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1.
I. Radhakrishna 《Environmental Geology》2001,40(3):369-380
Saline/fresh water interface structure is one of the most important and basic hydrogeological parameter that needs to be
estimated for studies related to coastal zone management, well-field design and understanding saline water intrusion mechanism/processes.
The success and stability of a groundwater structure in a coastal region depend upon an accurate estimate of interface structure
between saline and fresh water zones, aquifer-aquiclude boundaries and their lateral continuities and the interstitial water
qualities of aquifers. Self-potential and resistivity logs provide a reasonably good basis for such estimates and for sustainable
development of fresh groundwater resources. The interface depth structure for the Mahanadi delta region, as obtained and interpreted
through self-potential and resistivity logs, provides a fairly clear picture of the regional extensions and boundaries of
aquifers, aquicludes and interstitial water quality patterns. Aquifers in the northern sector of the basin and within the
framework of Birupa and Mahanadi are characterized by an interface depth range that varies between 40 and 280 m below ground
level (bgl) with brackish water on the top underlain by freshwater aquifers. The aquifers in the southern sector within the
framework of Khatjori/Devi and Koyakhai/Daya/Kushbhadra/Bhargavi are characterized by an interface depth range that varies
from 10 to 120 m with freshwater aquifers near the surface underlain by saline, brackish water aquifers. The inversion of
these major fluid systems appears to have taken place over a narrow zone between Mahanadi and Khatjori tributaries, possibly
over a wide subsurface ridge with separate basin characteristics.
Received: 29 November 1999 · Accepted: 2 May 2000 相似文献
2.
A tectono-geomorphic model of the hydrogeology of deeply weathered crystalline rock: Evidence from Uganda 总被引:7,自引:4,他引:3
Deeply weathered crystalline rock forms important aquifers for public water supply throughout low-latitude regions of Africa,
South America, and Asia, but these aquifers have considerable heterogeneity and produce low well yields. Aquifers occur in
the bedrock and overlying weathered mantle and are the products of geomorphic activity of meteoric water, principally deep
weathering and stripping. The fundamental relationship between the hydrogeology and geomorphology of these terrains has, however,
remained unresolved. This study demonstrates the ability of a recently developed tectono-geomorphic model of landscape evolution
in Uganda to explain the hydrogeological characteristics of two basins, as determined using a combination of textural analysis,
slug tests, packer tests, and pumping tests. The geopetal imprint of long-term deep weathering and erosional unloading is
identified in the vertical heterogeneity of the fractured-bedrock and weathered-mantle aquifers; horizontal heterogeneity
is lithologically controlled. The two units form an integrated aquifer system in which the more transmissive (5–20 m2/d) and porous weathered mantle provides storage to underlying bedrock fractures (transmissivity, T, ≈1 m2/d). The thickness and extent of the more productive weathered-mantle aquifer are functions of contemporary geomorphic processes.
The utility of the tectono-geomorphic model, applicable to deeply weathered environments, is that it coherently describes
the basin-scale hydrogeological characteristics of these complex terrains.
Received, June 1999/Revised, January 2000/Accepted, January 2000 相似文献
3.
The water and bed-sediment pollution status of the Padma River was determined by analysis of representative samples for selected
metals and ions. Water and bed-sediment samples were collected at a T-dam, Rajshahi, Bangladesh, for 7 months. Water and silt-metal
content analysis was performed using atomic absorption spectrophotometry or other analytical methods. The data showed the
variation of the metal ion-levels in water as follows: Ca 17.11–48.37 ppm, Na 17.51–20.09 ppm, K 1.00–3.60 ppm, Cr 2.80–7.00 ppm,
and SO4 4.17–5.48 ppm; in bed sediment, the levels were Cr 35–1050 ppm and Pb 12–48 ppm. The occurrence of Na, K and Ca was in the
normal range (US EPA permissible limit), but the levels of Cr in water were much higher than the permissible limit. The SO4 ion content was well below the pollution level. The concentration of Pb in the bed sediment was within the permissible limit
for the standard International Atomic Energy Agency (IAEA) Soil-5a, but the concentration of Cr in the bed sediment was significantly
higher than the permissible limit for the standard IAEA Soil-5a. Thus the Padma river water was polluted with Cr. The occurrence
of some ions showed a monthly variation.
