651
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Baloch MA. Groundwater vulnerability assessments: prioritizing water safety in times of austerity. JOURNAL OF ENVIRONMENTAL HEALTH 2013; 76:40-42. [PMID: 24341160 PMCID: PMC4809351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
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652
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Weber S, Chapuis RP. Interpretation of a pumping test with interference from a neighboring well. GROUND WATER 2013; 51:935-944. [PMID: 23289743 DOI: 10.1111/gwat.12014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In confined aquifers, the influence of neighboring active wells is often neglected when interpreting a pumping test. This can, however, lead to an erroneous interpretation of the pumping test data. This paper presents simple methods to evaluate the transmissivity (T) and storativity (S) of a confined aquifer under Theis conditions, when an interfering well starts pumping in the neighborhood of the tested well before the beginning of the test. These new methods yield better estimates of the T and especially S values than when the interfering well influence is neglected. They also permit to distinguish between interfering wells and other deviations from the Cooper-Jacob straight line, such as impermeable boundaries. The new methods were then applied on data obtained from a numerical model. The new methods require knowing the pumping rate of the interfering well and the time elapsed since the pumping started in each well, but contrary to previous methods, they do not require the aquifer natural level at the beginning of the test, which is often unknown if the interfering well has started pumping before the tested well.
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653
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Garabedian SP. Estimation of salt water upconing using a steady-state solution for partial completion of a pumped well. GROUND WATER 2013; 51:927-934. [PMID: 23336341 DOI: 10.1111/gwat.12013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A new steady-state analytical solution to the two-dimensional radial-flow equation was developed for drawdown (head) conditions in an aquifer with constant transmissivity, no-flow conditions at the top and bottom, constant head conditions at a known radial distance, and a partially completed pumping well. The solution was evaluated for accuracy by comparison to numerical simulations using MODFLOW. The solution was then used to estimate the rise of the salt water-fresh water interface (upconing) that occurs under a pumping well, and to calculate the critical pumping rate at which the interface becomes unstable, allowing salt water to enter the pumping well. The analysis of salt water-fresh water interface rise assumed no significant effect on upconing by recharge; this assumption was tested and supported using results from a new steady-state analytical solution developed for recharge under two-dimensional radial-flow conditions. The upconing analysis results were evaluated for accuracy by comparison to those from numerical simulations using SEAWAT for salt water-fresh water interface positions under mild pumping conditions. The results from the equation were also compared with those of a published numerical sharp-interface model applied to a case on Cape Cod, Massachusetts. This comparison indicates that estimating the interface rise and maximum allowable pumping rate using the analytical method will likely be less conservative than the maximum allowable pumping rate and maximum stable interface rise from a numerical sharp-interface model.
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654
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Weeks EP, Clark AC. Evaluation of near-critical overdamping effects in slug-test response. GROUND WATER 2013; 51:775-780. [PMID: 23163489 DOI: 10.1111/j.1745-6584.2012.01012.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A slug test behaves as a harmonic oscillator, subject to both inertial effects and viscous damping. When viscous and inertial forces are closely balanced, the system is nearly critically damped, and water-level recovery is affected by inertial effects, but does not exhibit oscillation. These effects were investigated by use of type curves, generated both by modification of Kipp's (1985) computer program and by use of the Butler-Zhan (2004) model. Utility of the type curves was verified by re-analysis of the Regina slug test previously analyzed by Kipp. These type curves indicate that near-critical inertial effects result in early-time delayed water-level response followed by merger with, or more rapid recovery than, response for the fully damped case. Because of this early time response, slug tests in the moderately over-damped range are best analyzed using log-log type curves of (1 - H/H(0)) vs. Tt/r(2c). Failure to recognize inertial effects in slug test data could result in an over-estimate of transmissivity, and a too-small estimate of storage coefficient or too-large estimate of well skin. However, application of the widely used but highly empirical Hvorslev (1951) method to analyze both the Regina slug test and type-curve generated data indicate that such analyses provide T values within a factor of 2 of the true value.
