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1.
One-third of the population of Oman depends upon groundwater extracted from the alluvium of the Batinah Plain, on the coast
of the Gulf of Oman. Deep geophysical exploration techniques were used to determine the depth and nature of the alluvium and
the boundaries of the aquifer. The base and structural controls of the alluvial basin at its contact with Tertiary marine
sediments and Cretaceous ophiolite were mapped with seismic reflection data, recorded originally for oil exploration. The
base of the alluvium dips northward from the foothills of the Northern Oman Mountains, reaching a maximum depth of 2000 m
at the coast. The varying facies of the alluvium are grossly characterised by different, overlapping ranges of electrical
resistivity, depending largely on the clay content and degree of cementation. Resistivities near the coast are reduced by
saline intrusion. These variations of resistivity were mapped with time-domain electromagnetic sounding along 400 km of profile,
to distinguish among the three zones of the alluvial aquifer. The wedge of saline intrusion was also delineated, up to 10 km
from the coast. The thickness of the saturated gravel aquifer ranges from 20–160 m in an area greater than 600 km2.
Received, April 1997 · Revised, January 1998 · Accepted, April 1998 相似文献
2.
Water quality of two streams near Yellowstone Park, Wyoming, following the 1988 Clover-Mist wildfire
In 1988, wildfire burned over 50% of the Jones Creek watershed near Yellowstone Park, Wyoming. Crow Creek, an adjacent watershed,
was unburned. Water quality data collected from 1989–1993 may show the fire's effect on weathering and nutrient transport.
Jones Creek had 25–75% larger concentrations of dissolved solids than Crow Creek during the sampling period. Both streams
revealed molar ratios consistent with the stoichiometry of andesine and pyroxene hydrolysis in the trachyandesites that underlie
the basins. During 1989, nitrate transported from the unburned Crow Creek basin peaked at 2 mmol ha–1 s–1. This was twice as much as Jones Creek, possibly indicating a source from ash fallout. By 1992 these rates diminished to
0.1 mmol ha–1 s–1 in Crow Creek and increased to 1.8 mmol ha–1 s–1 in Jones Creek, suggesting later nitrate mobilization in the burned watershed. Phosphorus transported from Jones Creek basin
averaged 0.011 mmol ha–1 s–1 during summer 1989, but fell to 0.004 mg ha–1 s–1 in subsequent years.
Received: 28 May 1997 · Accepted: 18 November 1997 相似文献
3.
Proposed groundwater withdrawals in the San Luis Valley of Colorado may lower the water table in Great Sand Dunes National
Monument. In response, the National Park Service initiated a study that has produced a generalized conceptual model of the
hydrologic system in order to assess whether a lowering of the water table might decrease the surface flow of lower Medano
Creek. Based upon information obtained during the drilling of several boreholes, there appear to be five important hydrostratigraphic
units underlying lower Medano Creek within the upper 30 m of the ground surface: 1. a perched aquifer overlying an aquitard
located between about 5 and 6 m below the ground surface; 2. the aquitard itself; 3. an unconfined aquifer located between
the upper and lower aquitards; 4. an aquitard located between about 27 and 29 m below the ground surface; and 5. a confined
underlying the lower aquitard. Because the areal extent of the aquitards cannot be determined from the borehole data, a detailed
conceptual model of the hydrogeologic system underlying lower Medano Creek cannot be developed. However, a generalized conceptual
model can be envisioned that consists of a complex system of interlayered aquifers and leaky aquitards, with each aquifer
having a unique hydraulic head. Water levels in the perched aquifer rise rapidly to their annual maximum levels in response
to the arrival of the flow terminus of Medano Creek during the spring runoff event, and the location of the flow terminus
is directly dependent upon the discharge of the creek. Water levels in the deeper, non-perched aquifers do not appear to fluctuate
significantly in response to the arrival of the flow terminus, demonstrating that it is unlikely that the proposed groundwater
withdrawals will decrease the surface flow of lower Medano Creek.
