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151.
152.
AUTOMATED METHODS FOR ESTIMATING BASEFLOW AND GROUND WATER RECHARGE FROM STREAMFLOW RECORDS1 总被引:1,自引:0,他引:1
ABSTRACT: To quantify and model the natural ground water recharge process, six sites located in the midwest and eastern United States where previous water balance observations had been made were compared to computerized techniques to estimate: (1) base flow and (2) ground water recharge. Results from an existing automated digital filter technique for separating baseflow from daily streamflow records were compared to baseflow estimates made in the six water balance studies. Previous validation of automated baseflow separation techniques consisted only of comparisons with manual techniques. In this study, the automated digital filter technique was found to compare well with measured field estimates yielding a monthly coefficient of determination of 0.86. The recharge algorithm developed in this study is an automated derivation of the Rorabaugh hydrograph recession curve displacement method that utilizes daily streamflow. Comparison of annual recharge from field water balance measurements to those computed with the automated recession curve displacement method had coefficients of determination of 0.76 and predictive efficiencies of 71 percent. Monthly estimates showed more variation and are not advocated for use with this method. These techniques appear to be fast, reproducible methods for estimating baseflow and annual recharge and should be useful in regional modeling efforts and as a quick check on mass balance techniques for shallow water table aquifers. 相似文献
153.
Elia M. Tapia‐Villaseor Eylon Shamir Sharon B. Megdal Jacob D. Petersen‐Perlman 《Journal of the American Water Resources Association》2020,56(3):409-430
Assessing groundwater resources in the arid and semiarid borderlands of the United States and Mexico represents a challenge for land and water managers, particularly in the Transboundary Santa Cruz Aquifer (TSCA). Population growth, residential construction, and industrial activities have increased groundwater demand in the TSCA, in addition to wastewater treatment and sanitation demands. These activities, coupled with climate variability, influence the hydrology of the TSCA and emphasize the need for groundwater assessment tools for decision‐making purposes. This study assesses the impacts of changes in groundwater demand, effluent discharge, and climate uncertainties within the TSCA from downstream of the Nogales International Wastewater Treatment Plant to the northern boundary of the Santa Cruz Active Management Area. We use a conceptual water budget model to analyze the long‐term impact of the different components of potential recharge and water losses within the aquifer. Modeling results project a future that ranges from severe long‐term drying to positive wetting. This research improves the understanding of the impact of natural and anthropogenic variables on water sustainability, with an accessible methodology that can be globally applied. 相似文献
154.
Rosario Sanchez Laura Rodriguez Cecilia Tortajada 《Journal of the American Water Resources Association》2020,56(3):360-378
The natural complexity, heterogeneity, and extent of transboundary aquifers around the world, have led to controversy over which method or criteria should be used to identify and delineate their boundaries. Currently, there is no standard methodology that aquifer‐sharing countries can use to delineate the area of a transboundary aquifer. In the case of Mexico and Texas, Mexico uses administrative boundaries, whereas Texas uses geological boundaries. This paper proposes a method for delineation and prioritization of aquifers (or aquifer areas) called effective transboundary aquifer areas (ETAAs), which uses a combination of physical criteria (geological boundaries, topography, and hydrography) and the location and density of active water wells in the borderland between Mexico and Texas. This method identifies the area of priority (productivity area) in the aquifer using pumping patterns or hot spots regardless of the aquifer’s surficial geological limits, therefore offering a more effective, local and practical management option at the transboundary level. Different geological features or pumping patterns will have different sizes and locations of ETAAs within the same aquifer. In West Texas, which is dominated by bolsons, the method produces limited options for ETAAs, whereas in South Texas in the easternmost border the identified ETAAs are more significant. 相似文献
155.
Luke Flores Ryan T. Bailey Catherine Kraeger‐Rovey 《Journal of the American Water Resources Association》2020,56(2):310-322
When the cone of influence of a pumping well reaches a nearby river, the resulting hydraulic gradient can induce enhanced seepage of streamflow into the aquifer. The rate of seepage is often modeled using analytical solutions that are simple to apply but may not reproduce field data due to mathematical assumptions not being met in the field. Furthermore, the appropriateness of such models has not been investigated in detail due to difficulty in measuring streamflow loss in the field. In this study, a field experiment was conducted on a reach of the South Platte River near Denver, Colorado to estimate pumping‐induced streamflow loss. A network of stream gauges, monitoring wells, and in situ measurements was used to observe streamflow rates, groundwater levels, and temperature to assess if pumping wells have a significant impact on streamflow, and to compare observed streamflow depletion against analytical solutions. Data collected suggest that pumping wells have a noticeable impact on streamflow. The analytical solutions proved accurate if streamflow was low and constant but performed poorly if streamflow was high and variable. Therefore, for this reach, the use of analytical solutions to predict streamflow may only be appropriate under low‐flow, constant‐flow conditions. Methods and results can be used to guide other streamflow depletion studies and to inform cases of pumping‐induced streamflow depletion, particularly in regard to water rights. 相似文献
156.
Friha Hadj Ammar Najiba Chkir Kamel Zouari Zohra Azzouz-Berriche 《Journal of environmental radioactivity》2010,101(9):681-691
The distributions of 238U and 234U in groundwater from the “Jeffara aquifer” were studied by using alpha spectrometric methods. The concentration ranges of 238U and 234U/238U activity ratios were 1.34 ± 0.17 to 3.43 ± 0.38 ppb, and 1.43 ± 0.23 to 1.82 ± 0.27 respectively. Variations in concentrations can be related not only to lithostratigraphic formations but also to different origins of groundwater. U content of Jeffara are found very similar to those of Continental Intercalaire aquifer in both El Hamma and Chenchou regions, indicating that the Continental Intercalaire is the dominant source of the groundwater. 相似文献
157.
