Showing papers on "Groundwater flow published in 1980"

Cross-Formational Gravity-Flow of Groundwater: A Mechanism of the Transport and Accumulation of Petroleum (The Generalized Hydraulic Theory of Petroleum Migration)

Abstract: Observations in deep sedimentary basins around the world confirm the theory of gravity-induced cross-formational flow of groundwater. Thus, geologically mature basins are hydraulically continuous environments in which the relief of the water table, commonly a subdued replica of the land surface, generates interdependent systems of groundwater flow with patterns modified by permeability differences. In these systems, meteoric waters infiltrate and move downward in upland recharge areas, migrate laterally under regions of medium elevations, and are discharged in topographic depressions. Where flow systems meet or part, relatively stagnant zones develop and flow directions change abruptly. The theory is advanced that in geologically mature basins, gravity-induced cross-formational flow is the principal agent in the transport and accumulation of hydrocarbons. The mechanism becomes operative after compaction of sediments and the concomitant primary migration cease, and subaerial topographic relief develops. Hydrocarbons from source or carrier beds are then moved along well-defined migration paths toward discharge foci of converging flow systems, and may accumulate en route in hydraulic or hydrodynamic traps. Accordingly, deposits are expected and observed to be associated preferentially with ascending limbs and stagnant zones of flow systems and hence to be characterized by relative potentiometric minima, downward increase in hydraulic heads possibly reaching artesian con itions, reduced or zero lateral hydraulic gradients, and relatively high groundwater salinity. Continuous flow of meteoric waters imports hydrocarbons into such traps until the trap capacity is reached. The excess becomes source material for new accumulations. A temporal change in surface topography causes a proportionate but delayed readjustment of the flow pattern and redistribution of petroleum. Nevertheless, some hydrocarbons may remain in place, constituting residual deposits in discharge and stagnant regions of relict flow systems. This study reconfirms previous versions of the hydraulic theory of petroleum migration as valid representations of component parts of the migration-accumulation process. However, by introducing the geometry of migration paths in the form of quantitatively defined groundwater flow patterns it integrates existing concepts and observations into a generalized hydraulic theory of petroleum migration.

Modeling groundwater flow over sloping beds

Abstract: A new approximation for two-dimensional Dupuit-Forchheimer flow of groundwater over a sloping bed is shown to be acceptable up to slope angles of at least 30°, when compared with known results for two steady flow situations. The approximation is suitable for three-dimensional numerical modeling and is recommended for situations in which the flow pattern is controlled by the bed slope.

The analysis of groundwater seepage in heterogeneous aquifers.

Abstract: Abstract The solutions of groundwater problems in unconfined aquifers with non-uniform hydraulic conductivity may often be obtained simply without recourse to approximation by considering the horizontal seepage through the aquifer. This is done by defining a potential function where K(z) is the hydraulic conductivity at a height z. h(x,y,z) the hydraulic head at a point (x,y,z) in the aquifer, and H the height of the phreatic surface, so that E satisfies Poisson's equation ▿2E= −d(x,y)+e(x,y), where d(x,y) and e(x,y) are the fluxes at the position (x,y) through the plane z=0 and the phreatic surface, respectively. The components of seepage Q x and Q y in the x and y directions are given by Q x = −∂E/∂x, Qy = −∂E/∂y. Examples are given of the use of the seepage analysis in the study of land drainage, well performance and groundwater-mound development. It is noted that the use of the Girinskii potential to obtain approximate solutions to groundwater problems gives in many situations fortuitously correct see...

228Ra and 226Ra content of groundwater in Fall Line aquifers.

