Environmental impact assessment in the Moradabad industrial area (rivers Ramganga-Ganga interfluve), Ganga Plain,India

Sediment samples collected in the Moradabad area, lying in the interfluve of the Ganga and Ramganga Rivers, were analysed for heavy metals, after studying the geomorphology of the area. Geomorphologically, the area can be divided into three terraces - the T₀, T₁ and T₂ surfaces. The rivers on these three surfaces show varying amounts of pollution depending upon the input from industries and urban settlements. The Ramganga River on the T₀ surface shows the highest amount of pollution. However, the pollution levels in all these rivers show a downstream dilution effect. The characteristic feature of the vast interfluve area (T₂ surface) is the presence of several, independent basins which are closed and rarely interact with each other or with any river. The sediments are redistributed and redeposited within the basin itself, and thus these basins serve as sinks. The sediments of one such basin in the study area show significant concentrations of arsenic, chromium, copper, nickel, lead, zinc and organic carbon. The concentrations of heavy metals in such a basin will show exponential increases with time, because there is no activity to funnel out the sediments and dilute the effect of pollution. This increase will pose more threats, as ultimately it will make its way laterally and vertically through the sediments, thereby polluting groundwater.     

Observed daily large-scale rainfall patterns during BOBMEX-1999

A daily rainfall dataset and the corresponding rainfall maps have been produced by objective analysis of rainfall data. The satellite estimate of rainfall and the raingauge values are merged to form the final analysis. Associated with epochs of monsoon these rainfall maps are able to show the rainfall activities over India and the Bay of Bengal region during the BOBMEX period. The intra-seasonal variations of rainfall during BOBMEX are also seen using these data. This dataset over the oceanic region compares well with other available popular datasets like GPCP and CMAP. Over land this dataset brings out the features of monsoon in more detail due to the availability of more local raingauge stations.     

Flood Management in India

In this paper, flood problems in India, regional variabilityof the problem, present status of the ongoing management measures, their effectiveness and futureneeds in flood management are covered. Flood problems in India are presented by four zonesof flooding, viz. (a) Brahmaputra River Basin, (b) Ganga River Basin, (c) North-WestRivers Basin, and (d) Central India and Deccan Rivers Basin. Some special problems,related to floods like dam break flow, and water logging in Tal areas, are also mentioned.Progress of various flood management measures, both structural and non-structural, arediscussed. In addition, future needs to achieve efficient and successful flood managementmeasures in India are also pointed out.     

A Technique for Direct Retrieval of Surface Specific Humidity Over Open Oceans from Irs-P4/Msmr Satellite Data

The Multi frequency Scanning Microwave Radiometer (MSMR) onboard Oceasat-1 was used to develop a retrieval method fornear-surface specific humidity by means of multivariate regressiontechnique. The MSMR measures the microwaveradiances in 8 channels at the frequencies of 6.6, 10.7, 18 and 21 GHzfor both vertical and horizontal polarizations. Regression coefficients were derived using the ship reports of the Comprehensive Ocean-Atmosphere Data Set (COADS) for the months of July, October and December, in 1999. Daily near-surface specific humidity data from COADS in 2° × 2° latitude/longitude bins and collocated brightness temperature data from MSMR were used to derive the coefficients. The derived coefficients werevalidated with humidity given in COADS.A linear relationship is established to determine the near-surface specifichumidity from MSMR brightness temperature (Tb) with an rms error of 1.2 g kg^-1 for individual situations and an rms errorof 0.84 g kg^-1 for monthly time scales over global oceans.The retrieval algorithm is validonly for the open sea regions.     

Site suitability evaluation for locating sewage treatment plants using remote sensing and gis — a case study of phillaur and phagwara townships in punjab

Level-II urban land use information available in this Town and Country Planning maps, Survey of India toposteets for Phillaur and Phagwara towns and the land use information generated through visual interpretation of satellite data was digitized, integrated and analysed using PAMAP GIS. The land use map of the two towns suggest that the wastelands located near the point of present disposal can be utilised for siting sewage treatment plants in both the towns. The STP sites suggested were away from the thickly habttared area. It was observed that some of the areas earmarked for locating STP’s, were partially brought under habitation before the execution of the preject. Hence, it is necessary that planning and execution of such projects should be done on a real time basis so that the sites identified for locating STP’s are not brought under other land uses.     

