• Journal of the Korean association of regional geographers
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• v.10 no.1
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• pp.192-205
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• 2004

The purpose of this paper is to analyze the factors, which have influence upon changes of hydrological environment in time series, and evaluate water balance changes caused by urbanization. The results of the analysis and evaluation are as follow: At first, the river runoff at Gwangju River Basin keep base flow of river by storage capacity recharged in June to September and show peak in August and minimum flow in May. The groundwater recharge by urbanization accounted for 46.1% of rainfall at early-urban stage, and decreased to 36.5% and 29.9% in the 1960's and the 1990's respectively, and is likely to decrease to 27.8% in the 2010's. On the other hand, the overland flow was 9.6% of rainfall in the 1960's and 16.2% in the 1990's, and is likely to increase to 18.3% in the 2010's. When such a phenomenon is kept continuously, distorted water balance shall be worsened to create not only frequent occurrence of urban flood but also decreased base flow of Gwangju River to accelerate dry stream phenomenon. The time series study on urban redevelopment and environment maintenance describes distorted phenomenon to supply the information for nature-friendly land use, and examines relations between human activities and natural environment.

• Journal of the Korean Geosynthetics Society
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• v.16 no.4
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• pp.231-240
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• 2017

Recently, there have been frequent occurrences of ground sink in the urban area, which have resulted in human and material damage and are accompanied by economic losses. This is caused by artificial factors such as soil loss, poor compaction, horizontal excavation due to the breakage of the aged sewage pipe, and lack of water proof at vertical excavation. The ground sink can be prevented by preliminary restoration and reinforcement through exploration, but it can be considered that it is not suitable for urgent restoration by the existing method. In this study, a model experiment was carried out to simulate the in-ground cavities caused by groundwater flow for developing non-excavation urgent restoration in underground cavity and the range of the relaxation zone was estimated by detecting the around the cavity using a relaxation zone detector. In addition, disturbance region and relaxation region were separated by injecting gypsum into cavity formed in simulated ground. The shape of the underground cavity due to the groundwater flow was similar to that of the failure mode III formed in the dense relative density ground due to water pipe breakage in the previous study. It was confirmed that the relaxed region detected using the relaxation zone detector is formed in an arch shape in the cavity top. The length ratio of the relaxation region to the disturbance region in the upper part of the cavity center is 2: 1, and it can be distinguished by the difference in the decrease of the shear resistance against the external force. In other words, it was confirmed that the secondary damage should not occur in consideration of the expandability of the material used as the injecting material in the pre-repair and reinforcement, and various ground deformation states will be additionally performed through additional experiments.

• Journal of Soil and Groundwater Environment
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• v.12 no.1
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• pp.87-96
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• 2007

Risk assessment was carried out in order to improve the remediation and management strategy on a contaminated gunnery site, where a flood control reservoir is under construction nearby. Six chemicals, including explosive chemicals and heavy metals, which were suspected to possess risk to humans by leaching events from the site were the target pollutants for the assessment. A site-specific conceptual site model was constructed based on effective, reasonable exposure pathways to avoid any overestimation of the risk. Also, conservative default values were adapted to prevent underestimation of the risk when site-specific values were not available. The risks of the six contaminants were calculated by API's Decision Support System for Exposure and Risk Assessment with several assumptions. In the crater-formed-area(Ac), the non-carcinogenic risks(i.e., HI values) of TNT(Tri-Nitro-Toluene) and Cd were slightly larger than 1, and for RDX(Royal Demolition Explosives), over 50. The total non-carcinogenic risk of the whole gunnery range calculated to a significantly high value of 62.5. Carcinogenicity of Cd was estimated to be about $10^{-3}$, while that of Pb was about $5\;{\times}\;10^{-4}$, which greatly exceeded the generally acceptable carcinogenic risk level of $10^{-4}{\sim}10^{-6}$. The risk assessment results suggest that an immediate remediation practice for both carcinogens and non-carcinogens are required before the reservoir construction. However, for more accurate risk assessment, more specific estimations on condition shifts due to the construction of the reservoir are required, and more over, the effects of the pollutants to the ecosystem is also necessary to be evaluated.

