• 한국농공학회지
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• 제21권1호
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• pp.53-62
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• 1979

Since the first installation of irrigation Systems in Korea , a large number of small and medium sized reservoirs have been constructed as the main water sources Some 412, 000 ha are at present irrigated from these sources of supply. Many of the reservoirs were designed in accordance with old low standards and have in addition suffered a loss in capacity through sedimentation. At the same time, water demand has increased with the in troduction of high yielding varieties of rice. The combination has resulted in severe water deficits. To study the problem, 16 sample reservoirs have been surveyed and analysed. The results of the study are summarized be low: 1. Average decrease in reservoir capacity from the installation to present-8% 2. Average soil erosion loss (m$^3$/km$^2$/year) is 536 m$^3$/km$^2$/year and average erosion depth of soil is 0. 5mm per year. 3. No relationship, between reservoir capacity per unit of watershed (m$^3$/km$^2$) and soil erosion loss was found. 4. Increases are required in reservoir capacity: 15.8% due to the introduction of HYV's; 16.6% due to the change of system losses from 10%to 25% The conclusion to be drawn from the above results is that existing reservoir capacity should be increased by an average of 32%. The unit storage capacity to be adopted should be 661 mm

• 한국물환경학회지
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• 제23권5호
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• pp.650-658
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• 2007

The Universal Soil Loss Equation (USLE) has been used in over 100 countries to estimate potential long-term soil erosion from the field. However, the USLE estimated soil erosion cannot be used to estimate the sediment delivered to the stream networks. For an effective erosion control, it is necessary to compute sediment delivery ratio (SDR) for watershed and sediment yield at watershed outlet. Thus, the Sediment Assessment Tool for Effective Erosion Control (SATEEC) was developed to compute the sediment yield at any point in watershed. In this study, the SATEEC was applied to the Sudong watershed, Chuncheon Gangwon to compare the sediment yield using area-based sediment delivery ratio (SDRA) and slope-based sediment delivery ratio (SDRS) at watershed outlet. The sediment yield using the SDRA by Vanoni, SYA and the sediment yield using the SDRS by Willams and Berndt, SYS were compared for the same sized watersheds. The 19 subwatersheds was 2.19 ha in size, the soil loss and sediment yield were estimated for each subwatershed. Average slope of main stream was about 0.86~3.17%. Soil loss and sediment yield using SDRA and SDRS were distinguished depending on topography, especially in steep and flat areas. The SDRA for all subwatersheds was 0.762, however the SDRS were estimated in the range of 0.553~0.999. The difference between SYA and SYS was -79.74~27.45%. Thus site specific slope-based SDR is more effective in sediment yield estimation than area-based SDR. However it is recommended that watershed characteristic need to be considered in estimating yield behaviors.

• 한국수자원학회논문집
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• 제43권11호
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• pp.995-1009
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• 2010

기후변화에 의해 집중호우의 빈도 및 강도가 증가하고 지속적인 유역개발에 따른 토지이용의 증가는 토양침식 및 토사유출로 인한 재해 및 환경문제를 야기한다. 현재 광범위하게 사용되고 있는 토양침식량 산정기법은 대부분 대상유역내의 평균 토양침식량을 산출하는 총량적 개념의 경험식이므로 호우기간동안의 침식 및 퇴적의 시 공간적 변화양상을 모의할 수 없다는 한계를 지니고 있다. 따라서 보다 합리적인 유역규모의 강우-유사-유출 메카니즘 해석을 위해서는 기존의 집중형 모의기법을 대체하고 다양한 기상학적/지형학적 정보를 활용할 수 있는 물리적 기반의 분포형 모형이 요구된다. 본 연구에서는 사면의 지표 및 지표하 흐름을 고려한 유출모의 모듈과 단위수류력 이론을 기반으로 하는 유사유출 모의모듈을 결합한 분포형 강우-유사-유출 모형을 확장개발하고, 용담댐 상류부의 천천유역에 적용하여 모형의 재현성 평가를 수행하였다. 수문곡선의 모의 결과 모형의 재현성은 우수하였으며, 유사량곡선의 경우 첨두부분에서 과소선정되는 경향이 나타났다. 또한, 지표면 유동거리 및 국부경사에 따른 침식 및 퇴적의 공간분포를 분석한 결과, 침식된 토사는 비교적 경사가 완만한 하천주변에 퇴적되었으며, 강우량과 침식 및 퇴적의 공간분포의 분석결과, 강우량의 증가에 따라 침식량이 증가하였으며, Thiessen망 유역별로 침식 및 퇴적 분포는 상이하게 나타났다.

