• Journal of Soil and Groundwater Environment
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• v.13 no.5
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• pp.20-32
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• 2008

Runoff characteristics of the Oedocheon in Jeju island were investigated using the long-term stream stage monitoring data. At the Cheonah valley in the upstream area and Oedocheon downstream, annual runoff occurred 21 and 12 times, respectively, and their average runoff periods were 21 days and 12 days, respectively. Stream stage response time to rainfall was 4 hours, and storm-water transfer from the upstream, Cheonah valley, to the Oedocheon downstream took about 2 hours. The stream discharge measurements had been carried out from Feb. 2004 to Jul. 2005, and showed that normal discharge of the Oedocheon was 0.39 $m^3$/sec in average. Stage-discharge curves were developed to estimate base flow (normal discharge) and (direct) surface runoff. The base flow separations by a numerical filtering technique illustrated that annual surface runoff and base flow accounted respectively for 31.8${\sim}$36.5%, 63.5${\sim}$68.2% of the total stream discharge.

• Economic and Environmental Geology
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• v.29 no.3
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• pp.315-323
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• 1996

An apatite drain was constructed on September 30, 1994 at the Green Valley Abandoned Coal Mine site near Terre Haute in west central Indiana. The primary objective of this experiment is to evaluate the long-term ability of the apatite drain to mitigate acid mine drainage (AMD) under field conditions. The drain 9 m long, 3.3 m wide, and 0.75 m deep, contain 95 rum to No. 30 mesh-size apatite ore (francolite) and receive AMD seepage from reclaimed gob piles, and designed according to the laboratory testing. The apatite drain was covered with limestone riprap and filter fabric to protect the drainage system from stormwater and siltation. The drain consists of about 50 metric tons of apatite ore obtained from a phosphate mine in Florida. A gabion structure was constructed downstream of the apatite drain to create a settling pond to collect precipitates. Apatite effectively removed iron up to 4,200 mg/l, aluminum up to 830 mg/l and sulfate up to 13,430 mg/l. The pH was nearly constant for the influent and effluent, ranging between 3.1 and 4.3. Flow rate measured at the gabion structure ranged from 3 to 4.5 l/m. Precipitates of iron and aluminum phosphate (yellow and white suspendid solids) continued to accumulate in the settling pond.

• Geophysics and Geophysical Exploration
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• v.6 no.4
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• pp.165-170
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• 2003

Recently, resistivity surveys have been frequently carried out over the irregular terrain such as mountainous area. Such an irregular terrain itself can produce significant anomalies which may lead to misinterpretations. In this study, topographic effects in resistivity survey were studied using the physical scale modeling as well as the numerical one adopting finite element method. The scale modeling was conducted at a pond, so that we could avoid the edge effect, the inherent problem of the scale modeling conducted in a water tank in laboratory. The modeling experiments for two topographic features, a ridge and a valley with various slope angles, confirmed that the results by the two different modeling techniques coincide with each other fairly well for all the terrain models. These experiments adopting dipole-dipole array showed the distinctive terrain effects, such that a ridge produces a high apparent resistivity anomaly at the ridge center flanked by zones of lower apparent resistivity. On the other hand, a valley produces the opposite anomaly pattern, a central low flanked by highs. As the slope of a terrain model becomes steeper, the terrain-induced anomalies become stronger, and moreover, apparent resistivity can become even negative for the model with extremely high slope angle. All the modeling results led us to the conclusion that terrain effects should be included in the numerical modeling and/or the inversion process to interpret data acquired at the rugged terrain area.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.859-865
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• 2011

This study looked into 110 sites of orchard fields to investigate the relationships between the physical and chemical properties of soils, including heavy metal contents, and the topographic characteristics of the fields in Jeonbuk province. The topographic distribution of orchard fields in Jeonbuk province was local valley and fans, hilly and mountains, mountain foot slopes, alluvial plains, diluvium, and fluvio-marine deposits. Forty-six percent (46%) of total orchard fields were located in the hilly and mountains. Soil texture of the local valley and fans was mostly sandy clay loam, and the soil texture of other topographical sites were varied. Bulk density, porosity, and soil hardness were not different among the various topographic sites. The content of plant available water was the highest (19.5%) in the sites of diluvium. Soil pH, electrical conductivity (EC), and exchangeable $Mg^{2+}$ content were the highest in the sites of fluvio-marine deposits, whereas the contents of soil organic matter (SOM), available phosphorus, and exchangeable $Ca^{2+}$, $K^+$, and $Na^+$ were not significantly different among the topographic sites. Also, soil pH and SOM content were generally in optimal ranges for the fruit plants in the orchard fields, but other values were mostly higher than those in optimum. In addition, the contents of heavy metals were much lower than the levels of Soil Contamination Warning Standard.