• Journal of Soil and Groundwater Environment
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• v.12 no.1
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• pp.73-86
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• 2007

Risk-based remediation strategy (RBRS) is a consistent decision-making process for the assessment and response to chemical release based on protecting human health and the environment. The decision-making process described integrates exposure and risk assessment practices with site assessment activities and remedial action selection to ensure that the chosen actions are protective of human health and the environment. The general sequences of events in Tier 1 is as follows: initial site assessment, development of conceptual site model with all exposure pathways, data collection on pollutants and receptors, and identification of risk-based screening level (RBSL). If site conditions do not meet RBSL, it needs further site-specific tier evaluation, Tier 2. In most cases, only limited number of exposure pathways, exposure scenarios, and chemicals of concern are considered the Tier 2 evaluation since many are eliminated from consideration during the Tier 1 evaluation. In spite of uncertainties due to the conservatism applied to risk calculations, limitation in site-specific data collections, and variables affecting the selection of target risk levels and exposure factors, RBRS provides us time- and cost-effectiveness of the remedial action. To ensure reliance of the results, the development team should consider land and resource use, cumulative risks, and additive effects. In addition, it is necessary to develop appropriate site assessment guideline and reliable toxicity assessment method, and to study on site-specific parameters and exposure parameters in Korea.

• Journal of Soil and Groundwater Environment
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• v.6 no.4
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• pp.25-40
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• 2001

In order to investigate the degree of heavy metal pollution, 280 urban gully-pot sediments were collected from 13 localities in eastern part of Seoul. The uncontaminated stream sediments were also studied for comparison. A series of studies have carried out concerning the physicochemical characteristics of the sediments and the distribution of Cd, Co, Cr, Cu, Ni, Pb, and Zn. Total metal concentrations of gully-pot sediments and uncontaminated stream sediments were analyzed using acid extraction. After predigestion with $NHO_3$, the sample was digested with mixed acid ($NHO_3$-$HClO_4$). The gully-pot sediments were characterized by very high concentrations of Zn, Cu, Pb and Cr, indicating an anthropogenic contribution of these metals to the sediment chemistry Heavy metal concentrations in the gully-pot sediments were 1-329 times higher than the mean content of metals in the uncontaminated stream sediments, depending on the metals. In particular, the highest mean concentrations of Zn, Cu, Pb and Cr were noticed in the gully-pot sediments from Yeouido, Junggu, Junggu, and Dongdaemungu, respectively. The mean value of total Zn concentration in the business and commercial areas is 2-3.5 times higher than that in industrial areas. This suggests that Zn is mainly derived from automobiles (rubber of automobile tires). The mean concentrations of Cu and Cr are significantly high in the commercial and industrial areas, indicating that industrial activities may cause the accumulation of Cu and Cr in the sediments. The Pb level in gully-pot sediments is comparatively low, due to the use of unleaded gasoline in automobiles since 1987.

• Journal of the Korea Institute of Building Construction
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• v.18 no.5
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• pp.447-453
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• 2018

Since 1960, Korea the town center was developed intensively due to rapid industrial development. As a result of the development, the population was concentrated in urban areas and the green area was decreased. Due to the decrease of the green area, the circulation system of the rainwater was changed, hence the rainwater was not introduced into the groundwater., On the other hand, the water on the surface of the road was changed into the water for flowing to the river and evaporation. The changes in the water flow cause many problems, and the depletion of the groundwater does not create an environment in which microorganisms and plants can live. in Korea, permeable pavement construction is increased to solve these problems, but existing pavement blocks have many problems. The pores of the permeable block are clogged due to the accumulation of dust or whitening phenomenon, and the permeability is lost. In this study, the solution of the problems of existing permeable block were suggested by using polymer and artificial permeable pipe, and strength, permeability and service life are increased, The relationship between the substitution rate of the polymer and the mixing ratio of the artificial permeable pipe was analyzed.

• Journal of Korean Society on Water Environment
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• v.33 no.1
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• pp.1-7
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• 2017

Bioretention systems, an advance low impact development and green infrastructure approach were currently utilized in different parts of the world because it promotes biodiversity thereby mimicking and preserving the pre-developed state of an area. This study investigated and compared the capability of four bioretention systems to identify factors affecting the hydraulic capabilities and pollutant removal efficiencies of each system. The two bioretention type A referred as Type A-C and Type A-FC were planted with perennials such as Chrysanthemum and Fan columbine, respectively. On the other hand, the two type B bioretention systems referred as Type B-A and Type B-JM were planted with shrub plant species such as Azalea and Japanese Meadowsweet, respectively. Based on the results, TV, infiltration mechanism, filter media depth and plant species were identified as the factors affecting the difference in flow attenuation, retained volume and pollutant removal efficiency of Type A-C, Type A-FC, Type B-A and Type B-JM bioretention systems. The design of bioretention Type B-A and Type B-JM were advantageous considering greater volume retention, groundwater recharge, longer HRT and peak flow attenuation and greater pollutant removal efficiency. On the other hand, the design of bioretention Type A-C and Type A-FC was more appropriate for design considering reduced groundwater contamination.

