• Journal of the Korean association of regional geographers
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• v.14 no.3
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• pp.212-223
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• 2008

The rainfall partitioning in a monogenetic volcano has been analysed using the hydrological data of a small catchment on Eoseungsaeng-oreum of Mount Halla and the meterological data of Eorimok Automated Weather System. The experimental catchment extends from 965 m to 1,169 m in altitude, and has an catchment area of $51,000\;m^2$ Eoseungsaeng-oreum is the scoria cone predominantly covered with Carpinus laxiflora and Quercus serrata. The analyzed periods are April 30 to September 12 and October 7 to November 19, 2007. The experimental catchment exhibits the total precipitation of 2,296.5 mm. Surface runoff amounts to 465 mm that is equivalent to 20.2% of the precipitation. By contrast, evapotranspiration accounts for 25.9% of the precipitation, and the remnant of 1,236.5 mm deep1y percolates underground through a basement. The rainy summer season, in particular, shows the highest deep percolation ratio of 62.2%. The deep percolation ratio of the experimental catchment is at 1east more two times than the ratio of a gneiss basin in Korea Peninsular. It has suggested that the experimental catchment is characterized by the higher portion of deep percolation in rainfall partitioning which reflects the highly permeable lithology in Jeju Island.

• Korean Journal of Ecology and Environment
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• v.48 no.1
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• pp.68-76
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• 2015

There is no willow riparian vegetation in Jeju Island, Korea. Instead, a genetically-isolated population of Adina rubella is found in some parts of the riparian system. We describe its syntaxonomy and synecology. A total of 27 phytosociological relev$\acute{e}$s were collected, 11 relev$\acute{e}$s from 91 sites and 16 relev$\acute{e}$s from the previously published relevant materials. Data were analyzed by traditional Braun-Blanquet method and multivariate PCoA (Principal coordinates analysis). New syntaxa are distinguished, Adinion rubellae all. nov. and its type association Tripogono-Adinetum rubellae ass. nov. with two subassociations, typicum and rhododendretosum poukhanensae. Adino-Rhododendretum poukhanensae Itow et al. 1993 was discarded owing to mismatch of syntaxonomy and syngeography of Adina and Rhododendron phytocoena. The alliance Adinion is Jeju's regional and partly ombrotrophic vegetation occurring in pothole and rock crevice where are independent on ground-water table. We also suggest a revised alliance, Rhododendrion poukhanensae Lee 2004 ex. hoc loco in Korean peninsula, as a corresponding syntaxon to Adinion, which completely differs from Phragmito-Salicion. Finally we pointed out that Adina phytocoena requiring an absolutely monitoring has been threatened by river maintenance project of local government.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.3
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• pp.105-111
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• 2020

We defined Jeju Wind Castle and analyzed the relationship between Hallasan-Oreum-Batdam, the main subject, for the first time. In Jeju, 1.5m high Batdam(Black Silk Road), 368 Oreums, Hallasan Mountain 1950m are all unique scenery. The verification of this paper demonstrates that Samdasoo's groundwater extraction sea level is equal to the height of Hallasan and that this problem is mathematically complete in neutral plane theory. Donnaeko(700meters above sea level)-Baeknokdamdongneung-Jindallebat-Seongpanak-Gyorae(453 meters)-Witsaeoreum(1700meters) is a rain belt that hits the low-air pressure air-conditioned North Pacific humidity rising from the southeast and the high-pressure cold air of Hallasan Peak. It rains a lot because - and + are neutral plane, which adds to zero. Hallasan is called Jinsan in Jeju history. The answer is Wind Castle. The number of Oreum in Jeju is 369 including Hallasan, and Batdam, which is about 1.5m high, does not collapse even with a typhoon blowing over 50m/s. Because the wind castle's core is 1.5 meters of Batdam and it is a triangular number.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.09a
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• pp.55-71
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• 2005

Jeju Island is mainly composed of basaltic lava flows and subordinate amounts of volcaniclastic sedimentary rocks. Jeju Province operates the monitoring wells for seawater intrusion problems around Jeju Island to evaluate of groundwater resources in coastal area. Various surveys and monitoring have been performed in boreholes, and also conventional geophysical well loggings conducted to identify basalt sequences and assess seawater intrusion problems. Various conventional geophysical well logs, including radioactive logs, electrical log, caliper log, and temperature and conductivity log and heat-pulse flowmeter log were obtained in 29 boreholes. The results of geophysical well loggings for saturated rocks are interesting and consistent. Natural gamma logs are useful in basalt sequences to sedimentary interbeds, unconsolidated U formation, and seoguipo formation with higher natural gamma log regardless of saturated or unsaturated basalts. Neutron logs are very effective to discriminate among individual lava flows, flow breaks, and sedimentary interbeds in saturated formation. In hyalocastite, porosity is high and resistivity is low, and we think that hyalocastite is a major pathway of fluid flow. In trachybasalt, porosity has a wide range and resistivity is high. In sedimentary interbeds, unconsolidated U formation and seoguipo formation, porosity is high and resistivity is low. The temperature logs in eastern area in Jeju are useful to interpret the hydrogeological unit and evaluate seawater intrusion in Suan area.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.17-20
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• 2002

The environmental tracers of $^3$H and NO$_3$ were investigated in terms of vertical connections between basaltic aquifers and underlying sedimentary formations of Seoguipo formation that is not found in eastern coastal area and U formation. In western coastal area, $^3$H shows values less than 0.5TU In the wells completed in Seoguipo formation whereas it is greater than 2TU in other area. For the wells in western area, NO$_3$ concentrations are below background level though the nearby land uses are mainly agricultural. The groundwater heads are much lower in eastern coastal area than western area in spite that recharge rate of eastern area is 1.7 times higher than that of western area. The basaltic aquifer is thicker by 70m in eastern coastal area than in western coastal area, which is insufficient to explain much lower groundwater heads in eastern area. These hydrogeological characteristics suggest that for the basaltic aquifers, the Seoguipo formation acts as a lower boundary which could limit downward groundwater flow in basaltic aquifers whereas the U formation is unlikely.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.306-306
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• 2022

