• The Journal of Engineering Geology
• /
• v.24 no.4
• /
• pp.597-608
• /
• 2014

It is widely assumed that climate change and other anthropogenically driven processes are having a serious impact on coastal environments. One such impact is saltwater intrusion into coastal aquifers, which has resulted in the loss of groundwater resources. The pattern of saltwater intrusion is strongly dependent on regional hydrogeological characteristics. This study reviews recent qualitative and quantitative research into this problem, and considers relevant case studies. In addition, the characteristics of the aquifers from two representative volcanic islands (Jeju Island, Korea and Oahu Island, USA) are compared. The fundamental theory of density-dependent flow used to model saltwater intrusion processes and the programs that are widely used to simulate saltwater intrusion based on density-driven problems are also investigated. It is expected that the knowledge gained from this review of previous studies can be used to help improve groundwater management practices in Korea and also to inform future interdisciplinary studies.

• The Journal of Engineering Geology
• /
• v.21 no.4
• /
• pp.305-312
• /
• 2011

Because groundwater recharge shows spatial-temporal variability due to climatic conditions, it is necessary to investigate land use and hydrogeological heterogeneity, and estimate the spatial variability in the daily recharge rate based on an integrated surface-groundwater model. The integrated SWAT-MODFLOW model was applied to compute physically based daily groundwater recharge in the Jincheon region. The temporal variations in estimated recharge were calibrated using the observed groundwater head at several National Groundwater Monitoring Stations and at automatic groundwater-monitoring sites constructed during the Basic Groundwater Investigation Project (2009-2010). For the whole Mihocheon watershed, including the Jincheon region, the average groundwater recharge rate is estimated to be 20.8% of the total rainfall amount, which is in good agreement with the analytically estimated recharge rate. The proposed methodology will be a useful tool in the management of groundwater in Korea.

• Journal of the Korean Geophysical Society
• /
• v.4 no.1
• /
• pp.71-84
• /
• 2001

A study was initiated to investigate whether the groundwaters being discharged into the sea could be used as a possible water resources. This paper presents a preliminary information about the groundwaters being discharged along the shoreline of East Sea. Major discharge sites were selected primarily on the basis of the informaion on surface temperatures of the sea. Hydrogeologic and geographic conditions were also considered in selecting the major discharge sites. The development possibility of the discharging groundwater were estimated roughly, considering populations, industries and social development compatibilities of the selected areas. Groundwater dams and linked usage with surface water were suggested as possible development methods for the groundwaters.. Based on this study, we selected about 60 sites as the major discharge areas and tentatively recommended 6 sites as optimal sites for development of groundwaters being discharged into the sea. However, detailed in-situ hydrogeologic surveys are required prior to the final decision.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.8 no.4
• /
• pp.23-32
• /
• 1988

The rates of infiltration contributed to the flow fo water in an unconfined aquifer under the partially penetrated stream at an ungaged station and the corresponding base flow in channel are coupled by using the hydraulic and/or hydrologic characteristics obtained from the geomorphologic and soil maps. For the determination of groundwater flow, the linearized model which is originally Boussinesq's nonlinear equation is applied in this study. Also, a stream flow routing model for base flow in channel is based on a simplification of the Saint-venant. The distributed runoff model with piecewise spatial uniformity is presented for obtaining its solution based on a finite difference technique of the kinematic wave equations. The method developed in this study was tested to the Bocheong watershed(area : $475.5km^2$) of the natural stream basin which is one of tributaries in Geum River basin in Korea. As a result, it is suggested that the rationality of hydro-graph separation according to a wide variability in hydrogeologic properties be worked out as developing the physically based subsurface model. The results of the present model are shown to be possible to simulate a base flow due to an arbitrary rate of infiltration for ungaged basins.

• Journal of Korea Water Resources Association
• /
• v.55 no.10
• /
• pp.823-833
• /
• 2022

This study aims to improve the runoff modeling accuracy of a basin using Hydrological Simulation Program-FORTRAN (HSPF) model by considering nonhomogeneous characteristics of a basin. By entering classified values according to the various types of land cover and soil to the parameters in HSPF-roughness coefficient (NSUR), infiltration (INFILT), and evapotranspiration (LZETP)- the heterogeneity of the Yongdam Dam basin was reflected in the model. The results were analyzed and compared with the one where the parameters were set as a single value throughout the basin. The flow rate and water quality simulation results showed improved results when classified parameters were used by land cover and soil type than when single values were used. The parameterization changed not only the flow rate, but also the composition ratio of each hydrologic components such as surface runoff, baseflow, and evapotranspiration, which shows the impact of the value set to a parameter on the entire hydrological process. This implies the importance of considering the heterogeneous characteristics of the land cover and soil of the basin when setting the parameters in a model.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2002.09a
• /
• pp.9-12
• /
• 2002

The purpose of this study is to understand the high saline water phenomenon of Handong-ri area in the eastern coast of Jeju Island, were investigate the tidal effect of groundwater level, variation of electric conductivity and temperature, geological logging on the monitoring wells, chemical water quality, and ratios of oxygen istope of groundwater and seawater Results in investigating variation of interface zone of freshwater and saline water represented that the hyaloclastites formed at below groundwater table is developing toward the coast; this area consisted of stratum of good permeability. Hyaloclastites is presumed the main path of the high salinity water There are a lot of movement by the tide at upper layer. Salinity of lower layer spreads to upper up step in proportion to tidal energy. Because of hydrogeological characteristics, Interface zone of freshwater and saline water is made, High salinity of groundwater occur in east coastal area of Jeju Island. Therefore, I think that high saline groundwater phenomenon is natural condition by simple mixing.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2003.09a
• /
• pp.540-542
• /
• 2003