Hilke Würdemann Fabian Mller Michael Kühn Wolfgang Heidug Niels Peter Christensen Günter Borm Frank R. Schilling the COSINK Group 《International Journal of Greenhouse Gas Control》2010,4(6):938-951
The CO2SINK pilot project at Ketzin is aimed at a better understanding of geological CO2 storage operation in a saline aquifer. The reservoir consists of fluvial deposits with average permeability ranging between 50 and 100 mDarcy. The main focus of CO2SINK is developing and testing of monitoring and verification technologies. All wells, one for injection and two for observation, are equipped with smart casings (sensors behind casing, facing the rocks) containing a Distributed Temperature Sensing (DTS) and electrodes for Electrical Resistivity Tomography (ERT). The in-hole Gas Membrane Sensors (GMS) observed the arrival of tracers and CO2 with high temporal resolution. Geophysical monitoring includes Moving Source Profiling (MSP), Vertical Seismic Profiling (VSP), crosshole, star and 4-D seismic experiments. Numerical models are benchmarked via the monitoring results indicating a sufficient match between observation and prediction, at least for the arrival of CO2 at the first observation well. Downhole samples of brine showed changes in the fluid composition and biocenosis. First monitoring results indicate anisotropic flow of CO2 coinciding with the “on-time” arrival of CO2 at observation well one (Ktzi 200) and the later arrival at observation well two (Ktzi 202). A risk assessment was performed prior to the start of injection. After one year of operations about 18,000 t of CO2 were injected safely. 相似文献
158.
石油烃污染会对人类生存的环境造成严重危害,地下水系统中石油烃污染物的研究已受到国内外的高度重视。本文针对某石油烃污染场地的污染状况及水文地质条件,利用模拟柱实验研究石油烃中常见组分苯和菲在典型含水层中的迁移转化,实验结果表明,苯和菲在4种含水层介质中(粉砂、中砂、粗砂、砾砂)受到的迁移阻滞作用都是随着粒径的减小而增大。菲在4种介质中的迁移速率要小于苯,说明4种介质对菲的阻滞作用要大于苯。通过检测各模拟柱出水中Fe2+、Fe3+、NH4+-N和NO3--N浓度的变化可知,在苯和菲的砾砂模拟柱中,由于水流速度快,试验周期短,模拟柱内各项指标变化较小,生物作用较弱;而在苯和菲的粗砂、中砂和粉砂模拟柱中,NO3--N浓度减少,NH4+-N和Fe3+含量增加,说明微生物开始利用NO3--N和Fe3+降解苯和菲,微生物对苯和菲在粗砂、中砂和粉砂中的迁移转化过程有显著的作用。 相似文献
159.
An approach is developed to simulate leaching of a dissolved chemical constituent in the vadose zone of an aquifer. Specifically,
nitrate loading at the water table for different water table depths, for a range of aquifer permeability values, and for different
cases of heterogeneity of the aquifer, are considered. Models from the literature are first used to derive soil–water characteristic
curves (water retention and hydraulic conductivity) from a grain size distribution curve for unsaturated conditions. Given
infiltration from the surface, the initial conditions for the chemical concentration, and the water content profile, leaching
of the chemical in the vadose zone is simulated as a function of both time and depth. The methodology is illustrated for a
permeable aquifer. Simulations are undertaken using a finite element code for saturated and unsaturated flow. Different scenarios
are simulated depending on the heterogeneity of the aquifer and the depth of the water table. Modeling results show that in
the example case studied, nitrate concentration loading at the water table does not depend strongly on the position of the
water table, but rather on the material properties of the aquifer. The contribution of this endeavor resides in the methodology
which allows a prediction of nitrate leaching using only the grain size property of the aquifer. It allows practitioners to
obtain a first assessment of leaching with limited data. 相似文献
160.
A method for quick assessment of CO2 storage capacity in closed and semi-closed saline formations 总被引:1,自引:0,他引:1
Quanlin Zhou Jens T. Birkholzer Chin-Fu Tsang Jonny Rutqvist 《International Journal of Greenhouse Gas Control》2008,2(4):626
Saline aquifers of high permeability bounded by overlying/underlying seals may be surrounded laterally by low-permeability zones, possibly caused by natural heterogeneity and/or faulting. Carbon dioxide (CO2) injection into and storage in such “closed” systems with impervious seals, or “semi-closed” systems with non-ideal (low permeability) seals, is different from that in “open” systems, from which the displaced brine can easily escape laterally. In closed or semi-closed systems, the pressure buildup caused by continuous industrial-scale CO2 injection may have a limiting effect on CO2 storage capacity, because geomechanical damage caused by overpressure needs to be avoided. In this research, a simple analytical method was developed for the quick assessment of the CO2 storage capacity in such closed and semi-closed systems. This quick-assessment method is based on the fact that native brine (of an equivalent volume) displaced by the cumulative injected CO2 occupies additional pore volume within the storage formation and the seals, provided by pore and brine compressibility in response to pressure buildup. With non-ideal seals, brine may also leak through the seals into overlying/underlying formations. The quick-assessment method calculates these brine displacement contributions in response to an estimated average pressure buildup in the storage reservoir. The CO2 storage capacity and the transient domain-averaged pressure buildup estimated through the quick-assessment method were compared with the “true” values obtained using detailed numerical simulations of CO2 and brine transport in a two-dimensional radial system. The good agreement indicates that the proposed method can produce reasonable approximations for storage–formation–seal systems of various geometric and hydrogeological properties. 相似文献