• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.509-514
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• 2015

Indicators of environmental conditions qualitatively and quantitatively describe the state of the environment and natural resources, and the OECD (Organization for Economic Cooperation and Development) has initiated and suggested AEIs (Agri-Environmental Indicators) to assess trends over time of the effects of agriculture on the environment and the effectiveness and efficiency of agricultural and environmental policy measures since 1990's. This study aims to develop the state indicators of water quality for agricultural water, surface and groundwater, to evaluate the environmental impacts of agricultural activities and policies by qualifying the environmental levels of a nation. Status indicators were calculated according to the agricultural water quality standards of OECD and Korea, and their trends were analyzed over time. Particularly, nitrate ($NO_3{^-}$) status indicators of ground water in 2013 were significantly lower than the ones in 2000. Overall, the water quality indicators of surface water in 2013 were higher than the ones in 2012, except for pH and DO. The groundwater quality indicators in 2013 were lower than those of previous years. The optimal management indicators were calculated to assess agricultural surface water and groundwater quality. The findings of this study indicated that the state indicators could play a significant role to establish policies and procedures for managing and conserving water resources. This study also discussed water pollution caused by agricultural and industrial effluents.

• Journal of Korea Water Resources Association
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• v.54 no.10
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• pp.835-848
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• 2021

In Jeju Island which has peculiarity for its geological features and hydrology system, hydrological factor analysis for the effective water management is necessary. Because in-situ hydro-meteorological data is affected by surrounding environment, the in-situ dataset could not be the spatially representative for the study area. For this reason, remote sensing data may be used to overcome the limit of the in-situ data. In this study, applicability assessment of MOD16 evapotranspiration data, Globas Land Data Assimilation System (GLDAS) based evapotranspiration/soil moisture data, and Advanced SCATterometer (ASCAT) soil moisture product which were evaluated their applicability on other study areas was conducted. In the case of evapotranspiration, comparison with total precipitation and flux-tower based evapotranspiration were conducted. And for soil moisture, 6 in-situ data and ASCAT soil moisture product were compared on each site. As a result, 57% of annual precipitation was calculated as evapotranspiration, and the correlation coefficient between MOD16 evapotranspiration and GLDAS evapotranspiration was 0.759, which was a robust value. The correlation coefficient was 0.434, indicating a relatively low fit. In the case of soil moisture, in the case of the GLDAS data, the RMSE value was less than 0.05 at all sites compared to the in-situ data, and a statistically significant result was obtained as a result of the significance test of the correlation coefficient. However, for satellite data, RMSE over than 0.05 were found at Wolgak and there was no correlation at Sehwa and Handong points. It is judged that the above results are due to insufficient quality control and spatial representation of the evapotranspiration and soil moisture sensors installed in Jeju Island. It is estimated as the error that appears when adjacent to the coast. Through this study, the necessity of improving the existing ground observation data of hydrometeorological factors is emphasized.

• The Korean Journal of Malacology
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• v.27 no.3
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• pp.229-246
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• 2011

This study was performed to know and compare the community structures of macrobenthic invertebrates of eight fishing grounds in the coastal waters of Jeju Island from September to October 2008. A total of 166 species was identified. Mollusks comprised 77 species (46.4%); Arthropods 24 (14.5%), Cnidarians 18 (10.8%); Poriferans 16 (9.6%); and the others including Echinoderms 33 (17.7%). Density and biomass were estimated to be 6,905 ind./$m^2$ and 113,100.7 gwwt/$m^2$, respectively. Gastropods was the most dominant taxon in terms of abundance (3,311 ind./$m^2$) and number of species as well, and Gastropods was predominant in biomass (55,789.2 gwwt/$m^2$). The dominant species were Omphalius pfeifferi, Astralium haematragum, Turbo cornutus, Ergalatax contraacta, Lithophaga cura, Anthocidaris crassispina, Herdmania monus in 5-15 m. Based on the cluster analysis, the study area could be divided into two station groups. The biodiversity, evenness and richness index appeared as follows: H' = 1.59-2.95, E' = 0.38-0.87, R = 3.3-10.4. The dominance index were highest in Daepo and lowest in Woljeong.

