Cones and craters on Mount Pavagadh,Deccan Traps: Rootless cones?

Rootless cones, also (erroneously) called pseudocraters, form due to explosions that ensue when a lava flow enters a surface water body, ice, or wet ground. They do not represent primary vents connected by vertical conduits to a subsurface magma source. Rootless cones in Iceland are well studied. Cones on Mars, morphologically very similar to Icelandic rootless cones, have also been suggested to be rootless cones formed by explosive interaction between surface lava flows and ground ice. We report here a group of gentle cones containing nearly circular craters from Mount Pavagadh, Deccan volcanic province, and suggest that they are rootless cones. They are very similar morphologically to the rootless cones of the type locality of Myvatn in northeastern Iceland. A group of three phreatomagmatic craters was reported in 1998 from near Jabalpur in the northeastern Deccan, and these were suggested to be eroded cinder cones. A recent geophysical study of the Jabalpur craters does not support the possibility that they are located over volcanic vents. They could also be rootless cones. Many more probably exist in the Deccan, and volcanological studies of the Deccan are clearly of value in understanding planetary basaltic volcanism.     

The assessment of potential land use in the proposed irrigation command using Remote Sensing and GIS

Standard false colour composites (Std. FCC) on 1:50,000 scale was visually interpreted in conjunction with soil survey to prepare physiographic-soil map. Thirteen mapping units were delineated indicating soil association at family-level. Soil and land resource was evaluated for their land capability and irrigation suitability for its sustained use under irrigation. Land capability and land irrigability maps were generated as attribute map. These maps were integrated to suggest potential land use map. Current land use/land cover map prepared by visual analysis was spatially analysed in relation to potential land use to study potential changes in land use / land cover using GIS. The study reveals that 14.66% area has no limitation and can be brought to intensive agriculture by double cropping.     

LOCAL SCOUR AROUND BRIDGE ABUTMENTS

1 INTRODUCTION The protrusion of a bridge abutment or a spur dike into the main channel creates a disturbance and obstruction to the otherwise equilibrium state of sediment transportation in an alluvial river. The flow accelerates and separates at the upstream face of the abutment as it moves past the obstacle, creating a vortex trail that moves downstream in a direction approximately perpendicular to the structure. The result is that the bed around the structure is eroded locally. The l…     

Following the Afar: Using remote tracking systems to analyze pastoralists' trekking routes

For nomadic pastoralists in arid environments, judicious migration of the herds is the principle strategy for short term survival and long term sustainability. Yet, this efficient mechanism is increasingly challenged by mounting population pressure, appropriation of land and restricted transboundary movements. Lack of information on trekking patterns and grazing areas makes it difficult for government authorities to protect the migration routes. Data are so scarce because the object of measurement is moving in directions no outsider can predict. Consequently, data collection is costly and laborious. The present study suggests the use of satellite telemetry to trace trekking routes in a near real-time mode that can operate without the presence of external observers on the ground. We report on a pilot that tests a remote tracking technique to locate the routing of a nomadic pastoralist during the dry spell, in the Afar region of Ethiopia. From a movement analysis we infer trekking routes and grazing areas as well as the spatial and temporal correlation between the vegetation cover index NDVI, and the visits by the herd. Our first results seem encouraging in that our data collection method can produce unique information relatively quickly and at low cost.     

Soil-Physiography relationship in Mahanadi Delta (Part) using Landsat Imagery

Visual Interpretation of Landsat Imagery (TM-FCC) on 1∶250,000 scale covering 2410 sq km in a part of Mahandi Delta, Kataka district, Orissa was carried out for delineating the physiographic units. The major physiographic units identified and delineated were ‘Delta plain’ and ‘Coastal plain’. These units were further subdivided on the basis of image elements. The abstraction level attained was ‘Family’ based on Soil Taxonomy. The soils of the beach were classified as Typic Ustipsamments; old coastal plain as fine, Typic Haplaquept and coarse loamy Aquic Ustifluvent; Tidal flat as fine Typic Haplaquept and fine loamy Aquic Ustifluvent; mud flat as fine Typic Haplaquept; Levee-plain complex as Typic Ustipsamment and fine loamy Typic Ustorthent; old Delta plain as fine Udic Ustochrept and Aeric Haplaquept and recent delta plain as fine loamy and coarse loamy Typic Ustorthent. The soils are mixed in mineralogy and Isohyperthermic in temperature regime.     

The distribution of sunspots over the Sun

The distribution of the sunspots for the period 1967–1987 (solar cycles 20 and 21) is presented here. We find that the ±11–20° latitude belt is most prolific for the occurrence of various spot types irrespective of magnetic-field ranges. Furthermore, longitudinally sunspots occur most prolifically at six or more places on the Sun. Spatially 7–9 zones are present in each hemisphere (north or south) of the Sun where about 50% sunspots occur and occupy only about 4% area of the Sun. During the above cycles at least 5 flare zones were regularly present in each hemisphere. The existing models cannot explain these active zones on the Sun. Thus, the present analysis emphasizes the need for a new magnetic models of the Sun.     

Application of remote sensing and GIS in watershed characterization and management

Short Note

Application of remote sensing and GIS in watershed characterization and management     

On the mechanical response of saturated cemented materials—part I: Theoretical considerations

Terzaghi's ‘effective stress’ principle, though originally developed for soils, has been extensively applied to water saturated cemented materials (such as concrete, rocks, masonry units, etc.). There are, however, serious reservations regarding its validity for this class of materials. In this paper an alternative stress decomposition is proposed. It is based on average stress measures in constitutents, i.e. the solid matrix and water. Constitutive relations governing the undrained response of a cemented aggregate mixture, treated as a brittle-plastic material, are derived. The framework is illustrated by some numerical examples pertaining to the behaviour of saturated concrete.