산을 관통하는 터널은 기존의 지하수위를 낮추어 지하수량 및 수질 변화와 함께 주변 식생에 영향을 미칠 수 있다. 본 연구는 서울시 내부 순환도로 건설에 따라 관악산을 관통할 예정인 터널 건설로 인한 지하수 환경변화를 이해하고자 한다. 즉, 현재 산출되는 지하수, 약수 및 지하수 화학특성을 파악하고 지하수 수문 자료와 연계하여 향 후 수질변화 가능성을 예측하고자 한다. 조사 지역에 분포하는 지하수는 지하수위가 대체로 최대 2m 정도에서 최대 20m를 넘지 않으며 일부 관정은 계절에 따라 수온 변화를 보여 지표수와 연계성을 시사한다. 전반적으로 중성에서 약산성을 띄며 이는 화강암과 화강 편마암으로 이루어진 이 지역의 지질특성에 기인한 것으로 생각된다. piper diagram에 도시하였을 경우 지표수는 지하수에 비하여 Na, K 에 비하여 Ca, Mg, Cl, SO$_4$가 우세한 반면 지하수와 약수의 경우 뚜렷한 특성 차이를 보이지 않으며 넓은 영역에 걸친 분포를 보인다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2012.05a
• /
• pp.428-432
• /
• 2012

SWAT모형을 이용하여 악근천, 호근천, 동흥천을 대표 3개 유역으로 구분하여 1990년 토지이용상태에 1980년부터 1999년까지의 기상자료를 사용하였고 2000년 토지이용상태에 2000년부터 2010년까지의 기상자료를 적용하여 분석한 결과, 적용 기간 평균 지하수 함양률은 30%로 분석되었다. 이러한 연구결과는 기존의 제주지역 지하수 함양량 분석연구에서 나타난 40-50%보다 훨씬 적은 값으로 나타나고 있음을 알 수 있었다. 이 결과는 투수성 다공질 지층이 제주지역의 지질특성을 고려하더라도 개발형태가 비투수성 포장형태이고, 개발된다면 육지지역과 같은 지하수함양특성과 비슷할 수 밖에 없음을 알 수 있었다. 또한 Markov-chain을 이용하여 장래토지이용상태를 분석한 결과 장래의 토지이용은 2000년 현재에 비해 산림 3.4%감소, 농경지 0.2% 증가, 수계 1.0% 증가, 도심지 0.5%증가 하는 것으로 나타났다. 토지이용상태에 따른 SWAT모형 분석을 비교한 결과 현재에 비해 유출량은 평균 22mm 증가하였으며, 증발산량은 평균 5mm감소, 함양량은 평균15mm감소하여 0.7% 정도 감소하는 것으로 토지이용상태가 함양량에 영향을 미치는 것으로 분석되었다.

• Journal of the Speleological Society of Korea
• /
• no.88
• /
• pp.51-62
• /
• 2008

동굴내부의 지형변형은 동굴내의 외인적인 요인과 내인적인 요인에 의하여 발달된다. 외인적인 요인으로서 기후변동에 의한 기온의 변화와 침출수의 증감 및 외부 이입물질 등을 들 수 있으며, 내인적인 요인으로서는 암석의 공극율, 지질환경, 단층 및 습곡면의 형상, 절리 및 균열면의 유무, 동굴지천의 구배 및 유속, 층리간의 이종의 암석게재 여부 등을 들 수 있다. 동굴 시스템은 수문 물리화학적 요소에 의해 형성되며 외부 기준면 통제에 의해서 암석학, 구조학, 기후학, 생물학, 토양학 등과 밀접한 상태에서 의존적인 발달 과정을 가진다. 동혈 내부의 침식은 유수의 입력 경우 유출과정에서 형성되며, 또한 유수의 비 입력 경우유출 및 액체용액의 분출에 의해서 형성된다. 다수의 동굴학자들은 동굴은 계절마다 침수되거나 빨리 흐르는 홍수에 의한 폭우에 의해 epiphreatic 상태에서 간헐적으로 포화되는 과정을 거치며 선택적으로 발달한다고 주장하고 있다. 혼합지대 동굴의 가장 좋은 예는 현재의 카르스트 지역에서 나타나는 것이 아니라 과거 제4기의 200만년전 동안보다 해수면이 더 안정적이었던 때에 이루어진 고 카르스트(Paleo Karst)에서 발견되고 있다.

• Economic and Environmental Geology
• /
• v.52 no.4
• /
• pp.299-312
• /
• 2019

This study analyzed variation of tidal channels associated with Shihwa reclamation project for corresponding observation period based on remote sensing approaches. The project period was subdivided to developing period, closed period, and open period based on developing and management plan of Shiwa lake, and number, length, width, and direction of tidal channels for each period were analyzed using CORONA, Landsat 5 TM, Landsat 7 ETM+, and orthorectified aerial photographs. Number of tidal channels decreased from developing to opening period while $3^{rd}$ order channles did not show noticeable changes. The length of tidal channels decreased during developing to closed period, and increasing trend of $2^{nd}$ and $3^{rd}$ order channels was observed for the opening period. The average widtrh of $2^{nd}$ and $3^{rd}$ order channels decreased from developing to closed period, and increased during open period. The direction of tidal channels showed NW and NE direction in general, while the rose diagram showed deacrased frequency of NE direction and increased frequency of NW direction during the open period. These variations in tidal channels are considered to be related to changes in tidal energy environment, where stable energy environment before the project was changed to disconnection of tidal energy by closed environment, and re-connection of the energy during the open period.