Hydromorphogeology and Remote Sensing applications for groundwater exploration in agnigundala mineralised belt, Andhra Pradesh, India

Hydromorphogeological studies have been carried out around Agnigundala mineralised belt (longitude 70°.39′ - 16°.51′ and latitude 16°.2′ - 16°.15′) using remote sensing IRS-IB and SPOT data for ground water exploration. Based on erosional and depositional characters of various geomorphic units like Hills (Structural and denudational) Pediment, Buried pediment, plains and valley fills have been identified in various lithologies like granite, granite gneiss, biotite schist, phyllite,. quartzite and dolomite. The acclamations of individual geomorphic units through visual interpretation are verified from field data. The groundwater potentials of the individual geomorphologic units have been evaluated to obtain a complete hvdrogcological picture of the area. The field data have further helped in quanlifying various geomorphological units with reference to their potential for ground water occurrence.     

Remote Sensing and GIS Approach for Delineation of Groundwater Potential and Groundwater Quality Zones of Western Doon Valley, Uttarakhand, India

Groundwater exploration in the Western Doon valley has been carried out to delineate the groundwater potential and groundwater quality zones suitable for domestic purposes based on the integrated use of Remote Sensing and Geographical Information Systems (GIS). The Western Doon Valley, occupying broad synclinal troughs in the evolving fold-thrust system of sub-Himalaya, which is filled by post-Siwalik fluvial and debris flow deposits in the late Quaternary-Holocene. The Western Doon Valley area is bounded by the Mussoorie range in the north with 1800–2800 m elevation and in the south by young topographic relief of the frontal Siwalik range with ~800 m average elevation. Groundwater quality of Western Doon valley through pictorially representation in the GIS environment, it is inferred that calcium, magnesium, total hardness and nitrate at some locations above the desirable limit. The groundwater prospects map has been prepared by integrating the hydrogeomorphologic, land use/land cover from satellite data (IRS-ID, LISS-III data) slope, soil, drainage density, depth to water table of pre-monsoon and post-monsoon periods (unconfined aquifer), water table fluctuation, static water level (confined to semi-confined aquifers), specific capacity, discharge and drawdown maps using index overlay method in the GIS environment. The groundwater prospects are depicted in five categories Very high, high, moderate, low and very low (runoff zone) integrated with the groundwater quality zones which have been prepared from hydrochemical data. The results indicated that 16.82 % of the area is under Very high potential zone category with 16.11 % and 0.71 % of desirable and undesirable quality of groundwater and 18.65 %, 42.06 %, 6.96 % and 15.46 % classified as high, moderate, low and very low potential zones with desirable and undesirable quality of groundwater for domestic purposes. This study be useful for designing the groundwater prospects and management plan for the sustainable development of study area.     

The solani-ganga interfluve; an application of remote sensing technique on soil resource mapping for agricultural planning

The area of the Solani-Ganga interfluve, which lies between 29°16′N to 30°15′N latitude and 77°45′E to 78°15′E longitude was undertaken for the present study using LANDSAT imagery of band 5 and 7 and the false colour composite on the scale of 1:250,000 in combination with aerial photographs (1:25,000). Major geomorphic units, e.g., Siwalik Hills. Solani-upper alluvial plain, Solani lower alluvial plain, ‘Tarai’ and Ganga alluvial plain were delineated on LANDSAT and colour composite. Sample areas selected from LANDSAT were studied on aerial photographs in details and soil physiography relationship was developed. The soils on Siwalik hills are classified as Orthents. The soils of the pledmont plain and the recent terraces of Solani river and its tributaries were Psamments, Orthents, Fluvents, Orchrepts and Aquepts. The soils of upper alluvial tract of the Ganga plain is mostly Ustalfs with inclusion of Aqualfs, while the strong hydromorphic Tarai tract consists of partly Aquepts, Ochrepts (cultivated) and partly of Aquolls, Ustolls and Ustalfs (under forest). The present study aims to pin point the nature of soil relief relationship with the help of LANDSAT imagery and aerial photographs and diagnose the intensity of the depletion of soil resources (by prevailing factors like swift run off of biykderfed torrents, fast-flow of ground water, soil creep, mass wasting) through field studies and then treat them with ecological dose of soil conservation. For agronomic development of the region, it is worked out that the present crop-combination and crop-rotation systems should be slightly modified according to its ecosystem to prevent the depletion of soil nutrients.     