• 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.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.6
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• pp.666-684
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• 2019

The horizontal distributions of eggs and larvae of chub mackerel Scomber japonicus were extensively surveyed in the vicinity of Korean waters between 31°75'N and 36°50'N during May and June in 2016 and 2017 (total of four surveys). We used a coupled bio-physical model (DisMELS) that combines an individual-based model (IBM) incorporating vertical migration of larvae and temperature-dependent survival to understand transport processes in the early life stage. Using the distributions of eggs and larvae from surveys, the potential spawning grounds were estimated at the northwest and southeast of Jeju Island and the central East China Sea in May, and at the southwestern East Sea and southern West Sea in June by running the model backward in time. In forward experiments within 30 days from the backward results, most larvae were transported to both the Korean and Japanese sides of the East Sea through the Korea Strait. However, the larvae released in the central East China Sea were transported to the Japanese side only, while those released in the southern West Sea were retained within that region. The survival rates at 30 days after release based on the simulation incorporating temperature-dependent survival throughout May and June were 29.7% in 2016 and 28.8% in 2017.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.2
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• pp.92-100
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• 1984

The seasonal variation of catch and the fishing ground formation of anchovy caught by gill net are studied by using the data for 14 years, 1969 to 1982, published by the Fisheries Research and Development Agency of Korea. The main fishing season of anchovy by gill net can be devised into two seasons: spring and autumn. The former begins early in spring, marks peak in May with the monthly mean catch of 3,000 $\frac{M}{T}$ and ends in summer. The latter begins early in autumn, marks peak in October with the monthly mean catch of 1,500$\frac{M}{T}$ and ends in winter. The fishing ground begins to be formed in the southern waters of Korea with the begining of spring fishing season, and it is extended all over the south-eastern waters from spring to summer and it is converged to the coastal areas from autumn to winter. From the calculation of correlationship between adjacent fishing sections, the fishing ground can be devided into three areas; the northern area of $37^{\circ}N$, the southern area of $35^{\circ}N$ and the area between $35^{\circ}N\;and\;37^{\circ}N$. In the northern area of $37^{\circ}N$, monthly centers of the fishing ground are located in the adjacent aea area of Sockcho-Jumunjin district in the whole year, and its annual mean variance shows about 8 miles in the latitudinal direction and 10 miles in the longitudinal direction. In the area between $35^{\circ}N\;and\;37^{\circ}N$, monthly centers are located in the adjacent sea area of Kijang-Kuryongpo district, and the variance shows about 10 miles in the longitudinal direction and 20 miles in the latitudinal direction. In the southern area of $35^{\circ}N$, monthly centers are located in the open sea in spring and summer, and are conversed to the coastal area in autumn and winter, and the variance shows 8 miles in the latitudinal direction and 35 miles in the longitudinal direction. Water temperature and salinity at the fishing ground where the anchovy gill net was effectively operated are estimated from 14 to $20^{\circ}C$ and from 33.0 to $34.0\%0$ respectively.

• Journal of Korea Water Resources Association
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• v.39 no.4 s.165
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• pp.299-311
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• 2006

In this paper it is outlined the methodology of estimating the parameters of water balance analysis method for calculating recharge, using ground water level rises in monitoring well when values of specific yield of aquifer are not available. This methodology is applied for two monitoring wells of the case study area in northern area of the Jeiu Island. A water balance of soil layer of plant rooting zone is computed on a daily basis in the following manner. Diect runoff is estimated by using SCS method. Potential evapotranspiration calculated with Penman-Monteith equation is multiplied by crop coefficients($K_c$) and water stress coefficient to compute actual evapotranspiration(AET). Daily runoff and AET is subtracted from the rainfall plus the soil water storage of the previous day. Soil water remaining above soil water retention capacity(SWRC) is assumed to be recharge. Parameters such as the SCS curve number, SWRC and Kc are estimated from a linear relationship between water level rise and recharge for rainfall events. The upper threshold value of specific yield($n_m$) at the monitoring well location is derived from the relationship between rainfall and the resulting water level rise. The specific yield($n_c$) and the coefficient of determination ($R^2$) are calculated from a linear relationship between observed water level rise and calculated recharge for the different simulations. A set of parameter values with maximum value of $R^2$ is selected among parameter values with calculated specific yield($n_c$) less than the upper threshold value of specific yield($n_m$). Results applied for two monitoring wells show that the 81% of variance of the observed water level rises are explained by calculated recharge with the estimated parameters. It is shown that the data of groundwater level is useful in estimating the parameter of water balance analysis method for calculating recharge.