Abstract: Studies of the radium isotopic content of groundwater from a Coastal Plain aquifer adjacent to the Fall Line in South Carolina show that elevated 228Ra and 226Ra concentrations are associated with the aquifer. There is little seasonal variation in the concentration of either radium isotope f

Fracture flow of groundwater in coal-bearing strata

Abstract: Fractures are of considerable importance to groundwater flow through lithified coal-bearing strata. Laboratory tests on core samples in many different studies in the northern Appalachians and northern Great Plains show sandstones, siltstones, shales, and claystones with air permeabilities ranging from less than 10/sup -10/ to 2.4 x 10/sup -6/ m/s. Generally, the air permeabilities were less than 10/sup -8/ m/s. These core tests indicate extremely low intergranular hydraulic conductivities and, in many cases, little or no difference is seen between sandstones and shales. Various aquifer tests, using wells in the same locations, invariably showed hydraulic conductivities to be much greater (10/sup -8/ to 10/sup -4/ m/s) than those estimated by laboratory techniques. In addition the hydraulic conductivity of highly fractured rock can be 10/sup 2/ to 10/sup 3/ times greater than slightly fractured rock. Even shales can be highly transmissive when extensively fractured. Rock joints and coal cleats occur in all coal basins, but their distribution and orientation may be variable. The greatest concentration of fractures usually occurs in faulted areas and in narrow fracture zones less than 100 m below ground surface. The majority of large inflows through rock into surface and underground mines occur at the faults andmore » fracture zones. By studying and understanding more about the structural control of fractures in coal basins, the larger inflows possibly could be avoided. This would reduce pumping and water treatment costs and lessen the depletion of groundwater resources in surrounding areas.« less

Groundwater Chemistry of Some Selected Areas in Southeastern Norway

Abstract: Within three areas in Southeastern Norway, Lake Mjosa district, As and Moss - Jeloy, groundwater samples for chemical analysis were collected during the years 1971–77 from 98 drilled wells in bedrocks. The water was taken at depths ranging from 15 m to 110 m below the land surface. The groundwater surface is usually present well below the overlying unconsolidated deposits of glacial, glacifluvial or marine origin. The movement of groundwater within the aquifers investigated is so slow that regional changes in water quality is not only dependent on weathering in the unsaturated zone, but also dependent on the solution of reservoir rocks below the groundwater surface. Variations in specific electrical conductance (20°C) largely reflects the different reservoir rock types. The highest values, around 550 μS/cm, are typically found in dark calcareous shales, while sandstones and gneisses give values around 300 μS/cm. The areas As and Moss-Jeloy are situated below the Late-Postglacial marine limit. The groundwater is here more or less influenced by ancient sea salts, perhaps also by fossil sea water, left over in sediments or in rock fractures. Brackish groundwater was also found. The composition of groundwater is largely governed by mineral-water equilibria. Most investigated water samples have not reached equilibrium with their surrounding minerals.

Calculation of steady state capillary rise from the groundwater table in multi-layered soil profiles.

Abstract: A computer program CRISP is presented to calculate steady state capillary rise from the groundwater table in single- and multi-layered soil profiles. The calculation is based on an integration of Darcy's equation and uses k-v functions, described with a modified formula of Brooks and Corey (1964). The three constants in this formula can be evaluated from texture and organic matter content, accounting for hysteresis (Bloemen, 1980). Application of the program CRISP shows that the heights of capillary rise from the groundwater table in single-layered soil profiles may be largely different. Of more interest for practical matters is capillary rise in multi-layered soil profiles, which may be strongly influenced by the depth of the groundwater table. The deepest admissable level of the groundwater table that guarantees a certain water supply to the root zone appears to vary widely for different soil profiles. This can be the starting point for a classification of soil profiles on the basis of their potentialities for capillary water supply. Characteristic textures and humus contents of upper soils and subsoils of different geo-genetical groups may thus become distinctive features. Possibly a subdivision of these groups is necessary. The depths of changes between distinguished layers are significant. The actual range of variations of the depth of the groundwater table should play part in a soil classification.