Received: 27 December 1995 · Accepted: 20 February 1996 相似文献
4.
Groundwater flow rate and contaminant migration in fissure-karstic aquifer of Opole Triassic system southwest Poland 总被引:1,自引:0,他引:1
This paper presents hydrogeological problems occurring during municipal water exploitation and mine dewatering. These activities
result in groundwater quantity and quality changes in the fissure-karstic aquifer. Increase of nitrate concentration up to
12 mg NNO3/l due to intensive fertilizer use, and high tritium concentration, show water system impact up to 100 m depth. Intensive
water exploitation produces large cones of depression with over 40-m water-level depletion in the Opole region. Flow rates
of major components and isotopes have been verified by chemical migration history. Some aspects of the protection policy of
this type of aquifer are also discussed.
Received: 7 March 1997 · Accepted: 17 November 1998 相似文献
5.
Understanding the geologic controls of porosity development and their relationship to the karst aquifer system in the Cambrian
Maynardville Limestone is important in determining possible contaminant transport pathways and provides essential data for
hydrologic models within the Oak Ridge Reservation of east Tennessee. In the Maynardville Limestone, several important factors
control porosity development: (1) lithologic controls on secondary microporosity and mesoporosity are related to dissolution
of evaporite minerals and dedolomitization in supratidal facies; (2) depth below the ground surface controls the formation
of karst features because the most active portion of the groundwater system is at shallow depths, and karst features are rare
below ≈35 m; and (3) structural controls are related to solution enlargement of fractures and faults.
Received: 21 May 1996 · Accepted: 30 August 1996 相似文献
6.
Analyses of 126 samples collected from 18 dug wells in the shallow basaltic aquifer over a period of 7 months have revealed
spatial as well as temporal changes in the chemical properties of groundwater. While the temporal changes have been attributed
to dilution and concentration phenomena governed by climatic factors, the spatial variations in the geochemical characteristics
of groundwater appeared to be related to pollution due to effluents from the Mula Sugar Factory. The cause of groundwater
pollution is the effluent carried by a stream flowing through the area. Fluctuations in the groundwater table, influent water
quality character of the stream, less capacity to accommodate large volume of effluent and occurrence of zero base flow (under
natural conditions) in the stream are the factors favoring infiltration of constituents of waste water into the underlying
weathered basaltic aquifer. Pollutants have entered into the shallow aquifer by downward percolation through the zone of aeration
to form a recharge mound at the water table and, further, lateral movement below the water table. The plume of polluted groundwater
has a lateral extent of a few meters in the upstream area and more than 400 m on either side of the stream in the downstream
part. The zone of polluted groundwater has an areal extent of more than 3.5 km2. Groundwater is the only source available for drinking and agricultural purposes. It is recommended that the base of the
lagoons and the stream used for release of plant effluent should be waterproofed for the protection of groundwater in the
Sonai area.
Received: 30 April 1997 · Accepted: 23 September 1997 相似文献
7.
Foresighted and determined local authorities, purposeful exploration (i.e. by seismic reflection) and extensive testing led
to the discovery of a substantial groundwater resource near the community of Seon (Switzerland) at a depth of 268–305 m. Production
tests revealed a hydraulic conductivity of ∼5.10–5 m/s, transmissivity of ∼5.10–4 m2/s and a storage coefficient of ∼2% in the aquifer. Pumping up to 1500 l/min is sustainable; the water quality complies chemically
and bacteriologically with drinking-water requirements. The residence time of several 103 years, determined by isotope techniques, guarantees protection from surface contamination. The elevated temperature of 19.5 °C
of the produced water enables combined use for drinking water and space heating. The environmental benefits are substantial:
the emission reduction amounts up to 780 tons/year CO2 and 1 ton/year SO2.
Received: 21 September 1998 · Accepted: 10 February 1999 相似文献
8.
