• 한국환경과학회지
• /
• 제17권2호
• /
• pp.257-267
• /
• 2008

Groundwater recharge characteristics in a fractured granite area, Mt. Geumjeong, Korea. was interpreted using bedrock groundwater and wet-land water data. Time series analysis using autocorreclation, cross-correlation and spectral density was conducted for characterizing water level variation and recharge rate in low water and high water seasons. Autocorrelation analysis using water levels resulted in short delay time with weak linearity and memory. Cross-correlation function from cross-correlation analysis was lower in the low water season than the high water season for the bedrock groundwater. The result of water level decline analysis identified groundwater recharge rate of about 11% in the study area.

• Water Engineering Research
• /
• 제2권3호
• /
• pp.161-169
• /
• 2001

Present study deals with the development of a numerical model for the estimation of net annual recharge by coupling the Galerkin's finite element flow simulationl model with the Gauss-Newton-Marquardt optimization technique. The developed coupled numerical model is applied for estimating net annual recharge for Mahi Right Bank Canal (MRBC) project the norms of Groundwater Resources Estimation committee (1984, 1997) and Indian Agricultural research Institute(1983). It is observed that the estimated net recharge by inverse modeling is closer to the net recharge estimated using the water balance approach. Further it is observed that the computed head distribution from the estimated recharge agree closely with the observed head distribution. The study concludes that the developed model for inverse modeling can be successfully applied to large groundwater system involving regional aquifers where reliable recharge estimation always requires considerable time and financial resources.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제16권6호
• /
• pp.66-78
• /
• 2011

It is getting difficult to manage water resources in South Korea because more than half of annual precipitation is concentrated in the summer season and its intensity is increasing due to global warming and climate change. Artificial recharge schemes such as well recharge of surface water and roof-top rainwater harvesting can be a useful method to manage water resources in Korea. In this study, potential artificial recharge site is evaluated using geographic information system with hydrogeological and social factors. The hydrogeological factors include annual precipitation, geological classification based on geological map, specific capacity and depth to water level of national groundwater monitoring wells. These factors were selected to evaluate potential artificial recharge site because annual precipitation is closely related to source water availability for artificial recharge, geological features and specific capacity are related to injection capacity and depth to water is related to storage capacity of the subsurface medium. In addition to those hydrogeological factors, social aspect was taken into consideration by selecting the areas that is not serviced by national water works and have been suffered from drought. These factors are graded into five rates and integrated together in the GIS system resulting in spatial distribution of artificial recharge potential. Cheongsong, Yeongdeok in Gyeongsangbuk-do and Hadong in Gyeongsangnam-do, and Suncheon in Jeollanam-do were proven as favorable areas for applying artificial recharge schemes. Although the potential map for artificial recharge in South Korea developed in this study need to be improved by using other scientific factors such as evaporation and topographical features, and other social factors such as water-curtain cultivation area, hot spring resorts and industrial area where groundwater level is severely lowered, it can be used in a rough site-selection, preliminary and/or feasibility study for artificial recharge.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제16권6호
• /
• pp.34-45
• /
• 2011

For the Hancheon drainage area in Jeju island, a groundwater flow model using Visual MODFLOW was developed to simulate artificial recharge through injection wells installed in the Hancheon reservoir. The model was used to analyze changes of the groundwater level and the water budget due to the artificial recharge. The model assumed that $2{\times}10^6m^3$ of storm water would recharge annually through the injection wells during the rainy season. The transient simulation results showed that the water level rose by 39.6 m at the nearest monitoring well and by 0.26 m at the well located 7 km downstream from the injection wells demonstrating a large extent of the affected area by the artificial recharge. It also shown that, at the time when the recharge ended in the 5th year, the water level increased by 81 m at the artificial reservoir and the radius of influence was about 2.1 km downstream toward the coast. The residence time of recharged groundwater was estimated to be no less than 5 years. The model also illustrated that 15 years of artificial recharge could increase the average linear velocity of groundwater up to 1540 m/yr, which showed 100 m/yr higher than before. Increase of groundwater storage due to artificial recharge was calculated to be $2.4{\times}10^6$ and $4.3{\times}10^6m^3$ at the end of the 5th and 10th years of artificial recharge, respectively. The rate of storage increase was gradually diminished afterwards, and storage increase of $5.0{\times}10^6m^3$ was retained after 15 years of artificial recharge. Conclusively, the artificial recharge system could augment $5.0{\times}10^6m^3$ of additional groundwater resources in the Hancheon area.

