논문 : 실내 모형과 현장 충적층에서 지하투과레이더를 이용한 지하수면 추정

김병우 ( Byung Woo Kim ),김형수 ( Hyoung Soo Kim ),최두형 ( Doo Houng Choi ),고용권 ( Yong Kwon Koh ) 대한지질공학회 2013 지질공학 Vol.23 No.3

지하수면과 불포화대의 수분 포화도가 지하투과레이더(GPR) 신호에 미치는 영향을 연구하기 위하여 실내 토조와 충적층 현장에서 GPR 조사를 수행하였다. 실내의 모래 채움 토조 실험에서, 지하수위를 변화시키기 위해 물을 탱크 바닥에 설치된 밸브를 통해 주입하고 배수시켰다. 지하수위와 수분포화도를 추정하기 위하여 모래 채움 토조에서 GPR 수직반사법(이후, VRP) 자료가 획득되었다. 실내 모래 채움 토조에서 획득한 GPR 신호는, 지하수위는 물론 함수율 변화에도 민감하게 반응함을 보여준다. 불포화대에서 GPR 속도는 함수율 변화에 따라 크게 조절되며, 주시 시간의 증가는 포화도의 증가로 해석된다. 함안군 이룡리 낙동강변 충적층에서 220m에 달하는 VRP 조사가, 지하수위를 추정하기 위하여 수행되었다. 현장 조사 결과, 포화 조건에서 GPR 신호의 첫 번째 반사면은 모관 상승에 의한 경계부를 지시하며, 실제 지하수면과는 차이가 있음을 지시한다. 보다 정확한 지하수위를 추정하기 위하여, Well-3호공 주변에서 중앙공심점(common mid-point, 이후, CMP) 방식 GPR 조사를 수행하였다. 그 결과, 모관 상승 경계부와 지하수면 속도를 구하였고, 이는 보다 상세한 지하수면과 심도별 포화도 정보를 제공하였다. 지하수면과 포화도 정보를 포함하는 GPR 조사 결과는 통기대의 현장 수리 지질학적 특성 조사에 유용한 수단이다. Ground penetrating radar (GPR) surveys were conducted in a sand tank model in a laboratory and at an alluvial field site to detect the groundwater table and to investigate the influence of saturation on GPR response in the unsaturated zone. In the sand tank model, the groundwater table and saturation in the sand layer were altered by injecting water, which was then drained by a valve inserted into the bottom of the tank. GPR vertical reflection profile (VRP) data were obtained in the sand tank model for rising and lowering of the groundwater table to estimate the groundwater table and saturation, Results of the lab-scale model provide informatiou on the sensitivity of GPR signals to changes in the water content and in the groundwater table. GPR wave velocities in the vadose zone are controlled mainly by variations in water content (increased travel time is interpreted as an increase in saturation), At the field site. VRP data were collected to a depth of 220 m to estimate the groundwater table at an alluvial site near the Nakdong river at Iryoug-ri. Haman-gun, South Korea. Results of the field survey indicate that nuder saturated conditions, the first reflector of the GPR is indicative of the capillary fringe and not the actual groundwater table. To measre the groundwater table more accurately. we performed a GPR survey using the common mid-point (CMP) method in the vicinity of well-3, and Sunk a well to check the groundwater table. The resultant CMP data revealed reflective events from the capillary fringe and groundwater table showing hyperbolic patterns. The normal moveont correction was applied to evaluate the velocity of the GPR, which improved the accuracy of saturation and groundwater table information at depth. The GPR results show that the saturation information, including the groundwater table. is useful in assessing the hydrogeologic properties of the vadose zone in the field.