The Lubin Głogów copper district (lgom) is in an area of copper mining, where ore is mined at a depth of 600–1200 m below
surface. Mine dewatering directly influences W-1 limestone aquifer of Permian (Zechstein) age and indirectly impacts a Triassic
sandstone aquifer as well as water-bearing sediments interbeded with the coals. The prediction of groundwater inflow into
mines has been performed using methods of mathematical modelling. In succeeding steps of the approach, the scheme of the hydrogeological
framework was changed starting from the one-layer model up to the four-layer model. The evolution of this hydrogeological
schematization is presented in this paper. The latest scheme characterizes such levels of details that allows the following
predictions: (1) expansion of depression in all aquifers is influenced by dewatering, (2) the widest extent of depression
is in the southern direction, (3) groundwater inflow to the Lubin and Rudna mines will remain at the same level, while the
inflow to the Polkowice mine will increase by 25%. Reliable prediction can be achieved by incorporating the entire recharge
and drainage area characteristics of the aquifer influenced by mine dewatering into the model.
Received: 7 March 1998 · Accepted: 7 December 1998 相似文献
9.
The Heretaunga Plains, Hawke's Bay, New Zealand, is underlain by Quaternary fluvial, estuarine-lagoonal, and marine deposits
infilling a subsiding syncline. Within the depositional sequence, river-channel gravels form one of the most important aquifer
systems in New Zealand. An interconnected unconfined–confined aquifer system contains groundwater recharged from the Ngaruroro
River bed at the inland margin of the plain, 20 km from the coast. At the coast, gravel aquifers extend to a depth of 250 m.
In 1994–95, 66 Mm3 of high quality groundwater was abstracted for city and rural water supply, agriculture, industry, and horticulture. Use
of groundwater, particularly for irrigation, has increased in the last 5 years. Concern as to the sustainability of the groundwater
resource led to a research programme (1991–96). This paper presents the results and recommends specific monitoring and research
work to refine the groundwater balance, and define and maintain the sustainable yield of the aquifer system. Three critical
management factors are identified. These are (1) to ensure maintenance of consistent, unimpeded groundwater recharge from
the Ngaruroro River; (2) to specifically monitor groundwater levels and quality at the margins of the aquifer system, where
transmissivity is <5000 m2/d and summer groundwater levels indicate that abstraction exceeds recharge; (3) to review groundwater-quality programs to
ensure that areas where contamination vulnerability is identified as being highest are covered by regular monitoring.
Received, January 1998 / Revised, August 1998, March 1999 / Accepted, April 1999 相似文献
10.
Jerome V. DeGraff David L. Wagner Alan J. Gallegos Margie DeRose Casey Shannon Todd Ellsworth 《Landslides》2011,8(3):343-353
On July 12, 2008, two convective cells about 155 km apart produced a brief period of intense rainfall triggering large debris
flows in the southern Sierra Nevada. The northernmost cell was centered over Oak Creek Canyon, an east-flowing drainage, and
its tributaries near Independence, CA, USA. About 5:00 p.m., debris flows passed down the South Fork and North Fork of Oak Creek to merge into a large single feature whose passage affected
the historic Mt. Whitney Fish hatchery and blocked California State Highway 395. At about the same time, the southernmost
cell was largely centered over Erskine Creek, a main tributary of the west-flowing Kern River. Debris flows issued from several
branches to coalesce into a large debris flow that passed along Erskine Creek, through the town of Lake Isabella, CA, USA
and into the Kern River. It was observed reaching Lake Isabella about 6:30 p.m. Both debris flows caused significant disruption and damage to local communities. 相似文献
11.
