Shallow groundwater flow and inverted fresh/saline-water interface in a hypersaline endorheic basin (Great Basin, USA)

AbstractPilot Valley is an 828-km2 arid-region endorheic basin in western USA. Bounding mountain ranges rise as much as 1,900 m above the nearly flat 379-km2 playa floor. Up to 3.8 m of Pleistocene Lake Bonneville mud and thin oolitic sand layers form the surface layer of the basin floor. Groundwater conditions were evaluated using data from shallow monitoring wells and borings, springs, infiltrometer measurements, slug and dilution tests, geophysical transects, and precision elevation surveys. Alluvial fan groundwater discharges at fan/playa interface springs and underflows to the shallow basin sediments along the western side of the basin; the groundwater only underflows along the eastern side. Precision surveying established a Lake Bonneville shore-line break in slope as the cause of the spring discharges. Tectonic tilting causes groundwater to flow from east to west and to the topographic low. Monthly measured and pressure transducer data established seasonal pressure responses and upward groundwater gradients. All basin groundwater is lost to evapotranspiration at the topographic low, where a thin salt pan has developed. Groundwater evolves from fresh to hypersaline near the alluvial fan/playa interface where there is an inverted salinity gradient and a groundwater pressure ridge. The pressure ridge and inverted salinity interface are due to: (1) osmotic pressure established between the oolitic sand of high hydraulic conductivity and the overlying low-hydraulic-conductivity lake mud at the fan/playa interface, and (2) the collision between fresh groundwater flow driven by a steep hydraulic head and hypersaline groundwater flow driven by a nearly flat hydraulic head.

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Forward Problems Solving of Groundwater Flow using Stochastic Groundwater Vistas Method

Jurnal Lahan Suboptimal ◽

10.36706/jlso.10.2.2021.525 ◽

2021 ◽

Vol 10 (2) ◽

pp. 160-169

Author(s):

Pramudita Triatmojo ◽

Mas Agus Mardyanto

Keyword(s):

Hydraulic Conductivity ◽

Groundwater Flow ◽

Physical Model ◽

Small Difference ◽

Simulation Method ◽

Stochastic Approach ◽

Hydraulic Head ◽

Scatter Plot ◽

Forward Problems ◽

Groundwater Vistas

In the forward problems, the hydraulic head value can be found by knowing the value of the groundwater parameter. Parameters of groundwater such as hydraulic conductivity, vary over space due to the variation of aquifer properties. Consequently, it is difficult or almost impossible to treat these kinds of variability by a deterministic approach because there is no exact value to be used as input for a parameter. The objective of this research was to obtain a mathematical model of groundwater flow made with the Groundwater Vistas Program that is in accordance with the physical model. Mathematical modeling of groundwater flow using the Groundwater Vistas Program with a stochastic approach and Monte Carlo simulation method where the input data (hydraulic conductivity, hydraulic head) is obtained from the physical model. Results showed that the sum of squares value from the scatter plot diagram of all realization points had a very small value (close to or even zero). The residual mean diagram showed the error value of all realizations had a very low value close to zero. The calculated head value (computed) compared with the results of the observation had a fairly small difference value (ranging from 0.0006−0.009 m). These results were considered quite good because in modeling it is impossible to get modeling results that are exactly the same as those being modeled. The results show that Groundwater Vistas can be used for modeling with very small errors and it can estimate values of hydraulic heads quite well.

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Numerical modeling of saline water transport in the lower Nam Kam Basin, Amphoe That Phanom, Changwat Nakhon Phanom, Thailand

Water Science & Technology ◽

10.2166/wst.2001.0414 ◽

2001 ◽

Vol 44 (7) ◽

pp. 157-157

Author(s):

K. Srisuk ◽

V. Sribooniue ◽

C. Buaphan ◽

L. Archvichai ◽

W. Youngme ◽

...

