Grey degree and grey prediction of groundwater head   总被引：2，自引：0，他引：2  

Y.-L.?YehEmail author  T.-C.?Chen 《Stochastic Environmental Research and Risk Assessment (SERRA)》2004,18(5):351-363

Boundary types and geologic conditions, which possess random and obscure characteristics, produce variations in groundwater heads. In this study, a groundwater flow system was regarded as a grey system and a grey degree defined and quantified those characteristics. Data were obtained from field records in Gao-Shu and De-Xie Stations, which are located in the upper and middle sites of Pingtung Plain, Taiwan, respectively. An estimated interval was used to represent the upper and lower groundwater head limits. The analyses showed that the grey degree in the wet season was smaller than in the dry season. This was due to the greater uncertainty in groundwater pumping and rainfall recharge in the dry season. With high confidence levels, the grey degree of the groundwater heads decreased. Under spatial distribution, the uncertainty of the groundwater pumping and rainfall recharge in the middle zone was greater than in the upper zone because the middle zone included residential districts and agricultural regions. Thus, the grey degree in the upper zone was less than the middle zone. The grey model can be used to predict a groundwater head based on the observed groundwater head data and the random degree in the groundwater head each month can be judged by the grey interval.  相似文献   

A numerical method of moments for solute transport in physically and chemically nonstationary formations: linear equilibrium sorption with random K<Subscript>d</Subscript>     

B. X.?HuEmail author  J.?Wu  D.?Zhang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2004,18(1):22-30

A Lagrangian perturbation method is applied to develop a method of moments for solute flux through a three-dimensional nonstationary flow field. The flow nonstationarity stems from medium nonstationarity and internal and external boundaries of the study domain. The solute flux is described as a space-time process where time refers to the solute flux breakthrough through a control plane (CP) at some distance downstream of the solute source and space refers to the transverse displacement distribution at the CP. The analytically derived moment equations for solute transport in a nonstationarity flow field are too complicated to solve analytically, a numerical finite difference method is implemented to obtain the solutions. This approach combines the stochastic model with the flexibility of the numerical method to boundary and initial conditions. The developed method is applied to study the effects of heterogeneity and nonstationarity of the hydraulic conductivity and chemical sorption coefficient on solute transport. The study results indicate all these factors will significantly influence the mean and variance of solute flux.  相似文献   

Groundwater resources assessment of the Koyna River basin,India   总被引：2，自引：1，他引：1  

Pradeep?K.?NaikEmail author  Arun?K.?Awasthi 《Hydrogeology Journal》2003,11(5):582-594

The Western Ghats (hills) region of the Indian peninsula in western India receives heavy precipitation (4,000–6,000 mm/year), but the headwater basins that coalesce runoff from these hills retain very small quantities of water due to the steep topography. However, the narrow valleys in these hills support agriculture based on surface water irrigation, and several medium to large irrigation projects have already been constructed with well-defined canal networks. These developments have boosted agricultural productivity in the region, but at the same time they are causing an economic disparity between the command areas (irrigated by these canals) and non-command areas. Water-logging problems are also occurring in low-lying areas. While these problems are mainly due to poor groundwater management strategies in the region, the groundwater resources in these headwater basins should be properly assessed and suitable measures taken for uniform groundwater development. As a first step in this direction, groundwater resources have been assessed as a case study for the lower Koyna River basin, a head water basin on the east of the main ridge of the Western Ghats.Regional specific yield (0.012) and groundwater recharge have been estimated on the basis of water table fluctuation method. Groundwater recharge amounting to 57 MCM (million m³) in a year takes place in the region through vertical percolation of rainwater (31 MCM), return flow of water applied for irrigation (23 MCM), and recharge due to surface water tanks (3 MCM). Recharge to deeper aquifers has been estimated at 1 MCM during dry seasons (November–May). Safe yield has been estimated at 58 MCM annually which includes the present groundwater draft by wells for domestic, stock, and irrigational needs estimated at 16.50 MCM per year and the natural losses from the groundwater system which are mostly baseflow and spring discharges amounting to 38 MCM (35 MCM baseflow + 3 MCM spring flow) per year, out of which 7 MCM is already being directly pumped from the tributaries of the Koyna River for irrigational needs. Thus, there remains a balance of only 3.5 MCM of groundwater for further groundwater development. Assuming that at least 25% (7 MCM) of the unutilized baseflow (28 MCM) can be brought to fruitful use, about 10.5 MCM (7+3.5 MCM) of groundwater can be used in the existing hydrogeological environment through about 500 additional wells.