Groundwater quality in parts of Central Ganga Basin, India 总被引:1,自引:0,他引:1
This paper deals with the drinking water quality of the Ganga-Kali sub-basin which occupies 1300 km2 over parts of Aligarh and Etah districts. Water samples were collected from shallow and deep aquifers and were analyzed for
major ions and trace elements. The analytical data were interpreted according to published guidelines. Chemical analysis shows
that the groundwater in the basin is alkali bicarbonate type. Trace element studies of water from the shallow aquifer show
that the concentration of toxic metals Fe, Mn, Cd, Pb, and Cr+6 are above permissible limits which may present a health hazard. The water from the deep aquifer is comparatively free from
contamination. The aquifers are subject to contamination due to sewage effluents and excessive use of fertilizers and pesticides
in agriculture.
Received: 7 December 1998 · Accepted: 2 March 1999 相似文献
12.
Yangtze Delta, China: Taihu lake-level variation since the 1950s, response to sea-level rise and human impact 总被引:1,自引:0,他引:1
Hydrological records collected from water gauge stations since the 1950s demonstrate that the Taihu lake level is rising.
The average rate of the lake-level rise is 0.4–1.1 mm/year during the non-flood season, resulting directly from a rise in
sea level. High rates of 3.0–5.0 mm/year of rise are even recorded during the wet season. This indicates increasing human
activities such as reclamation, sluicing and embanking, which significantly hinder the expulsion of extra lake water to the
coast shortly after a rainfall. Generally, the lake level of the western inlet is higher than that of the eastern outlet.
However, the lake-level difference between the west and east has been diminished annually from ∼10–15 cm in the 1950s to <3 cm
at the present time. During non-flood seasons, the lake-level difference even appears to be reversed, indicating a retrogression
of the lake flow from east to west. It is predicted that the Taihu drainage basin will lose much of its natural water-expelling
ability in the next 50 years as the sea level continues to rise, and retrogression will likely occur during the flood season
in the near future.
Received: 13 March 1998 · Accepted: 21 July 1998 相似文献
13.
Simulation of seawater intrusion into the Khan Yunis area of the Gaza Strip coastal aquifer 总被引:4,自引:3,他引:1
The Gaza Strip coastal aquifer is under severe hydrological stress due to over-exploitation. Excessive pumping during the
past decades in the Gaza region has caused a significant lowering of groundwater levels, altering in some regions the normal
transport of salts into the sea and reversing the gradient of groundwater flow. The sharp increase in chloride concentrations
in groundwater indicates intrusion of seawater and/or brines from the western part of the aquifer near the sea.
Simulations of salt-water intrusion were carried out using a two-dimensional density-dependent flow and transport model SUTRA
(Voss 1984). This model was applied to the Khan Yunis section of the Gaza Strip aquifer. Simulations were done under an assumption
that pumping rates increase according to the rate of population growth, or about 3.8% a year. Model parameters were estimated
using available field observations. Numerical simulations show that the rate of seawater intrusion during 1997–2006 is expected
to be 20–45 m/yr. The results lead to a better understanding of aquifer salinization due to seawater intrusion and give some
estimate of the rate of deterioration of groundwater.
Received, September 1997 Revised, January 1998, July 1998 Accepted, August 1998 相似文献
14.
Short-term geomorphic and hydrologic effects of subsidence induced by longwall mining under Burnout Creek, Utah were evaluated.
During the year after longwall mining, 0.3–1.5 m of subsidence was measured near impacted reaches of the mountain stream channel.
The major channel changes that occurred in a 700-m reach of Burnout Creek that was subsided from 1992 to 1993 were: (1) increase
in lengths of cascades and to a lesser extent glides; (2) increases in pool length, numbers and volumes; (3) increase in median
particle diameter of bed sediment in pools; and (4) some constriction in channel geometry. Most of the changes appeared short-lived,
with channel recovery approaching pre-mining conditions by 1994. In a 300-m reach of the South Fork that was subsided from
1993 to 1994, only channel constriction was observed, although any impacts on pool morphology may have been confounded by
heavy grazing in the riparian reaches during the dry summer of 1994. Similar near-channel sedimentation and loss of pool volume
between 1993 and 1994 were noted throughout Burnout Creek and in adjacent, unmined James Creek. Subsidence during the 3-year
period had no effect on baseflows or near-channel landslides.
