Cloud height determination using satellite stereoscopy from Along Track Scanning Radiometer onboard ERS-1 satellite: A simulation study

The first ERS-1 satellite launched in May 1991 promises to make a substantial contribution towards the cloud stereoscopy. One of its payload, Along Track Scanning Radiometer (hereafter ATSR) has IR split window channels and scans the earth conically leading to earth views at two view angles (0° and 55°) in two curved swaths registered with respect to each other in image frame. This enables us to construct stereoscopic image of a cloud thereby determining its height geometrically. The present paper describes the utility of ATSR onboard ERS-1 in retrieving cloud height by synthetic stereo imaging over NOAA-AVHRR visible and thermal band observations.     

Extensional tectonic activity in the cratonward parts (peripheral bulge) of the Ganga Plain foreland basin,India

Flexural subsidence of the Indian lithosphere created the foreland basin in front of the emerging Himalayan mountain belt. The continued northward push of the Indian plate and thrust sheet loading in the Himalayan orogen caused an up-warping along its cratonward margin, in the form of a regional gentle bulge. In the cratonward peripheral bulge small-scale to moderate size deformation features, e.g., gentle folds (up-arching of the sediment layers), extensional normal faults and uplifted tilted blocks, and incised river channels with 20-60-m-high cliffs, developed. Cliff sections of many rivers in this cratonward part of the foreland basin expose deposits of latest Pleistocene-Holocene age and show evidences of active tectonics in the last few thousand years: vertical uplift leading to deep incision of the river system, development of prominent fractures cutting through the sedimentary succession, bending and tilting of the strata, and tilted blocks. In the Late Quaternary relaxation phase of the Himalayan orogen-foreland, there is increased vertical tectonic activity in the region of the peripheral bulge. The vertical uplift in this part of the Ganga Plain foreland basin caused the rivers (including the axial rivers) to make further deep incision without shifting from their courses. During periods of increased tectonic activity in the Himalayan region, i.e., the addition of thrust slices more rapidly, probably caused the maximum down-bending in the proximal part of the Ganga plain foreland basin. The high amplitude and asymmetric nature of this foreland basin is partly controlled by extensional tectonism.     

Induction at short periods in the horizontal field variations in the Indian peninsula

A study of the horizontal components of certain short-period magnetic-fluctuation events, viz., storm sudden commencements and bays, shows appreciable anomalies at two of the five magnetic observatories in peninsular India. The electric current patterns deduced from the magnetic horizontal induced variations imply channelling of induced currents through the Palk Straits and around the southern tip of the Indian peninsula. An interesting feature of these anomalies is that while the induced magnetic vertical variations are strongly correlated with the horizontal northward magnetic field, the electric current concentrations flow parallel to the coast; southwest, near Annamalainagar, and north near Trivandrum. The observations are interpreted in terms of a regional, east-west, induced electric current pattern which is perturbed in the vicinity of the two observatories by the Indian peninsula.     

Estimation of model parameter of Sumatra earthquake using empirical Green’s function technique and generation of hypothetical earthquake scenario for Andaman Island, India

Empirical Green??s function (EGF) technique is considered to be most effective technique for simulation of ground motions due to a finite earthquake source. In the present paper, this technique has been used to simulate ground motion due to a great earthquake. The coastal region of Sumatra Island has been visited by a great earthquake on December 26, 2004. This earthquake has been recorded at several broadband stations including a nearest broadband station PSI in Indonesia. The shear wave contributions in both horizontal components have been simulated at PSI station using EGF technique. The comparison of simulated and observed waveform has been made for various possibilities of rupture parameters in terms of root mean square error. The final rupture model supports rupture velocity of 3.0?km/s with nucleation point supporting northward propagating rupture that coincide with high-slip asperity defined by Sorensen et al. (Bull Seism Soc Am 97:S139?CS151, 2007). The final modeling parameters have been used to simulate record at MDRS station in coastal state of Tamilnadu, India. In an attempt to model a scenario of great earthquake in the Andaman Island, a hypothetical rupture plane is modeled in this region. The event occurred on August 10, 2008 of magnitude 6.2 (M _w ) recorded on strong motion array at Port Blair has been used as EGF to simulate records due to the hypothetical great earthquake. Possibilities of earthquake due to the oblique strike-slip and thrust mechanism have been modeled in the present paper. Several possibilities of nucleation point for both cases has been considered, and it is seen that variation of peak ground acceleration at Port Blair station for strike-slip and thrust mechanism is 126?C738 gals and 647?C2,571 gals, respectively, which indicate high seismic hazard potential of Andaman Island.     

