• Environmental Engineering Research
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• v.16 no.2
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• pp.61-67
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• 2011

The water quality from nonpoint source run off results from different land use types has been studied. The construction of a buffer strip is one method of nonpoint source pollutant control. The Soil and Water Assessment Tool (SWAT) model has been applied to estimate the pollutant removal through the buffer strip. When the non-business land has been changed into grass to form a buffer-strip, the change of land use effects the results of the model according to measures of the water quality. The data from a water level station within the watershed in the years 2006 and 2007 was used for calibration and validation of the model. Under the rainfall conditions in 2007, the removal rates of SS, BOD, TN, TP were 11.5%, 9.5%, 1.2%, and 4.5%, respectively. During the rainy days, the removal rates at the buffer strip were 92.3% of SS, 91.2% of BOD, 82.4% of TN, and 83.5% of TP. The pollutants from nonpoint sources were effectively removed by over 80% as they passed through the buffer strips. Rainfall resulted in soil erosion, which led to an increase in the SS concentration, therefore, the construction of buffer strips protected the streams from SS inflows. Since TN concentrations are affected by the inflows of ground water and the N concentration of the rainfall, the removal rate of TN was relatively lower than for the other pollutants.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1120-1124
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• 2007

본 연구에서는 하수재이용에 따른 영향을 분석하기 위하여 수질, 토양 및 지표생물 모니터링을 실시하였으며 이를 분석하였다. 본 시험을 위하여 경기도 수워시 하수처리장 인근의 재이용 시험지구와 경기도 화성시 팔탄면 소재의 기천 시험 포장을 대비지구로 선정하였다. 본 연구에서는 환경부에서 제시한 하수처리 재이용 수질 권고기준에 제시된 수질기준과 본 시험에 사용된 재처리수를 비교하였으며, 대비지구의 경우 농업용수 수질기준과 비교하였다. 관개용수에 따른 토양에서의 영향을 분석하였으며, 재이용 관개지구가 대비지구에 비하여 TN, TP의 영양염류와 EC의 값이 높게 나타났다. 그리고 중금속의 토양집적은 나타나지 않았다. 농업용수 재이용에 따른 생태 환경 영향을 분석하기 위하여 대상지구에 지표생물 계측망을 구성하여 영농기간 중 생물다양성의 서식처 유형과 분포, 우점 구조, 그리고 육상지표생물의 발생 정도에 대하여 조사 분석하였다. 분석결과, 실험구와 대조구 두 지역의 곤충 및 거미류 종구성, 기능구별 유사도 등은 유사도가 높게 나타났으며, 우점종 구조에서도 차이가 없었다. 다만, 농업재용수의 높은 유기물 함량에 의해 실험구 지역에서 깔따구의 발생량이 많았다.

• Journal of Soil and Groundwater Environment
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• v.22 no.6
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• pp.104-111
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• 2017

As carcass disposal is increasing widely in Republic of Korea, there is a need to comprehensively analyze the impacts and subsequent damages of carcass disposal. Especially, since environmental policy aims to not only reduce environmental damages, but also enhance overall sustainability, we apply the concept of environmental welfare to assess the comprehensive impact of carcass disposal, especially focusing on the rural area. In specific, assessment criteria were suggested based on the four categories related to environmental welfare, which were 'environmental quality', 'level of environmental service', 'environmental safety', and 'participation, openness to public, and communication'. The results showed negative impacts of carcass disposal in environmental, social and economical elements. Overall decrease in environmental quality negatively impacts the other elements of environmental welfare. Furthermore, there were discrepancies of level of impacts and damages among stakeholder. In the end, we suggest critical elements that need to be applied in relevant policies and regulation to promote effective carcass disposal management.

