Assessment of climate change impact and potential adaptation measures on wheat yield using the DSSAT model in the semi-arid environment

Natural Hazards - Crop simulation models are essential tools to facilitate the evaluation and application of crop production practices under different climate scenarios. The present study analyzed...     

Remote sensing of mountain snow using active microwave sensors: a review

This work provides an overview of various methods for estimating snow cover and properties in high mountains using remote sensing techniques involving microwaves. Satellite-based remote sensing with its characteristics such as synoptic view, repetitive coverage and uniformity over large areas has great potential for identifying the temporal snow cover. Many sensors have been used in the past with various algorithms and accuracies for this purpose. These methods have been improving with the use of Synthetic Aperture Radar sensors, working in different microwave frequencies, polarisation and acquisition modes. The limitations, advantages and drawbacks are illustrated while error sources and strategies on how to ease their impacts are also reviewed. An extensive list of references, with an emphasis on studies since 1990s, allows the reader to delve into specific topics.     

Two‐dimensional physically based finite element runoff model for small agricultural watersheds: II. Model testing and field application

Mathematical models are useful analysis tools to understand problems in watersheds associated with runoff, and to find solutions through land use changes and best management practices. However, before a model is applied in the field, it must be tested and checked to ensure that the model represents the real world adequately. In this paper, a two‐dimensional physically based finite element runoff model ROMO2D has been verified and validated by comparing the model output with analytic solution under simplified conditions, published data, and field measurements. Calibration of the model was done manually through a multi‐objective calibration procedure, using observed field data. Before going for field validation/application of ROMO2D, analysis was carried out to determine the optimum number of finite elements into which the watershed should be discretized and the size of the time step. A sensitivity analysis of the model was performed using the observed values of watershed parameters. The model was applied to a 1·45 ha agricultural watershed located in the Shiwalik foothills (India) to simulate runoff. The results demonstrated the potential of the model to simulate runoff from small agricultural watersheds for individual storm events with reasonable accuracy. Copyright © 2008 John Wiley & Sons, Ltd.     

Statistical analysis on yearly seismic moment release data to demarcate the source zone for an impending earthquake in the Himalaya

Tectonism in the Himalayan fold-thrust belt had generated great earthquakes in the past and will spawn more in the future. Sequential cumulative moment release data of macroearthquakes (Mb ≥ 4.5) over the years 1964–2006 in four zones of the Himalaya was analysed by nonparametric RUD method. The Z values of RUD analysis had neither rejected nor supported the null hypothesis of randomness. However, the Hurst analysis and plot, a statistical procedure to identify clustering of low and high values in a time series, brought out a pattern for earthquake prognostication. The pattern was a negative sloping segment representing a sluggish moment release over years, followed by a positive sloping segment indicating a sudden high moment release with occurrence of medium/large size earthquake(s). In recent past, such a negative sloping has been found in Zones B (1992–2006) and D (1998–2006), indicating an impending moderate/mega earthquake event in near future.     

Lyra's cosmology of hybrid universe in Bianchi-V space-time

In this paper we have searched for the existence of Lyra's cosmology in a hybrid universe with minimal interaction between dark energy and normal matter using Bianchi-V space-time. To derive the exact solution, the average scale factor is taken as a =(t~ne~(kt))1/m which describes the hybrid nature of the scale factor and generates a model of the transitioning universe from the early deceleration phase to the present acceleration phase. The quintessence model makes the matter content of the derived universe remarkably able to satisfy the null, dominant and strong energy condition. It has been found that the time varying displacement β(t) co-relates with the nature of cosmological constant Λ(t). We also discuss some physical and geometrical features of the universe.     