Demarcation of spatial extension of kandi (piedmont) area in bist doab (Punjab) through analysis of landsat imagery

The analysis of Landsat imagery has enabled to demarcate the exact limits of the Piedmont Zone (Kandi Area) an important geomorphic unit of the Bist Doab. The study reveals that this Piedmont has the shape of a large fan and covers aboutone third of the total area of Bist Doab.     

Seismic hazard maps of Yangon and its surrounding areas

The purpose of this study is to develop probabilistic seismic hazard maps for Yangon and its surrounding areas including ‘Peak Ground Acceleration’ values for 2% and 10 % probability of the exceedance in 50 years at rock sites. The present study area is situated between the latitudes of N 13°37′ and N 20°2′ and the longitudes of E 93°35′ and E 99°5′. The study areas are focused on nine source zones centered around Yangon with the radius of about 200 km. The probabilistic seismic hazard maps are created by ArcGIS-9.3 software.     

Sampling Design for Global Scale Mapping and Monitoring of Agriculture

Gathering timely information of the global agriculture production of major and commercially important crops has become essential with globalization of the agriculture commodities. Remote sensing based crop production forecasting and monitoring is emerging as one of the most viable solutions for such large area monitoring task. A suitable sampling strategy is the basic requirement towards this. In the present study, different sampling sizes using agricultural area as the sampling frame has been used to analyse the optimum sampling size for continent level assessment. Land use/cover map of the world using 300 m resolution MERIS data was used to generate the agriculture area mask. Grid size of (i) 5° × 5° (ii) 1° × 1° (iii) 30′ × 30′ (iv) 15′ × 15′ (v) 7.5′ × 7.5′ and (vi) 5′ × 5′ were used. Percent crop area was estimated for the grids of all sizes. The grid size of 15′ × 15′ was found to be optimum for global monitoring, as not much change Ws observed in the distribution of the grids after reducing the sample size. Stratification was done using simple random and stratified random sampling method. Stratification using the ‘cumulative square-root of frequency method that resulted in five strata performed best in terms of the variance of the population.     

Runoff Estimation and Morphometric Analysis for Hesaraghatta Watershed Using IRS–1D LISS III FCC Satellite Data

The study area, Hesaraghatta watershed is located between 77° 20′ to 77° 42′ E longitude and 13° 10′ to 13° 24′ N latitude with an area of 600.01 km². Thematic layers such as Land Use/Land Cover, drainage, soil and hydrological soil group were generated from IRS–1D LISS III satellite data (FCC). An attempt was made to estimate runoff using Soil Conservation Service (SCS) curve number model and it was estimated to be 1960, 2066, 1870 and 1810 mm for sub-watersheds 1, 2, 3 and 4 respectively. Quantitative morphometric analysis was carried out for the entire watershed and the four sub-watersheds independently by estimating their (a) linear aspects like stream order, stream length, stream length ratio, bifurcation ratio, length of overland flow, drainage pattern (b) aerial aspects like shape factor, circulatory ratio, elongation ratio and drainage density and (c) relief aspects like basin relief, relief ratio, relative relief and ruggedness number. Drainage density was estimated to be 1.23 km/km² designating the study area as a very coarse textured watershed.     

Comparison of mean gravity anomalies at elevation with corresponding ground anomalies

In support of requirements for the U.S. Air Force Cambridge Research Laboratories, gravity anomalies have been upward continued to several elevations in different areas of the United States. One area was 34⁰ to 40⁰ N in latitude and 96⁰ to 103⁰ W in longitude, generally called the Oklahoma area. The computations proceeded from 26, 032 point anomalies to the prediction of mean anomalies in 14, 704, 2.5′×2.5′ blocks and 9,284, 5′×5′ blocks. These anomalies were upward continued along 28 profiles at 5′ intervals for every 30′ in latitude and longitude. These anomalies at elevations were meaned in various patterns to form mean 30′×30″, 1⁰×1⁰, 5⁰×5⁰ blocks. Comparisons were then made to the corresponding ground values. The results of these comparisons lead to practical recommendations on the arrangement of flight profiles in airborne gravimetry.     