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Resumen La región de las montañas de Western Ghats, al Oeste de la Península India, registra elevados valores de precipitación (de 4.000 a 6.000 mm/a), pero las condiciones topográficas de dichas montañas no permiten la existencia de acuíferos de entidad suficiente para albergar volúmenes grandes de aguas subterráneas. Los valles estrechos de las montañas sí permiten el desarrollo de las aguas superficiales, de manea que se ha realizado varios proyectos medianos y grandes de riego mediante redes de canales bien definidas. Estos desarrollos han propiciado un aumento de la producción agrícola en la región, pero, a la vez, se ha agudizado las diferencias económicas entre las zonas regadas y las no regadas. Además, las depresiones topográficas están padeciendo problemas de inundación. Como estos problemas son principalmente debidos a estrategias deficientes de gestión de las aguas subterráneas, se recomienda que los recursos subterráneas de las cuencas de cabecera sean adecuadamente determinados, y que se adopte medidas apropiadas para desarrollarlos uniformemente. El primer paso ha consistido en determinar los recursos subterráneos de la cabecera del río Koynam, situada al Este de la Sierra principal de los Western Ghats. Se ha estimado todos los parámetros de recarga y descarga, así como los recursos renovables, en la cuenca del río Koyna ubicada aguas debajo de la presa de Koyna.

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Résumé La région des Collines occidentales (Western Ghats) de la péninsule indienne en Inde occidentale reçoit de fortes précipitations (4.000–6.000 mm/an); mais les bassins situés en tête qui convergent dans ces collines retiennent très peu d'eaux souterraines du fait des mauvaises conditions de pente en surface. Les vallées étroites dans ces collines offrent de larges espaces pour la mise en valeur des eaux de surface, en sorte que plusieurs projets d'irrigation moyens ou importants ont déjà été réalisés dans ces régions avec un réseau bien défini de canaux. Cette mise en valeur a réellement poussé la productivité agricole de la région, mais en même temps elle produit aussi une disparité économique entre les régions desservies (zones irriguées par ces canaux) et non desservies. Des problèmes relatifs à l'eau se posent également dans les zones basses. Alors que ces problèmes sont surtout dus à de médiocres stratégies de gestion dans la région, il est recommandé que les ressources en eaux souterraines dans ces bassins en tête soient correctement évaluées et que des mesures adéquates soient prises en vue d'une mise en valeur uniforme des eaux souterraines. À titre de première étape dans cette direction, les ressources en eaux souterraines ont été évaluées lors d'une étude de cas du bassin de la rivière Koyna, un bassin de tête situé à l'est de la chaîne principale des Collines Occidentales. Tous les paramètres d'entrée et de sortie ont été estimés et un bilan a été réalisé entre ces deux composantes. Les ressources statiques et dynamiques en eaux souterraines ont été estimées et un rendement sûr a été déterminé pour le bassin de la rivière Koyna en aval du barrage de Koyna.

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Analytical solutions for bacterial energy taxis (chemotaxis): Traveling bacterial bands     

Wei Long  Markus Hilpert 《Advances in water resources》2007

Motile bacteria may form bands that travel with a constant speed of propagation through a medium containing a dissolved substrate, to which they respond energy tactically. We generalize the analytical solution by Keller and Segel for such bands by accounting for (1) the presence of a porous medium, (2) substrate consumption described by a Monod kinetics model, and (3) an energy tactic response model derived by Rivero et al. Specifically, we determine the concentration profiles of the bacteria and the substrate. We also derive various expressions for the band velocity. The band velocity is also shown to equal the energy tactic velocity at the bacterial peak divided by tortuosity.  相似文献   

Simultaneous determination of aquifer parameters and zone structures with fuzzy c-means clustering and meta-heuristic harmony search algorithm     

M. Tamer Ayvaz 《Advances in water resources》2007

This study proposes an inverse solution algorithm through which both the aquifer parameters and the zone structure of these parameters can be determined based on a given set of observations on piezometric heads. In the zone structure identification problem fuzzy c-means (FCM) clustering method is used. The association of the zone structure with the transmissivity distribution is accomplished through an optimization model. The meta-heuristic harmony search (HS) algorithm, which is conceptualized using the musical process of searching for a perfect state of harmony, is used as an optimization technique. The optimum parameter zone structure is identified based on three criteria which are the residual error, parameter uncertainty, and structure discrimination. A numerical example given in the literature is solved to demonstrate the performance of the proposed algorithm. Also, a sensitivity analysis is performed to test the performance of the HS algorithm for different sets of solution parameters. Results indicate that the proposed solution algorithm is an effective way in the simultaneous identification of aquifer parameters and their corresponding zone structures.  相似文献   