• Korean Journal of Environment and Ecology
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• v.35 no.3
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• pp.294-304
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• 2021

This study aims to obtain basic data for systematic restoration by analyzing the monitoring results of the Shimwon Valley Ecological Landscape Restoration Project area in Jirisan National Park. In 2017, when the restoration project was completed, 12 monitoring plots and 4 control plots were installed for vegetation monitoring, and changes in the relative dominance, species diversity index and similarity between 2017 and 2020 were analyzed. The species diversity index of the surveyed areas where trees were planted during the restoration project was 0-1.4552, and the similarity index with the control group was 0% except for one survey area at 1.32%. The very low species diversity index and similarity index in the survey areas were attributed to the loss of trees planted during the restoration project due to death, damage by wild boars, or erosion by running water. On the other hand, the species diversity index was 0.9538-2.3222 in the monitoring plot where no tree was planted, and the similarity index was analyzed to be as high as 8.33%. It is necessary to continue the long-term monitoring for the development of ecological landscape restoration methods in the national park and analysis of the succession in monitoring plots where no trees were planted.

• Journal of Korea Soil Environment Society
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• v.2 no.1
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• pp.35-44
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• 1997

A column study using artificial acid rain was conducted to evaluate the buffering capacities in soil layer and host rock. In an effort to compare the effect of composition of host root two valleys of which compositions of host rock are different were chosen within the study area and the pHs of the water flowing in the valleys were measured from May, 1996 to October, 1996. The pHs of the artificial acid rain prepared by adding appropriate amounts of both sulfuric and nitric acids to distilled water were 3, 4, and 5, and the column effluents were analyzed for major cations and anions. The cation exchange capacities(CECs) of A Horizon and the B Horizon were 9.68 and 6.16 meq/100g, respectively, Compared to the B Horizon, the pH in the column effluent of A Horizon with larger CEC was higher. The sums of $Ca^{2+}$, $Mg^{2+}$, $Na^{+}$in the column effluents gradually decreased, indicating the loss of CEC by acid rain. The field study showed that pHs of the surface water in the valleys increased as the water flows downwards. The magnitude of this buffering capacity was greater for the valley in which smectite in addition to kaolinite and illite was a weathered product of host rocks. This also indicates that host rock as well as soil layer retains the buffering capacity.

• Journal of Wetlands Research
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• v.10 no.3
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• pp.57-68
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• 2008

For improving water quality and hish habitat environment the targeted instream flows added to the field measurement of low flow at each reach along Wonju Cheon are calculated by depth, velocity, and the present lower channel width with considering the landscape, aquatic environment, and natural ecological function. Target instream flow increasing ranged from $0.03m^3/s$ of upstream to $0.90m^3/s$ of downstream according to the proposed depths of 0.10m to 0.30m and velocity of 0.2m/s. The methods for target instream flow increasing are base flow increasing by watershed management, non polluted discharge inflow from valley and combined sewer by sewerage system modification, and discharges from upstream reservoirs and detention basins near-by stream. The possible increasing flow rates are $0.19m^3/s$ to $3.42m^3/s$ which are 1.4 to 2.5 times of low flow to be measured which are the equivalent targeted instream flows along Wonju Cheon. The BOD-based water quality improvement are analyzed by QUAL2E. The habitat suitability indices by PHABSIM of Zacco temmincki as target species at middle stream of Wonju Cheon improve significantly by low flow increasing, which is very important to improve water quality and fish habitat.