Keyword(s):

Hydraulic Conductivity ◽

Groundwater Flow ◽

Water Transport ◽

Saline Water ◽

Numerical Technique ◽

Ground Surface ◽

Northern Region ◽

Vertical Hydraulic Conductivity ◽

Longitudinal Dispersivity ◽

The Impact

The objective of the project is to establish a conceptual groundwater model over the lower Nam Kam Basin in order to apply a numerical technique for the prediction of the impact of saline water transport due to the proposed weir across the Nam Kam River. Hydrogeological investigations including mapping, drilling, piezometer installations and monitoring were systematically conducted during 1997 to 1998. Brackish groundwater is saturated under the area with a depth of 30-60 m. Groundwater regionally flows from the south (the Phu Phan Range) to the north and discharges to the Nam Kam River. Another direction is from the northern region to the southern region, discharging to the central region. A two-dimensional model was constructed along the principal gradient in the NW-SE direction. There are several local recharge and discharge areas across the Nam Kam floodplain. A local groundwater flow is active within the depth of 2 m to 30 m below the ground surface within the sand and gravel unit. Simulations were calibrated with hydraulic heads and salinity of groundwater in the piezometers. It is found that the recharge and evapotranspiration rates are 1% to 40% of the rainfall and 10% to 15% of a pan evaporation, respectively. The ranges of horizontal hydraulic conductivity to vertical hydraulic conductivity are 0.1 to 0.01. The possible longitudinal dispersivity values of the hydrostratigraphic units are 20 m to 500 m, but the transverse dispersivity is less than the longitude by one order of magnitude. The comparison of calculated heads and measured heads give a root mean square error of less than 1 m. The different salinity concentrations are still in a range of 2000 - 5000 mg/l. Ten year simulation of saline water transport indicates that the reservoir ponding with water level at +140.5 m above mean sea level may divert groundwater flow and discharging to the northern boundary of the reservoir at Ban Don Kao.

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Shallow groundwater chemical evolution, isotopic hyperfiltration, and salt pan formation in a hypersaline endorheic basin: Pilot Valley, Great Basin, USA

Hydrogeology Journal ◽

10.1007/s10040-021-02371-7 ◽

2021 ◽

Author(s):

A. L. Mayo ◽

D. G. Tingey

Keyword(s):

Great Basin ◽

Chemical Evolution ◽

Isotopic Fractionation ◽

Shallow Groundwater ◽

Alluvial Fan ◽

Mineral Dissolution ◽

Driving Mechanism ◽

Evaporative Water ◽

Salt Pan ◽

Endorheic Basin

AbstractEndorheic basin brines are of economic significance as sources of boron, iodine, magnesium, potassium, sodium sulfate, sodium carbonate, and tungsten, and they are a major source of the critical metal lithium. Although evaporation is the primary hypersalinization driver for evaporative water bodies, recent investigations have proposed more novel mechanisms for some subsurface brine. This investigation explores shallow groundwater hypersalinization. The chemical evolution and isotopic fractionation of shallow hypersaline groundwater in the clay-rich arid endorheic basin sediments of Pilot Valley, Great Basin (USA), were investigated. Groundwater evolves from fresh in the mountain bedrock and alluvial fans, to brackish and saline at the alluvial fan–playa interface, and to hypersaline in the upper 12 m of basin sediments. Alluvial fan systems are isolated from each other and have varying groundwater 3H and 14C travel times. Nonevaporative in-situ isotopic fractionation of up to −8‰ in δ18O is attributed to clay sequence hyperfiltration. Groundwater flow-path sulfate and chloride mineral dissolution is the primary driving mechanism for both interface and basin groundwater evolution. Evaporation only impacts the groundwater quality in a small portion of the basin where the groundwater is within ~1 m of the ground surface. Here capillary action carries dissolved soluble salts to the land surface. Episodic flooding redissolves and carries the precipitated salt to the annually flooded salt pan where it accumulates as a salt crust during the dry season. The Pilot Valley model may help explain the buildup accumulative layers of soluble salt that when remobilized becomes subsurface brine.