Detailed gravimetric geoid for the North Atlantic

A detailed gravimetric geoid in the North Atlantic Ocean, named DGGNA-77, has been computed, based on a satellite and gravimetry derived earth potential model (consisting in spherical harmonic coefficients up to degree and order 30) and mean free air surface gravity anomalies (35180 1°×1° mean values and 245000 4′×4′ mean values). The long wavelength undulations were computed from the spherical harmonics of the reference potential model and the details were obtained by integrating the residual gravity anomalies through the Stokes formula: from 0 to 5° with the 4′×4′ data, and from 5° to 20° with the 1°×1° data. For computer time reasons the final grid was computed with half a degree spacing only. This grid extends from the Gulf of Mexico to the European and African coasts. Comparisons have been made with Geos 3 altimetry derived geoid heights and with the 5′×5′ gravimetric geoid derived byMarsh andChang [8] in the northwestern part of the Atlantic Ocean, which show a good agreement in most places apart from some tilts which porbably come from the satellite orbit recovery.     

Statistics of GPS ionospheric scintillation and irregularities over polar regions at solar minimum

A statistical study of the occurrence characteristic of GPS ionospheric scintillation and irregularity in the polar latitude is presented. These measurements were made at Ny-Alesund, Svalbard [78.9°N, 11.9°E; 75.8°N corrected geomagnetic latitude (CGMLat)] and Larsemann Hills, East Antarctica (69.4°S, 76.4°E; 74.6°S CGMLat) during 2007–2008. It is found that the GPS phase scintillation and irregularity activity mainly takes place in the months 10, 11 and 12 at Ny-Alesund, and in the months 5, 6 at Larsemann Hills. The seasonal pattern of phase scintillation with respect to the station indicates that the GPS phase scintillation occurrence is a local winter phenomenon, which shows consistent results with past studies of 250 MHz satellite beacon measurements. The occurrence rates of GPS amplitude scintillation at the two stations are below 1%. A comparison with the interplanetary magnetic field (IMF) B _y and B _z components shows that the phase scintillation occurrence level is higher during the period from later afternoon to sunset (16–19 h) at Ny-Alesund, and from sunset to pre-midnight (18–23 h) at Larsemann Hills for negative IMF components. The findings seem to indicate that the dependence of scintillation and irregularity occurrence on geomagnetic activity appears to be associated with the magnetic local time (MLT).     

The reduction correction in North America

An inverse Poisson integral technique has been used to determine a gravity field on the geoid which, when continued by analytic free space methods to the topographic surface, agrees with the observed field. The computation is performed in three stages, each stage refining the previous solution using data at progressively increasing resolution (1^o×1^o, 5′×5′, 5/8′×5/8′) from a decreasing area of integration. Reduction corrections are computed at 5/8′×5/8′ granularity by differencing the geoidal and surface values, smoothed by low-pass filtering and sub-sampled at 5′ intervals. This paper discusses 1^o×1^o averages of the reduction corrections thus obtained for 172 1^o×1^o squares in western North America. The 1^o×1^o mean reduction corrections are predominantly positive, varying from −3 to +15mgal, with values in excess of 5mgal for 26 squares. Their mean andrms values are +2.4 and 3.6mgal respectively and they correlate well with the mean terrain corrections as predicted byPellinen in 1962. The mean andrms contributions from the three stages of computation are: 1^o×1^o stage +0.15 and 0.7mgal; 5′×5′ stage +1.0 and 1.6mgal; and 5/8′×5/8′ stage +1.3 and 1.8mgal. These results reflect a tendency for the contributions to become larger and more systematically positive as the wavelengths involved become shorter. The results are discussed in terms of two mechanisms; the first is a tendency for the absolute values of both positive and negative anomalies to become larger when continued downwards and, the second, a non-linear rectification, due to the correlation between gravity anomaly and topographic height, which results in the values continued to a level surface being systematically more positive than those on the topography.     

Geomorphic interpretation of the Landsat images in Tamilnadu

Landsat imagery were used to interpret the geomorphic festures in the northern part of Tamilnadu between latitudes 11° and 12°30′ N and longitudes 77° and 80° E. Different geomorphic regions were identified with the aid of ground truths. These geomorphic regions, in general, are controlled by the underlying rock types. As the different geomorphic regions have different signatures in the Landsat images, the geomorphic interpretation, which helps to bring out the regional geology is possible with the aid of ground truths.     