The Zihuatanejo, Mexico, earthquake of 1994 December 10 (M= 6.6): source characteristics and tectonic implications

An analysis of the Zihuatanejo, Mexico, earthquake of 1994 December 10 ( M = 6.6), based on teleseismic and near-source data, shows that it was a normal-faulting, intermediate-depth ( H = 50 ± 5 km) event. It was located about 30 km inland, within the subducted Cocos plate. The preferred fault plane has an azimuth of 130°, a dip of 79° and a rake of −86°. The rupture consisted of two subevents which were separated in time by about 2 s, with the second subevent occurring downdip of the first. The measured stress drop was relatively high, requiring a Δσ of about a kilobar to explain the high-frequency level of the near-source spectra. A rough estimate of the thickness of the seismogenic part of the oceanic lithosphere below Zihuatanejo, based on the depth and the rupture extent of this event, is 40 km.
This event and the Oaxaca earthquake of 1931 January 15 ( M = 7.8) are the two significant normal-faulting, intermediate-depth shocks whose epicentres are closest to the coast. Both of these earthquakes were preceded by several large to great shallow, low-angle thrust earthquakes, occurring updip. The observations in other subduction zones show just the opposite: normal-faulting events precede, not succeed, updip, thrust shocks. Indeed, the thrust events, soon after their occurrence, are expected to cause compression in the slab, thus inhibiting the occurrence of normal-faulting events. To explain the occurrence of the Zihuatanejo earthquake, we note that the Cocos plate, after an initial shallow-angle subduction, unbends and becomes subhorizontal. In the region of the unbending, the bottom of the slab is in horizontal extension. We speculate that the large updip seismic slip during shallow, low-angle thrust events increases the buckling of the slab, resulting in an incremental tensional stress at the bottom of the slab and causing normal-faulting earthquakes. This explanation may also hold for the 1931 Oaxaca event.     

Dehydration melting of tonalites. Part I. Beginning of melting

 The beginning of dehydration melting in the tonalite system (biotite-plagioclase-quartz) is investigated in the pressure range of 2–12 kbar. A special method consisting of surrounding a crystal of natural plagioclase (An₄₅) with a biotite-quartz mixture, and observing reactions at the plagioclase margin was employed for precise determination of the solidus for dehydration melting. The beginning of dehydration melting was worked out at 5 kbar for a range of compositions of biotite varying from iron-free phlogopite to iron-rich Ann₇₀, with and without titanium, fluorine and extra aluminium in the biotite. The dehydration melting of phlogopite + plagioclase (An₄₅) + quartz begins between 750 and 770°C at pressures of 2 and 5 kbar, at approximately 740°C at 8 kbar and between 700 and 730°C at 10 kbar. At 12 kbar, the first melts are observed at temperatures as low as 700°C. The data indicate an almost vertical dehydration melting solidus curve at low pressures which bends backward to lower temperatures at higher pressures (> 5 kbar). The new phases observed at pressures ≤ 10 kbar are melt + enstatite + clinopyroxene + potassium feldspar ± amphibole. In addition to these, zoisite was also observed at 12 kbar. With increasing temperature, phlogopite becomes enriched in aluminium and deficient in potassium. Substitution of octahedral magnesium by aluminium and titanium in the phlogopite, as well as substitution of hydroxyl by fluorine, have little effect on the beginning of dehydration melting temperatures in this system. The dehydration melting of biotite (Ann₅₀) + plagioclase (An₄₅) + quartz begins 50°C below that of phlogopite bearing starting composition. Solid reaction products are orthopyroxene + clinopyroxene + potassium feldspar ± amphibole. Epidote was also observed above 8 kbar, and garnet at 12 kbar (750°C). The experiments on the iron-bearing system performed at ≤ 5 kbar were buffered with NiNiO. The f _{O 2} in high pressure runs lies close to CoCoO. With the substitution of octahedral magnesium and iron by aluminium and titanium, and replacement of hydroxyl by fluorine in biotite, the beginning of dehydration melting temperatures in this system increase up to 780°C at 5 kbar, which is 70°C above the beginning of dehydration melting of the assemblage containing biotite (Ann₅₀) of ideal composition. The dehydration melting at 5 kbar in the more iron-rich Ann₇₀-bearing starting composition begins at 730°C, and in the Ann₂₅-bearing assemblage at 710°C. This indicates that quartz-biotite-plagioclase assemblages with intermediate compositions of biotite (Ann₂₅ and Ann₅₀) melt at lower temperatures as compared to those containing Fe-richer or Mg-richer biotites. This study shows that the dehydration melting of tonalites may begin at considerably lower temperatures than previously thought, especially at high pressures (>5 kbar). Received: 27 December 1995 / Accepted: 7 May 1996     