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655
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Langevin CD, Zygnerski M. Effect of sea-level rise on salt water intrusion near a coastal well field in southeastern Florida. GROUND WATER 2013; 51:781-803. [PMID: 23145832 DOI: 10.1111/j.1745-6584.2012.01008.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A variable-density groundwater flow and dispersive solute transport model was developed for the shallow coastal aquifer system near a municipal supply well field in southeastern Florida. The model was calibrated for a 105-year period (1900 to 2005). An analysis with the model suggests that well-field withdrawals were the dominant cause of salt water intrusion near the well field, and that historical sea-level rise, which is similar to lower-bound projections of future sea-level rise, exacerbated the extent of salt water intrusion. Average 2005 hydrologic conditions were used for 100-year sensitivity simulations aimed at quantifying the effect of projected rises in sea level on fresh coastal groundwater resources near the well field. Use of average 2005 hydrologic conditions and a constant sea level result in total dissolved solids (TDS) concentration of the well field exceeding drinking water standards after 70 years. When sea-level rise is included in the simulations, drinking water standards are exceeded 10 to 21 years earlier, depending on the specified rate of sea-level rise.
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656
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Williams DE. Drawdown distribution in the vicinity of nonvertical wells. GROUND WATER 2013; 51:745-751. [PMID: 23216076 DOI: 10.1111/gwat.12000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Recent developments in subsurface intake systems for ocean desalination plants are considering use of angled wells (slant wells) completed in permeable materials beneath the ocean floor. Conventional drawdown equations for vertical or horizontal wells are inadequate to properly describe the drawdown distribution in the vicinity of slant wells. Using the principle of superposition combined with standard well hydraulics, universal drawdown equations (UDE) are presented which calculate the drawdown distribution in the vicinity of production wells with inclination angles ranging from 0° (horizontal wells) to 90° (vertical wells). The method is computationally simple and other than the normal assumptions for standard well equations, it only requires that the calculated drawdown represent the drawdown which would be measured in a fully penetrating observation well. Solutions using the UDE are developed for confined, unconfined and semi-confined (leaky) aquifers and compared with analytical equations for vertical and horizontal wells, and with a numerical model for slant wells. The UDE is also applied to pumping test data from the Dana Point slant well project in Southern California.
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657
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Jin Y, Yang H, Wei Z, Ma H, Ge X. Rice male development under drought stress: phenotypic changes and stage-dependent transcriptomic reprogramming. MOLECULAR PLANT 2013; 6:1630-45. [PMID: 23604203 DOI: 10.1093/mp/sst067] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Drought affects rice reproduction and results in severe yield loss. The developmental defects and changes of gene regulation network in reproductive tissues under drought stress are largely unknown. In this study, rice plants subjected to reproductive stage drought stress were examined for floral development and transcriptomic changes. The results showed that male fertility was dramatically affected, with differing pollen viability in flowers of the same panicle due to aberrant anther development under water stress. Examination of local starch distribution revealed that starch accumulated abnormally in terms of position and abundance in anthers of water-stressed plants. Microarray analysis using florets of different sizes identified >1000 drought-responsive genes, most of which were specifically regulated in only one or two particular sizes of florets, suggesting developmental stage-dependent responses to drought. Genes known to be involved in tapetum and/or microspore development, cell wall formation or expansion, and starch synthesis were found more frequently among the genes affected by drought than genome average, while meiosis and MADS-box genes were less frequently affected. In addition, pathways related to gibberellin acid signaling and abscisic acid catabolism were reprogrammed by drought. Our results strongly suggest interactions between reproductive development, phytohormone signaling, and carbohydrate metabolism in water-stressed plants.
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658
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Kato M, Kumasaka MY, Ohnuma S, Furuta A, Kato Y, Shekhar HU, Kojima M, Koike Y, Dinh Thang N, Ohgami N, Ly TB, Jia X, Yetti H, Naito H, Ichihara G, Yajima I. Comparison of Barium and Arsenic Concentrations in Well Drinking Water and in Human Body Samples and a Novel Remediation System for These Elements in Well Drinking Water. PLoS One 2013; 8:e66681. [PMID: 23805262 PMCID: PMC3689667 DOI: 10.1371/journal.pone.0066681] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 05/09/2013] [Indexed: 01/12/2023] Open
Abstract
Health risk for well drinking water is a worldwide problem. Our recent studies showed increased toxicity by exposure to barium alone (≤700 µg/L) and coexposure to barium (137 µg/L) and arsenic (225 µg/L). The present edition of WHO health-based guidelines for drinking water revised in 2011 has maintained the values of arsenic (10 µg/L) and barium (700 µg/L), but not elements such as manganese, iron and zinc. Nevertheless, there have been very few studies on barium in drinking water and human samples. This study showed significant correlations between levels of arsenic and barium, but not its homologous elements (magnesium, calcium and strontium), in urine, toenail and hair samples obtained from residents of Jessore, Bangladesh. Significant correlation between levels of arsenic and barium in well drinking water and levels in human urine, toenail and hair samples were also observed. Based on these results, a high-performance and low-cost adsorbent composed of a hydrotalcite-like compound for barium and arsenic was developed. The adsorbent reduced levels of barium and arsenic from well water in Bangladesh and Vietnam to <7 µg/L within 1 min. Thus, we have showed levels of arsenic and barium in humans and propose a novel remediation system.