Received: 19 August 1999 · Accepted: 12 October 1999 相似文献
4.
This study presents the first U–Pb zircon data on granitoid basement rocks of the Tatra Mountains, part of the Western Carpathians
(Slovakia). The Western Carpathians belong to the Alpine Carpathian belt and constitute the eastern continuation of the Variscides.
The new age data thus provide important time constraints for the regional geology of the Carpathians as well as for their
linkage to the Variscides. U–Pb single zircon analyses with vapour digestion and cathodoluminescence controlled dating (CLC-method)
were obtained from two distinct granitoid suites of the Western Tatra Mountains. The resulting data indicate a Proterozoic
crustal source for both rock suites. The igneous precursors of the orthogneisses (older granites) intruded in Lower Devonian
(405 Ma) and were generated by partial melting of reworked crustal material during subduction realated processes. In the Upper
Devonian (365 Ma), at the beginning of continent–continent collision, the older granites were affected by high-grade metamorphism
including partial melting, which caused recrystallisation and new zircon growth. A continental collision was also responsible
for the generation of the younger granites (350–360 Ma). The presented data suggest multi-stage granitoid magmatism in the
Western Carpathians, related to a complex subduction and collision scenario during the Devonian and Carboniferous.
Received: 19 February 1999 / Accepted: 3 December 1999 相似文献
5.
Pascal Richet Alan Whittington François Holtz Harald Behrens Susanne Ohlhorst Max Wilke 《Contributions to Mineralogy and Petrology》2000,138(4):337-347
A review of published and newly measured densities for 40 hydrous silicate glasses indicates that the room-temperature partial
molar volume of water is 12.0 ± 0.5 cm3/mol. This value holds for simple or mineral compositions as well as for complex natural glasses, from rhyolite to tephrite
compositions, prepared up to 10–20 kbar pressures and containing up to 7 wt% H2O. This volume does not vary either with the molar volume of the water-free silicate phase, with its degree of polymerization
or with water speciation. Over a wide range of compositions, this constant value implies that the volume change for the reaction
between hydroxyl ions and molecular water is zero and that, at least in glasses, speciation does not depend on pressure. Consistent
with data from Ochs and Lange (1997, 1999), systematics in volume expansion for SiO2–M2O systems (M=H, Li, Na, K) suggests that the partial molar thermal expansion coefficient of H2O is about 4 × 10−5 K−1 in silicate glasses.
Received: 30 June 1999 / Accepted: 5 November 1999 相似文献
6.
The aquifer system of the Upper Triassic Keuper Sandstone, an important source of drinking water in northern Bavaria, is
affected by elevated arsenic concentrations. Within the study area of 8000 km2, no evidence exists for any artificial source of arsenic. Data from about 500 deep water wells show that in approximately
160 wells arsenic concentrations are 10–150 μg/L. The regional distribution of arsenic in the groundwater shows that elevated
arsenic concentrations are probably related to specific lithofacies of the aquifers that contain more sediments of terrestrial
origin. Geochemical measurements on samples from four selected well cores show that arsenic has accumulated in the rocks.
This indigenous arsenic is the source of arsenic in the groundwater of certain facies of the middle unit of the Keuper Sandstone.
Received, June 1998 / Revised, January 1999, May 1999 / Accepted, June 1999 相似文献
7.
