• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.698-703
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• 2012

This survey was conducted to obtain basic data of the quality of groundwater for agriculture in Gyeongnam province. Groundwater samples from paddy 15, upland 15, and plastic film house 30 sites were collected on April, July, and October in every two years from 2002 to 2008. According to the result of water quality analysis, groundwater quality was suitable for irrigation purpose averagely. The $NO_3$-N contents by land use were in the order of plastic film house > upland > paddy field and its contents were 6.53, 4.80, and $3.68mg\;L^{-1}$, respectively. In annual changes of water quality, pH was no significant change in paddy, upland, and plastic film house by 6.6~6.9. EC was increased in upland and plastic film house in 2008 and majors factors were $NO_3$-N and $Cl^-$. In upland and plastic film house, $NO_3$-N contents were 4.72 and $6.52mg\;L^{-1}$ in 2002, respectively, whereas they were 5.63 and $8.70mg\;L^{-1}$ in 2008, respectively. Of the investigated sites, $NO_3$-N was exceeded water quality standards for agriculture by 3.3~15.0% in plastic film house and $Cl^-$ was exceeded water quality standards for agriculture by 2.2% in upland of 2004. The $NO_3$-N contents were decreased with well depth and their contents were $5.38mg\;L^{-1}$ from 3~10 m, $4.87mg\;L^{-1}$ from 10~20 m, and $2.58mg\;L^{-1}$ from above 30 m. The $NO_3$-N contents by soil texture were highest in sandy loam by $5.73mg\;L^{-1}$ and lowest in clay loam by $4.13mg\;L^{-1}$. The $NO_3$-N contents by crops category were in order of fruit vegetables > leaf vegetables > rice > fruits > beans, contents of fruit vegetables and leaf vegetables were 5.81 and $5.30mg\;L^{-1}$, respectively.

• 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.

• 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.

• Journal of Korean Society for Geospatial Information Science
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• v.19 no.4
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• pp.23-33
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• 2011

In this study, the data that examined the chloride ion concentration of ground water wells in the west coast of Jeollabukdo applying the GIS spatial estimation method were analyzed. In particular, through the designation of a validation point among ground water wells and then the analysis of error characteristics of the chloride ion concentration by each method of IDW (Inverse Distance Weight), Spline, and Kriging Interpolation method which is proper for estimating salt water intrusion was selected. The main conclusion from this study is as follows. First, as a result of analyzing the error characteristics of various spatial estimation methods by using the data from the chloride ion concentration of 485 ground water wells, the IDW method was found to be the most appropriate for estimating chloride ion concentration by salt water intrusion. Second, analyzing the average chloride ion concentration of the targeted regions has revealed that Gunsan-si with the record of $541mg/{\ell}$ did not meet water quality standards even for industrial use. Both Gimje-si and Gochang-gun satisfied drinking water quality standards and Buan-gun with $272mg/{\ell}$ was slightly below the standards for drinking water. Third, concerning the results of analysis according to administrative districts, as the areas adjacent to the west coast such as Daemyeong-dong, Joong-dong, Jangjae-dong and Guemam-dong in Gunsan-si are found to have very high chloride ion concentration, and both Hoehyeon-myeon and Daeya-myeon bounded by the Mankeong river did not meet water quality standards even for industrial use. From these facts, it is concluded that salt water intrusion has a great effect on Gunsan-si generally.

• 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.

• Journal of Korea Water Resources Association
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• v.41 no.8
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• pp.835-843
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• 2008

In Korea, riverbank filtration has drawn attention since 1990's as an alternative having potential to stably meet the ever-increasing water demand. Some cities located in the Nak-dong River Basin are currently supplying water through riverbank filtration. This research is on the application of riverbank filtration for stable water quality in Seoul. For this purpose, we have evaluated developable amount of water with riverbank filtration for the Han River. This paper focuses on the Kwangnaru site, which was selected through a systematic analysis in the companion paper. We have conducted groundwater modeling for a proposed system of wells and an artificial lake. In the Kwangnaru district, the river length to constitute a well system was identified to be about 1,200m, due to the topography and the field condition such as ecosystem preservation zone. After many design changes, it was found that the maximum developable amount of $23.36\;million\;m^3$/year could be obtained, when 16 pumping wells were built in every 80 meters along with an artificial lake upstream.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.455-455
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• 2015