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659
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Allevi RP, Krometis LAH, Hagedorn C, Benham B, Lawrence AH, Ling EJ, Ziegler PE. Quantitative analysis of microbial contamination in private drinking water supply systems. JOURNAL OF WATER AND HEALTH 2013; 11:244-55. [PMID: 23708572 DOI: 10.2166/wh.2013.152] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Over one million households rely on private water supplies (e.g. well, spring, cistern) in the Commonwealth of Virginia, USA. The present study tested 538 private wells and springs in 20 Virginia counties for total coliforms (TCs) and Escherichia coli along with a suite of chemical contaminants. A logistic regression analysis was used to investigate potential correlations between TC contamination and chemical parameters (e.g. NO3(-), turbidity), as well as homeowner-provided survey data describing system characteristics and perceived water quality. Of the 538 samples collected, 41% (n = 221) were positive for TCs and 10% (n = 53) for E. coli. Chemical parameters were not statistically predictive of microbial contamination. Well depth, water treatment, and farm location proximate to the water supply were factors in a regression model that predicted presence/absence of TCs with 74% accuracy. Microbial and chemical source tracking techniques (Bacteroides gene Bac32F and HF183 detection via polymerase chain reaction and optical brightener detection via fluorometry) identified four samples as likely contaminated with human wastewater.
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660
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Heaney CD, Wing S, Wilson SM, Campbell RL, Caldwell D, Hopkins B, O'Shea S, Yeatts K. Public infrastructure disparities and the microbiological and chemical safety of drinking and surface water supplies in a community bordering a landfill. JOURNAL OF ENVIRONMENTAL HEALTH 2013; 75:24-36. [PMID: 23858663 PMCID: PMC4514614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The historically African-American Rogers-Eubanks community straddles unincorporated boundaries of two municipalities in Orange County, North Carolina, and predates a regional landfill sited along its border in 1972. Community members from the Rogers-Eubanks Neighborhood Association (RENA), concerned about deterioration of private wells and septic systems and a lack of public drinking water and sewer services, implemented a community-driven research partnership with university scientists and community-based organizations to investigate water and sewer infrastructure disparities and the safety of drinking and surface water supplies. RENA drafted memoranda of agreement with partners and trained community monitors to collect data (inventory households, map water and sewer infrastructure, administer household water and sewer infrastructure surveys, and collect drinking and surface water samples). Respondents to the surveys reported pervasive signs of well vulnerability (100%) and septic system failure (68%). Each 100-m increase in distance from the landfill was associated with a 600 most probable number/100 mL decrease in enterococci concentrations in surface water (95% confidence interval = -1106, -93). Pervasive private household water and sewer infrastructure failures and poor water quality were identified in this community bordering a regional landfill, providing evidence of a need for improved water and sanitation services.
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661
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Garcia CA, Halford KJ, Fenelon JM. Detecting drawdowns masked by environmental stresses with water-level models. GROUND WATER 2013; 51:322-332. [PMID: 23469925 PMCID: PMC3675638 DOI: 10.1111/gwat.12042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 01/23/2013] [Indexed: 06/01/2023]
Abstract
Detecting and quantifying small drawdown at observation wells distant from the pumping well greatly expands the characterized aquifer volume. However, this detection is often obscured by water level fluctuations such as barometric and tidal effects. A reliable analytical approach for distinguishing drawdown from nonpumping water-level fluctuations is presented and tested here. Drawdown is distinguished by analytically simulating all pumping and nonpumping water-level stresses simultaneously during the period of record. Pumping signals are generated with Theis models, where the pumping schedule is translated into water-level change with the Theis solution. This approach closely matched drawdowns simulated with a complex three-dimensional, hypothetical model and reasonably estimated drawdowns from an aquifer test conducted in a complex hydrogeologic system. Pumping-induced changes generated with a numerical model and analytical Theis model agreed (RMS as low as 0.007 m) in cases where pumping signals traveled more than 1 km across confining units and fault structures. Maximum drawdowns of about 0.05 m were analytically estimated from field investigations where environmental fluctuations approached 0.2 m during the analysis period.