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Effects of Decaying Hydraulic Conductivity on the Groundwater Flow Processes in a Managed Aquifer Recharge Area in an Alluvial Fan

Water ◽

10.3390/w13121649 ◽

2021 ◽

Vol 13 (12) ◽

pp. 1649

Author(s):

Peipeng Wu ◽

Lijuan Zhang ◽

Bin Chang ◽

Shuhong Wang

Keyword(s):

Hydraulic Conductivity ◽

Groundwater Flow ◽

Artificial Recharge ◽

Managed Aquifer Recharge ◽

Alluvial Fan ◽

Travel Times ◽

Aquifer Recharge ◽

Recharge Area ◽

Flow Processes ◽

Ambient Groundwater

Groundwater artificial recharge and medium characteristics represent the major factors in controlling the groundwater flow processes in managed aquifer recharge areas. According to the depositional features of alluvial fans, an analogous homogeneous phreatic sand tank aquifer and the corresponding inhomogeneous scale numerical models were established to investigate the groundwater flow under the combined influence of artificial recharge (human activities) and decaying hydraulic conductivity (medium characteristics). In this study, groundwater flow through a managed aquifer recharge area in an alluvial fan was analyzed under the conditions of decaying hydraulic conductivity (K) with depth or length from apex to apron. The results showed that groundwater flow processes induced by artificial recharge were significantly controlled by the increasing decay exponents of K. The decaying K with depth or length in alluvial fan areas expanded the degree of influence of artificial recharge on groundwater flow. With the increase of decay exponents, the flow directions gradually changed from a horizontal to vertical direction. Groundwater age and spatial variability could also be increased by the increasing decay exponents. The residence time distributions (RTDs) of ambient groundwater and artificially recharged water exhibited logarithmic, exponential, and power law behavior. Penetration depth and travel times of ambient groundwater flow could be affected by artificial recharge and decay exponents. Furthermore, with the increase of decay exponents, the thickness of the artificially recharged water lens and travel times of artificially recharged water were increased. These findings have important implications for the performance of managed aquifer recharge in alluvial fan areas as well as the importance of considering the gradual decrease of K with depth and length.

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MODELING CLIMATE CONSTRAINTS ON THE FORMATION OF PLUVIAL LAKE BONNEVILLE IN THE GREAT BASIN, USA

10.1130/abs/2019ne-328050 ◽

2019 ◽

Author(s):

Bryce K. Belanger ◽

◽

William H. Amidon ◽

Benjamin Laabs ◽

Jeffrey S. Munroe

Keyword(s):

Great Basin ◽

Lake Bonneville

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Transboundary geophysical mapping of geological elements and salinity distribution critical for the assessment of future sea water intrusion in response to sea level rise

Hydrology and Earth System Sciences ◽

10.5194/hess-16-1845-2012 ◽

2012 ◽

Vol 16 (7) ◽

pp. 1845-1862 ◽

Cited By ~ 55

Author(s):

F. Jørgensen ◽

W. Scheer ◽

S. Thomsen ◽

T. O. Sonnenborg ◽

K. Hinsby ◽

...

Keyword(s):

Groundwater Flow ◽

Sea Level Rise ◽

Sea Level ◽

Preferential Flow ◽

Sea Water ◽

Saline Water ◽

Seismic Survey ◽

Salinity Distribution ◽

Geological Structures ◽

The North

Abstract. Geophysical techniques are increasingly being used as tools for characterising the subsurface, and they are generally required to develop subsurface models that properly delineate the distribution of aquifers and aquitards, salt/freshwater interfaces, and geological structures that affect groundwater flow. In a study area covering 730 km2 across the border between Germany and Denmark, a combination of an airborne electromagnetic survey (performed with the SkyTEM system), a high-resolution seismic survey and borehole logging has been used in an integrated mapping of important geological, physical and chemical features of the subsurface. The spacing between flight lines is 200–250 m which gives a total of about 3200 line km. About 38 km of seismic lines have been collected. Faults bordering a graben structure, buried tunnel valleys, glaciotectonic thrust complexes, marine clay units, and sand aquifers are all examples of geological structures mapped by the geophysical data that control groundwater flow and to some extent hydrochemistry. Additionally, the data provide an excellent picture of the salinity distribution in the area and thus provide important information on the salt/freshwater boundary and the chemical status of groundwater. Although the westernmost part of the study area along the North Sea coast is saturated with saline water and the TEM data therefore are strongly influenced by the increased electrical conductivity there, buried valleys and other geological elements are still revealed. The mapped salinity distribution indicates preferential flow paths through and along specific geological structures within the area. The effects of a future sea level rise on the groundwater system and groundwater chemistry are discussed with special emphasis on the importance of knowing the existence, distribution and geometry of the mapped geological elements, and their control on the groundwater salinity distribution is assessed.

