Evolution of narrow-band spectrum of two random Stokes wavetrains in deep water

Ocean Dynamics - Fourth-order nonlinear evolution equation (NLEE), which is an excellent starting point for the analysis of nonlinear deep water surface waves, are used here to investigate the...     

Chemistry of springwater in Almora, Central Himalaya, India

 A field study was conducted to assess variations in physico-chemical characteristics of water of the springs located within the boundary of a Central Himalayan town where the springwater is used for drinking purposes. Monitoring of 12 springs was carried out for three seasons (winter, summer and monsoon). The results indicate direct influence of unplanned sewage disposal on the springwater quality as reflected by significant regional variations in the concentration of nitrates, chlorides, sulfates, sulfides and electrical conductivity. Population density varies within the town from 3110 to 14 137 persons/km^–2 and has direct relationship with water quality. Springs located in the densely populated area had higher concentrations of all these compounds. Concentrations of nitrates up to 60 ppm were observed in some springs, making water unsuitable for human consumption. No significant changes were observed in springwater quality during different seasons. Received: 3 February 1995 · Accepted: 27 February 1996     

Stable isotopes in the source waters of the Yamuna and its tributaries: seasonal and altitudinal variations and relation to major cations

Water samples from the Yamuna and its tributaries, one of the major river systems draining the Himalaya, have been analysed for their stable oxygen and hydrogen isotopes during three seasons (summer, monsoon and post‐monsoon). The data show clear seasonal and altitudinal variations; waters from higher altitudes and those collected during monsoon season are characterized by relatively depleted isotopic composition. Regression analysis of δD–δ¹⁸O data of samples collected during summer and monsoon seasons shows that the slope of the best‐fit lines are nearly identical to those of precipitation at New Delhi for the same period. The similarity in their slopes suggests that the isotopic composition of precipitation contributing water to these rivers are reasonably well preserved in both monsoon and non‐monsoon seasons, however, during the non‐monsoon period both rainfall and river waters carry signatures of evaporation. The ‘deuterium excess’ in river waters during the three seasons though overlap with each other, the values during October are higher. This can be understood in terms of recycled moisture contributions to precipitation. The ‘altitude effect’ for δ¹⁸O in these waters is determined to be 0·11‰ per 100 m, a factor of about two less than that reported for the Ganga source waters from similar altitudinal range. The variability in altitude effects in rivers draining the Himalaya seems to be controlled by the ‘amount effect’ associated with the monsoon. The significant spatial variability in altitude effect in these river basins, which are a few hundred kilometers apart, suggests that reconstruction of palaeoelevation in the Himalaya, based on δ¹⁸O‐altitude gradients, would depend critically on its proper assessment in the region. This study has established a relationship between total cation abundance and δ¹⁸O in waters of the Yamuna mainstream; total cations (corrected for cyclic components) double for a 1·4 km decrease in altitude as the Yamuna flows downstream. Copyright © 2002 John Wiley & Sons, Ltd.     

Identification of AlF Molecular Lines in Sunspot Umbral Spectra

High resolution FTS sunspot umbral spectra from NSO/Kitt Peak were used to detect rotational lines due to 11 electronic transitions of the molecule AlF, in the wavelength region 4400 – 9000 Å. The presence of lines due to bands C – A (0,0), (0,1), (0,2) and (1,2), D – A (0,0) and (0,1), F – A (0,0), G – A (0,0), and F – B (0,0) is confirmed. Further, the presence of lines due to C – A (1,0) and (1,1) transitions is treated as doubtful because of heavy blending in the region, by rotational lines of TiO. Among the identified lines, those which are well resolved were selected for measurement of equivalent widths. The measured values for the bands D – A (0,0) and F – A (0,0) were used to estimate the respective effective rotational temperatures to be 1240 ± 120 K and 2390 ± 400 K.     

On the formation of Jupiter

Arguments are presented to show that Jupiter could not have been formed as a star of mass 0.001M and that the observed excess energy is not due to gravitational contraction from an extended, gaseous state.     

Analysis of Y-component of Geomagnetic Field and SYM-H Index Using Wavelet Multiresolution Analysis

Geomagnetism and Aeronomy - Electrodynamical coupling between the solar wind’s plasma and the Earth’s magnetosphere creates geomagnetic disturbances recorded on the ground. This work...     

Constraining probabilistic chloride mass-balance recharge estimates using baseflow and remotely sensed evapotranspiration: the Cambrian Limestone Aquifer in northern Australia

Hydrogeology Journal - Regional-scale estimates of groundwater recharge are inherently uncertain, but this uncertainty is rarely quantified. Quantifying this uncertainty provides an understanding...     

Shoreline Change Analysis at Chilika Lagoon Coast,India Using Digital Shoreline Analysis System

Shoreline is the dynamic interfaces of both terrestrial and marine environment, which constantly affected by natural coastal processes includes wave, tide, littoral drift and cyclonic storms as well as coastal development. Wave induced littoral drift and fluvial discharge causing the gradual inlet migration and has the concurrent impact on shoreline of Chilika lagoon. This study is to determine the long-term shoreline changes along the coast of Chilika lagoon. Historical satellite images were used to analyse the shoreline erosion and accretion based on statistical approach. The satellite data from 1975 to 2015 were processed by using ERDAS Imagine and the shorelines are extracted. The shoreline oscillation was analysed at an interval of 100 m along the coast of Chilika lagoon using DSAS software. Most commonly used statistical methods such as end point rate and linear regression rate are used. The shoreline change analysis for entire coast of the lagoon since 40 years (1975–2015) indicates that 62% is of accretion, 25% is under stable coast and erosion is 13%. The result reveals that the lagoon coast shows high accretion of 9.12 m/year at updrift side of the lagoon inlet whereas the downdrift side shows high erosion of ??10.73 m/year due to the wave induced northeasterly longshore sediment transport round the year and riverine discharge. This study would provide the potential erosion and accretion area at Chilika lagoon coast and would help in adaptive shoreline management plan.     

Morphological Dynamics of the Rivers of Brahmaputra

The Singrauli region is known for fluoride contamination and its effect on human population. In this work the possible sources of fluoride contamination in Rihand reservoir water is constrained. They include slurry water, fly ash and coal samples of various thermal power plants, coal seams and granites of the region. Petrographic study depicted the presence of fluoride bearing minerals - flour apatite in pink granite. Preliminary scanning electron microscope studies revealed presence of fluorine peak in coal samples. The chemical analysis confirmed the presence of fluoride in fly ash (12.6 mg/kg), drain water (5.34 mg/l), soil (6.1 mg/kg), coal (3.1 mg/kg). They confirmed the source of fluoride from coal of thermal power plant which utilized coal from Singrauli coal seam (1.6 mg/kg). Further the Rihand reservoir water is also enriched by fluoride contaminant (upto 4.7 mg/l). This contaminates groundwater of the area as well. The contaminated water used for drinking and agriculture affects health of inhabitants in the area. It is concluded that the main source of fluoride contamination in the study area is due to coal burnt in thermal power plant and pink granite formation of the area, both anthropogenic and geogenic sources are implied.