• Tunnel and Underground Space
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• v.27 no.6
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• pp.343-350
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• 2017

Amid increasingly saturated ground space, development of underground space has been booming throughout the world and excavation has been underway near the structure above or under the ground level. But the ground subsidence caused by improper or poor construction technologies, underground water leakage, sudden changes of stratum and the problem with earth retaining system component has been emerged as hot social issue. To deal with such problems nationwide, establishment of preventive and proactive disaster management and rapid restoration system has been pushed now. In this study, collection of the data on technology development trend to secure the underground safety was made, taking into account of internal change elements (changing groundwater level, damage to underground utilities, etc) and external change elements (vehicle load, earthquake and ground excavation, etc) during excavation. Amid the growing need of ground behavior analysis, ground subsidence evaluation technology, safe excavation to prevent ground subsidence and reinforcement technology, improvement of rapid restoration technology in preparation for ground subsidence and development of independent capability, this study is intended to introduce the technology development in a bid to prevent the ground subsidence during excavation. It's categorized into prediction/evaluation technology, complex detect technology, waterproof reinforcement technology, rapid restoration technology and excavation technology which, in part, has been in process now.

• Journal of the Korean Association of Geographic Information Studies
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• v.2 no.2
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• pp.45-58
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• 1999

Digital map is utilized for an effective display of the distributions of the hydrogeological variables such as water table height(hydraulic head) and log-transmissivity(lnT) in north Pohang, KyungBug. Specifically the geostatistical method kriging is used to construct the distributions in an unconfined aquifer from a finite set of measured data. The experimental variograms for both the head and lnT suggest spherical models with nugget of 0 and range of 6km. The kriged results by using these variograms show that the head decreases primarily from the west to the east with a large peak in the north-western part and lnT is at the maximum level in the central part with outwardly decreasing trend. The constructed delineation is also used to calculate the flow field in the region. Finite differences with second order consistency are used to calculate the fluxes in the east(x) and north(y) across a vertical cross-section of unit width and height equal to the thickness of the wet zone in the aquifer. It is demonstrated that the flow is dominantly in the east with diverging trend on the eastern hillside of the water table peak. A few convergent spots also appear.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1913-1917
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• 2009

국제사회의 분위기와 더불어 국내에서도 에너지 자원의 지속적인 개발과 이용에 대한 관심이 높아지고 있다. 그 중 수자원의 지속적인 확보와 개발은 가장 현실적이고 우선적인 문제로 인식되고 있으며 수자원확보/환경/개발 및 이용 등의 여러 분야에서 그간의 정량적 성과가 하나 둘씩 도출되어 적용 단계에 이르기도 하였다. 하지만 지하수의 경우 기초자료의 미흡과 불확실성, 함양량 및 개발가능량에 대한 산정기법의 적용성 문제, 체계화된 개발 및 이용에 대한 인식이 부족한 실정이다. 특히, 도시지역의 경우는 인구의 증가로 인하여 지하수이용량이 급격하게 증가하고 잠재적 지하수오염 가능성이 높아져 지하수환경의 악화를 초래하고 이로 인하여 하천 환경에도 영향을 미칠 수 있기 때문에 지하수개발가능량의 평가 및 체계적인 이용과 관리가 반드시 필요하나 지하수함양에 결정적인 영향을 미치는 토지피복상태가 지속적으로 변화하여 지하수함양량에도 매년 변화가 있으며 이에 따라 개발가능량도 변하고 있어 지하수 개발과 관리 및 이용에 많은 어려움을 겪고 있는 실정이다. 본 논문에서는 부산광역시 수영구 일대를 대상으로 도시화 현상으로 변화하는 토지피복상태를 분석하고 그 결과를 반영하여 1961년부터 2007년까지의 지하수함양량 및 함양률을 산정하였다. 연구대상지역의 토지피복상태는 1975년 이전까지는 시가화지역이 18.6%, 농업지역이 30.0%, 산림이 48.8%, 초지가 0.1%, 나지가 2.0%, 수역이 0.5%를 차지하고 있었으나 1980년${\sim}$1985년에 농업지역이 18.3% 감소하고 시가화지역이 15.0% 증가하는 큰 변화가 나타났으며 1995년${\sim}$2000년에도 농업지역이 5.5% 감소하고 시가화지역이 5.4% 증가하는 변화를 나타냈다. 전 연도에 걸쳐 산림지역과 초지, 나지, 수역에서의 변화는 크지 않았다. 연구대상지역의 평균 강우량은 1509.3mm이고 지하수평균함양량은 216.0mm이며 지하수평균함양률은 14.3%로 나타났다. 연최대함양량은 강우량이 2138.1mm인 1970년에 408.9mm이며 연최대함양률은 강우량이 1492.6mm인 1984년에 19.8%이다. 연최소함양량은 강우량이 901.5mm인 1988년에 71.9mm이며 연최소함양률은 같은해에 8.0%로 나타났다. 또한 연도의 증가에 따라 강우량은 증가하였으나 지하수함양량은 감소하는 경향을 나타내었다.