Distribution characteristics and processes along flow paths of shallow groundwater in the Tan-Lu fault zone in Anhui province, China

Dejian Wang,Jiazhong Qian,Weidong Zhao,Xiaoliang Hou,Wei Wang,Lei Ma 한국지질과학협의회 2022 Geosciences Journal Vol.26 No.4

To disclose the distribution characteristics, the situation of flow and storage, and processes along flow paths of shallow groundwater in Tan-Lu fault zones, nine hundred and seven groundwater table elevations data and one hundred hydrochemical samples of shallow groundwater were taken from the Tan-Lu fault zone in Anhui province to analyze the characteristic of groundwater distribution. The geographic information system (GIS) method was used to analyze the spatial distribution characteristics of groundwater tables, total dissolved solids (TDS) and chloride ion (Cl−). Geophysical prospecting, drilling material and regional hydrogeological survey were utilized to disclose groundwater storage and flow regime in the fault zone. The results show that the Tan-Lu fault zone in Anhui province has controlled groundwater flow into the Jiashan basin, Hefei basin, Chaohu area and Qianshan basin, which developed from north to south in this area. Groundwater in theses basins have recharged from surrounding areas to form a water storage space. Geophysical prospecting and drilling technology revealed that the Tan-Lu fault zone provided a flow channel and storage space for groundwater. Faults provide preferential channels in some areas for the groundwater flow and circulation, eventually deep hot-water flows upward and discharges in the form of hot-springs. The identification of the groundwater flow pathway can help to provide a reliable scientific basis for regional spatial development and utilization of groundwater resources.

지하수위와 연계된 습지 식생의 비선형 동역학

이옥정(Okjeong Lee),김상단(Sangdan Kim) 한국습지학회 2019 한국습지학회지 Vol.21 No.2

식생과 지하수위 사이의 양방향 상호 작용은 습지 식생의 동역학에 많은 영향을 미친다. 본 연구에서는 지하수위에 의해 영향을 받는 습지 식생의 비선형 동역학이 분석된다. 지하수위에 대한 영향은 습지 식생의 지배방정식에서 손실 항으로 설명되며, 지하수위 변화에 따라서 습지 식생이 어떻게 서로 다른 두 개의 안정적인 상태로 수렴될 가능성이 있게 되는지를 살펴보게 된다. 이러한 개념적 접근법으로부터 지하수위 변화에 따라 현재 습지에 존재하는 식생이 소멸되어 다른 식생 종으로 안정화되는 대변환에 대한 취약성이 분석된다. Bi-directional interaction between vegetation and groundwater table has a great influence on the dynamics of wetland vegetation. In this study, nonlinear dynamics of wetland vegetation affected by groundwater are analyzed. The effect on groundwater is described as a loss term in the governing equation of wetland vegetation and it is explored how the wetland vegetation is likely to converge into two attractors by groundwater table change. From this conceptual approach, the vulnerability to catastrophic shifts in stable state where the current vegetation species are extinct and stabilized by other vegetation species is analyzed in response to groundwater table.

높은 지하수위 지반 속에 설치된 지중연속벽의 인발저항력

홍원표,침니타 한국지반공학회 2014 한국지반공학회논문집 Vol.30 No.9

A series of model tests were conducted in order to observe the failure surface generated around a diaphragm wall embedded in ground with high groundwater table. Images of the soil deformation around the model wall were captured during the test. The configuration of the failure surface in soil around the model wall could be obtained from analyzing the image of the soil deformation. Based on the configuration of the failure surface observed in the model test, an analytical approach was proposed to predict the uplift capacity of a diaphragm wall installed in ground. The analytical approach considers not only the wall properties such as length, thickness and surface roughness of diaphragm walls but also the soil strength properties such as the internal friction angle and the cohesion of soil. The predicted uplift capacity of a diaphragm wall shows a good agreement with the experimental one measured in the model test.

