• Journal of the Korean Society of Groundwater Environment
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• v.5 no.3
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• pp.123-128
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• 1998

Leaky aquifer (two-aquifer) system in this study consist of an upper unconfined and a lower confined aquifer with a leaky layer between them. It is assumed that water is withdrawn from the confined aquifer of the aquifer system, the upper unconfined aquifer will be affected by the leaky aquifer separating the upper and lower aquifer. In order to analyze the leaky aquifer, the determination of hydraulic parameters is needed. In this paper, hydraulic parameters are suggested by improved SM (slope-matching) method. To know variation of groundwater head in leaky aquifer systems, an numerical scheme is made using the finite difference method. To verify the numerical scheme, its solution is compared to analytical one. The solution of them agrees well in one-dimensional system at steady-state condition. And heads of groundwader are computed upper and lower aquifer in two-dimensional system.

• Journal of Soil and Groundwater Environment
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• v.7 no.4
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• pp.10-16
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• 2002

The multi-aquifer system separated by semipervious leaky beds was analyzed. The finite difference scheme of the Crank-Nicolson method is applied to obtain the solution for this system. The solution of this scheme was compared with the analytical solution for two-layer aquifer systems with one-dimensional steady state. The results showed a good agreement between analytical and numerical solution for two-layer aquifer systems. So, the numerical scheme can be extended to multi-aquifer system. When the pumping is tried for single or multi aquifer, the computation of the groundwater heads was possible for each aquifer in the multi-aquifer with two-dimensional system. So, it might be helpful for the effective groundwater management.

• Journal of Soil and Groundwater Environment
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• v.6 no.4
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• pp.73-81
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• 2001

With the development of industry and standard of living, the quantity of groundwater consumption has been increasing. For the analysis of groundwater, to determine the hydraulic parameters of aquifer is very important. Various numerical methods have been developed to solve aquifer tests and eliminate the subjectivity of traditional graphical type curve methods. The slope-matching method, which matches the slope of the Theis type curve to the slope of the field data, can be used to numerically solve pump tests for both leaky and nonleaky aquifers. A FORTRAN program on based slope-matching method was developed to obtain the transmissivity, storage coefficient, and leaky factor from pumping test data automatically. Results derived from published data show that the improved slope-matching method gives parameters close to the ones derived by the slope-matching method.

• The Journal of Engineering Geology
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• v.4 no.3
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• pp.311-319
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• 1994

This paper presents a sensitivity analysis to obtain best fit of hydraulic parameters of leaky fractal aquifer. The sensitivity analysis uses the least squares method. The hydraulic parameters (generalized transmissivity and generalized storage coefficient) can be easily determined by the sensitivity analysis for various flow dimensions and different values of the leakage factor. Furthermore, the sensitivity analysis was applied to variable-rate pump tast at several abstraction wells, A computer program was developed to evaluate the hydraulic parameters by the sensitivity analysis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.6
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• pp.555-561
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• 2020

In this study, the applicability of Hunt's analytical solution for a two-layered leaky aquifer system, which was developed to estimate stream depletion due to the groundwater pumping of the upper shallow aquifer, was evaluated. The 5-year averaged stream depletions were estimated using Hunt's analytical solution for various combinations of hydraulic characteristic values such as transmissivity, storage coefficient of the two aquifers, interlayer leakage coefficient, stream-well distance, hydraulic conductivity of the streambed, and stream width. Through comparison with the numerical solution accurately simulated with a MODFLOW groundwater flow model, the analytical solution derived by regarding the stream width as a point was evaluated. It was found that the error in the stream depletion calculated by the analytical solution can be reduced to less than 0.05 when the stream-well distance is greater than the stream width or when the stream depletion factor (SDF) is more than about 3,000 days. In addition, when the streambed hydraulic conductivity is less than 1 m/d, the hydraulic diffusion coefficient of the lower aquifer layer is less than 100 ㎡/d, the hydraulic diffusion coefficient ratio of the upper and lower aquifer layers is 5 or more, and the leakage coefficient between the layers is less than 0.0004 m/d, the overall analytical solutions were overestimated compared with the numerical solutions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.6
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• pp.1001-1008
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• 2017

This study was to evaluate the stream depletion rate from groundwater pumping with varying stream-well distance, aquifer transmissivity, storage coefficient, leakage coefficient, streambed hydraulic conductance using the Zlotnik and Tartakovsky analytical solution which considers a two-layer leaky aquifer-stream-well system. For the hydraulic conditions applied in this study, the streambed hydraulic conductance and the aquitard leakage coefficient were assessed to have a dominant influence on the stream depletion rate. In order to evaluate the applicability of Zlotnik and Tartakovsky analytical solution ignoring the change in the drawdown in the lower aquifer and applying the fixed head boundary condition, the solution was compared with Hunt analytical solution derived from the more practical conditions simultaneously taking into account the drawdown changes in the upper and lower aquifers. As a result, the Zlotnik and Tartakovsky analytical solution is suitable for predicting short-term effects of less than one year in the pumping period, and when the stream depletion factor (SDF) is greater than 2,500 days, or when the product of the leakage coefficient and the stream-well distance is less than 10 cm/s.