Analytical solutions for flow to a well through a fault     

Erik I. Anderson   《Advances in water resources》2006,29(12):1790-1803

We present explicit analytical solutions to problems of steady groundwater flow to a pumping well in an aquifer divided by an infinite, linear fault. The transmissivity of the aquifer is allowed to jump from one side of the fault to the other to model the juxtaposition of host rocks with different hydrologic properties caused by faulting. The fault itself is represented as a thin anisotropic inhomogeneity; this allows the fault to act as a combined conduit–barrier to groundwater flow, as is commonly described in the literature. We show that the properties of the fault may be represented exactly by two lumped parameters—fault resistance and fault conductance—and that the effects of the fault on flow in the adjacent aquifer is independent of the fault width. We consider the limiting cases of a purely leaky and a purely conductive fault where the fault domain may be replaced exactly by internal boundary conditions, and we investigate the effects of fault properties on the flow behavior in the adjacent aquifers. We demonstrate that inferring fault properties based on field observations of head in the aquifer is inherently difficult, even when the fault may be described by one of the two limiting cases. In particular, the effects of a leaky fault and a conductive fault on heads and discharges in the aquifer opposite the fault from the well, are shown to be identical in some cases.  相似文献   

Modeling surface and ground water mixing in the hyporheic zone using MODFLOW and MT3D   总被引：1，自引：0，他引：1  

Laura K. Lautz  Donald I. Siegel 《Advances in water resources》2006

We used a three-dimensional MODFLOW model, paired with MT3D, to simulate hyporheic zones around debris dams and meanders along a semi-arid stream. MT3D simulates both advective transport and sink/source mixing of solutes, in contrast to particle tracking (e.g. MODPATH), which only considers advection. We delineated the hydrochemically active hyporheic zone based on a new definition, specifically as near-stream subsurface zones receiving a minimum of 10% surface water within a 10-day travel time. Modeling results indicate that movement of surface water into the hyporheic zone is predominantly an advective process. We show that debris dams are a key driver of surface water into the subsurface along the experimental reach, causing the largest flux rates of water across the streambed and creating hyporheic zones with up to twice the cross-sectional area of other hyporheic zones. Hyporheic exchange was also found in highly sinuous segments of the experimental reach, but flux rates are lower and the cross-sectional areas of these zones are generally smaller. Our modeling approach simulated surface and ground water mixing in the hyporheic zone, and thus provides numerical approximations that are more comparable to field-based observations of surface–groundwater exchange than standard particle-tracking simulations.  相似文献   

Groundwater-supported evapotranspiration within glaciated watersheds under conditions of climate change   总被引：1，自引：0，他引：1  

Denis Cohen  Mark Person  Ronnie Daannen  Sharon Locke  Dave Dahlstrom  Victor Zabielski  Thomas C. Winter  Donald O. Rosenberry  Herb Wright  Emi Ito  John L. Nieber  William J. Gutowski  Jr 《Journal of Hydrology》2006,320(3-4):484-500

This paper analyzes the effects of geology and geomorphology on surface-water/-groundwater interactions, evapotranspiration, and recharge under conditions of long-term climatic change. Our analysis uses hydrologic data from the glaciated Crow Wing watershed in central Minnesota, USA, combined with a hydrologic model of transient coupled unsaturated/saturated flow (HYDRAT2D). Analysis of historical water-table (1970–1993) and lake-level (1924–2002) records indicates that larger amplitude and longer period fluctuations occur within the upland portions of watersheds due to the response of the aquifer system to relatively short-term climatic fluctuations. Under drought conditions, lake and water-table levels fell by as much as 2–4 m in the uplands but by 1 m in the lowlands. The same pattern can be seen on millennial time scales. Analysis of Holocene lake-core records indicates that Moody Lake, located near the outlet of the Crow Wing watershed, fell by as much as 4 m between about 4400 and 7000 yr BP. During the same time, water levels in Lake Mina, located near the upland watershed divide, fell by about 15 m. Reconstructed Holocene climate as represented by HYDRAT2D gives somewhat larger drops (6 and 24 m for Moody Lake and Lake Mina, respectively). The discrepancy is probably due to the effect of three-dimensional flow. A sensitivity analysis was also carried out to study how aquifer hydraulic conductivity and land-surface topography can influence water-table fluctuations, wetlands formation, and evapotranspiration. The models were run by recycling a wet year (1985, 87 cm annual precipitation) over a 10-year period followed by 20 years of drier and warmer climate (1976, 38 cm precipitation). Model results indicated that groundwater-supported evapotranspiration accounted for as much as 12% (10 cm) of evapotranspiration. The aquifers of highest hydraulic conductivity had the least amount of groundwater-supported evapotranspiration owing to a deep water table. Recharge was even more sensitive to aquifer hydraulic conductivity, especially in the lowland regions. These findings have important implications for paleoclimatic studies, because the hydrologic response of a surface-water body will vary across the watershed to a given climate signal.  相似文献   