농업용수 수요량을 산정하는 방법으로서는 계측 및 추정방법에 따라 사용수량을 직접 계측하는 방법, 대표작물의 단위수량으로 추정하는 방법, 증발산 이론을 이용하여 추정하는 방법 등이 있다. 우리나라에서는 현실적으로 농업지역에서의 계측자료가 충분하지 못하고, 자연조건에 따라 크게 좌우되는 농업용수 특성상 증발산 이론에 의한 수요량 추정기법이 주로 적용되고 있으며, 그 중에서도 필요수량 개념의 접근법이 과거로부터 많이 활용되어 왔다. 이 방법은 경작지 내 작물의 생육에 필요한 수량을 공급하기 위한 목적으로 저수지나 관정 등의 시설용량 결정 및 계획 수립을 위해 활용되는 방법으로서, 1965년도 처음 수립된 수자원장기종합계획에서부터 현재까지 우리나라 농업용수 수요량 추정에 적용되어 왔으며, 제주도 수자원관리종합계획에서도 적용되었다. 또 다른 접근법으로서 유역에서의 물수지 관점에서 경작지 내 물 사용에 의해 감소되는 하천 수량을 산정함으로써 순물소모량을 추정하는 방법이 있다. 물수지 분석은 장래의 용수수요와 기준년의 자연유량을 비교함으로써 향후의 안정적 용수수급을 계획하기 위한 방법으로서 많이 활용되고 있다. 우리나라에서는 1977년 낙동강유역 하구조사 기술보고서에서 처음 순물소모량 개념을 도입하여 수요량을 추정하였으며, 이후 제3차 수자원장기종합계획(1991-2011), 21세기를 바라보는 수자원전망(1993) 등에서 이 방법을 통해 미래의 용수수급 전망을 분석한 바 있다. 본 연구에서는 제주도 지역의 수자원 부존량 해석 및 장래 용수 이용에 따른 수자원의 과부족 해석, 수자원관리계획 수립을 위한 목적으로 순물소모량 개념을 적용하였다. 제주도는 경지면적 중 밭의 비율이 99%이상이며, 대부분 관정에 의한 지하수를 이용하여 스프링클러 또는 점적관개에 의해 용수량을 공급하고 있다. 따라서, 제주도 지질 특성 및 밭작물 관개특성을 고려하여 제주도 지역에 적합한 순물소모량 산정식을 제안하고, 이에 따라 시험유역을 대상으로 대표작물(감귤, 콩 등)에 대한 순물소모량을 산정하였다.

• Journal of Soil and Groundwater Environment
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• v.10 no.6
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• pp.32-44
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• 2005

314 pumping test data of the National Groundwater Monitoring Wells (NGMWs) are analyzed to present statistical properties of fractured-rock and alluvial aquifers of Korea such as distribution of hydraulic conductivity, empirical relations between transmissivity and specific capacity, and time-drawdown patterns of pumping and recovery test. The mean hydraulic conductivity of alluvial aquifers (1.26 m/day) is 17 times greater than that of fractured-rock aquifers (0.076 m/day). Hydraulic conductivity of fracture-rock aquifers ranges in value over 4 orders of magnitude which coincide with representative values of fractured crystalline rocks and shows distinctive differences among rock types with the lowest values for metamorphic rocks and the highest values for sedimentary rocks. In consideration of the estimated transmissivity with some simplifying assumptions, it Is likely that $32\%$ of groundwater flow for NGMWs would occur through fractured-rock aquifers and $68\%$ through alluvial aquifers. Based on 314 pairs of data, empirical relations between transmissivity and specific capacity are presented for both fractured-rock and alluvial aquifers. Depending on time-drawdown patterns during pumping and recovery test, NGMWs are classified into $4\~5$ types. Most of NCMWs $(83.7\%)$ exhibit the recharge boundary type, which call be attributed to sources of water supply such as streams adjacent to the pumping well, the vertical groundwater flux between fractured-rock and the alluvial aquifers, and the delayed yield associated with gravity drainage occurring in unconfined aquifers.

• Economic and Environmental Geology
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• v.38 no.3 s.172
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• pp.261-272
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• 2005

The groundwaters in the basin of Seomjin River are classified mainly into Na-Cl type with high EC and $NaHCO_3$ type with low EC, and are characterized by enriched $K^+,\;Mg^{2+},\; NO_3^-,\; and\;SO_4\;^{2-}$ contents. The epm fraction of $Na^+Cl^-$ in TDS increases in general with increasing EC of groundwater. The correlation patterns among dissolved ions indicate that $Na^+\;and\;Cl^-$ are derived mainly from intruded seawater, and $K^+,\;Mg^{2-},\;and\;SO_4\;^{2-}$ from anthropogenic source such as a chemical fertilizer. The groundwaters that exceed the recommended limits far agricultural irrigation water contains $23\%\;of\;Cl^-$ reflecting sea-water intrusion, but $50\%\;of\;NO_3^-$ as an anthropogenic pollution, among the wells investigated. In risk assessment of groundwaters by the EC-SAR relationship, only $40\%$ of the groundwaters shows the suitable quality for agricultural irrigation water without any sodium and salinity hazards. Consequently, the pollution sources that cause degradation of groundwater quality in the basin of Seomjin River are the usage of chemical fertilizers and the intrusion of seawater, resulted primarily from the extension of riverward backflow of seawater and secondarily from the overpumping of groundwater.

• The Journal of Engineering Geology
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• v.9 no.2
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• pp.147-159
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• 1999

Geostatistical methods were used for the groundwater flow analysis in a heterogeneous anisotropic aquifer. This study area is located at Sonbul-myeon in Hampyong-gun of Cheonnam Province which is a hydrogeological project area of KORES(Korea Resources Cooperation). Linear regression analysis shows that the topographic elevation and groundwater level of this area have very high correlation. Groundwater-level contour maps produced by ordinary kriging and cokringing have large differences in mountain areas, but small differences in hill and plain areas near the West Sea. Comparing two maps on the basis of an elevation contour map, a groundwater-level contour map using cokriging is more accurate. Analyzing the groundwater flow on two groundwater-level contour maps, the groundwater of study area flows from the high mountain areas to the plain areas near the West Sea. To verify the enffectiveness of geostatistical methods for the groundwater flow analysis in a heterogeneous anisotropic aquifer, the flow directions of groundwater were measured at two groundwater boreholes by a groundwater flowmeter system(model 200 $GeoFlo^{R}$). The measured flow directions of groundwater almost accord with those estimated on two groundwater-level contour maps produced by geostatistical methods.