• Journal of Korea Water Resources Association
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• v.49 no.11
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• pp.923-930
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• 2016

This study was to evaluate the stream depletion from groundwater pumping in shallow aquifer using the Hunt's analytical solution (2009) which considers a two-layer leaky aquifer-stream system. From the total 2,187 cases of simulations with combinations of various aquifer and stream properties, the streamflow depletion rates divided by the groundwater pumping rate showed the low values when the stream depletion factor (SDF) is higher than 1,000-10,000, and was more sensitive to the aquitard hydraulic conductivity than the streambed hydraulic conductivity. The comparison of the Hunt's solution (2009) with the Hunt's solution (1999) of a single layer aquifer indicated that the maximum difference between the dimensionless stream depletions calculated by using both solutions is above 0.3, and the stream depletion is significantly affected by the hydraulic properties of the $2^{nd}$ layer as the SDF of the first layer increases. The Hunt's solution (2009) was applied to the real shallow groundwater well that is located in Chunju-Si, and the results revealed that the groundwater pumping has significant effects on streamflow in a short period of time, showing that the dimensionless stream depletion exceeds 0.8 within a few days. It was also found that the shallow groundwater pumping effects on stream depletion are highly dependent on the stream-well distance for the locations with high hydraulic diffusivity of $1^{st}$ layer and low vertical leakance between $1^{st}$ and $2^{nd}$ layers.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.5
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• pp.139-145
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• 2009

An analytical solution of groundwater flow is applied to design soil vacuum extraction for removing volatile organic compounds from the unsaturation zone. The governing equation of gas or vapor flow in porous media is nonlinear in that gas density depends on gas pressure. A linear equation suggested by researcher is similar to that of groundwater flow. The pressure drawdowns of confined and leaky aqufiers are calculated using Massmann's field data, and the pressure drawdowns are compared. A solution of Theis equation calculated by Massmann is modified using GASSOLVE9 program in this paper. The pressure drawdown using Hantush's analytical solution for leaky aquifer also compared to that of Massmann. Hantush's analytical solution gives good approximations to pressure drawdown.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.5
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• pp.769-777
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• 2016

The objective of this study was to evaluate the stream depletion from groundwater pumping in deep aquifer using the Ward and Lough's analytical solution (2011) which considers a two-layer leaky aquifer system. The calculated results for each pumping from the 110 wells beside streams showed a wide range of non-dimensional stream depletion, that is the streamflow depletion rate divided by the groundwater pumping rate, from lower than 0.1 to more than 0.9 on average for 5 years depending on the specific properties of well location. From the comparison with Hunt's solution (1999) of a single layer aquifer, the Ward and Lough's solution showed about 50% lower than the Hunt's solution due to the difference of hydraulic properties between the first and second layers as well as the lagged effect of vertical leakance. It was also found that the groundwater pumping has a minor effect on the stream depletion if the stream depletion factor (SDF) of the 1st layer is higher than about 1,000 or the SDF of the 2nd layer is higher than about 100, or the vertical leakance is smaller than $10^{-5}s^{-1}$. Furthermore, in the present study, the variations of the stream depletion were assessed according to the magnitude of unmeasured hydraulic properties such as transmissivity and storage coefficient of the 1st layer, vertical hydraulic conductivity of the 2nd layer, the streambed hydraulic conductance.

• The Journal of Engineering Geology
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• v.13 no.1
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• pp.67-82
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• 2003

Pumping test data obtained from five natural mineral-water producing companies (Siwon Saemmul, Daejeong Eumryo, Jain Guanguang, Cheongsu Eumryo and Hanju Sikpum) that are located within 1 km radius around Mockcheon area were analyzed. Theis(1935), Papadopulos-Cooper(1967), Hantush(1960, 1962), Hantush-Jacob(1955), Moench(1985), Neuman-Witherspoon(1969), Gringarten-Witherspoon(1969) and Gringarten-Ramey(1974) equations were applied to the pumping test analysis. The result of the pumping test analysis shows that wedge-typed confined aquifer model (Hantush, 1962) and leaky confined aquifer Case-1 model (Moench, 1985) were suitable for the study area. The models match well with geologic structure in the study area which controls aquifer by means of two major thrust faults having Nl8E and NS strikes, respectively.