Quantitative Geomorphic Approach for Identifying Active Deformation in the Foreland Region of Central Indo-Nepal Himalaya

Geotectonics - Globally the remote sensing and geomorphometric analysis are frequently used for the assessment of tectonic activity. We used satellite-driven DEM data to analyze regional scale...     

Transport Characteristics of the Near-Surface Layer of the Nucleus of Comet 67P/Churyumov–Gerasimenko

Solar System Research - The paper considers the free molecular flow of gas through the dusty porous surface layer of a comet nucleus. The study is based on computer models of generation of a porous...     

Origin of high fluoride in groundwater in the North Gujarat-Cambay region, India

This paper reports on the origin of high fluoride in a regional alluvial aquifer system under water stress in the North Gujarat-Cambay (NGC) region in western India. This region is severely affected by endemic fluorosis due to ingestion of groundwater containing excessive fluoride. With an objective to understand factors controlling high fluoride concentration in groundwater of this region, 225 groundwater samples have been analysed for various chemical parameters. Samples were collected from different depth zones tapping shallow dug wells, geothermal springs, hand-pumps and tubewells, including free flowing artesian wells up to 450 m depth from the aquifers in the Quaternary alluvial formation covering most of the study area. No relation was found between fluoride concentration and depth of sampled groundwater. However, certain sub-aquifer zones have been identified within the Cambay Basin where groundwater contains relatively high fluoride concentration. In general, areas of high fluoride overlap areas with high electrical conductivity (EC). On the west flank of the Cambay Basin in the low lying belt linking Little Rann of Kachchh-Nalsarovar-Gulf of Khambhat (LRK-NS-GK), high fluoride and EC in shallow aquifers originate from evaporative enrichment. On the east flank of Cambay Basin, some high fluoride pockets are observed which are probably due to preferential dissolution of high fluoride bearing minerals. On this flank high fluoride is also associated with thermal springs. Within the Cambay Basin, alternating belts of low and high fluoride concentrations are ascribed to groundwater recharge during the past wet and arid climatic phases, respectively. This is based on groundwater radiocarbon age contours of ~20 ka overlapping the high fluoride belt.

---

Resumen Este artículo reporta sobre el origen de altas concentraciones de flúor en un sistema regional de acuíferos bajo presión hídrica en la región del norte de Gujarat-Cambay (NGC) del occidente de India. Esta región está afectada severamente por fluorosis endémica debido a la ingestión de agua subterránea que contiene exceso de flúor. Se tomaron 225 muestras de agua subterránea las cuales fueron analizadas por varios parámetros químicos con el objetivo de entender los factores que controlan las elevadas concentraciones de flúor en esta región. Las muestras se colectaron a diferentes profundidades en pozos someros, manantiales geotermales, pozos con bombas de mano, y pozos entubados incluyendo pozos artesianos de flujo libre de hasta 450 m de profundidad emplazados en los acuíferos de la formación aluvial Cuaternaria que cubre la mayor parte del área de estudio. No se encontró ninguna relación entre la concentración de flúor y la profundidad de las muestras de agua subterránea. Sin embargo, se identificaron dentro de la cuenca Cambay algunas zonas sub-acuíferas donde el agua subterránea contiene concentraciones relativamente altas de flúor. En general, las áreas con elevada concentración de flúor están sobrepuestas a áreas de alta conductividad eléctrica (CE). Sobre el flanco occidental de la cuenca Cambay, en la faja baja que une Little Rann con Kachchh-Nalsarovar-Golfo de Khamhat (LRK-NS-GK), las altas concentraciones de flúor y altas CE en acuíferos someros se derivan de enriquecimiento por evaporitas. Sobre el flanco oriental de la cuenca Cambay se observaron algunos cuerpos con alta concentración de flúor los cuales se deben probablemente a la disolución preferencial de minerales con alto contenido de flúor. En este flanco el alto contenido de flúor también se asocia con manantiales termales. Dentro de la cuenca Cambay existen fajas alternantes, con concentraciones altas y bajas de flúor, las cuales se atribuyen a recarga de agua subterránea durante las fases climáticas pasadas, húmedas y áridas, respectivamente. Este planteamiento se basa en contornos de edades de ~20 ka de radiocarbono que están sobrepuestos a la faja alta en flúor.