• Tunnel and Underground Space
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• v.28 no.3
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• pp.258-276
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• 2018

The accurate and quantitative ground information on the hydraulic conductivity characteristics of rock mass is one of the key factors for evaluation of the hydro-geological behaviour of rock mass around an excavated opening under high water pressure. For tunnel and rock structures in seabed, where the sea acts as an infinite source of water, its importance become greater with increasing construction depth below sea level. In this study, to improve the problems related with poor system configuration and incorrect data acquisition of previous hydraulic packer testing equipment, we newly developed an integrated main frame and 30 bar level waterproof downhole sonde apparatus, which were optimized for deep hydraulic packer test in seabed rock mass. Integration of individual test equipment into one frame allows safe and efficient field testing work on a narrow offshore drilling platform. For the integrated type main frame, it is possible to make precise stepwise control of downhole net injection pressure at intervals of $2.0kg_f/cm^2$ or less with dual hydraulic oil volume controller. To ensure the system performance and the operational stability of the prototype mainframe and downhole sonde apparatus, the field feasibility tests were completed in two research boreholes, and using the developed apparatus, the REV(Representative Elementary Volume) scale deep hydraulic packer tests were successfully carried out at a borehole located in the basalt region, Jeju. In this paper, the characteristics of the new testing apparatus are briefly introduced and also some results from the laboratory and in-situ performance tests are shown.

• Asian Journal of Turfgrass Science
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• v.23 no.2
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• pp.219-228
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• 2009

The construction procedures and artificial turf maintenance program on golf course definitely influence on the distortion of its environment. Soil microbial communities in soil profile were affected directly by those practises on turf areas. In Jeju island, the environmental impact assessment has been required to apply the first quality class granular activated carbon(GAC), which has a high absorbent character to agricultural chemicals, on the soil profiles of golf green system to reduce the pesticide leaching to ground water. This research was carried out to analyze the changes of microbial communities and chemical properties on soil profiles where GAC had been applied at the construction stage at two golf courses in Jeju. The changes of soil microbial population and chemical properties associated with construction methods of soil profile and agrochemical management program were analyzed by monthly at the surface and sub-soil profiles during April through October, 2007. The total numbers of bacteria and fungi, soil moisture content, soil physio-chemical properties were measured on greens and fairways of the both golf courses with different GAC treatment on the green and fairway soil profiles. The results showed that GAC had positive effects on the water holding capacity, pH and EC, however, it did not improved the holding capacity of available nutrients ${NO_3}^-,{NH_4}^+$, and phosphorus by its sorption phenomenon. In microbial count test, the total numbers of bacteria and fungi showed a great variation during sampling dates. That may directly relate to the agrochemical application, however, the ratio of total bacterial number versus total fungus number showed a constant value on a sub-soil of 15~30cm depth. Thus, the construction method of GAC in soil profile, and application of fertilizer and pesticide, both impacted on the changes of microbial population. It's means that the construction method of soil profile and turf management using agro-materials might greatly affect on the turfgrass culture and the environment of golf course.

• Korean Journal of Environment and Ecology
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• v.30 no.2
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• pp.165-172
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• 2016

Mallard and Spot-billed ducks that are typical wintering water birds use the wide rice field in the center of the water system as a wintering ground. I try to figure out the daily movement distance from Home-Range to wintering ground for mallard and spot-billed ducks in Mangyunggang, Dongjingang where located in central region. In 2015 wintering period by using a Cannon-net, I attached WT-300 to 5 mallard and 5 spot-billed ducks. Daily movement distance is an overall average 0.89km, the largest distance was 31.09km. Daily movement distance of mallard was 0.97km, the largest distance was 28.78km. Daily movement distance of Spot-billed ducks was 0.80km, the largest distance was 33.39km. Home-Range analysis is used by the SHP files that is compatible with GIS and ArcGIS 9.0 Animal Movement Extension, it was analyzed using the Minimum Convex Polygon Method (MCP) and the Kernel Density Estimation (KDE). The behavior rights of two kinds of ducks was $490.34km^2$ by Minimum Convex Polygon Method (MCP) ($SD=311.20km^2N=10$), an important habitats Kernel Density Estimation (KDE 50%) was $42.24km^2$. Home-Range of Mallard (MCP) was $568.02km^2$, it is wider than home-range(MCP) of spot-billed duck $397.13km^2$ relatively, the core habitats of mallard is $53.05km^2$, it is wider than mallard's core habitats(KDE 50%) $29.26km^2$ relatively.