• 한국환경과학회지
• /
• 제23권4호
• /
• pp.625-635
• /
• 2014

Temporal variation of groundwater levels in Jeju Island reveals time-delaying and dispersive process of recharge, mainly caused by the hydrogeological feature that thickness of the unsaturated zone is highly variable. Most groundwater flow models have limitations on delineating temporal variation of recharge, although it is a major component of the groundwater flow system. A new mathematical model was developed to generate time series of recharge from precipitation data. The model uses a convolution technique to simulate the time-delaying and dispersive process of recharge. The vertical velocity and the dispersivity are two parameters determining the time series of recharge for a given thickness of the unsaturated zone. The model determines two parameters by correlating the generated recharge time series with measured groundwater levels. The model was applied to observation wells of Jeju Island, and revealed distinctive variations of recharge depending on location of wells. The suggested model demonstrated capability of the convolution method in dealing with recharge undergoing the time-delaying and dispersive process. Therefore, it can be used in many groundwater flow models for generating a time series of recharge.

• 한국환경과학회지
• /
• 제19권6호
• /
• pp.779-785
• /
• 2010

To solve a problem of water supply on urban areas, groundwater recharge has to be assessed not only for evaluating the possibility of groundwater development but also for identifying a sustainable aquifer system for water resource development. The assessment of groundwater recharge has been challenged since the land use has been changed constantly. In this study, the groundwater recharge and its ratio were assessed from 1961 to 2007 in Su-yeong-gu, Busan, South Korea by analyzing precipitation, land use, and soil characteristics. For land use analysis, the urbanization change was considered. The land use areas for the residential, agricultural, forest, pasture, bare soil, and water in 1975 occupy 18.6 %, 30.0%, 48.8%, 0.1%, 2.0%, and 0.5% of total area, respectively. The land use ratios were sharply changed from 1980 to 1985; the agricultural area was decreased to 18.3%, and the residential area was increased to 15.0%. From 1995 to 2000, the agricultural area was decreased to 5.5%, and the residential area was increased to 5.4%. The annual averages of precipitation, groundwater recharge, and its ratio were 1509.3 mm, 216.0 mm, and 14.3% respectively. The largest amount of the groundwater recharge showed in 1970 as 408.9 mm, comparing to 2138.1 mm of annual rainfall. Also, the greatest ratio of the groundwater recharge was 19.8% in 1984 with 1492.6 mm of annual rainfall. The lowest amount and ratio of the groundwater recharge were 71.9 mm and 8.0% in 1988, relative to 901.5 mm of annual precipitation. As a result, it is concluded that rainfall has increased, whereas groundwater recharge has decreased between 1961 and 2007.

• 지질공학
• /
• 제30권3호
• /
• pp.269-278
• /
• 2020

본 연구에서는 현장 주입 시험 및 3차원 수치모델을 이용하여 상류 소분지에서의 수직정을 이용한 지하수 인공함양 효과를 예비 평가하였다. 현장 주입 시험의 주입량, 지하수위 및 입도 분석 자료에 의한 수리전도도 등을 이용하여 모델의 공당 주입량을 20, 37.5, 60, 75 ㎥/day로 설정하였으며, 주입 간격에 따른 총 28개의 경우에 대하여 MODFLOW를 활용한 수치모델을 실시하여 지하수위 및 물수지 변화를 분석하였다. 주입 후 주변 관측정에서의 지하수위 상승이 공당 주입량과 비례적인 선형 관계를 보이진 않았으며, 주입 간격이 길어지면 누적 효과가 감소하여 최대 수위상승 시기가 짧아지는 것으로 나타났다. 또한 4가지 경우의 공당 주입량을 매일 연속으로 주입하여 총량 1,200 ㎥을 주입할 경우, 주입량 대비 36.5~65.3%의 함양 효과가 나타나는 것으로 분석되었다. 그러나 장기간의 가뭄에 대응하고 보다 지속적인 양수를 위해서는 차수벽 등 지하수 저류시설을 병행한다면 보다 효과적일 것으로 보이며, 추후 주입 시설의 최적화 및 함양-취수의 시나리오 확보를 통하여 안정적인 인공함양 시스템 구축이 가능할 것이다.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제25권1호
• /
• pp.12-24
• /
• 2020