• Journal of the Korean Geosynthetics Society
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• v.17 no.2
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• pp.33-40
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• 2018

Characteristics of interface friction between cohesionless soils and geotechnical structure surfaces play an important role in the analysis of earth load and resistance on the structure. In general, geotechnical structures are mainly composed of either steel or concrete, and their surface roughnesses with respect to soil particle sizes influence the interface characteristics between soils and the structures. Accurate assessment of the interface friction characteristics between soils and structures is important to ensure the safety of geotechnical structures, such as mechanically stabilized earth walls reinforced with inextensible reinforcements, piles embedded into soils, retaining wall backfilled with soils. In this study, based on the database of high quality interface friction tests between frictional soils and solid surfaces from literature, equation representing peak interface friction angle is proposed. The influential factors of the peak interface friction angle are relative roughness between soil and solid surface, relative density of frictional soil, and residual (constant volume) interface friction angle. Futhermore, for the developed equation of the interface friction angle, its uncertainty was assessed statistically based on Goodness-of-fit test results.

• Journal of Korean Society of Forest Science
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• v.101 no.3
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• pp.412-425
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• 2012

Concrete Soil Erosion Control Dam, which blocks flow of debris flow in torrential stream, are reported to lose expected functions due to structural failure and collapses, caused by poor construction, material deterioration and external impacts. In this paper, an integrity assessment technique for debris barriers was proposed, which allows preliminary detection of problems inherent in debris barriers. The proposed integrity assessment technique is a non-destructive method based on SASW method, one of surface-wave tests. In this paper, a practical procedure and analysis guidelines in applying the SASW technique to debris barrier was proposed and its validity was verified using five decrepit debris barriers older than 20-year old. As a result, the SASW method was validated for the reliable grade evaluation method for concrete soil erosion control dam, and the resulting grades turned out to agree with the results determined by Sabang Associations.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.5
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• pp.35-42
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• 2011

This study is to check the applicability of SWAT-APEX (Soil and Water Assessment Tool-Agricultural Policy / Environmental eXtender) model as combined watershed and field models by applying the APEX to paddies in a watershed (465.1 $km^2$) including Yedang reservoir. Firstly, the SWAT were calibrated with 3 years (2000~2002) daily streamflow and monthly water quality (T-N and T-P) data, and validated for another 3 years (2003~2005) data. The average Nash-Sutcliffe model efficiency (ME) of streamflow during validation was 0.73, and the coefficient of determination ($R^2$) of T-N and T-P were 0.77 and 0.73 respectively. Next, running the SWAT-APEX model with the SWAT calibrated parameters for paddies, the $R^2$ of T-N and T-P were 0.80 and 0.76 respectively. The results showed that SWAT-APEX model was more correctly predicted for T-N and T-P loads than SWAT model. The difference results between watershed and field models was predicted to have substantial impact on NPS loads, especially on T-N and T-P loads. Therefore, to improve negative NPS load simulations should be considered the model characteristics as simulating mechanism to properly select the NPS model for agricultural watershed.

• Korean Journal of Environmental Agriculture
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• v.24 no.2
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• pp.98-105
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• 2005

Groundwater sampled from 24 tube wells of three districts namely Sherpur, Gaibandha and Naogaon in Bangladesh was appraised for their water quality for irrigation and agro-based industrial usage. All waters under test were slightly alkaline to alkaline (pH = 7.2 to 8.4) in nature and were not problematic for crop production. As total dissolved solid (TDS), all groundwater samples were classified as fresh water (TDS<1,000 mg/L) in quality. Electrical conductivity (EC) and sodium adsorption ratio (SAR) values reflected that waters under test were under medium salinity (C2), high salinity (C3) and also low alkalinity (S1) hazard classes expressed as C2S1 and C3S1. As regards to EC and soluble sodium percentage (SSP), groundwater samples were graded as good and permissible in category based on soil properties and crop growth. All water samples were free from residual sodium carbonate (RSC) and belonged to suitable in category. Water samples were under soft moderately hard, hard and very hard classes. Manganese, bicarbonate and nitrate ions were considered as major pollutants in some water samples and might pose threat in soil ecosystem for long-term irrigation. For most of the agro-based industrial usage, Fe and Cl were considered as troublesome ions. On the basis of TDS and hardness, groundwater samples were not suitable for specific industry. Some water samples were found suitable for specific industry but none of these waters were suitable for all industries. The relationship between water quality parameters and major ions was established. The correlation between major ionic constituents like Ca, Mg, K, Na, $HCO_3$ and Cl differed significantly. Dominant synergistic relationships were observed between EC-TDS, SAR-SSP, EC-Hardness, TDS-Hardness and RSC-Hardness.