Changes in Soil Salinity and Upland Crop Productivity in Reclaimed Land as Affected by Groundwater Table

Su Hwan Lee,Yang Yeol Oh,Jin Hee Ryu,Hak Sung Lee,Bang Hoon Kang,Hee Kyeong Ock,Kang Ho Jung 한국토양비료학회 2020 한국토양비료학회지 Vol.53 No.4

Soil salinization driven by groundwater distribution in the reclaimed land is one of the major limiting factors for crop cultivation and soil management. In this study, the effects of two different water table depth (G1 site with intermediate and deep vs. G2 site with shallow depth) of groundwater (on soil salinity, water and crop productivity were investigated. The rainfall event greatly impacted the groundwater recharging rate and salt leaching. The falling groundwatr table depth from 30 to 80 cm together with higher evaporation at G2 site caused soil salinization in the rhizosphere, whereas increases in soil salinity at G1 site was negligible. Overall, soil water content at G2 site was higher than that at G1 site. The positive correlation of soil salinity with soil water content (r² = 0.69) and negative with groundwater table (r² = 0.89) indicated hydraulic connection between groundwater table and soil surface. The deeply falling groudwater table with negative water balance (Evaporation > Rainfall) induced drought-combined salt stress to crop. Soybean was much more susceptible to soil salinty stress and excess-moisture injury than maize, suggesting that the crop selection and practices to reduce crop vulnerability to abiotic stresses(salt and water) should be considered for sustainable and stable agriculture in reclaimed land. Our results highlight that groundwater table depth would play a crucial role in founding cropland suitability and the optimum groundwater table to avoid salinization and excessve wetting might be 1.5 - 2.0 m.

A generalized groundwater fluctuation model based on precipitation for estimating water table levels of deep unconfined aquifers

Jeong, Jina,Park, Eungyu,Shik Han, Weon,Kim, Kue-Young,Suk, Heejun,Beom Jo, Si Elsevier 2018 Journal of hydrology Vol.562 No.-

<P><B>Abstract</B></P> <P>A generalized water table fluctuation model based on precipitation was developed using a statistical conceptualization of unsaturated infiltration fluxes. A gamma distribution function was adopted as a transfer function due to its versatility in representing recharge rates with temporally dispersed infiltration fluxes, and a Laplace transformation was used to obtain an analytical solution. To prove the general applicability of the model, convergences with previous water table fluctuation models were shown as special cases. For validation, a few hypothetical cases were developed, where the applicability of the model to a wide range of unsaturated zone conditions was confirmed. For further validation, the model was applied to water table level estimations of three monitoring wells with considerably thick unsaturated zones on Jeju Island. The results show that the developed model represented the pattern of hydrographs from the two monitoring wells fairly well. The lag times from precipitation to recharge estimated from the developed system transfer function were found to agree with those from a conventional cross-correlation analysis. The developed model has the potential to be adopted for the hydraulic characterization of both saturated and unsaturated zones by being calibrated to actual data when extraneous and exogenous causes of water table fluctuation are limited. In addition, as it provides reference estimates, the model can be adopted as a tool for surveilling groundwater resources under hydraulically stressed conditions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A generalized estimation for water table fluctuation is developed. </LI> <LI> The method can estimate water table level in unconfined aquifers of various depths. </LI> <LI> To model unsaturated infiltration fluxes, a gamma distribution function is adopted. </LI> <LI> The applicability of the model to deep water table aquifers is demonstrated. </LI> </UL> </P>

An approach to evaluate groundwater recharge from streamflow and groundwater records

Wen-Jui Kung,Hsin-Fu Yeh,Hung-I Lin,Wei-Ping Chen,Cheng-Haw Lee 한국지질과학협의회 2013 Geosciences Journal Vol.17 No.3

To assess groundwater recharge, this study provided a composite method combining the recession-curve-displacement method and water-table fluctuation method. First, the initial recharge reference value was determined using the water-table fluctuation method. The corresponding groundwater discharge was then determined from the recharge reference value using the recession-curve-displacement method. Furthermore, the recession segment of the match between groundwater discharge and streamflow was computed. The recharge reference value was repeatedly adjusted to achieve a good fit with the recession segment for groundwater discharge and streamflow, thereby attaining the final groundwater recharge using the proposed method. Finally, the groundwater recharge of the Lanyang Creek basin in Taiwan was estimated as a case study. A comparison of recession-curve-displacement method and proposed composite method are presented. Estimation results show that the number of recharge events, recharge timing of these events, groundwater recharge events that satisfy recession theory, and range of transmissivity can be obtained using the proposed composite method. Comparison results demonstrate that the number of groundwater recharge events obtained with the composite method was greater than that acquired with the recession-curve-displacement method. However, the annual recharge and seasonal recharge obtained with the recession-curve-displacement method and composite method were close.