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662
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Molofsky LJ, Connor JA, Wylie AS, Wagner T, Farhat SK. Evaluation of methane sources in groundwater in northeastern Pennsylvania. GROUND WATER 2013; 51:333-49. [PMID: 23560830 PMCID: PMC3746116 DOI: 10.1111/gwat.12056] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Accepted: 02/26/2013] [Indexed: 05/10/2023]
Abstract
Testing of 1701 water wells in northeastern Pennsylvania shows that methane is ubiquitous in groundwater, with higher concentrations observed in valleys vs. upland areas and in association with calcium-sodium-bicarbonate, sodium-bicarbonate, and sodium-chloride rich waters--indicating that, on a regional scale, methane concentrations are best correlated to topographic and hydrogeologic features, rather than shale-gas extraction. In addition, our assessment of isotopic and molecular analyses of hydrocarbon gases in the Dimock Township suggest that gases present in local water wells are most consistent with Middle and Upper Devonian gases sampled in the annular spaces of local gas wells, as opposed to Marcellus Production gas. Combined, these findings suggest that the methane concentrations in Susquehanna County water wells can be explained without the migration of Marcellus shale gas through fractures, an observation that has important implications for understanding the nature of risks associated with shale-gas extraction.
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663
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Blouin M, Martel R, Gloaguen E. Accounting for aquifer heterogeneity from geological data to management tools. GROUND WATER 2013; 51:421-431. [PMID: 22924605 DOI: 10.1111/j.1745-6584.2012.00982.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A nested workflow of multiple-point geostatistics (MPG) and sequential Gaussian simulation (SGS) was tested on a study area of 6 km(2) located about 20 km northwest of Quebec City, Canada. In order to assess its geological and hydrogeological parameter heterogeneity and to provide tools to evaluate uncertainties in aquifer management, direct and indirect field measurements are used as inputs in the geostatistical simulations to reproduce large and small-scale heterogeneities. To do so, the lithological information is first associated to equivalent hydrogeological facies (hydrofacies) according to hydraulic properties measured at several wells. Then, heterogeneous hydrofacies (HF) realizations are generated using a prior geological model as training image (TI) with the MPG algorithm. The hydraulic conductivity (K) heterogeneity modeling within each HF is finally computed using SGS algorithm. Different K models are integrated in a finite-element hydrogeological model to calculate multiple transport simulations. Different scenarios exhibit variations in mass transport path and dispersion associated with the large- and small-scale heterogeneity respectively. Three-dimensional maps showing the probability of overpassing different thresholds are presented as examples of management tools.
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664
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Eguchi S, Sawamoto M, Shiba M, Iiyama I, Hasegawa S. Wellbore-wall compression effects on monitored groundwater levels and qualities. GROUND WATER 2013; 51:452-460. [PMID: 22924593 DOI: 10.1111/j.1745-6584.2012.00979.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The effects of wellbore-wall compression from rough excavation on monitored groundwater levels and qualities under natural hydraulic gradient conditions were investigated in a shallow clayey Andisol aquifer. Nine wellbores reaching the underlying aquitard at about 2.6-m depth were constructed by dynamic cone penetrometry to mimic rough wellbore construction. Five of these were constructed under wet aquifer soil conditions and the remaining four under dry conditions. A 15-month period monitoring showed that the groundwater levels in the wellbores constructed under wet conditions responded significantly in retard of, and in narrower ranges than, those constructed under dry conditions. The wellbore-wall hydraulic conductivities at the former wellbores were calculated to be more than one to two orders of magnitude lower than those at the latter ones. Furthermore, remarkable nitrate removal attributable to the occurrence of a heterotrophic denitrification was observed in one of the former wellbores. In contrast, the groundwater levels and qualities in the latter wellbores appeared to be generally similar to those monitored in the conventional soil coring and augering-derived wellbores. Our results suggest that the wellbore-wall compression induced by rough excavation under wet and soft aquifer soil conditions leads to a substantial decrease in the wellbore-wall hydraulic conductivity, which in turn can lead to unreliable groundwater levels and qualities. This problem can occur in clayey Andisols whenever the aquifer soil is wet; however, the problem can be largely avoided by constructing the wellbore under dry and hard aquifer soil conditions.
