Change detection in Sal forest in Dehradun Forest Division using remote sensing and geographical information system

The review of study site have revealed the change in vegetation cover of Sal Dense to Sal Medium and Sal Open in 6 forest Mosaics owing to biotic and abiotic conditions prevailing in the specific areas. Analysis carried out using thematic map derived from aerial photograph of 1976 and satellite data of IRS 1C LISS III False Colour Composite (FCC) of March 1999 revealed the cause for change in forest density classes. Deforestation, encroachment and agriculture have been identified as the underlying causes, which have affected some specific locations to a marked extent. There has been a progressive and remarkable change among vegetation classes from 1976 to 1999. It is evident from forest type and density map that Sal density has significantly reduced from Sal Dense 65.61 % in 1976 to Sal Dense 11.12% in the year 1999 followed by Sal Open 11.18 % and Sal Medium 18.24 %. The overall change has been estimated to be 42.11% of the total forested area.     

Elevation,slope aspect and integrated nutrient management effects on crop productivity and soil quality in North-west Himalayas,India

On farm bio-resource recycling has been given greater emphasis with the introduction of conservation agriculture specifically withclimate change scenarios in the mid-hills of the north-west Himalaya region（NWHR）. Under this changing scenario, elevation, slope aspect and integrated nutrient management（INM） may affect significantly soil quality and crop productivity. A study was conducted during 2009-2010 to 2010-2011 at the Ashti watershed of NWHR in a rainfed condition to examine the influence of elevation, slope aspect and integrated nutrient management（INM） on soil resource and crop productivity. Two years of farm demonstration trials indicated that crop productivity and soil quality is significantly affected by elevation, slope aspect and INM. Results showed that wheat equivalent yield（WEY） of improved technology increased crop productivity by -20%-37% compared to the conventional system. Intercropping of maize with cowpea and soybean enhanced yield by another 8%-17%. North aspect and higher elevation increased crop productivity by 15%-25% compared to south aspect and low elevation（except paddy）. Intercropping of maize with cowpea and soybean enhanced yield by another 8%-15%. Irrespective of slope, elevation and cropping system, the WEY increased by -30% in this region due to INMtechnology. The influence of elevation, slope aspect and INM significantly affected soil resources（SQI） and soil carbon change（SCC）. SCC is significantly correlated with SQI for conventional（R2 = 0.65＊）, INM technology（R2 = 0.81＊） and for both technologies（R2 = 0.73＊）. It is recommended that at higher elevation.（except for paddy soils） with a north facing slope, INM is recommended for higher crop productivity; conservation of soil resources is recommended for the mid hills of NWHR; and single values of SCC are appropriate as a SQI for this region.     

Effect of linear waves on kinetic Alfvén wave localization and turbulent spectrum

We have presented the localization of kinetic Alfvén wave (KAW) in intermediate β plasma (m _e /m _i ?β?1) by developing a model based on pump kinetic Alfvén wave and finite amplitude magnetosonic fluctuations. When KAW is perturbed by these background magnetosonic fluctuations, filamentary structures of KAW magnetic field are formed. First, a semi analytical model based on paraxial approximation has been developed to understand this evolution process. Localized structures and magnetic fluctuation spectrum of KAW has also been studied numerically for finite frequency of KAW. The calculated magnetic fluctuation spectrum follows two types of scalings. Above the proton gyroradius scale lengths (in inertial range), spectrum follows Kolmogorovian scaling. Below this scale dispersion starts and the spectrum steepens to about \(k_{x}^{-2.5}\) . The result shows the steepening of power spectra which can be responsible for particle acceleration in solar wind due to the energy transfer from larger to smaller lengthscales. Obtained magnetic turbulent spectra are consistent with observations of Cluster spacecraft in solar wind.     

An integrated approach for ground water investigation in part of Fatehpur Sikri of district agra-a case study

The Fatehpur Sikri area infringing the western UP, Rajasthan border was investigated for its water supply crisis in respect of poor quality and quantity as well. The study has indicated presence of two parallel quartz reefs running in NE-SW direction. Geohydrological and photogeological studies have revealed the possibility of subsurface extension of quartz reefs. However, this weathered area along reefs is promising water bearing zone. Paleo channels are also marked during studies and the area found suitable for ground water exploitation. A map showing various categories is also presented.     