• 한국토양비료학회지
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• 제25권4호
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• pp.311-324
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• 1992

Polymeric substances in organic matter of soils aggregate soil particles into a crumb structure which greatly influences such properties as water movement, aeration and heat transfer. Poorly-structured soils may be improved by the incorporation of synthetic polymers where the main objects are : promoting germination or establishing crops, improving drainage, combating wind and water erosion, and reducing evaporation from the surface of soil under arid condition.

• 한국토양비료학회지
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• 제39권3호
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• pp.173-183
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• 2006

서낙동강 유역에서 USLE모형을 이용하여 농경지의 작물생산량 및 농업용수 수질과 관련 있는 농경지의 토양침식량을 평가하였다. 모형인자의 data set은 구축에 드는 노력과 시간의 소모를 최소화하고자 정밀토양도, 인공위성 영상 및 DEM자료로부터 RS와 GIS를 이용하여 구축하였는데, 토양상별 K 인자를 정밀토양도에 적용하여 주제도를 작성하고, 인공위성 영상(Landsat TM)으로부터 토지 피복도를 작성하여 C 및 P 인자의 주제도를 작성하였으며, DEM으로부터 LS 인자 주제도를 작성하였다. R인자는 서낙동강 유역 내에 위치하는 김해농업기술센터의 AWS 자료를 이용하여 계산하였다. 농경지발생 토양침식량은 유역전체 발생량의 31.5%였고, 농경지 토양유실량의 97.5%는 밭토양에서 일어나는 것으로 나타났다. 이는 서낙동강 유역이 삼각주평야지대로 경사가 거의 없으나 밭토양의 30.4%는 severe 및 very severe의 침식정도에 분포하였기 때문이다. 또한 식생의 토지 피복 상태 및 강우량의 정도에 따라 작물재배기(5월~9월)와 비재배기(10월~4월)로 나누어 토양침식량을 평가한 결과, 작물재배기는 연간 토양유실위험도와 유사한 경향이었고, 작물비재배포기는 R 값이 작물재포기의 약 1/5에 불과하였음에도 산과 인접한 경사지 밭토양의 일부는 severe 및 very severe의 토양침식 등급을 나타내어서 토양침식 관리에 주의가 필요하였다.

• 대한환경공학회지
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• 제37권2호
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• pp.92-98
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• 2015

알루미늄 호일 부식 실험을 이용하여 초음파 토양 세척 공정의 설계를 위한 기초 연구가 수행되었다. 36 kHz 초음파 발생 모듈이 하부에 장착된 대형 초음파 반응기에 파이렉스 재질의 소형 반응기를 위치시키고 글라스 비드 크기(1, 2, 4 mm), 파이렉스 반응기 내 글라스 비드 높이(5, 10, 15, 20 mm), 글라스 비드 위 물 높이(5, 10, 15, 20 mm) 등의 다양한 조건에서 실험을 진행하였다. 실험 결과, 글라스 비드의 입자 크기가 클수록, 글라스 비드 위 수위가 증가할수록 알루미늄 호일의 부식 정도가 크게 증가하였는데 이는 입자가 클수록 빈 공간이 많이 생겨 초음파 감쇠 현상이 덜 일어나게 되기 때문이며, 또한 수위가 증가할수록 동일한 에너지 유입 조건에서 초음파 캐비테이션 현상이 보다 활성화되기 때문으로 판단되었다. 그러나 글라스 비드를 지나면서 초음파 감쇠 현상이 심하게 일어나 알루미늄 호일의 부식 정도가 상대적으로 매우 약하게 확인되어 부식이 활발하게 일어나는 반응기 하부, 즉 심각한 초음파 감쇠 현상이 일어나지 않는 바닥 부분으로 입자들을 지속적으로 보낼 수 있는 기계적 교반 등의 방안이 제안되었다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2008년도 학술발표회 논문집
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• pp.194-198
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• 2008