Dehydration melting of tonalites. Part II. Composition of melts and solids

 Dehydration melting of tonalitic compositions (phlogopite or biotite-plagioclase-quartz assemblages) is investigated within a temperature range of 700–1000°C and pressure range of 2–15 kbar. The solid reaction products in the case of the phlogopite-plagioclase(An₄₅)-quartz starting material are enstatite, clinopyroxene and potassium feldspar, with amphiboles occurring occasionally. At 12 kbar, zoisite is observed below 800°C, and garnet at 900°C. The reaction products of dehydration melting of the biotite (Ann₅₀)-plagioclase (An₄₅)-quartz assemblage are melt, orthopyroxene, clinopyroxene, amphibole and potassium feldspar. At pressures > 8 kbar and temperatures below 800°C, epidote is also formed. Almandine-rich garnet appears above 10 kbar at temperatures ≥ 750°C. The composition of melts is granitic to granodioritic, hence showing the importance of dehydration melting of tonalites for the formation of granitic melts and granulitic restites at pressure-temperature conditions within the continental crust. The melt compositions plot close to the cotectic line dividing the liquidus surfaces between quartz and potassium feldspar in the haplogranite system at 5 kbar and a _{H 2O} = 1. The composition of the melts changes with the composition of the starting material, temperature and pressure. With increasing temperature, the melt becomes enriched in Al₂O₃ and FeO+MgO. Potash in the melt is highest just when biotite disappears. The amount of CaO decreases up to 900°C at 5 kbar whereas at higher temperatures it increases as amphibole, clinopyroxene and more An-component dissolve in the melt. The Na₂O content of the melt increases slightly with increase in temperature. The composition of the melt at temperatures > 900°C approaches that of the starting assemblage. The melt fraction varies with composition and proportion of hydrous phases in the starting composition as well as temperature and pressure. With increasing modal biotite from 20 to 30 wt%, the melt proportion increases from 19.8 to 22.3 vol.% (850°C and 5 kbar). With increasing temperature from 800 to 950°C (at 5 kbar), the increase in melt fraction is from 11 to 25.8 vol.%. The effect of pressure on the melt fraction is observed to be relatively small and the melt proportion in the same assemblage decreases at 850°C from 19.8 vol.% at 5 kbar to 15.3 vol.% at 15 kbar. Selected experiments were reversed at 2 and 5 kbar to demonstrate that near equilibrium compositions were obtained in runs of longer duration. Received: 27 December 1995 / Accepted: 7 May 1996     

Landslide hazard and risk assessment mapping of mountainous terrains - a case study from Kumaun Himalaya, India

Landslides are studied systematically in order to evaluate the nature of hazard and the damages to the human life, land, roads, buildings and other properties. This can be expressed in terms of risk, which is a function of hazard probability and damage potential. A risk map will indicate the priorities for landslide hazard management. A new approach to risk assessment mapping using a risk assessment matrix (RAM) is presented.