---

Résumé Cet article étudie lorigine des teneurs élevées en Fluorure dans un système aquifère alluvial régional, soumis à un stress hydrique dans le Nord Gujarat–région Cambay (NGC) à lOuest de lInde. Cette région est sévèrement affectée par une fluorose endémique, due à lingestion deau souterraine très riche en fluor. Avec pour objectif de comprendre les paramètres contrôlant les fortes teneurs en fluor, 225 échantillons deau souterraine ont été analysés sur différents paramètres. Les échantillons ont été pris à différentes profondeurs : puits de surface, sources géothermiques, pompes à main, forages artésiens jaillissant dont la profondeur avoisine les 450 m dans les formations alluviales quaternaire recouvrant la plus grande partie de la région étudiée. Il ny a pas de relation entre la profondeur et les teneurs en fluorure. Néanmoins, certaines zones sub-aquifères ont été identifiées dans le Basin de Cambay où leau souterraine présentait des concentrations relativement élevées en fluorure. En général les zones de hautes concentrations en fluorure recouvrent les zones à fortes conductivité électrique (abréviation en anglais: EC). Sur le flanc Ouest du bassin de Cambay dans le mince lit reliant Little Ran de Kachchh-Nalsarovar au golfe de Khambhat (LRK-NS-GK), les fortes teneurs en fluorure et les EC dans la nappe phréatique proviennent de lenrichissement par les évaporites. Sur le flanc Est du bassin, des poches de teneurs élevées en fluorures ont été observées, probablement dues à des dissolutions préférentielles de minéraux fluorés. Sur ce flanc des teneurs sont également associées à la présence de sources géothermales. Dans le bassin de Cambay, les alternances de couches lits à fortes teneurs et de lits à faibles teneurs sont expliquées par la recharge durant les périodes climatiques humides et les périodes climatiques plus sèches. Ceci est corroboré par les datations au radiocarbone (environ 20.000 an) au dessus du lit riche en fluorure.

     

Aerial remote sensing application in hydrogeological and geomorphic mapping of a rocky terrain: A case study from Uttar Pradesh

Ground water prospecting in hard rock areas of Uttar Pradesh is quite difficult, owing to the geological and geomorphic controls of sub-surface strata on the occurrence and movement of ground water resources, and, therefore, it requires systematic investigations, mainly with the aid of remotely sensed and data, which undoubtedly provide realistic information on the hydrogeological conditions, geomorphologic features, drainage patterns etc. of any rocky area. In this paper, an endeavour has been made to locate ground water possibilities in the drought-affected, rocky terrain of the southern Mirzapur district of Uttar Pradesh, covering part of block Muirpur which is mainly characterised by the varied geological formations, including Archean complex, pre-Vindhyan matasediments and Gondwana formation, through the application of air photointerpretation technique, primarily based on the geologic/geomorphologic approach. The hydro-investigation in the area was carried out using panchromatic aerial photos of 1∶60,000 scale, chiefly to identify the drainage patterns, major geomorphic geo structural and lithological units; as these may control the ground water regime of the area, Further. the present study was also ably supported with limited field survey and hydrogeological data, for achieving reliable results.     

Role of remote sensing in demarcation of alluvial fan deposits in Tarai-Bhabar belt of Nainital District (U.P.) and the environmental impact assessment

Remotely sensed data has unique advantage aver conventional data collection techniques in the study of geomorphology, as physiographical and geo-structural parameters are mostly discernible on the imagery. In the present study an attempt has been made to identify and evaluate the process of geomorphological evolution and hydrogeological conditions, temporal changes in pattern of geomorphic elements and overall impact on environment in alluvial fan region in Nainital District using multidate satellite data from Landsat (1975, 1986) and IRS (1993), through visual interpretation technique. The landuse changes are quite prominent in alluvial fan of upper and lower zone. As a consequence of deforestation, an area of 16 sq. km. of natural forest cover has been lost over a span of 18 years (1975–1993) leading to the increase in rate of erosion as well as environmental degradation in upstream areas. The study suggests that the ground water utilization in Tarai belt without replenishment of confined aquifers and installation of more tubewells in Bhabar belt may lead to total failure of flowing wells and subsequently disturb the balanced ecosystem.