Influence of contaminated Vistula River water on the groundwater entering the Zakrzówek limestone quarry, Cracow region, Poland 总被引:1,自引:0,他引:1
Chemical composition of water inflows in the Zakrzówek quarry, developed in fractured and karstified Upper Jurassic limestones,
is controlled by infiltration of polluted water from the Vistula River and by infiltrating meteoric water. The river water
TDS value is 2.5 g/dm3. The quarry waters have 0.6–2.0 g/dm3 TDS. Highly mineralised waters belong to Cl-Na type. With decreasing TDS the percentage of sulphates, calcium, magnesium
and hydrocarbonates increases. This seems to result from various processes including dilution of polluted river water, leaching
of aquifer rocks, and ion exchange. The transfer time of river water to the quarry is about 100–120 days. Concentration of
contaminants contained in the river water declines during the migration through limestones to the quarry.
Received: 7 March 1997 · Accepted: 7 December 1998 相似文献
8.
Environmental impact of mining waste disposal on a tropical lowland river system: a case study on the Ok Tedi Mine, Papua New Guinea 总被引:3,自引:0,他引:3
The 1000 km long Ok Tedi/Fly River system receives about 66 Mt/year of mining waste from the Ok Tedi copper-gold porphyry
mine. Mine input has increased the suspended sediment load of the Middle Fly River about 5–10 times over the natural background.
A significant yet unknown amount of copper-rich material deposits unevenly in the extensive tropical lowland floodplain. Recent
alluvial sediments of the Fly River floodplain have copper contents of 620 mg/kg (±1σ: 430–900), whereas the regional background
is 40 mg/kg (±σ: 25–60). This pattern is mirrored and enhanced by the gold dispersal pattern with a 7 ppb Au background versus
a 140–275 ppb population in mine-derived material. Very high deposition rates (around 4 cm/y) of mine-derived sediment were
determined in locations close to the creeks and channels which link the Fly River with the outer floodplain. A thin layer
of 1–5 cm of copper-rich material (400–900 mg/kg Cu) was usually found on the bottom of drowned (tributary) valley lakes.
Average dissolved copper content in waters of the inner floodplain is around 9 μg/l (±1σ: 5–14) as compared to unpolluted
water from the outer floodplain with < 2 μg/l Cu. The present Fly River water, about 600 km downstream of the mine site, has
concentrations of 17 ± 3 μg/l dissolved Cu.
Received: 30 June 1996 / Accepted: 9 January 1997 相似文献
9.
V. D. Mats O. M. Khlystov M. De Batist S. Ceramicola T. K. Lomonosova A. Klimansky 《International Journal of Earth Sciences》2000,89(2):229-250
New high-resolution seismic reflection data from the central part of Lake Baikal provide new insight into the structure and
stratigraphy of Academician Ridge, a large intra-rift accommodation zone separating the Central and North Baikal basins. Four
seismic packages are distinguished above the basement: a thin top-of-basement unit; seismic-stratigraphic unit X; seismic-stratigraphic
unit A; and seismic-stratigraphic unit B. Units A and B were cored on selected key locations. The four packages are correlated
with a series of deposits exposed on the nearby western shores: the Ularyar Sequence (Oligocene); the Tagay Sequence (Lower
to Middle Miocene); the Sasa Sequence (Upper Miocene to Lower Pliocene); the Kharantsy Sequence (Upper Pliocene); and the
Nyurga Sequence (Lower Pleistocene). Based on stratal relationships, sedimentary geometries, distribution patterns and principal
morphostructural elements – both onshore and offshore – we propose a new palaeogeographic evolution model for the area. In
this model progressive tectonic subsidence of the Baikal basins and successive pulses of uplift of various segments of the
rift margins lead to: (a) formation of the ridge as a structural and morphological feature separating the Central and North
Baikal basins during the Middle to Late Miocene; (b) gradual flooding of the main parts of the ridge and establishment of
a lacustrine connection between the two rift basins during the Late Miocene; and (c) total submergence of the top parts of
the crest of the ridge during the latest Pleistocene. This new model helps to better constrain numerous phases in the structural
evolution of the Baikal Rift, in which the Academician Ridge as an accommodation zone plays a crucial role.
Received: 26 November 1999 / Accepted: 12 March 2000 相似文献
10.