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665
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Gusyev MA, Haitjema HM, Carlson CP, Gonzalez MA. Use of nested flow models and interpolation techniques for science-based management of the Sheyenne National Grassland, North Dakota, USA. GROUND WATER 2013; 51:414-420. [PMID: 23013059 DOI: 10.1111/j.1745-6584.2012.00989.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Noxious weeds threaten the Sheyenne National Grassland (SNG) ecosystem and therefore herbicides have been used for control. To protect groundwater quality, the herbicide application is restricted to areas where the water table is less than 10 feet (3.05 m) below the ground surface in highly permeable soils, or less than 6 feet (1.83 m) below the ground surface in low permeable soils. A local MODFLOW model was extracted from a regional GFLOW analytic element model and used to develop depth-to-groundwater maps in the SNG that are representative for the particular time frame of herbicide applications. These maps are based on a modeled groundwater table and a digital elevation model (DEM). The accuracy of these depth-to-groundwater maps is enhanced by an artificial neural networks (ANNs) interpolation scheme that reduces residuals at 48 monitoring wells. The combination of groundwater modeling and ANN improved depth-to-groundwater maps, which in turn provided more informed decisions about where herbicides can or cannot be safely applied.
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666
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Lu C, Werner AD, Simmons CT, Robinson NI, Luo J. Maximizing net extraction using an injection-extraction well pair in a coastal aquifer. GROUND WATER 2013; 51:219-228. [PMID: 22880816 DOI: 10.1111/j.1745-6584.2012.00973.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In this study, we examine the maximum net extraction rate from the novel arrangement of an injection-extraction well pair in a coastal aquifer, where fresh groundwater is reinjected through the injection well located between the interface toe and extraction well. Complex potential theory is employed to derive a new analytical solution for the maximum net extraction rate and corresponding stagnation-point locations and recirculation ratio, assuming steady-state, sharp-interface conditions. The injection-extraction well-pair system outperforms a traditional single extraction well in terms of net extraction rate for a broad range of well placement and pumping rates, which is up to 50% higher for an aquifer with a thickness of 20 m, hydraulic conductivity of 10 m/d, and fresh water influx of 0.24 m(2) /d. Sensitivity analyses show that for a given fresh water discharge from an inland aquifer, a larger maximum net extraction is expected in cases with a smaller hydraulic conductivity or a smaller aquifer thickness, notwithstanding physical limits to drawdown at the pumping well that are not considered here. For an extraction well with a fixed location, the optimal net extraction rate linearly increases with the distance between the injection well and the sea, and the corresponding injection rate and recirculation ratio also increase. The analytical analysis in this study provides initial guidance for the design of well-pair systems in coastal aquifers, and is therefore an extension beyond previous applications of analytical solutions of coastal pumping that apply only to extraction or injection wells.
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667
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Swistock BR, Clemens S, Sharpe WE, Rummel S. Water quality and management of private drinking water wells in Pennsylvania. JOURNAL OF ENVIRONMENTAL HEALTH 2013; 75:60-66. [PMID: 23397651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Pennsylvania has over three million rural residents using private water wells for drinking water supplies but is one of the few states that lack statewide water well construction or management standards. The study described in this article aimed to determine the prevalence and causes of common health-based pollutants in water wells and evaluate the need for regulatory management along with voluntary educational programs. Water samples were collected throughout Pennsylvania by Master Well Owner Network volunteers trained by Penn State Extension. Approximately 40% of the 701 water wells sampled failed at least one health-based drinking water standard. The prevalence of most water quality problems was similar to past studies although both lead and nitrate-N were reduced over the last 20 years. The authors' study suggests that statewide water well construction standards along with routine water testing and educational programs to assist water well owners would result in improved drinking water quality for private well owners in Pennsylvania.