Hydrochemistry and isotope compositions of groundwater from the Shihongtan sandstone-hosted uranium deposit, Xinjiang, NW China     

Maozhong Min  Xinjian Peng  Xianlin Zhou  Haiming Qiao  Jinping Wang  Li Zhang 《Journal of Geochemical Exploration》2007,93(2):91-108

Groundwaters and surface water in the Shihongtan sandstone-hosted U ore district, Xinjiang, NW China, were sampled and analyzed for their major-, and trace element concentrations and oxygen, hydrogen, boron and strontium isotope compositions in order to assess the possible origins of the waters and water–rock interactions that occurred in the deep aquifer system. The waters in the study district have been grouped into three hydrochemical facies: Facies 1, potable spring-water, is a pH neutral (7.0), Na–Ca–HCO₃ type water with low total dissolved solids (TDS; 0.2 g/l, fresh) and has δ¹⁸O of − 8.3‰, δD of − 48.2‰,δ¹¹B of 1.5‰, and ⁸⁷Sr/⁸⁶Sr of 0.70627. Facies 2 groundwaters are mildly acidic to mildly alkaline (pH of 6.5–8.0, mean 7.3), Na–Ca–Mg–Cl–SO₄ type waters with moderate TDS (8.2 g/l–17.2 g/l, mean 9.3 g/l, brackish) and haveδ¹⁸O values in the − 5.8‰ to − 9.3‰ range (mean − 8.1‰), δD values in the − 20.8‰ to − 85.5‰ range (mean − 47.0‰),δ¹¹B values in the + 9.5‰ to + 39.1‰ range (mean + 17.1‰), and ⁸⁷Sr/⁸⁶Sr values in the 0.70595 to 0.70975 range (mean 0.70826). Facies 3, Aiting Lake water, is a mildly alkaline (pH = 7.4), Na–Ca–Mg–Cl–SO₄ type water with the highest TDS (249.1 g/l, brine) and has δ¹⁸O of − 2.8‰, δD of − 45.8‰,δ¹¹B of 21.2‰, and ⁸⁷Sr/⁸⁶Sr of 0.70840. The waters from the study district show a systematic increase in major, trace element and TDS concentrations and δ¹¹B values along the pathway of groundwater migration which can only be interpreted in terms of water–rock interaction at depth and strong surface evaporation. The hydrochemical and isotopic data presented here confirm that the groundwaters in the Shihongtan ore district are the combined result of migration, water–rock interaction and mixing of meteoric water with connate waters contained in sediments.  相似文献   

A generalization of the fractal/facies model     

Fred J. Molz  Tomasz J. Kozubowski  Krzysztof Podgórski  James W. Castle 《Hydrogeology Journal》2007,15(4):809-816

In order to generalize the fractal/facies concept, a new stochastic fractal model for ln(K) increment probability density functions (PDFs) is presented that produces non-Gaussian behavior at smaller lags and converges to Gaussian at larger lags. The model is based on the classical Laplace PDF. The new stochastic fractal family is called fractional Laplace motion (fLam) having stationary increments called fractional Laplace noise (fLan). This fractal is different from other fractals because the character of the underlying increment PDFs changes dramatically with lag size, which leads to lack of self-similarity. Data also appear to display this characteristic. In the larger lag size ranges, approximate self-affinity does hold. The basic field procedure for further testing of the fractional Laplace theory is to measure ln(K) increment distributions along transects, calculate frequency distributions from the data, and compare results to appropriate fLan family members. The variances of the frequency distributions should also change with lag size (scale) in a prescribed manner. There are mathematical reasons such as the geometric central limit theorem, for surmising that fLam/fLan may be more fundamental than other approaches that have been proposed for modeling ln(K) frequency distributions.  相似文献