Received: 10 April 1998 · Accepted: 21 September 1998 相似文献
15.
Toxic metal contamination in the lateral lakes of the Coeur d'Alene River valley, Idaho 总被引:3,自引:0,他引:3
K.F. Sprenke W.C. Rember S.F. Bender M.L. Hoffmann F. Rabbi V.E. Chamberlain 《Environmental Geology》2000,39(6):575-586
The 11 lateral lakes of Coeur d'Alene River valley in northern Idaho have received heavy metal contamination from over a
century of upstream mining. The lateral lakes lie within the flood plain of the Coeur d'Alene River, and in their bottom sediments
is preserved a stratigraphic record of the upstream mining operations. To characterize the contaminated sediments in the lateral
lakes, sampling techniques, including the Livingston piston corer and the Huttenen freeze box, have been developed by Quaternary
geologists to preserve the vertical stratigraphy in the samples. From 26 cm to over 55 cm of undisturbed tailing sediments,
commonly with “varve-like” features, have been found in each of the lateral lakes, with maximum concentrations by weight of
lead at 3.8%, zinc at 3.4%, arsenic at 340 mg/kg, cadmium at 120 mg/kg and mercury at 7 mg/kg. The contamination in the lakes
appears to be restricted to the shallow subsurface and heavy metal concentrations generally drop to background levels within
a meter of depth.
Received: 22 May 1998 · Accepted: 21 September 1998 相似文献
16.
Land-use changes on the Sheyenne Delta in southeastern North Dakota, USA, have prompted research on impacts to the unconfined
Sheyenne Delta aquifer (SDA). This study examines effects of the saline discharge of a flowing artesian well that taps the
Dakota aquifer (DAK) on SDA groundwater chemistry and soil salinity. Objectives were to map the saline plume in the SDA using
induction techniques, to assess chloride migration in the SDA, and to evaluate induction sensitivity to moderately saline
sands. Induction data, collected in a 2.9-ha grid, were compared to 31 soil profiles analyzed for gravimetric moisture, electrical
conductivity, and chloride. Soil salinization is widespread, but only 7% of the area meets the 4-dS/m threshold for saline
soils. SDA chloride distribution was determined on transects oriented with and perpendicular to the flow path determined from
induction readings. Chloride was detected in the aquifer 550 m from the source, indicating a transport rate of 21 m/yr. Complex
recharge and discharge patterns and hummocky relief contribute to a wide chloride plume at this site. A mass balance based
on soil-water content and chloride concentration shows that only 4% of the chloride from the DAK well remains in the grid
volume.
Received, January 1998 · Revised, January 1999 · Accepted, March 1999 相似文献
17.
B. J. M. Goes 《Hydrogeology Journal》1999,7(3):294-304
The Hadejia–Nguru Wetlands are annually inundated flood plains in semi-arid northeastern Nigeria. The area has a unique ecosystem
that forms a natural barrier against the encroachment of the Sahara desert. Both the rich wetland vegetation and local farmers
using shallow tube wells depend on a groundwater mound (with a water table less than 6 m below the surface) that is present
in the unconfined aquifer under the flood-plain area. Using well records (1991–97) and a hydrogeologic profile based on piezometers
that were monitored for two years, it is shown that recharge through the annually inundated flood plains is the source of
the groundwater mound. Maintenance of the groundwater-recharge function of the flood plains depends on wet-season releases
from two large upstream dams. On the basis of a water-budget method, the mean (1991–97) wet-season unconfined groundwater
recharge in the flood-plain area between Hadejia and Nguru and in the immediate vicinity (1250 km2) is estimated to be 132 mm (range, 73–197 mm). Outflow from the unconfined flood-plain aquifer to the unconfined upland aquifer
is approximately 10% of the wet-season flood-plain recharge. The unconfined groundwater outflow from the flood-plain area
can provide a significant contribution to the present-day rural water supply in the surrounding uplands, but it does not offer
much potential for additional groundwater abstraction. In addition to outflow to the upland aquifer (∼14 mm), the distribution
of the annually recharged water volume of the shallow flood-plain aquifer is (1) domestic uses (3 mm), (2) small-scale irrigation
(∼15 mm), and (3) evapotranspiration ( 1 100 mm). Along the hydrogeologic profile, the recharge in the upland (i.e., outflow
from the unconfined flood-plain aquifer and possibly diffuse rain-fed recharge) is in balance with the water uses (i.e., domestic
uses, groundwater outflow, and evapotranspiration). The absence of a seasonal water-level trend in the two piezometers in
the upland indicates that no rain-fed recharge occurs through preferential path-way (macropore) flow.