Geomorphic analysis of upper Assam Plains and adjoining areas for hydrocarbon exploration

‘Terrain Analysis’ of the the Assam Plains and adjoining areas of the Naga foothills and Mikir hills plateau has been carried out using LANDSAT images and cartographic maps, essentially as an aid for planning seismic surveys for hydrocarbon exploration. The terrain is divisible into five geomorphic zones of distinct characters and processes of evolution. They are: i) Brahmaputra flood plains, ii) Assam Alluvial Plains, iii) Naga Piedmont plains, iv) Mikir Denudational hills, and v) Naga Structural Hills. A number of geomorphic anomalies have been identified in these zones. Maximum number of the anomalies occur in the piedmont zone which is considered to be most prospective since suitable hydrocarbon generation and entrapment conditions exist in that part of the basin. There dominant trends of lineaments striking ENE-WSW NW-SE and E-W are observed in the area in that order of extent and frequency. The last mentioned appears to be youngest which has off-setted even the Naga Thrust. Five distinct planation surfaces/summit levels have been identified in the Mikir as well as Naga hills. They are correlatable with the known unconformities at the top of basement, top of Barails, top of Girujan, top of Namsang and top of Dihing Formations. The subsurface lithology expected during shot hole drilling for seismic surveys has been predicted considering the process of evolution of each zone.     

Least-squares prediction of horizontal coordinate distortions in Canada

A least-squares prediction method is described to estimate horizontal coordinate distortions at lower order points of a network using known coordinate differences (NAD27 coordinate distortions Δϕ′s and Δλ′s) at higher order points between NAD27 coordinates and coordinates derived from a recent (MAY 76), relatively distortion free, adjustment of these points. Empirical autocovariance functions of Δϕ and Δλ and crosscovariance function between Δϕ and Δλ are derived from some 5,250 data points and modelled using series of exponential functions. Empirical mean square values of Δϕ and Δλ, which are a measure of the distortions in NAD27 ϕ and λ, are 0.051 and 0.645 arcsecs² respectively. The corresponding mean value of the product ΔϕΔλ, which is a measure of the correlation between Δϕ and Δλ, is 0.056 arcsecs². The accuracy obtainable for predicted Δϕ and Δλ at an arbitrary point (e.g., lower order station) is a function of the accuracy and configuration of known Δϕ′s and Δλ′s in the surrounding area. Accuracies obtainable for various types of data configuration are given. Under favorable conditions taking place in about 60% of cases, accuracies in terms of ms agreement with known values of 0″.02 (0.6 m) and 0″.01 (0.2 m along parallel at latitude 50°) for the predicted latitude and longitude distortions are obtainable. Finally, a comparison with a method based on the use of complex polynomials is made. Presented at International Symposium on Geodetic Networks and Computations, Munich, August–September 1981.     

Evaluation of deflections of the vertical using topographic-isostatic and astrogeodetic data for the area of Greece

The evaluation of deflections of the vertical for the area of Greece is attempted using a combination of topographic and astrogeodetic data. Tests carried out in the area bounded by 35°≤ϕ≤42°, 19°≤λ≤27° indicate that an accuracy of ±3″.3 can be obtained in this area for the meridian and prime vertical deflection components when high resolution topographic data in the immediate vicinity of computation points are used, combined with high degree spherical harmonic expansions of the geopotential and isostatic reduction potential. This accuracy is about 25% better than the corresponding topographic-Moho deflection components which are evaluated using topographic and Moho data up to 120 km around each station, without any combination with the spherical harmonic expansion of the geopotential or isostatic reduction potential. The accuracy in both cases is increased to about 2″.6 when the astrogeodetic data available in the area mentioned above are used for the prediction of remaining values. Furthermore the estimation of datum-shift parameters is attempted using least squares collocation.     

Determination of geoidal heights and deflections of the vertical for the hellenic area using heterogeneous data

Mean gravity anomalies, deflections of the vertical, and a geopotential model complete to degree and order180 are combined in order to determine geoidal heights in the area bounded by [34°≦ϕ≤42°, 18°≦λ≦28°]. Moreover, employing point gravity anomalies simultaneously with the above data, an attempt is made to predict deflections of the vertical in the same area. The method used in the computations is least squares collocation. Using empirical covariance functions for the data, the suitable errors for the different sources of observations, and the optimum cap radius around each point of evaluation, an accuracy better than±0.60m for geoidal heights and±1″.5 for deflections of the vertical is obtained taking into account existing systematic effects. This accuracy refers to the comparison between observed and predicted values.     