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668
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Tegel W, Elburg R, Hakelberg D, Stäuble H, Büntgen U. Early Neolithic water wells reveal the world's oldest wood architecture. PLoS One 2012; 7:e51374. [PMID: 23284685 PMCID: PMC3526582 DOI: 10.1371/journal.pone.0051374] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 11/06/2012] [Indexed: 11/18/2022] Open
Abstract
The European Neolithization ~6000-4000 BC represents a pivotal change in human history when farming spread and the mobile style of life of the hunter-foragers was superseded by the agrarian culture. Permanent settlement structures and agricultural production systems required fundamental innovations in technology, subsistence, and resource utilization. Motivation, course, and timing of this transformation, however, remain debatable. Here we present annually resolved and absolutely dated dendroarchaeological information from four wooden water wells of the early Neolithic period that were excavated in Eastern Germany. A total of 151 oak timbers preserved in a waterlogged environment were dated between 5469 and 5098 BC and reveal unexpectedly refined carpentry skills. The recently discovered water wells enable for the first time a detailed insight into the earliest wood architecture and display the technological capabilities of humans ~7000 years ago. The timbered well constructions made of old oak trees feature an unopened tree-ring archive from which annually resolved and absolutely dated environmental data can be culled. Our results question the principle of continuous evolutionary development in prehistoric technology, and contradict the common belief that metal was necessary for complex timber constructions. Early Neolithic craftsmanship now suggests that the first farmers were also the first carpenters.
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669
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Kelson V. Predicting collector well yields with MODFLOW. GROUND WATER 2012; 50:918-926. [PMID: 22339406 DOI: 10.1111/j.1745-6584.2012.00910.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Groundwater flow models are commonly used to design new wells and wellfields. As the spatial scale of the problem is large and much local-scale detail is not needed, modelers often utilize two-dimensional (2D) or quasi three-dimensional models based on the Dupuit-Forchheimer assumption. Dupuit models offer a robust set of tools for simulating regional groundwater flow including interactions with surface waters, the potential for well interference, and varying aquifer properties and recharge rates. However, given an assumed operating water level or drawdown at a well screen, Dupuit models systematically overpredict well yields. For design purposes, this discrepancy is unacceptable, and a method for predicting accurate well yields is needed. While published methods exist for vertical wells, little guidance is available for predicting yields in horizontal screens or collector wells. In plan view, a horizontal screen has a linear geometry, and will likely extend over several neighboring cells that may not align with rows or columns in a numerical model. Furthermore, the model must account for the effects of converging three-dimensional (3D) flow to the well screens and hydraulic interference among the well screens; these all depend on the design of a specific well. This paper presents a new method for simulating the yield of angled or horizontal well screens in numerical groundwater flow models, specifically using the USGS code MODFLOW. The new method is compared to a detailed, 3D analytic element model of a collector well in a field of uniform flow.
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670
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Shaver R. On the utility of calculating and interpreting apparent storativity. GROUND WATER 2012; 50:496-499. [PMID: 22372714 DOI: 10.1111/j.1745-6584.2012.00919.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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671
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Criss RE, Criss EM. Prediction of well levels in the alluvial aquifer along the lower Missouri River. GROUND WATER 2012; 50:571-577. [PMID: 22034862 DOI: 10.1111/j.1745-6584.2011.00877.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Temporal variations in the head of wells in the alluvial aquifer along the lower Missouri River are accurately simulated by summation of linear differential terms involving daily variations in river stage and effective precipitation. Scaling parameters were optimized using a fourth order Adams-Bashforth-Moulton method, providing predictions for head that are typically accurate within ±1.5 feet (0.5 m) over intervals of 1 to 15 years. Parameter magnitudes represent the product of realistic aquifer properties and geometric factors.
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672
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Tang G, Watson DB, Parker JC, Brooks SC. A spreadsheet program for two-well tracer test data analysis. GROUND WATER 2012; 50:614-620. [PMID: 21797850 DOI: 10.1111/j.1745-6584.2011.00841.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Two-well tracer tests are often conducted to investigate subsurface solute transport in the field. Analyzing breakthrough curves in extraction and monitoring wells using numerical methods is nontrivial due to highly nonuniform flow conditions. We extended approximate analytical solutions for the advection-dispersion equation for an injection-extraction well doublet in a homogeneous confined aquifer under steady-state flow conditions for equal injection and extraction rates with no transverse dispersion and negligible ambient flow, and implemented the solutions in Microsoft Excel using Visual Basic for Application (VBA). Functions were implemented to calculate concentrations in extraction and monitoring wells at any location due to a step or pulse injection. Type curves for a step injection were compared with those calculated by numerically integrating the solution for a pulse injection. The results from the two approaches are similar when the dispersivity is small. As the dispersivity increases, the latter was found to be more accurate but requires more computing time. The code was verified by comparing the results with published-type curves and applied to analyze data from the literature. The method can be used as a first approximation for two-well tracer test design and data analysis, and to check accuracy of numerical solutions. The code and example files are publicly available.