Geochemistry, genesis, and health implications of fluoriferous groundwaters in the upper regions of Ghana 总被引:9,自引:2,他引:9
The most appropriate and widely used source of drinking water for the populations of the upper regions of Ghana is groundwater.
In general, groundwater quality is acceptable except for some parts of the Bolgatanga and Bongo Districts, where there are
occurrences of elevated levels of natural groundwater fluoride. Concentrations of groundwater fluoride in excess of the World
Health Organization (WHO) maximum guideline value (1.5 mg/l) in the Bongo area have been known since 1978. However, the effect
of fluoride on people ingesting the water did not receive public and medical attention until October 1993, when health personnel
were asked to investigate the cause of stained teeth in school children. The investigation established that 62% of the total
population of school children in the Bongo area had dental fluorosis. Against this background, a study was initiated to understand
the geochemistry, genesis, and distribution of fluoride in relation to the geology of the area. Groundwater fluoride in the
upper regions ranges from 0.11 to 4.60 ppm, with the highest concentrations associated with the fluorine-enriched Bongo coarse-grained
hornblende granite and syenite suite. The source of groundwater fluoride within the Bongo granitoids is dissolution of the
mineral fluorite and dissolution of and anion exchange with micaceous minerals and their clay products. Applying the WHO recommended
guideline values for fluoride in drinking water reveals that 49% of wells in the area deliver water below the optimum level
of 0.5 mg/l F–; these populations are thus prone to dental caries. Twenty-eight percent of the wells fall within the optimum interval for
good dental health (0.5–1.5 mg/l F–). Twenty-three percent of the wells have concentrations above the recommended maximum guideline limit of 1.5 mg/l F–; this population is susceptible to dental and possibly skeletal fluorosis. Climatic conditions of the area suggest that the
individual water consumption is in the order of 3 to 4 l which is higher than the WHO estimate of 2 l/adult/day. In addition,
dietary intake for the upper region population is probably higher than WHO baseline values (0.2–0.5 mg/day). This implies
that a much higher population is susceptible to developing dental and skeletal fluorosis than originally suspected. Geochemical
symbol plot maps help geochemists understand factors controlling the distribution and uptake of fluoride in the upper regions,
but they are of minimal value to health officials responsible for planning epidemiological studies and dental health education
programs in the region. By casting fluoride data into contoured 'geochemical health-risk maps' using intake interval guidelines
more closely aligned to regional climatic and dietary conditions, health officals can better judge the impacts (regional and
population based) of fluoride on segments of the population, such as various sex and age groups.
Received: 11 March 1997 · Accepted: 17 June 1997 相似文献
11.
Amleto A. Pucci Jr. 《Hydrogeology Journal》1999,7(3):251-263
A transient 1-D, two-pathway non-equilibrium deterministic advective dispersion model was used to examine the distribution
of chloride (43–100 mg/L) and sulfate (57–894 mg/L) concentrations in the 35-m-thick section of the Lower confining unit,
Atlantic Coastal Plain, New Jersey, USA. The model was used to constrain hypotheses about how pore-water chemistry changed
over time. Explanations of the solute concentrations were explored by inverse and direct methods given a few known constraints,
including concentrations of pore-water constituents from 12 core samples, reported simulated flow rates, and estimated hydrogeologic
properties. The hypothesis that is best supported by the model results is that the distribution of chloride and sulfate concentrations
in the confining unit reflect the history of the aquifer system since it was filled with seawater at the last eustatic high,
about 84×103yr BP. The model simulates fresh-water flushing of the seawater-permeated silts at a steady upward pore-water flow velocity
of 8.8×10–6 m/d, with a dispersion coefficient of 9.2×10–7 m2/d, a dimensionless partition expression for chloride, βCl=0.981, and a dimensionless exchange coefficient, ωCl=0.31×10–2. Sulfate concentrations were simulated over the flow path using flow and dispersion values calculated for chloride transport
plus a retardation term. Parameters for sulfate transport include retardation coefficient=4.51, βSO4=0.994, and ωSO4=0.31×10–2. Sensitivity analysis indicates that the model is most sensitive to flow velocity, and that fresh-water flushing of the confining
unit is best simulated by having seawater concentration levels at the inflow boundary of the confining unit exponentially
decrease with a concentration half-life rate of 825 yr.