Geothermal resources in the Rio Grande Rift: origins and potential

Abstract: Numerous geothermal anomalies are associated with the Rio Grande Rift and to evaluate the geothermal potential of these anomalies have been evaluated Forced convection models, driven by groundwater flow seem to provide the most generally applicable explanation for the source of the anomalies Examples from the Mesilla and Albuquerque-Belen basins support these models The models predict maximum temperatures in the convection systems of 124 to 139/sup 0/C (255 to 282/sup 0/F), and geothermometry studies generally support this result Higher temperatures are indicated for the Jemez Mountains where magmatic heat is thought to be the anomaly source

Groundwater use for snow melting on the road

Abstract: Groundwater use for snow melting on the road began in Nagooka in 1961. Thereafter the shosetsu (snow melting) pipe system using the heat energy of groundwater spread rapidly all over Japan except for Hokkaido. The total length of the shosetsu pipe comprised 571 km in 1977. A preferable range of groundwater temperatures for the shosetsu pipe is from 8° to 18°C, which corresponds to the groundwater temperature in Japan. The actual condition of groundwater use for the shosetsu pipe has been investigated in Nagaoka, where groundwater pumping in total amounts to 5 x 105 m3/day in the heavy snow season. The use of groundwater for shosetsu pipe in Nagaoka is confronted with two serious problems to be overcome. They are land subsidence and competition with other groundwater uses. For purposes of making clear the mechanism of groundwater recharge and of seeking means of groundwater management for the Nagaoka groundwater basin, a digital simulation of groundwater flow was made by using the horizontal two-dimensional model. The results are satisfactory and reveal that one of the main sources of recharge is the Shinano River which flows through the city. The simulation will be a useful means in considering a future plan of groundwater management.

The role of large-scale permeability measurements in fractured rock and their application at stripa

Abstract: The macropermeability experiment at the Stripa mine in Sweden is part of the Swedish-American Cooperative Program on Radioactive Waste Storage in Mined Caverns in Crystalline Rock (1,2). The experiment is an attempt to improve permeability characterization techniques for the analysis of regional groundwater flow through low permeability rock in the vicinity of a nuclear waste repository. This experiment consists of monitoring flow into, and pressure surrounding a 5 m x 5 m x 33 m long drift called the ventilation drift at the 335 m level of the Stripa mine (Fig. 1). This paper examines the theoretical problems associated with making such a measurement and describes the actual experiment now in progress.

Nonlinearity in groundwater flow

Abstract: Since 1856 when Darcy laid the basis for the calculation of the flow of water through sands, researchers have been interested in groundwater flow. Groundwater is essential for agriculture and water supply, but it also plays an important role when soil is used as a construction element, such as for dykes, roads and foundations. The mechanical behaviour of saturated or dry, fine graded or coarse soils are quite different. The theory of groundwater mechanics must be based on the system: water-soil-air. Up to now study has been restricted to mainly saturated and/or undeformable soil. In this thesis the contemporary theory is extended to compressible fluid flow in a semi-saturated deformable porous medium; a water-soil-air mixture, the air in which appears in the form of micro-bubbles. The pore water moves, whereas the soil itself deforms. It is assumed that this deformation behaviour is linear and free of rotations. From a fundamental reconsideration it is shown that the mechanical behaviour of this system can be formulated in a rather simple way taking into account various nonlinear effects. Convective terms and the variation of the permeability related to soil deformation are included. The validity of the formulation derived is discussed. A general solving procedure applying the Mellin transformation technique allows elucidation of the influence of these nonlinear terms on the basis of analytical solutions of some characteristic problems. In the phenomenon of groundwater flow so-called moving boundaries also occur. The free surface of natural groundwater, which actually varies, is such a boundary. This implies that the domain in which the process of porous flow is considered, changes (geometric nonlinearity). This aspect is explained. Transient phreatic porous flow problems can be solved by applying numerical models. In the discussion reference is made to the extensive literature. In conclusion, the following statements hold for nonlinear groundwater flow. In most practical cases the linear theory is sufficiently accurate, nonlinearity becomes manifest in a reduction of the area of influence, and time dependent porous flow problems can be explicitely solved applying a time step much larger than formerly assumed.

Fault control of groundwater flow and hydrochemistry in the aquifer system of the Castlecomer Plateau, Ireland

Abstract: Summary The Westphalian strata of the Castlecomer Plateau contain two main sandstone aquifers that are in variable hydraulic continuity due to major fault displacements. The faulting separates the plateau into three effectively independent groundwater blocks. A hydrochemical study shows that carbonate dissolution and ion exchange are the two dominant chemical processes active in the aquifer and that the degree to which they occur is a function of the ability of the aquifer to transmit water which is controlled by fault displacement.