• Journal of Korea Soil Environment Society
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• v.1 no.2
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• pp.15-21
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• 1996

Effects of acid deposition on the acidification of surface water over a short term period were studied during June~October, 1995. A reservoir located in Chunchon, Kangwondo was selected for this study because this reservoir had received little man-made pollutants. Geological survey within the study area was carried out and the pH of a small and shallow stream flowing from the mountain valley down to the reservoir was monitored. Rainfall was measured by using a rain gauge and the precipitation was collected by automatic precipitation sampler. During the study period, rain pH was in the range of 3.81~5.77 with an average of 4.8. The EC was in the range of 5~189$\mu$S/cm with an average of 10.6$\mu$S/cm. ionic composition of the rainfall showed that of the anions, deposition of ${SO_4}^{2-}$, was highest with 3,119.7 kg/$\textrm{km}^2$, and it was $NH^{4+}$ with 1,053.2kg/$\textrm{km}^2$ for cations. The surface water pHs were maintained neutral or weak basic representing little evidence of acidification regardless of the acidic rainfall pH. Every time of sampling, however, the pHs exhibited increasing tendency as elevation of measuring site of the stream became lowered, which indicated the impacts of acid-base reactions by acidic or basic substances during travel of water downstream. This result suggested the necessity of further research to determine the respective buffering capacity of soil and underlying rocks.

• Journal of Korea Water Resources Association
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• v.55 no.12
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• pp.999-1009
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• 2022

The Chuncheon Mullori area is an underprivileged area for water welfare that does not have a local water supply system. Here, water is supplied to the village by using a small-scale water supply facility that uses underground water and underground water as the source. To solve the problem of water shortage during drought and to prepare for the increasing water demand, a sand dam was installed near the valley river, and this facility has been operating since May 2022. In this study, in order to evaluate the reliability of water supply when a sand dam is assumed during a drought in the past, groundwater runoff simulation results using MODFLOW were used to generate inflow data from 2011 to 2020, an unmeasured period. After performing SWAT-K basin hydrologic modeling for the watershed upstream of the existing water intake source and the sand dam, the groundwater runoff was calculated, and the relative ratio of the monthly groundwater runoff for the previous 10 years to the monthly groundwater runoff in 2021 was obtained. By applying this ratio to the 2021 inflow time series data, historical inflow data from 2011 to 2020 were generated. As a result of analyzing the availability of water supply during extreme drought in the past for three cases of demand 20 m³/day, 50 m³/day, and 100 m³/day, it can be confirmed that the reliability of water supply increases with the installation of sand dams. In the case of 100 m³/day, it was analyzed that the reliability exceeded 90% only when the existing water intake source and the sand dam were operated in conjunction. All three operating conditions were evaluated to satisfy 50 m³/day or more of demand based on 95% reliability of water supply and 30 m³/day or more of demand based on 99% of reliability.

• Journal of Korea Water Resources Association
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• v.55 no.11
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• pp.923-929
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• 2022

The Chuncheon Mullori area is an underprivileged area of water welfare where local water supply is not supplied, and it is supplying water to the villages with small water supply facilities using lateral flow and groundwater as water sources. This is an area with poor water supply conditions, such as relying on water trucks due to water shortages during the recent severe drought. Therefore, in order to solve the problem of water shortage during drought and to prepare for the increasing water demand, a sand dam was installed along the valley, and this facility has been operating since May 2022. In this study, repeated simulations were performed according to the hydraulic conductivity of the filler material and the storage coefficient value for the inflow condition for about two years from mid-March 2020 to mid-March 2022. For each case, the amount of discharge through the perforated drain pipe was calculated. Overall, as the hydraulic conductivity increased, the amount of discharge and its ratio increased. However, when the hydraulic conductivity of the second floor was relatively low, the amount of discharge increased and then decreased as the hydraulic conductivity of the third floor increased. This is considered to be due to the fact that the water level was kept low due to the rapid drainage compared to the net inflow into the third floor because the water permeability of the third floor and the drainage coefficient of the drain pipe were large. As a result of simulating the flow of the open channel in the upper part of the sand dam as a hypothetical groundwater layer with very high hydraulic conductivity, the decrease in discharge rate was slower than the increase in the hydraulic conductivity of the hypothetical layer, but it was clearly shown that the discharge volume decreased relatively as the hydraulic conductivity of the virtual layer increased.