Received, January 1997 / Revised, April 1998, October 1998, January 1999 / Accepted, January 1999 相似文献
12.
A strong geochemical gradient was observed in the thick overburden aquifer of the Asa drainage basin. Different types of
groundwater occur at different (downslope) locations and groundwater table depths. The following sequence was noticed with
increasing distance downslope or with increasing groundwater table depth:
1. Ca–Mg–HCO3 water at about 390-m groundwater table elevations or upslope locations.
2. Ca–Mg–HCO3–Cl water at middle-slope locations or groundwater table elevations of about 350 m above sea level;
3. Ca–Mg–SO4–Cl water at downslope locations or groundwater table elevations of about 300 m above sea level.
In this basin, changes in the type of water are expected at about every 40–50 m depth from the surface. Statistical analysis
via the determination of the correlation coefficient (r) and regression analysis shows that about 80–99% of the variation in groundwater chemistry is accounted for by the topography,
using the model presented in this paper. The rate of change in the sequence will depend on the permeability of the aquifer,
which determines the rate of groundwater flow and the residence time, and the nature of recharge.
Received: 4 February 1997 · Accepted: 22 July 1997 相似文献
13.
Water from the Kombat mine was delivered to the Omatako dam via the 263-km-long Grootfontein-Omatako canal during test runs
in 1997. It is intended to supply water from Kombat and other underground mines in the Otavi Mountain Land to the capital
Windhoek. The Cu-Pb-Zn orebodies are hosted by carbonate rocks and the mine waters are supersaturated with respect to calcite
and CO2. Along the length of the canal, the CO2 partial pressure drops from 10−2.1 atm at the inlet of the Kombat mine to 10−3.5 atm at the end of the canal. This is accompanied by a drop in Ca concentration from about 60 to about 20 mg/l. The heavy
metal concentrations (Cd, Cu, Mn, Pb and Zn) drop along the course of the canal to values far below the national drinking-water
standard. Scavenging by calcium carbonate precipitation is the major depletion mechanism.
Received: 21 June 1999 · Accepted: 29 August 1999 相似文献
14.
A. Rimi 《International Journal of Earth Sciences》1999,88(3):458-466
Thermal and deep seismic soundings data are used to study the dependence between the compressional Pn velocity and the surface heat flow or the temperature at the Moho discontinuity in Morocco. This correlation indicates a
significant decrease in Pn velocity where high heat flow and Moho temperature are observed. This result is consistent with respect to other regions
of the world. Crustal heat generation models and geotherms are constructed for the major Moroccan geological domains extending
from the Precambrian units in the south to the Alpine units in the north. The crustal contribution in surface heat flow is
on average 35 mWm–2, with high values of 41–42 mWm–2 in the western and eastern Meseta where Hercynian granite intrusions could enrich the crust in radioactive heat sources.
High mantle heat flow values are obtained beneath the Alboran neogene basin (62 mWm–2), the Rif (47 mWm–2), the Middle Atlas (41 mWm–2), and the south Atlantic margin (40 mWm–2) where the crust is thinned by an extensional tectonic regime. Despite their similar formation context, the intra-continental
belts of the Middle and the High Atlas show different geothermal field components. A lithospheric heating process in the Middle
Atlas could be the result of a Plio-Quaternary basaltic volcanism. Finally, the Precambrian basement of the Anti-Atlas like
all the West African shield is a stable domain showing the lowest subsurface temperatures.
Received: 14 January 1998 / Accepted: 29 June 1999 相似文献
15.