The Shallow Subsurface Temperature Field in the Netherlands

Abstract: Shallow subsurface temperatures in The Netherlands were measured in groundwater observation wells Based on the measurements, temperature maps have been assembled showing temperature intervals of one degree centigrade for depths between 25 and 250 m below ground surface

Linear system models for regional aquifer evaluation studies

Abstract: A generalized linear system model is formulated to analyze several types of groundwater flow problems. An iterative procedure is developed to predict aquifer response due to pumping demand by considering the analytical relationships governing the groundwater flow. Historical pumping rates, groundwater levels, stream stages, and estimated storage coefficients are used as inputs to the model. The model outputs are the aquifer transmissivities and the predicted groundwater levels. The sensitivity of the model to variations in the estimated storage coefficients is investigated. The technique is illustrated by considering a realistic but hypothetical regional aquifer system, and the results are demonstrated to be satisfactory. The technique is insensitive even to large errors in the estimated storage coefficients. The number of simultaneous equations to be solved and hence the computational time required are much smaller than those encountered in the conventional numerical models of aquifer systems. Aquifer transmissivity and storage coefficient values are computed as a part of this procedure. Therefore expensive pumping tests that are usually required to estimate these aquifer parameters are not necessary in this technique.

PATHS groundwater hydrologic model

Abstract: A preliminary evaluation capability for two-dimensional groundwater pollution problems was developed as part of the Transport Modeling Task for the Waste Isolation Safety Assessment Program (WISAP) Our approach was to use the data limitations as a guide in setting the level of modeling detail PATHS Groundwater Hydrologic Model is the first level (simplest) idealized hybrid analytical/numerical model for two-dimensional, saturated groundwater flow and single component transport; homogeneous geology This document consists of the description of the PATHS groundwater hydrologic model The preliminary evaluation capability prepared for WISAP, including the enhancements that were made because of the authors' experience using the earlier capability is described Appendixes A through D supplement the report as follows: complete derivations of the background equations are provided in Appendix A Appendix B is a comprehensive set of instructions for users of PATHS It is written for users who have little or no experience with computers Appendix C is for the programmer It contains information on how input parameters are passed between programs in the system It also contains program listings and test case listing Appendix D is a definition of terms

Correlation between photolinears and the movement of groundwater in the Lonavala area, Pune district, Maharashtra

Abstract: The study of the photolinears and the groundwater flow directions in the Lonavala area of the Pune distrtict suggests the relationship between these two parameters. In the western part of the Lonavala area the groundwater flow lines are running along a dark toned linear trending N 20° - 30°W. This linear is a fracture controlled linear valley covered by dense vegetation which is supported by the groundwater channelised along this linear. The higher specific capacities of the dugwells situated along the trend of this linear also suggest the movement of groundwater along the linear.

Hydrogeologic properties and ground-water chemistry of the Rattlesnake Ridge interbed at well 699-25-80 (DB-14) Hanford Site

Abstract: Offsite migration studies were conducted to characterize the hydraulic properties and groundwater chemistry of confined aquifer systems within the Hanford Site. These studies support the recommendations in ERDA-1538 to provide input for hydrologic modeling of groundwater flow within the Hanford Site, to afford information concerning possible contamination of underlying confined aquifer systems and to make the results available to the public. This report presents analytical results and aquifer test procedures used in characterizing the Rattlesnake Ridge interbed at well 699-25-80. The overall close association in groundwater chemistries and presence of elevated nitrate levels suggest that the Rattlesnake Ridge interbed may be locally in communication with the overlying unconfined aquifer system. Other physical evidence which indicates a potential local communication with the unconfined aquifer system includes: favorable stratigraphic position; absence of the confining Elephant Mountain basalt in surrounding areas; and intersection of a recharge boundary during aquifer tests of well 699-25-80.

