Dynamic groundwater resources of National Capital Territory,Delhi: assessment,development and management options

Groundwater is one of the important source of water supply to meet the requirements of National Capital Territory (NCT) of Delhi, India which is a fast developing urban conglomeration. An assessment of dynamic groundwater resources of NCT Delhi has been attempted based on the methodology known as Ground Water Resources Estimation Methodology—1997. The methodology includes assessment of annual replenishable groundwater resources using water level fluctuation approach and empirical norms, estimation of the annual quantity of groundwater withdrawal and categorization of the assessment units based on the status of groundwater utilization and water level trend. Annual replenishable groundwater resources of NCT Delhi is about 297 million cubic meter (mcm) while the annual groundwater draft is about 480 mcm. This is because of over-exploitation of replenishable resources in seven out of nine districts of the Capital Territory. Based on the assessment of dynamic groundwater resources, a broad groundwater management plan has been proposed in this paper. This include augmentation of groundwater resources through rain water harvesting schemes to be implemented on a large scale, regulation on groundwater withdrawal in vulnerable areas, development of Yamuna flood plain aquifer and declaration of Delhi ridge as groundwater sanctuary.     

Application of ridge-regression in inversion of low-latitude magnetic anomalies derived from space measurements

Anomalies in total field, horizontal, and vertical components over the Indian region derived from MAGSAT measurements have been inverted through the ridge-regression method, basically to test: (1) the application of the method in deriving a stable estimate of crustal magnetisation, and (2) the relative amount of information on crustal magnetisation contained in scalar vis-a`-vis vector data. Results show that the instabilities in magnetisation solution that appear when Mayhew's conventional method is applied in low latitudes could be removed through the ridge-regression technique. It was also noticed that magnetisation distribution estimated through the inversion of the total field(B) does not relate well with the geological features in the equatorial region. Inversion of theZ-anomaly alone gives realistic results for the equatorial region but not over higher latitudes. We conclude that a joint inversion ofX- andZ-anomalies provides a magnetisation estimate consistent with known geological features both for equatorial and higher latitudes.     

Anthropogenic influences on toxic metals in water and sediment samples collected from industrially polluted Cuddalore coast,Southeast coast of India

The present study was carried out to investigate the impact of anthropogenic influences on Cuddalore coast, Southeast coast of India, with regard to physicochemical parameters and heavy metal concentration in the surface water and sediment samples of the study area. The samples were collected in different seasons of the year (January–December 2010) and analysed for physicochemical parameters (Temperature, pH, salinity, nitrate, nitrite, ammonia, phosphate and silicate) and heavy metals (Cd, Cu, Pb and Zn) using standard methods. Results showed that physicochemical characteristics and heavy metals concentration in the samples of the study area were varied seasonally and spatially. The concentrations of heavy metals in water and sediment samples of the study area were higher in the monsoon season compared with those of other seasons. The heavy metal concentration in collected samples was found to be above WHO standards. The order of heavy metals in water and sediment samples was Pb > Cu > Cd > Zn. The heavy metal data were analysed through widely using multivariate statistical methods including principle component analysis (PCA) and cluster analysis (CA). CA classified the sampling sites into three clusters based on contamination sources and season. The PCA revealed that the season has a huge impact on the levels, types and distribution of metals found in water and sediment samples. The study also shows the main basis of heavy metals pollution at Cuddalore coast is land based anthropogenic inputs as a result of discharging of waste from industries, municipal, agricultural activities and sewage into estuarine regions, which carries the wastes into coastal area during tidal action. Statistical analyses and experimental data revealed that the Cuddalore coast may cause health risk to the recreational users and fisher folk, ultimately warrants environmental quality management to control heavy metal contamination.     

Crustal Magnetic Studies over Krishna-Godavari Basin in Eastern Continental Margin of India

Total field magnetic data were collected over the Krishna-Godavari basin covering 20, 000 sq.km with an average spacing of 8.5 km. This was mainly to study the long wavelength features related with the deep structures. Aeromagnetic map of the region compared well with the ground maps. The anomaly maps show a combination of NE-SW, NS/NNE-SSW and NW-SE trends. The anomalies of ground data are transformed to isolate the sources at different depths. The second vertical derivative and downward continuation maps bring out clearly the NE-SW and NS/NNE-SSW trends related to the coastal basin and Eastern Ghats implying that they are shallow. These are probably superposed on much deeper NW-SE trending structural features of Pre-Gondwana breakup as evidenced in the Horizontal Gradient of Pseudogravity and upward continuation maps. From the offshore magnetic data it appears that these trends extend up to the Ocean Continent Boundary. It is inferred that the deeper features are associated with rifting of Dharwar and Bastar cratons within the Indian plate, prior to the rifting of India from Gondwanaland. The superposed horst and graben structures are related to the formation of the pull-apart Krishna-Godavari basin as a result of rifting and drifting of India from Gondwanaland. These two structural features are associated with two different tectonic events.     

Wave-coupling at the magnetopause

The paper considers wave coupling for an arbitrary direction of propagation on the basis of single fluid hydromagnetic equations appropriate for a rarefied plasma. The analysis is used to study the transfer of solar wind momenta into the magnetosphere. It is found that wave refraction is significant only during disturbed conditions for waves travelling with the wind. Enhanced reflection of waves might be important even under quiet conditions in the flanks of the magnetosphere.     