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Geological and groundwater flow model of a submarine groundwater discharge site at Hanko (Finland), northern Baltic Sea

Hydrogeology Journal ◽

10.1007/s10040-021-02313-3 ◽

2021 ◽

Author(s):

Samrit Luoma ◽

Juha Majaniemi ◽

Arto Pullinen ◽

Juha Mursu ◽

Joonas J. Virtasalo

Keyword(s):

Hydraulic Conductivity ◽

Groundwater Flow ◽

Baltic Sea ◽

Submarine Groundwater Discharge ◽

Flow Model ◽

Groundwater Discharge ◽

Coarse Grained ◽

Local Geometry ◽

Groundwater Flow Model ◽

Submarine Groundwater

AbstractThree-dimensional geological and groundwater flow models of a submarine groundwater discharge (SGD) site at Hanko (Finland), in the northern Baltic Sea, have been developed to provide a geological framework and a tool for the estimation of SGD rates into the coastal sea. The dataset used consists of gravimetric, ground-penetrating radar and shallow seismic surveys, drill logs, groundwater level monitoring data, field observations, and a LiDAR digital elevation model. The geological model is constrained by the local geometry of late Pleistocene and Holocene deposits, including till, glacial coarse-grained and fine-grained sediments, post-glacial mud, and coarse-grained littoral and aeolian deposits. The coarse-grained aquifer sediments form a shallow shore platform that extends approximately 100–250 m offshore, where the unit slopes steeply seawards and becomes covered by glacial and post-glacial muds. Groundwater flow preferentially takes place in channel-fill outwash coarse-grained sediments and sand and gravel interbeds that provide conduits of higher hydraulic conductivity, and have led to the formation of pockmarks on the seafloor in areas of thin or absent mud cover. The groundwater flow model estimated the average SGD rate per square meter of the seafloor at 0.22 cm day−1 in autumn 2017. The average SGD rate increased to 0.28 cm day−1 as a response to an approximately 30% increase in recharge in spring 2020. Sensitivity analysis shows that recharge has a larger influence on SGD rate compared with aquifer hydraulic conductivity and the seafloor conductance. An increase in recharge in this region will cause more SGD into the Baltic Sea.

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Quantitative investigations of the hydraulic connection between a large reservoir and a buried valley aquifer in southern Alberta

Canadian Geotechnical Journal ◽

10.1139/t05-065 ◽

2005 ◽

Vol 42 (5) ◽

pp. 1461-1473 ◽

Cited By ~ 1

Author(s):

B D Smerdon ◽

C A Mendoza ◽

A M McCann

Keyword(s):

Groundwater Flow ◽

Flow Model ◽

Hydraulic Head ◽

Water Levels ◽

Groundwater Flow Model ◽

Reservoir Level ◽

Hydraulic Connection ◽

Southern Alberta ◽

Approximate Location ◽

Pumping Rates

Quantitative investigations, including two aquifer tests and development of a three-dimensional (3D) groundwater flow model, were required to determine the hydraulic connection between an irrigation reservoir and a buried valley aquifer in southern Alberta. Evidence of seepage was detected in the buried valley aquifer 10 km east of the Pine Coulee reservoir at the onset of filling in 1999, when the reservoir level exceeded an elevation of 1035 m above sea level (a.s.l.). Concern for an increase in the local water table and the creation of artesian conditions in the aquifer prompted this study to determine the approximate location of a seepage window that appeared to be connecting the reservoir and aquifer. Observations of hydraulic head in the aquifer during the pumping tests revealed a barrier boundary when the reservoir level was at an elevation of 1035 m a.s.l. and a recharge boundary condition when the elevation exceeded 1039 m a.s.l. These data were used to calibrate a 3D groundwater flow model, which was needed to determine the hydraulic properties and approximate location of the leakage zone. The quantitative investigation showed that seepage likely occurred through the sideslopes of the flooded coulee, rather than through the low-permeability coulee floor sediments or the embankment dam. Further simulations illustrated the expected seepage rates at various reservoir supply levels and the pumping rates required for relief wells installed in the buried valley aquifer to maintain historic aquifer hydraulic head. A brief postanalysis indicated that the forecasted pumping rates were only 15% lower than have been required to maintain preconstruction water levels in the buried valley aquifer.Key words: dams, seepage analysis, groundwater modelling, buried valley aquifer, pumping test.

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