Potential source zones for Himalayan earthquakes: constraints from spatial�Ctemporal clusters

The Himalayan fold-thrust belt has been visited by many disastrous earthquakes (magnitude > 6) time and again. This active collisional orogen bordering Indian subcontinent in the north remains a potential seismic threat of similar magnitude in the adjoining countries like India, Pakistan, Nepal, Bhutan and China. Though earthquake forecasting is riddled with all conjectures and still not a proven presumption, identifying likely source zones of such disastrous earthquakes would be an important contribution to seismic hazard assessment. In this study, we have worked out spatio-temporal clustering of earthquakes (Mb ?? 4.5; 1964?C2006) in the Himalayas. ??Point density?? spatial statistics has helped in detecting 22 spatial seismicity clusters. Earthquake catalog is then treated with a moving time-distance window technique (inter-event time 35 days and distance 100 ± 20 km) to bring out temporal clusters by recognizing several foreshock-main shock-aftershock (FMA) sequences. A total of 53 such temporal sequences identified in the process are confined within the 22 spatial clusters. Though each of these spatio-temporal clusters deserves in-depth analysis, we short-listed only eight such clusters that are dissected by active tectonic discontinuities like MBT/MCT for detail study. Spatio-temporal clusters have been used to constrain the potential source zones. These eight well-defined spatio-temporal clusters demonstrate recurrent moderate to large earthquakes. We assumed that the length of these clusters are indicating the possible maximum rupture lengths and thus empirically estimated the maximum possible magnitudes of eight clusters that can be generated from them (from west to east) as 8.0, 8.3, 8.2, 8.3, 8.2, 8.4, 8.0 and 7.7. Based on comparative study of the eight cluster zones contemplating with their temporal recurrences, historical seismic records, presence of intersecting faults and estimated magnitudes, we have guessed the possibility that Kangra, East Nepal, Garhwal and Kumaun?CWest Nepal clusters, in decreasing order of earthquake threat, are potential source zones for large earthquakes (??7.7 M) in future.     

Spatial and temporal variations in thunderstorm casualties over India

Thunderstorms are one of the most dangerous convective weather events. Despite the recent advances in prediction of convective storms worldwide, thousands of casualties occur annually. In the present study, the authors highlight specifically, thunderstorm‐related casualties reported in India from 1978–2012. Analysis of long‐term data have revealed about 16 308 casualties resulting from 1381 thunderstorm events with an average of 465 casualties occurring annually. The maximum number of casualties were concentrated in north‐eastern and central north‐eastern states. About 80 per cent of total casualties were recorded in West Bengal (23 per cent), Assam (20 per cent), Orissa (14 per cent), Bihar (13 per cent) and Jharkhand (8 per cent) states. The national casualties rate per million population per year and casualties density standardized by area has been found to be 0.50 and 5.07, respectively. Male casualties were found to be more prominent than female and children casualties, probably due to the larger proportion of males performing their work outdoors. The number of thunderstorm events and casualties was observed to be highest during pre‐monsoon season and lowest during winter. It is believed that the findings from this study will help policy makers to draw strategies to cope with the perils of thunderstorms.     

Low energy neutral atom imaging on the Moon with the SARA instrument aboard Chandrayaan-1 mission

This paper reports on the Sub-keV Atom Reflecting Analyzer (SARA) experiment that will be flown on the first Indian lunar mission Chandrayaan-1. The SARA is a low energy neutral atom (LENA) imaging mass spectrometer, which will perform remote sensing of the lunar surface via detection of neutral atoms in the energy range from 10 eV to 3 keV from a 100km polar orbit. In this report we present the basic design of the SARA experiment and discuss various scientific issues that will be addressed. The SARA instrument consists of three major subsystems: a LENA sensor (CENA), a solar wind monitor (SWIM), and a digital processing unit (DPU). SARA will be used to image the solar wind-surface interaction to study primarily the surface composition and surface magnetic anomalies and associated mini-magnetospheres. Studies of lunar exosphere sources and space weathering on the Moon will also be attempted. SARA is the first LENA imaging mass spectrometer of its kind to be flown on a space mission. A replica of SARA is planned to fly to Mercury onboard the BepiColombo mission.