"Making Place": The "Pacific Solution" and Australian Emplacement in the Pacific and on Refugee Bodies

In September 2001, Australia effected a "Pacific Solution" to its "refugee problem": the interception and transfer of "unauthorised boat arrivals" to processing centres in the Pacific Third World. These centres were agreed to by poor countries that were approached precisely because of their vulnerability and dependence upon Australia, in exchange for increases in aid. Australia thereby created a regional refugee problem and, in so doing, Australian seignorage also demands that the laws of those sovereign countries be placed in stasis so that people not convicted of a crime may be detained indefinitely. The Pacific region, in effect, came to be mapped in terms of its utility to Australia, both downplaying and concealing complex economic, social and political issues. This essay studies the Pacific Solution as a means of Australian "emplacement" in the Pacific and on refugee identity/bodies. Both refugee identity and the Pacific Third World are assessed in terms of their utility in serving as sites for Australian emplacement, whereby and wherein the borders of Australia are reinforced, to the detriment of extant "local" emplacements.     

Stability of the magnetopause

The Magnetosphere-Solar Wind boundary is treated as a tangential discontinuity between collisionless plasma described by C.G.L. equations. An estimate is made, analytically, of the minimum shear speed required to render the interface unstable for propagation in any arbitrary direction. It is found that even systems, which are, for all shear speeds, stable towards propagation parallel to the field, are rendered unstable by propagation away from the field, in some velocity domain. Numerical evaluations for parameters characteristic of the Solar wind-Magnetosphere boundary show that the interface could be unstable even under relatively quiet conditions.     

Determination of the orbital parameters of binary pulsars

We present a simple method for determination of the orbital parameters of binary pulsars, using data on the pulsar period at multiple observing epochs. This method uses the circular nature of the velocity space orbit of Keplerian motion and produces preliminary values based on two one-dimensional searches. Preliminary orbital parameter values are then refined using a computationally efficient linear least-squares fit. This method works for random and sparse sampling of the binary orbit. We demonstrate the technique on (i) the highly eccentric binary pulsar PSR J0514−4002 (the first known pulsar in the globular cluster NGC 1851) and (ii) 47 Tuc T, a binary pulsar with a nearly circular orbit.     

Aeromagnetic signatures of Precambrian shield and suture zones of Peninsular India

In many Precambrian provinces the understanding of the tectonic history is constrained by limited exposure and aeromagnetic data provide information below the surface cover of sediments,water,etc.and help build a tectonic model of the region.The advantage of using the aeromagnetic data is that the data set has uniform coverage and is independent of the accessibility of the region.In the present study,available reconnaissance scale aeromagnetic data over Peninsular India are analyzed to understand the magnetic signatures of the Precambrian shield and suture zones thereby throwing light on the tectonics of the region.Utilizing a combination of differential reduction to pole map,analytic signal,vertical and tilt derivative and upward continuation maps we are able to identify magnetic source distribution,tectonic elements,terrane boundaries,suture zones and metamorphic history of the region.The magnetic sources in the region are mainly related to charnockites,iron ore and alkaline intrusives.Our analysis suggests that the Chitradurga boundary shear and Sileru shear are terrane boundaries while we interpret the signatures of Palghat Cauvery and Achankovil shears to represent suture zones.Processes like metamorphism leave their signatures on the magnetic data:prograde granulites(charnockites)and retrograde eclogites are known to have high susceptibility.We fnd that charnockites intruded by alkali plutons have higher magnetization compared to the retrogressed charnockites.We interpret that the Dharwar craton to the north of isograd representing greenschist to amphibolite facies transition,has been subjected to metamorphism under low geothermal conditions.Some recent studies suggest a plate tectonic model of subductionecollisioneaccretion tectonics around the Palghat Cauvery shear zone(PCSZ).Our analysis is able to identify several west to east trending high amplitude magnetic anomalies with deep sources in the region from Palghat Cauvery shear to Achankovil shear.The magnetic high associated with PCSZ may represent the extruded high pressureeultra high temperature metamorphic belt(granulites at shallow levels and retrogressed eclogites at deeper levels)formed as a result of subduction process.The EW highs within the Madurai block can be related to the metamorphosed clastic sediments,BIF and mafc/ultramafc bodies resulting from the process of accretion.     

Comparison of an algebraic multigrid algorithm to two iterative solvers used for modeling ground water flow and transport

Numerical solution of large-scale ground water flow and transport problems is often constrained by the convergence behavior of the iterative solvers used to solve the resulting systems of equations. We demonstrate the ability of an algebraic multigrid algorithm (AMG) to efficiently solve the large, sparse systems of equations that result from computational models of ground water flow and transport in large and complex domains. Unlike geometric multigrid methods, this algorithm is applicable to problems in complex flow geometries, such as those encountered in pore-scale modeling of two-phase flow and transport. We integrated AMG into MODFLOW 2000 to compare two- and three-dimensional flow simulations using AMG to simulations using PCG2, a preconditioned conjugate gradient solver that uses the modified incomplete Cholesky preconditioner and is included with MODFLOW 2000. CPU times required for convergence with AMG were up to 140 times faster than those for PCG2. The cost of this increased speed was up to a nine-fold increase in required random access memory (RAM) for the three-dimensional problems and up to a four-fold increase in required RAM for the two-dimensional problems. We also compared two-dimensional numerical simulations of steady-state transport using AMG and the generalized minimum residual method with an incomplete LU-decomposition preconditioner. For these transport simulations, AMG yielded increased speeds of up to 17 times with only a 20% increase in required RAM. The ability of AMG to solve flow and transport problems in large, complex flow systems and its ready availability make it an ideal solver for use in both field-scale and pore-scale modeling.