Aquifers in the arid alluvial basins of the southwestern U.S. are recharged predominantly by infiltration from streams and
playas within the basins and by water entering along the margins of the basins. The Tucson basin of southeastern Arizona is
such a basin. The Santa Catalina Mountains form the northern boundary of this basin and receive more than twice as much precipitation
(ca. 700 mm/year) as does the basin itself (ca. 300 mm/year). In this study environmental isotopes were employed to investigate
the migration of precipitation basinward through shallow joints and fractures. Water samples were obtained from springs and
runoff in the Santa Catalina Mountains and from wells in the foothills of the Santa Catalina Mountains. Stable isotopes (δD
and δ18O) and thermonuclear-bomb-produced tritium enabled qualitative characterization of flow paths and flow velocities. Stable-isotope
measurements show no direct altitude effect. Tritium values indicate that although a few springs and wells discharge pre-bomb
water, most springs discharge waters from the 1960s or later.
Received, February 1997 · Revised, September 1997 · Accepted, September 1997 相似文献
16.
Hydrogeologic data of 455 water wells comprising geologic logs, water qualities, and aquifer test results are analyzed to
determine hydrogeological characteristics, water quality, and sustainable yield of the groundwater resources of Cheju volcanic
island. The groundwater of the island occurs in unconsolidated pyroclastic deposits and clinkers interbedded in highly jointed
basaltic and andesitic rocks as high-level, basal, and parabasal groundwater under unconfined conditions. The total storage
of groundwater is estimated at about 44 billion m3. The average transmissivity and specific yield of the aquifer are at about 0.34 m2 s–1(29300 m2 day–1) and 0.12, respectively. The average annual precipitation is about 3.39 billion m3, of which 1.49 billion m3– equivalent to 44.0% of the total annual precipitation – is recharged into aquifers, with 0.638 billion m3 year–1 of runoff and 1.26 billion m3 year–1 of evapotranspiration. Based on a groundwater budget analysis, the sustainable yield is estimated at about 0.62 billion m3 year–1, equivalent to 41.6% of annual recharge. A low-permeability marine sedimentary formation (Sehwari formation), composed of
loosely cemented sandy silt, was recently found to be situated at 120±68 m below mean sea level. If the said marine sediment
is distributed as a basal formation of the freshwater zone of the island, most of its groundwater will be of parabasal type.
So the marine sediment is one of the most important hydrogeological boundaries and groundwater occurrences in the area.
Received: 16 January 1997 / Accepted: 16 June 1997 相似文献
17.
In order to characterize the hydraulic properties of an aquifer in Finland comprising two subvertical fracture zones, observation-well
responses were matched with generalized radial flow (GRF) type curves. The responses in six wells out of seven are consistent
with the GRF model. The fractional flow dimensions (1–1.2 and 1.5) were determined by regression analysis of straight-line
slopes and type-curve matching. In each test, the flow dimensions in the neighboring fracture zone range from 2–2.25. Comparisons
of the late-time responses with the asymptotic GRF solution and the flow dimensions obtained by reversing the pumping and
observation points suggest homogeneous hydraulic properties. Deviations in responses can be explained by flow-path tortuosity.
After assessments of the extent of the flow and radial distances along the fracture system, hydraulic conductivities and storativities
were determined from the results of the type-curve matching procedure. The obtained hydraulic conductivities are 1.3×10–5 to 7.9×10–5 m/s and 5.0×10–6 to 2.5×10–5 m/s for the western and the eastern fracture zones, respectively. The results were verified by applying them to analytical
solutions for pumping wells. The calculated pumping-well responses are consistent with the observations. The analysis of flow
dimension also enhances qualitative interpretations on the hydrogeology of fracture zones.
Received, April 1997 · Revised, September 1997 · Accepted, May 1998 相似文献
18.
The occurrence, movement and control of groundwater, particularly in hard-rock areas, are governed by different factors such
as topography, lithology, structures like fractures, faults and nature of weathering. An attempt is made in the present study
to investigate the extent of the influence of structures such as fractures and thereby delineate the nature of subsurface
lithology with the help of an electrical resistivity method. For this study, the Upper Gunjanaeru River basin, Cuddapah district
Andhra Pradesh was chosen to determine groundwater potentials. In order to understand the significance of the fracture pattern,
geological, hydrogeomorphological and lineament maps were prepared based on the field data and also from the LANDSAT TM imagery.