Regional thermohydrological effects of an underground repository for nuclear wastes in hard rock

Abstract: The principal mechanism for underground migration of radionuclides is transport with groundwater. In the selection and assessment of suitable sites as potential repositories of nuclear wastes, it is important to predict the effects of heat generated by the wastes upon the water movement between the repository and the biosphere. With the absence of relevant engineering experience and the limitation on duration of in situ testing, simulation of global and long term thermal responses of the rock mass in hypothetical models is the main method for the understanding of the mechanism and the identification of the sensitive parameters controlling groundwater flow. This paper presents results of two sets of calculations: 1) Regional temperature effects are studied for different waste forms, repository dimensions and rock formations. The type of reprocessing treatment and the length of cooling period of the nuclear wastes before emplacement into the repository are found to be two of the more important factors. 2) Thermally induced fluid flow is calculated assuming a simple two-fracture system to make a “worst case” estimate of the transit time of water from repository to ground surface. Recharge capacity from the surrounding formation is found to be a controlling factor.

Experimental Study on Determining Unsaturated Property of Soil

Abstract: This paper deals with the experimental study of hydraulic properties of unsaturated soil. In treating unsaturated zone, a great deal more data are required than are required for the saturated zone, but these properties of soils must be known to apply the finite element approach to actual groundwater flow problems. The purposes of this paper are to propose a rational basis of getting experimental relationships between prossure head() and hydraulic conductivity(K) and between pressure head() and volumetric moisture content(θ) with "the instantaneous profile method" in a laboratory. An apparatus was constructed and test procedures were developed to measure pressure head and volumetric moisture content by using pressure transducers and low-energy gamma ray attenuation. The technique of a low-energy gamma radiation apparatus does provide a means for accurate measurement of water content without disturbing the system into which water is moving. Furthermore rapid measurement of water content becomes possible at any position in a soil so that water content changes with time may easily be followed. The tensiometer~transducer system provides a most valuable means of measuring pressure head with rapid response and with provision of a complete record of the pressure head changes with time.

Development and validation of GWHEAD, a three-dimensional groundwater head computer code

Abstract: A computer code has been developed to solve the groundwater flow equation in three dimensions. The code has finite-difference approximations solved by the strongly implicit solution procedure. Input parameters to the code include hydraulic conductivity, specific storage, porosity, accretion (recharge), and initial hydralic head. These parameters may be input as varying spatially. The hydraulic conductivity may be input as isotropic or anisotropic. The boundaries either may permit flow across them or may be impermeable. The code has been used to model leaky confined groundwater conditions and spherical flow to a continuous point sink, both of which have exact analytical solutions. The results generated by the computer code compare well with those of the analytical solutions. The code was designed to be used to model groundwater flow beneath fuel reprocessing and waste storage areas at the Savannah River Plant.

Thermal Effects On Groundwater Flow Around A Radioactive Waste Depository In Hard Rock

Abstract: The heat output from high level radioactive waste buried in hard rock can give rise to groundwater convection currents. These flows can change the natural groundwater flows for thousands of years after the decommissioning and sealing of a depository. This paper presents the results of some recent calculations of this effect and discusses the possible consequences for water-borne leakage of radionuclides back to the biosphere.

Water distribution and movement in an unsaturated Piedmont soil profile

Abstract: The purpose of the study was to further investigate the deep seepage - groundwater recharge phenomenon, to develop models of the deep seepage process and to examine moisture displacement in the profile as it relates to the transport of pollutants from the soil surface downward to the groundwater. The study consisted of field investigations and model development. Field investigations include soil moisture and water table measurements, observations of surface runoff and interflow, and a radioactive tracer study. Two computer programs were written using the IBM simulation language CSMP. In one, called the Root Zone Model, precipitation and temperature data are used to estimate runoff, evapotranspiration and storage in the root zone. Any excess moisture is considered to percolate below the root zone as deep seepage. The second program, called the Deep Seepage model, uses the deep seepage calculated in the Root Zone Model and simulates its movement through the unsaturated zone to the pheatic surface, at a depth of 20m.