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Levison JK, Novakowski KS. Rapid transport from the surface to wells in fractured rock: a unique infiltration tracer experiment. JOURNAL OF CONTAMINANT HYDROLOGY 2012; 131:29-38. [PMID: 22326689 DOI: 10.1016/j.jconhyd.2012.01.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Revised: 01/03/2012] [Accepted: 01/04/2012] [Indexed: 05/31/2023]
Abstract
A unique infiltration tracer experiment was performed whereby a fluorescent dye was applied to the land surface in an agricultural field, near Perth, Ontario, Canada, to simulate the transport of solutes to two pumped monitoring wells drilled into the granitic gneiss aquifer. This experiment, interpreted using the discrete-fracture capability of the numerical model HydroGeoSphere, showed that solute transport from the surface through thin soil (less than 2m) to wells in fractured bedrock can be extremely rapid (on the order of hours). Also, it was demonstrated that maximum concentrations of contaminants originating from the ground surface will not necessarily be the highest in the shallow aquifer horizon. These are important considerations for both private and government-owned drinking water systems that draw water from shallow fractured bedrock aquifers. This research illustrates the extreme importance of protecting drinking water at the source.
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674
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Gleeson T, Alley WM, Allen DM, Sophocleous MA, Zhou Y, Taniguchi M, VanderSteen J. Towards sustainable groundwater use: setting long-term goals, backcasting, and managing adaptively. GROUND WATER 2012; 50:19-26. [PMID: 21599658 DOI: 10.1111/j.1745-6584.2011.00825.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The sustainability of crucial earth resources, such as groundwater, is a critical issue. We consider groundwater sustainability a value-driven process of intra- and intergenerational equity that balances the environment, society, and economy. Synthesizing hydrogeological science and current sustainability concepts, we emphasize three sustainability approaches: setting multigenerational sustainability goals, backcasting, and managing adaptively. As most aquifer problems are long-term problems, we propose that multigenerational goals (50 to 100 years) for water quantity and quality that acknowledge the connections between groundwater, surface water, and ecosystems be set for many aquifers. The goals should be set by a watershed- or aquifer-based community in an inclusive and participatory manner. Policies for shorter time horizons should be developed by backcasting, and measures implemented through adaptive management to achieve the long-term goals. Two case histories illustrate the importance and complexity of a multigenerational perspective and adaptive management. These approaches could transform aquifer depletion and contamination to more sustainable groundwater use, providing groundwater for current and future generations while protecting ecological integrity and resilience.
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675
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Chiu YC, Nishikawa T, Martin P. Hybrid-optimization algorithm for the management of a conjunctive-use project and well field design. GROUND WATER 2012; 50:103-117. [PMID: 21635245 DOI: 10.1111/j.1745-6584.2011.00828.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Hi-Desert Water District (HDWD), the primary water-management agency in the Warren Groundwater Basin, California, plans to construct a waste water treatment plant to reduce future septic-tank effluent from reaching the groundwater system. The treated waste water will be reclaimed by recharging the groundwater basin via recharge ponds as part of a larger conjunctive-use strategy. HDWD wishes to identify the least-cost conjunctive-use strategies for managing imported surface water, reclaimed water, and local groundwater. As formulated, the mixed-integer nonlinear programming (MINLP) groundwater-management problem seeks to minimize water-delivery costs subject to constraints including potential locations of the new pumping wells, California State regulations, groundwater-level constraints, water-supply demand, available imported water, and pump/recharge capacities. In this study, a hybrid-optimization algorithm, which couples a genetic algorithm and successive-linear programming, is developed to solve the MINLP problem. The algorithm was tested by comparing results to the enumerative solution for a simplified version of the HDWD groundwater-management problem. The results indicate that the hybrid-optimization algorithm can identify the global optimum. The hybrid-optimization algorithm is then applied to solve a complex groundwater-management problem. Sensitivity analyses were also performed to assess the impact of varying the new recharge pond orientation, varying the mixing ratio of reclaimed water and pumped water, and varying the amount of imported water available. The developed conjunctive management model can provide HDWD water managers with information that will improve their ability to manage their surface water, reclaimed water, and groundwater resources.
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