Magnetic method applied to mineral exploration

Developments which have led to an enormous increase in the use of magnetic surveys for mineral exploration during the past 30 years are reviewed here. Advances in instrumentation and digital compilation of data have come about largely due to the extensive use of the airborne magnetometer as a geologic mapping tool. Currently there is a growing interest in the use of the aeromagnetic gradiometer for exploration surveys in the Precambrian Shield areas. The advantages of gradiometry as a complement to total field surveys is becoming well recognized. Miniaturized electronics has reduced the cost and size of many magnetic survey instruments and ancillary equipments. Advanced compensation techniques have made it possible to make optimum use of the increased sensitivity of magnetometers for various high-resolution applications.Quantitative interpretation of magnetic data in terms of models of causative bodies has advanced largely due to the development of computerized multiparameter inversion methods. Many of these permit interpreter interaction through computer-graphic display system to impose sensible geologic constraints. Several survey contractors have the software and hardware facilities to perform various data enhancement techniques and also interactive modelling. Susceptibility mapping and magnetization mapping techniques are of great potential utility in mineral exploration. There is still a great need for studies into the relationship between rock magnetism and magnetic anomalies.     

A second derivative method of resistivity sounding

The second vertical derivatives of gravity and magnetic potential are widely used in geophysical prospecting because of their better resolution. On the same basis an attempt has been made to obtain the expressions for the second vertical derivative of the electrical potential and to compute its nature for comparison. Derivative responses over a two-layered earth and also over an anticlinal structure have been computed and it is shown that the second vertical derivative sounding could be employed for greater accuracy in finding out the thickness of such beds or the inclination of the sides of the anticline and its depth when compared with normal resistivity sounding     

Experimental superensemble forecasts of tropical cyclones over the Bay of Bengal

This study entails the implementation of an experimental real time forecast capability for tropical cyclones over the Bay of Bengal basin of North Indian Ocean. This work is being built on the experience gained from a number of recent studies using the concept of superensemble developed at the Florida State University (FSU). Real time hurricane forecasts are one of the major components of superensemble modeling at FSU. The superensemble approach of training followed by real time forecasts produces the best forecasts for tracks and intensity (up to 5 days) of Atlantic hurricanes and Pacific typhoons. Improvements in track forecasts of about 25–35% compared to current operational forecast models has been noted over the Atlantic Ocean basin. The intensity forecasts for hurricanes are only marginally better than the best models. In this paper, we address tropical cyclone forecasts over the Bay of Bengal for the years 1996–2000. The main result from this study is that the position and intensity errors for tropical cyclone forecasts over the Bay of Bengal from the multimodel superensemble are generally less than those of all of the participating models during 1- to 3-day forecasts. Some of the major tropical cyclones, such as the November 1996 Andhra Pradesh cyclone and October 1999 Orissa super cyclone were well handled by this superensemble approach. A conclusion from this study is that the proposed approach may be a viable way to construct improved forecasts of Bay of Bengal tropical cyclone positions and intensity.     

Internal wave characteristics in the eastern Arabian Sea during summer monsoon

The time series BT profiles and surface winds and atmospheric pressure, collected in the deep waters off Ratnagiri and Karwar during summer monsoon were utilized to document the characteristics of internal waves (IW). Low-frequency (≤2, cycle per day (cpd)) IW off Ratnagiri are found to propagate at 83 cm/s with wavelengths of 45 km and wave heights upto 40 m. These parameters for high-frequency (>2 cpd) IW off Karwar correspond to 99 cm/s, 3 km and 23 m. The IW off Karwar appear to leave the station at 70° (±10°) (measured from the horizontal). The data sets were further analysed to address the harmonic composition of the IW and identify the possible sources for the observed IW fields. Power spectra of the IW indicated energy peaks at inertial (0·6 cpd) and tidal (1 and 2 cpd) frequencies off Ratnagiri and in the high-frequency band of 0·5–2·0 cycles per hour off Karwar. The coherence between the IW and wind/tide is found to be good at several frequencies within the IW spectrum. This feature probably suggests tides as a source for the IW of tidal frequencies and winds and tides as a joint source for the IW at the remaining frequencies.     

Reflection and transmission ofSH waves in an initially stressed medium consisting of a sandy layer lying over a fluid-saturated porous solid

Biot's theory is employed to study the reflection and transmission ofSH waves in a sandy layer lying over a fluid-saturated porous solid half-space. The entire medium is considered under constant initial stress. Effects of sandiness, initial stress, anelasticity and viscosity of the interstitial fluid on the partitioning of energy are studied. In the presence of initial stress the incident wave starts attenuating when incider beyond a certain angle (depending upon the amount of initial stress), even if the medium is perfectly clastic. Anelasticity of the solid layer results in the dissipation of energy during transmission. The direction of attenuation vector of incident wave affects the dissipation energy to a large extent. Effect on partitioning of energy reverse at incidence after the critical angle. A complete account of energy returmed back to the underlying half-space and that which is dissipated in the overlying layer has been discussed analytically as well as numerically.