Received, June 1998 / Revised, November 1998, January 1999 / Accepted, January 1999 相似文献
18.
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
19.
Patterns in groundwater chemistry resulting from groundwater flow 总被引:18,自引:7,他引:11
Pieter J. Stuyfzand 《Hydrogeology Journal》1999,7(1):15-27
Groundwater flow influences hydrochemical patterns because flow reduces mixing by diffusion, carries the chemical imprints
of biological and anthropogenic changes in the recharge area, and leaches the aquifer system. Global patterns are mainly dictated
by differences in the flux of meteoric water passing through the subsoil. Within individual hydrosomes (water bodies with
a specific origin), the following prograde evolution lines (facies sequence) normally develop in the direction of groundwater
flow: from strong to no fluctuations in water quality, from polluted to unpolluted, from acidic to basic, from oxic to anoxic–methanogenic,
from no to significant base exchange, and from fresh to brackish. This is demonstrated for fresh coastal-dune groundwater
in the Netherlands. In this hydrosome, the leaching of calcium carbonate as much as 15 m and of adsorbed marine cations (Na+, K+, and Mg2+) as much as 2500 m in the flow direction is shown to correspond with about 5000 yr of flushing since the beach barrier with
dunes developed. Recharge focus areas in the dunes are evidenced by groundwater displaying a lower prograde quality evolution
than the surrounding dune groundwater. Artificially recharged Rhine River water in the dunes provides distinct hydrochemical
patterns, which display groundwater flow, mixing, and groundwater ages.
Received, May 1998 · Revised, August 1998 · Accepted, October 1998 相似文献
20.
Salt-water intrusion and nitrate contamination in the Valley of Hermosillo and El Sahuaral coastal aquifers, Sonora, Mexico 总被引:1,自引:0,他引:1
The Valley of Hermosillo coastal aquifer, state of Sonora, northwestern Mexico, has been over-exploited for the last four
decades, in order to maintain agricultural activity in one of the most important irrigation districts of the Mexican Republic.
The over-exploitation has resulted in the development of several drawdown cones and in the lowering of the water table to
as much as 50 m below mean sea level. Contamination of the aquifer in the form of salt-water intrusion from the Gulf of California
and high nitrate concentrations is the consequence of human activities. A hydrogeochemical zonation of the aquifer, based
on the presence of different water families, led to the identification of a coastal band approximately 30 km wide that is
affected by salt-water intrusion. Conductivity of the sampled water and the interpretation of the ratio Na/Cl×1000 was used
to identify the location of three major intrusion plumes in this coastal band. The background nitrate contamination of the
aquifer is about 4 ppm, but contents as great as about 17 ppm occur in some wells. Irrigation with raw sewage and movement
of contaminants in areas of high hydraulic gradients within the drawdown cones probably are responsible for localized peaks
of the nitrate concentration.
Received, October 1996 Revised, September 1997, May 1998 Accepted, July 1998 相似文献