2015년부터 2019년까지 우리나라에서는 평균 18,521 ha의 경작지에 가뭄피해가 발생하였다. 이 중 평균 11,260 ha는 밭으로 피해의 60% 이상이 밭에서 발생하는 것으로 나타났다. 밭 가뭄 피해는 2016년과 2018년에 크게 발생하였으며, 제주에서 가장 큰 피해가 발생하였다. 또한 강원도, 충청남도의 여러 지역에서 지속적인 피해가 나타났다. 농업 가뭄을 대응하기 위하여 저수지와 지하수 관정 등을 활용하고 있지만, 밭에 대한 구체적이고 체계적인 가뭄 대응 방안은 미비하다. 따라서 본 연구에서는 밭 가뭄에 대한 취약성을 지역별로 평가하고 이를 기반으로 우선 관리지역을 선정하는 방안을 검토하였다. 밭 가뭄 취약성 평가에는 위협 요인, 피해 요인, 해소 요인을 평가 기준을 설정하였다. 밭 가뭄에 대한 위협 요인은 토양 수분량의 정도로 제시할 수 있으며 본 연구에서는 1995년부터 2014년까지 20년간의 강수량, 증발산량 등의 기상 및 토양 자료를 활용하여 분석하였다. 피해 요인은 피해를 입는 밭이 대상으로 행정구역 단위로 평가를 수행함에 따라 행정구역별 밭 비율을 산정하여 활용하였다. 해소 요인은 가뭄 피해를 감소시킬 수 있는 활동을 반영하는 평가 기준으로서 본 연구에서는 저수지와 지하수관정 등 밭 가뭄 저감에 활용할 수 있는 요소를 반영하였다.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.10
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• pp.566-573
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• 2016

In order to support effective usage of groundwater as an alternative water resource in future, we investigated distribution characteristics of minerals related with human health. While recent studies tended to focus on small scale, this study broadened research area up to nationwide scale to understand groundwater hydrology and regional, geological distributions of minerals in wide area; we investigated mineral distributions of national groundwater monitoring networks, developed GIS-based mineral maps, and reviewed correlation with geological features. As a result, calcium showed the highest concentration among 5 minerals (Ca, Mg, Na, K, Si) and potassium showed the lowest. Calcium concentration in limestone and sedimentary zone was the highest, and that in pore-volcanic-rock zone was the lowest. While calcium, magnesium and sodium showed differences in concentrations in intrusive-igneous-rock and sedimentary zone, potassium was not within geological features. When we studied regional differences, there were no tendency, but Jeju and Gangwon area showed differences in concentrations of calcium and silica.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.3
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• pp.315-322
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• 2008

Recently there has been a great deal of interest in promotion of the utilization of rainwater. In this paper, we compared qualities of the rainwater collected from the top of vinyl houses to those of precipitated rainwater itself in Jeju Island. The pH of the collected rainwater was acidic and lower than the precipitated one. As a storm progresses, the pH of the collected water gradually increases. Ranges of EC of the precipitated and collected rainwater were 1-118 and $1-475{\mu}S/cm$. Most of Cl and turbidity values of the collected rainwater were less than 20 mg/L and 20 NTU, while those of the precipitated rainwater were less than 10 mg/L and 5 NTU. Differences in qualities between precipitated and collected rainwater indicate that qualities of the collected rainwater should be changed by the first flush effects, and imply that long term continuous monitoring for the qualities of collected rainwater is essential to quantify the first flush phenomenon more accurately.

• Journal of Environmental Science International
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• v.25 no.12
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• pp.1727-1738
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• 2016

In this study, groundwater flow was analyzed targeting Dae-jeong watershed, which exhibited the largest variations of groundwater levels at the identical elevation points among the 16 watersheds of Jeju Island. The issues of the methods applied in practice were identified and improvement plans were suggested. This groundwater-flow estimates derived by applying hydraulic conductivity values onto zones of equal topographic ground level were found to be quite different from actual measured groundwater flow. Conversely, groundwater-flow estimates that utilized hydraulic conductivity values applied onto groundwater-level equipotential lines indicated relatively lesser divergences from actual measured groundwater flow. The reliabilities of the two approaches were assessed for 60 randomly selected points on DEM (digital elevation model) maps, The method using hydraulic conductivity values applied onto groundwater-level contours turned out to be the more reliable approach for the Dae-jeong watershed in Jeju Island.

• Journal of Environmental Science International
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• v.24 no.4
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• pp.449-459
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• 2015

The depth of low permeable layer in Jeju Island was analyzed using the geologic columnar section data. The highest low permeable layer was found in center of Mt. Halla and the deepest area was in eastern part of Jeju Island. The study area, Seongsan watershed, is located in the eastern part of Jeju where the low permeable layer showing deep in a northward direction. Based on this analysis, the MODFLOW modeling was performed for groundwater flow of Seongsan watershed. The boundary of Seongsan watershed was set up as a no-flow and the modeling result showed the difference -0.26~0.62 m compared to the observed groundwater level. Meanwhile, MODFLOW model results considering low permeable layer showed -0.26~0.36 m differences compared to groundwater level and indicated more accurate than no-flow method result. Therefore, to interpret the groundwater flow over Seongsan watershed, comprehensive consideration including the low permeable layer distribution below the basalt layer is needed.