On the disturbance due to a point source in an inhomogeneous medium     

Sarva Jit Singh 《Pure and Applied Geophysics》1967,67(1):83-94

Summary The problem of a point source in an isotropic, inhomogeneous fluid medium is discussed. It is assumed that the density of the fluid is constant and the acoustic velocity varies with depth asc=c ₀(1 +m z) wherem is a constant andc ₀ is, the velocity at the level of the origin. An approximate expression for the field due to a point source in such a medium is obtained when the medium is infinite as well as when it is semi-infinite. It is found that the results obtained agree with the WKB solution of the problem.  相似文献   

Plane strain deformation of a multi-layered poroelastic half-space by surface loads     

Sarva Jit Singh  Sunita Rani 《Journal of Earth System Science》2006,115(6):685-694

The Biot linearized quasi-static theory of fluid-infiltrated porous materials is used to formulate the problem of the two-dimensional plane strain deformation of a multi-layered poroelastic half-space by surface loads. The Fourier-Laplace transforms of the stresses, displacements, pore pressure and fluid flux in each homogeneous layer of the multi-layered half-space are expressed in terms of six arbitrary constants. Generalized Thomson-Haskell matrix method is used to obtain the deformation field. Simplified explicit expressions for the elements of the 6 × 6 propagator matrix for the poroelastic medium are obtained. As an example of the possible applications of the analytical formulation developed, formal solution is given for normal strip loading, normal line loading and shear line loading.  相似文献   

Quasi-static deformation of a layered half-space by a long strike-slip fault     

Nat Ram Garg  Sarva Jit Singh 《Journal of Earth System Science》1988,97(1):11-20

Theoretical expressions for the surface displacement and shear stress caused by a long strike-slip dislocation in an elastic layer overlying an elastic half-space are derived and the correspondence principle is used to obtain the quasi-static response when the half-space is Maxwell-viscoelastic. Variation of the surface displacement and shear stress with horizontal distance is studied for various times and vertical extents of the fault. It is seen that the quasi-static response differs significantly from the corresponding elastic response.  相似文献   

On two-dimensional elastic dislocations in a multilayered half-space     

Sarva Jit Singh  Nat Ram Garg 《Physics of the Earth and Planetary Interiors》1985,40(2):135-145

The two-dimensional problem of a long displacement dislocation in a multilayered half-space is studied. Both plane strain and antiplane strain cases are considered. The Thomson-Haskell matrix method is used to obtain the static field caused by the dislocation. The source is represented in terms of the jumps at the source level in the depth-dependent factors in the Fourier integral representation of the displacements and stresses due to the source in an infinite medium. Explicit expressions for the surface displacements due to dip-slip and strike-slip faults of arbitrary dip are obtained. The formulation developed is quite convenient for numerical computation.  相似文献   

Quasi-static deformation due to two-dimensional seismic sources embedded in an elastic half-space in welded contact with a poroelastic half-space     

Sunita Rani  Sarva Jit Singh 《Journal of Earth System Science》2007,116(2):99-111

The Biot linearized theory of fluid saturated porous materials is used to study the plane strain deformation of a two-phase medium consisting of a homogeneous, isotropic, poroelastic half-space in welded contact with a homogeneous, isotropic, perfectly elastic half-space caused by a two-dimensional source in the elastic half-space. The integral expressions for the displacements and stresses in the two half-spaces in welded contact are obtained from the corresponding expressions for an unbounded elastic medium by applying suitable boundary conditions at the interface. The case of a long dip-slip fault is discussed in detail. The integrals for this source are solved analytically for two limiting cases: (i) undrained conditions in the high frequency limit, and (ii) steady state drained conditions as the frequency approaches zero. It has been verified that the solution for the drained case (ω → 0) coincides with the known elastic solution. The drained and undrained displacements and stresses are compared graphically. Diffusion of the pore pressure with time is also studied.  相似文献   

Point Source in a Layer Overlying a Semi-infinite Solid with Special Reference to Diffracted Waves–Aperiodic Source     

Sarva Jit Singh 《Geophysical Journal International》1967,12(2):209-223

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Evaluation of heavy metal contamination in groundwater samples from Kapas Island,Terengganu, Malaysia   总被引：1，自引：0，他引：1  

Noorain Mohd Isa  Ahmad Zaharin Aris  Wan Ying Lim  Wan Nor Azmin Wan Sulaiman  Sarva Mangala Praveena 《Arabian Journal of Geosciences》2014,7(3):1087-1100