• Journal of Ecology and Environment
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• v.31 no.3
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• pp.213-223
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• 2008

The increasing area of abandoned rice fields could provide new opportunities for wetland restoration in Asia. However, it is unknown how quickly or completely abandoned rice fields will recover from agricultural disturbances. We assessed water quality and plant community succession in abandoned rice fields with different hydrology in a mountain valley to understand the effects of hydrological regime on recovery. Water level, soil redox potential, water quality, plant composition, and primary production were measured. The sites, coded as D6, N13, and N16, had been recovering for 6, 13, and 16 years by 2006. N13 and N16 have been recovering naturally whereas D6 has been drained with a nearby dike and was tilled in 2001. The typical hydroperiods of D6, N13, and N16 were no surface water, permanently flooded, and seasonally flooded, respectively. The major change in vegetation structure of both D6 and N13 was the replacement of herbaceous species by woody species. Drawdown accelerated this change because Salix koreensis grew better in damp conditions than in flooded conditions. Phragmites japonica reduced plot-level plant species richness. The removal efficiency of $NH_4-N$, $NO_3-N$, and $PO_4-P$ from water varied seasonally, ranging between -78.8 to 44.3%, 0 to 97.5%, and -26.0 to 44.4%, respectively. In summary, abandoned rice fields quickly became suitable habitat for native wetland plant species and improved regional water quality. Variation among our sites indicates that it is likely possible to manage abandoned rice fields, mostly through controlling hydrology, to achieve site-specific restoration goals.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.9
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• pp.504-512
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• 2016

In this study, we investigated the environmental impact of organic and conventional paddy by monitoring soil properties and water quality. We sampled and analyzed topsoil (0~15 cm), subsoil (15~30 cm), and water of organic and conventional paddy fields in Yongin and Anseong, South Korea. The statistical significance between groups was determined by Duncan's multiple range test. The results show that T-P concentrations in both topsoil and subsoil of Anseong paddy were higher than those of Yongin paddy. The significant difference of T-P between organic and conventional paddy was observed in Anseong but not in Yongin. T-N of organic paddy soil was lower than that of conventional paddy in both Anseong and Yongin region. Water content for subsoil of organic paddy in Anseong was significantly different from others, which is consistent with the results of silt-clay content. pH and EC of water in conventional paddy were higher than those in organic paddy. In Anseong, COD, T-P, and $PO_4-P$ concentration of conventional paddy were higher than those of organic paddy. The regression analysis presented that there were no significant relationship between soil properties and water quality data except T-N.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.2
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• pp.235-243
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• 2019

Radioactive materials are released into the air and deposited on the surface soil after a nuclear accident. Radionuclides deposited in soil are transported by precipitation to nearby environments and contaminate the surface water system. Basic data on surface watershed and soil erosion models have been collected and analyzed to evaluate the behavior of radionuclides deposited on surface soil after a nuclear accident. Data acquisition and analysis in aquatic environment were performed to investigate the physical characteristics and variation of biota in rivers and lakes of the Nakdong river area near the Wolsong nuclear power plant. For these purposes, a digital map, and hydrological, water quality and biota data were gathered and a systematic database (DB) was constructed in connection with them. Constructed aquatic DB will be supplied and used in surface watershed and soil erosion models for investigation of long-term movement of radionuclides in adsorptive form in surface soil. Finally, basic data and established models will be utilized for general radiological impact assessment in aquatic environment.