This study was conducted to examine an artificial recharge system, which was considered to be an alternative for securing additional groundwater resources in a high-density greenhouse region. An injection well with a depth of 14.0 m was placed in an alluvial plain of the zone. Eight monitoring wells were placed in a shape of dual circles around the injection well. Aquifer tests showed that the aquifer was comprised with high-permeable layer with hydraulic conductivities of 1.5×10^-3~2.4×10^-2 cm/sec and storage coefficients of 0.07~0.10. A step injection test resulted in a specific groundwater-level rising (Sr/Q) values of 0.013~0.018 day/㎡ with 64~92% injection efficiencies. Results of the constant-rate injection test with an optimal injection rate of 100 ㎥/day demonstrated an enormous storage capacity of the alluvial aquifer during ten experimental days. To design an optimal recharge system for an artificial recharge, the high-permeable layer should be isolated by dual packers and suitable pressure should be applied to the injection well in order to store water. An anisotropy ratio of the alluvial aquifer was evaluated to be approximately 1.25 : 1 with an anisotropy angle of 71 degrees, indicating intervals among injection wells are almost the same.

• 지질공학
• /
• 제29권4호
• /
• pp.483-494
• /
• 2019

본 연구에서는 다양한 현장 조사를 통하여 지하수 인공함양의 범위를 결정하고 함양 방법별 장단점을 평가하여 적정 기법을 검토하는데 있다. 지하수 인공함양을 위한 대상 대수층 및 취수방법의 결정은 대수층의 특성을 고려하여 결정하게 된다. 충청남도 홍성군 갈산면 신곡마을을 대상으로 전기비저항탐사, 시추조사, 투수시험, 입도분석 등을 실시한 결과, 상부 충적층에 비하여 하부 풍화토 및 풍화암 구간의 수리전도도가 양호한 편으로 나타났다. 양수시험에 의하면 9시간 까지는 심도 12 m에서 안정적인 지하수위를 유지하였으나 이후 지하수위 강하가 재차 발생하는 이방성의 대수층 특성을 보이는 것으로 나타났다. 따라서 함양 우물, Ditch 및 Pond 등 3가지 유형의 인공함양 방법을 검토한 결과, 투수성이 양호한 풍화토 및 풍화암 구간까지 직접 주입이 가능한 함양 우물 방식과 상류 지역에서의 선형의 주입으로 함양효과를 높일 수 있는 Ditch 방식을 혼합하는 방안을 제시하였다. 이와 같은 함양의 대상과 방법 선정 결과는 현장의 시험 시공을 통하여 평가될 예정이며, 이 과정을 통하여 국내 지류 중상류 지역에서의 적용성을 검증한다면 상시 물부족 지역의 용수 확보에 기여할 것으로 본다.

• 자원환경지질
• /
• 제41권4호
• /
• pp.427-442
• /
• 2008

지하수 함양량 산정은 지하수자원의 효율적인 관리 측면에서 매우 중요하다. 본 연구에서는 물수지분석법과 연구지역의 지질과 토양의 수리지질학적 특성을 이용하여 울산광역시 중괘천-보은천 지역의 지하수 함양량을 산정하였다. 증발산량은 Thornthwaite 방법으로 계산하였으며, 직접유출량은 SCS-CN 방법으로 산정하였다. 지하수 함양량은 266 mm/년로 30년 평균 강수량 1296 mm/년의 20.6%에 해당하며, 증발산량은 779 mm/년 (60.1%), 직접유출량은 119 mm/년 (9.2%)로 산정되었다. 강수량과 지하수 함양량 간에는 강수량과 증발산량, 강수량과 직접유출량에 비해 상관성이 높게 나타난다. 이는 증발산량 및 직접유출량 보다 지하수 함양량이 강수량에 대해서 더 민감하게 반응한다는 것을 지시한다.