An attempt has been made to delineate the hydrochemistry for a small island based on the major ions and heavy metal concentrations. In this investigation, six sampling campaigns were conducted to measure the concentrations of major ions (Ca, Mg, Na, K, HCO₃, Cl, and SO₄) and heavy metals (Zn, Cr, Pb, Mn, As, and Cu) in groundwater samples collected from seven sampling stations (boreholes) located on Kapas Island, Terengganu, Malaysia. The distribution of major ions is illustrated by a piper plot where Ca–HCO₃ is the dominant type. In addition, the concentrations of heavy metals demonstrate that Mn shows as being the highest concentrated heavy metal in the groundwater sampled in the sampling campaigns; the average Mn content in groundwater sampled was 54.05 μg/L. However, a comparison of the heavy metal (Mn, Cr, Zn, As, Pb, and Cu) concentrations in groundwater samples with the Drinking Water Quality Standard prescribed by World Health Organization reveals that none of these heavy metals exceeded the recommended threshold limits. The principal component analyses (PCA) extracted four components that control the groundwater chemistry. Components 1 and 2 from the PCA analyses extracted approximately 52.11 % of the total variance, which represent the heavy metals (As and Mn) and physical parameters (pH, redox potential, electrical conductivity, temperature, and total dissolved solids). Based on the output of the PHREEQC hydrogeochemical software, several species of heavy metals exist, in which the dominant species found are Mn²⁺, PbCO₃, Cu(OH)₂, and Zn⁺.  相似文献   

Sustainable groundwater management on the small island of Manukan,Malaysia   总被引：1，自引：1，他引：0  

Sarva Mangala Praveena  Mohd Harun Abdullah  Kawi Bidin  Ahmad Zaharin Aris 《Environmental Earth Sciences》2012,66(3):719-728

Numerical models are capable of simulating various groundwater scenarios and relate it towards groundwater management. This paper focuses on numerical modeling and water balance approaches in the search for a sustainable management plan in Manukan Island. The impacts of pumping and recharge rates represented by groundwater scenarios were investigated by means of hydraulic heads, chloride concentrations and water balance components. Overpumping and inconsistency in recharge rate are the stresses shown in Scenario A. Scenario B involved with reduction pumping rate by 25% has shown an increase in groundwater levels, chloride concentration and groundwater storage. Scenario C showed the most promising finding compared with Scenarios A and B. Highest hydraulic heads, lowest chloride concentration (1,552.2 mg/L) and positive groundwater storage (254.3 m³/day) were obtained in Scenario C. Chloride concentration in pumping wells still exceeds World Health Organization International Standard limit in Scenario C which illustrates an additional water treatment is needed. Nevertheless, in view of a compromise groundwater management plan in study area, Scenario C is the best plan so far to protect the groundwater resources in the study area. More understanding of the artificial recharge method (percolation tank) and study site by means of modeling studies is needed. Additionally, further progress is needed in obtaining the water usage data from each part to determine the best pumping rate. A sustainable groundwater management plan is crucial to maintain the natural resources and social benefits as well as to protect the ecological balance of Manukan Island.  相似文献   

Hydrochemical changes in a small tropical island’s aquifer: Manukan Island, Sabah, Malaysia   总被引：1，自引：0，他引：1  

A. Z. Aris  M. H. Abdullah  K. W. Kim  S. M. Praveena 《Environmental Geology》2009,56(8):1721-1732

Small islands groundwater are often exposed to heavy pumpings as a result of high demand for freshwater consumption. Intensive exploitation of groundwater from Manukan Island’s aquifer has disturbed the natural equilibrium between fresh and saline water, and has resulted increase the groundwater salinity and leap to the hydrochemical complexities of freshwater–seawater contact. An attempt was made to identify the hydrochemical processes that accompany current intrusion of seawater using ionic changes and saturation indices. It was observed that the mixing between freshwater–seawater created diversity in geochemical processes of the Manukan Island’s aquifer and altered the freshwater and seawater mixture away from the theoretical composition line. This explained the most visible processes taking place during the displacement.  相似文献   

Application of the chemometric approach to evaluate the spatial variation of water chemistry and the identification of the sources of pollution in Langat River, Malaysia     

Wan Ying Lim  Ahmad Zaharin Aris  Sarva Mangala Praveena 《Arabian Journal of Geosciences》2013,6(12):4891-4901

The current study presents the application of selected chemometric techniques—hierarchical cluster analysis (HCA) and principal component analysis (PCA)—to evaluate the spatial variation of the water chemistry and to classify the pollution sources in the Langat River. The HCA rendered the sampling stations into two clusters (group 1 and group 2) and identified the vulnerable stations that are under threat. Group1 (LY 1 to LY 14) is associated with seawater intrusion, while group 2 (LY 15 to LY 30) is associated with agricultural and industrial pollution. PCA analysis was applied to the water datasets for group 1 resulting in four components, which explained 85 % of the total variance while group 2 extracted six components, explaining 88 % of the variance. The components obtained from PCA indicated that seawater intrusion, agricultural and industrial pollution, and geological weathering were potential sources of pollution to the study area. This study demonstrated the usefulness of the chemometric techniques on the interpretation of large complex datasets for the effective management of water resources.  相似文献