by lithology; albeit Ea of all order sub-basins is independent of tectonic uplift. Based on Ea, all fourth and fifth order sub-basins were categorised in three classes. The analysis of hypsometric curve parameters showed that sub-basins of first category (Ea < 0.35) is characterised by upward-concave curve, fluvial process dominated and early old stage landscape. Sub-basins of second category (0.35 < Ea < 0.45) reflects concave-convex curve, dominance of fluvial process and mature landscape; whereas third category sub-basins (Ea > 0.45) are diffusive process dominated and belong to late youth to early mature stage.

Hypothetical scenario–based impact assessment of climate change on runoff potential of a basin

Climate change and its impact on hydrological processes are causes for widespread concern and challenge. In this regard, large numbers of global and regional circulation models (GCMs and RCMs) have been developed to study the future climate. However, these GCMs and RCMs have large uncertainties in defining climate scenarios. The uncertainties associated with these models provided an opportunity to investigate the impact of climate change on the runoff potential of a major basin in India under different assumed plausible hypothetical scenarios. These scenarios were developed by increasing the temperature by 1°C, 2°C and 3°C and rainfall by 5%, 10% and 15%, and then combinations of both. Understanding the hydrologic response of very large river basins again poses a huge challenge to hydrologists. Therefore, an attempt has been made to exploit the capabilities of a variable-infiltration-capacity macro-scale hydrological model to simulate the Satluj river basin. It was found that a slight change in climate may cause huge differences in the hydrological regime of the basin.