Use of aerial photographs in the study of watershed characteristics

Watershed characteristics are studied using aerial photographs for two streams (choes) in the KANDI area of Punjab. Characteristic mapped include, soil erosion, landuse, drainage, topography. The photointerpretation was supplemented with field checks of the interpreted data. The interpreted data shows large areas of soil eroded and the development of bad land due to large scale cutting of the vegetation both in the Siwalik Hills and KANDI area.     

Ultra-high degree spherical harmonic analysis and synthesis using extended-range arithmetic

We present software for spherical harmonic analysis (SHA) and spherical harmonic synthesis (SHS), which can be used for essentially arbitrary degrees and all co-latitudes in the interval (0°, 180°). The routines use extended-range floating-point arithmetic, in particular for the computation of the associated Legendre functions. The price to be paid is an increased computation time; for degree 3,000, the extended-range arithmetic SHS program takes 49 times longer than its standard arithmetic counterpart. The extended-range SHS and SHA routines allow us to test existing routines for SHA and SHS. A comparison with the publicly available SHS routine GEOGFG18 by Wenzel and HARMONIC SYNTH by Holmes and Pavlis confirms what is known about the stability of these programs. GEOGFG18 gives errors <1 mm for latitudes [-89°57.5′, 89°57.5′] and maximum degree 1,800. Higher degrees significantly limit the range of acceptable latitudes for a given accuracy. HARMONIC SYNTH gives good results up to degree 2,700 for almost the whole latitude range. The errors increase towards the North pole and exceed 1 mm at latitude 82° for degree 2,700. For a maximum degree 3,000, HARMONIC SYNTH produces errors exceeding 1 mm at latitudes of about 60°, whereas GEOGFG18 is limited to latitudes below 45°. Further extending the latitudinal band towards the poles may produce errors of several metres for both programs. A SHA of a uniform random signal on the sphere shows significant errors beyond degree 1,700 for the SHA program SHA by Heck and Seitz.     

Integrated resource study for conservation and management of Ropar wetland ecosystem, Punjab

Integrated resource study in Ropar wetland ecosystem was undertaken to analyse physiography, drainage, landuse and vegetation status. Various thematic maps have been prepared using black and white aerial photographs on 1:20,000 scale and IRS 1A LISS-II (FCC) on 1:50,000 scale. The Ropar wetland ecosystem is comprised of six major landforms i.e. Siwalik hills, Valley, Piedmont plain, Alluvial plain, River terraces and River courses. The study area show high drainage density with sub dendritic and sub parallel drainage. The area has poor vegetative cover which results in extensive erosion and sedimentation of Ropar lake. The water spread and. qualitative turbidity level in the notified wetland area was also monitored. Anthropogenic pressure, industrial pollution, sedimentation, eutrophication, illegal fishing and flooding have been identified as major threats to the wetland. Keeping in view the threats to Ropar wetland, the conservation measures have been suggested.     

The effect of topography on the determination of the geoid using analytical downward continuation

The method of analytical downward continuation has been used for solving Molodensky’s problem. This method can also be used to reduce the surface free air anomaly to the ellipsoid for the determination of the coefficients of the spherical harmonic expansion of the geopotential. In the reduction of airborne or satellite gradiometry data, if the sea level is chosen as reference surface, we will encounter the problem of the analytical downward continuation of the disturbing potential into the earth, too. The goal of this paper is to find out the topographic effect of solving Stoke’sboundary value problem (determination of the geoid) by using the method of analytical downward continuation. It is shown that the disturbing potential obtained by using the analytical downward continuation is different from the true disturbing potential on the sea level mostly by a −2πGρh 2/p. This correction is important and it is very easy to compute and add to the final results. A terrain effect (effect of the topography from the Bouguer plate) is found to be much smaller than the correction of the Bouguer plate and can be neglected in most cases. It is also shown that the geoid determined by using the Helmert’s second condensation (including the indirect effect) and using the analytical downward continuation procedure (including the topographic effect) are identical. They are different procedures and may be used in different environments, e.g., the analytical downward continuation procedure is also more convenient for processing the aerial gravity gradient data. A numerical test was completed in a rough mountain area, 35°<ϕ<38°, 240°<λ<243°. A digital height model in 30″×30″ point value was used. The test indicated that the terrain effect in the test area has theRMS value ±0.2−0.3 cm for geoid. The topographic effect on the deflections of the vertical is around1 arc second.