Further, electrical resistivity surveys were conducted to determine the subsurface lithology and also to confirm the studies
of LANDSAT imagery. The isoresistivity contour map has been prepared based on the 45 VES conducted to determine the resistivity
variations in the study area. The isoresistivity contours obtained were found to conform to the structural trends obtained
by geological studies and also confirm the relationship between the structure and secondary porosity present in the rocks.
The lineaments in the area have two preferred directions. One set is a NE-SW direction (N 30°–70° E; S 30°–70° W) and another
is a NW-SE direction (N 0°–30° W; S 0°–30° E and N 60°–80° W; S 60°–80° E). The water-table contour map shows that the direction
of groundwater flow is south to north.
Received: 3 March 1997 · Accepted: 17 June 1997 相似文献
19.
V. V. S. Gurunadha Rao R. L. Dhar T. Jayachand C. S. Khoker 《Environmental Geology》2000,39(10):1138-1146
Mathura oil refinery was commissioned during 1977 and effluent storage ponds were constructed at the same time. These storage
ponds receive wastewater from the refinery at a rate of 10000 m3/day. After treatment, waste water is discharged through a 3-km pipeline to a stream leading to the Yamuna river. The groundwater-monitoring
as well as water-quality monitoring was carried at 24 observation wells in the refinery site during 1997. The water quality
measurements indicated total dissolved chloride and sulphate concentration of native groundwater as 400 mg/l, whereas elevated
levels up to 600 mg/l were found at the wells close to polishing ponds. Thus combined transport of chloride and sulphate was
simulated in the mass transport model. A three-dimensional flow, pathlines and mass transport model of the aquifer system
were constructed to analyze the impact of seepage from polishing ponds contaminating the groundwater regime. The permeability
of aquifer varies between 1.5–2.5 m/day. The porosity of formation was assumed as 0.2. The constant head and constant concentration
boundaries were assigned to the nodes representing effluent storage ponds. Longitudinal dispersivity of 100 m, horizontal
transverse dispersivity of 10 m and vertical transverse dispersivity of 0.01 m were assumed. The mass transport model was
calibrated for 20 years by comparing total dissolved chloride and sulphate concentrations from 1997. The model predictions
indicate further migration of contaminants on the east of effluent ponds in future.
Received: 4 January 1999 · Accepted: 12 July 1999 相似文献
20.
Land subsidence due to groundwater withdrawal: potential damage of subsidence and sea level rise in southern New Jersey, USA 总被引:6,自引:0,他引:6
Land subsidence due to groundwater withdrawal combined with a global sea level rise creates a serious environmental problem
in the coastal region. Groundwater withdrawal results in fluid pressure change in the layers. The pressure change in the layers
induces both elastic and inelastic land compaction. The elastic compaction can be recovered if the water level rises again
and inelastic compaction becomes permanent. Groundwater response to barometric pressure change is used to estimate the elastic
compaction in this study. The storativity, specific storage and other layer and hydrological information are used to estimate
the inelastic compaction of the layers due to fluid withdrawal. The discussed methods are applied to estimate and predict
the subsidence potentials resulting from overdrafting of the groundwater in the southern New Jersey. The estimated subsidence
is about 2–3 cm near the location of monitoring wells in Atlantic, Camden, Cumberland and Cape May Counties over the past
20 years. If the current trend of water-level drop continues, the average subsidence in southern New Jersey in the vicinity
of some monitoring wells will be about 3 cm in the next 20 years. The rise of global sea level is about 2 mm/year on average.
Because of the very gentle slope in southern NJ, the combination of subsidence and sea level rise will translate into a potentially
substantial amount of land loss in the coastal region in each 20 year period. This combination will also accelerate the coastal
flooding frequency and the erosion rate of the New Jersey coastal plain, and pose a serious threat to the coastal economy.
Received: 15 December 1997 · Accepted: 30 June 1998 相似文献