기술보고 : 우리나라 지하수 개발가능량 산정의 현황과 전망

일문 ( Il Moon Chung ),김지태 ( Jitae Kim ),이정우 ( Jeong Woo Lee ),장선우 ( Sun Woo Chang ) 대한지질공학회 2015 지질공학 Vol.25 No.3

우리나라 지하수 개발가능량의 현황을 기출간된 지하수 관리 기본계획 보고서 내용을 기반으로 정리했다. 또한 지하수 개발가능량의 결정적인 요소인 지하수 함양량 산정기법을 검토하였다. 최종적으로 일정기간 수행된 지하수 기초조사 보고서에 나타난 지역별 지하수 개발가능량 산정기법을 검토, 요약했다. 지하수 개발가능량의 개선을 위해서는 개선된 기법(물수지 분석, 개선된 지하수위 변동법)의 적용과 함께 지속가능한 지하수 관리개념의 도입이 필요할 것으로 판단된다. We summarize the status of exploitable groundwater reserves in Korea based on reports of the National Basic Groundwater Plan, and review methods for estimating groundwater recharge rates, as recharge is a key factor in the estimation of exploitable groundwater reserves. We also outline the various methods used to assess exploitable groundwater reserves in previous groundwater investigation reports. Regarding advancements in the estimation of exploitable groundwater, we recommend that enhanced estimation methodologies (e.g., the water balance method and the advanced water table fluctuation method) and sustainable groundwater management concepts be adopted in the near future.

Estimation of Groundwater Recharge in Sukhuma District of Laos

VONGPHACHANH, SINXAY Korea Water Resources Association 2019 물과 미래(한국수자원학회지) Vol.52 No.8

This study is presented to estimate groundwater recharge in Sukhuma District of Southern Laos. The groundwater recharge is estimated by using the water table fluctuation method from observation groundwater levels at eleven domestic wells and five paired observation wells (shallow and deep). The results show that a value of specific yield for the shallow fractured sandstone aquifer in the Sukhuma District is quantified at approximately 0.03, Groundwater recharge for 2012-13 and 2015-16 is estimated at 5% (118 mm) and 4% (95 mm) of annual rainfall. respectively. The results of the current study provide useful basic information for future groundwater resource management planning in Sukhuma District. The methods applied in this study may be also useful for studying the groundwater recharge in regions with limited field data.

지하수위 변동법에 의한 함양량 산정: 하천-대수층 상호작용의 영향

구민호,김태근,김성수,정성래,강인옥,이찬진,김용철,Koo, Min-Ho,Kim, Tae-Keun,Kim, Sung-Soo,Chung, Sung-Rae,Kang, In-Oak,Lee, Chan-Jin,Kim, Yongcheol 한국지하수토양환경학회 2013 지하수토양환경 Vol.18 No.5

The water-table fluctuation (WTF) method has been often used for estimating groundwater recharge by analysis of waterlevel measurements in observation wells. An important assumption inherent in the method is that the water level rise is solely caused by precipitation recharge. For the observation wells located near a stream, however, the water-level can be highly affected by the stream level fluctuations as well as precipitation recharge. Therefore, in applying the WTF method, there should be consideration regarding the effect of stream-aquifer interactions. Analysis of water-level hydrographs from the National Groundwater Monitoring Wells of Korea showed that they could be classified into three different types depending on their responses to either precipitation recharge or stream level fluctuations. A simple groundwater flow model was used to analyze the errors of the WTF method, which were associated with stream-aquifer interactions. Not surprisingly, the model showed that the WTF method could greatly overestimate recharge, when it was used for the observation wells of which the water-level was affected by streams. Therefore, in Korea, where most groundwater hydrographs are acquired from wells nearby a stream, more caution is demanded in applying the WTF method.