Significant soil erosion and water quality degradation issues are occurring at highland agricultural areas of Kangwon province because of agronomic and topographical specialities of the region. Thus spatial and temporal modeling techniques are often utilized to analyze soil erosion and sediment behaviors at watershed scale. The Soil and Water Assessment Tool (SWAT) model is one of the watershed scale models that have been widely used for these ends in Korea. In most cases, the SWAT users tend to use the readily available input dataset, such as the Ministry of Environment (MOE) land cover data ignoring temporal and spatial changes in land cover. Spatial and temporal resolutions of the MOE land cover data are not good enough to reflect field condition for accurate assesment of soil erosion and sediment behaviors. Especially accelerated soil erosion is occurring from agricultural fields, which is sometimes not possible to identify with low-resolution MOD land cover data. Thus new land cover data is prepared with cadastral map and high spatial resolution images of the Doam-dam watershed. The SWAT model was calibrated and validated with this land cover data. The EI values were 0.79 and 0.85 for streamflow calibration and validation, respectively. The EI were 0.79 and 0.86 for sediment calibration and validation, respectively. These EI values were greater than those with MOE land cover data. With newly prepared land cover dataset for the Doam-dam watershed, the SWAT model better predicts hydrologic and sediment behaviors. The number of HRUs with new land cover data increased by 70.2% compared with that with the MOE land cover, indicating better representation of small-sized agricultural field boundaries. The SWAT estimated annual average sediment yield with the MOE land cover data was 61.8 ton/ha/year for the Doam-dam watershed, while 36.2 ton/ha/year (70.7% difference) of annual sediment yield with new land cover data. Especially the most significant difference in estimated sediment yield was 548.0% for the subwatershed #2 (165.9 ton/ha/year with the MOE land cover data and 25.6 ton/ha/year with new land cover data developed in this study). The results obtained in this study implies that the use of MOE land cover data in SWAT sediment simulation for the Doam-dam watershed could results in 70.7% differences in overall sediment estimation and incorrect identification of sediment hot spot areas (such as subwatershed #2) for effective sediment management. Therefore it is recommended that one needs to carefully validate land cover for the study watershed for accurate hydrologic and sediment simulation with the SWAT model.

• 한국농공학회논문집
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• 제55권6호
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• pp.127-133
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• 2013

The purpose of this study was to investigate maximum and minimum grain size which eroded by wind according to soil and wind conditions, such as top soil water content, roughness, land slope, wind velocity and proportion of grain size under 0.84mm. For performing this study, portable wind erosion tunnel was designed and utilized during field test, which facilitated measuring actual wind erosions under artificially controlled wind conditions. In the result, maximum, minimum grain size had strong negative correlation with roughness while weak positive correlation with wind velocity. Also, Slope which means the effect of gravity also influence grain size erodible by winds. Based on these results, regression equations were suggested for predicting maximum and minimum grain sizes by using multiple linear regression analysis from SPSS 20.0. The equation for maximum grain size erodible by winds showed a good agreement with the observed data with $R^2$=0.896. Other equation for minimum grain size had $R^2$=0.777.

• 한국농공학회지
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• 제39권2호
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• pp.113-123
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• 1997

This study was initiated to build runoff plots, install soil and water quality monitoring systems and collect background data from the plots and neighboring soils as the 1st year study of a 5 year project to assess soil quality and develop the management practices for environmentally sound agriculture in mountainous soils. Eleven $3{\times}15m$ runoff plots and monitoring systems were installed at a field of National Alpine Agricultural Experiment Station to monitor soil quality and discharge of nonpoint source pollutants. Corn and potato were cultivated under different fertilizer, tillage and residue cover treatments. The soil has a single-layered cluster structure that has a relatively good hydrologic properties and can adsorb a large amount of nutrient. Concentrations of T-N, $NH_4$-N, and $NO_3$-N of surface soil sampled in the winter were relatively high. Runoff quality in the winter and thawing season in the spring was largely dependent on surface freezing, snow accumulation, temperature, surface thawing depth and so on. Runoff during the thawing season caused serious soil erosion but runoff quality during the winter was relatively good. Serious wind erosion from unprotected fields after the fall harvest were obserbed and best management practices to reduce the erosion need to be developed.

• 농업과학연구
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• 제38권4호
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• pp.739-745
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• 2011

The MUSLE was utilized in this study to estimate soil erosion using daily precipitation which was main influential factor in soil loss estimation. Various scenarios were simulated to evaluate how transition of slope, agricultural products and precipitation could affect soil loss in the field. It was found that slope was the most affecting factor in soil loss estimation. Especially 1.8 times the soil loss was expected with potato at 45% slope compared with codonopsis at same slope with MUSLE model. Fortunately, farmers had planted codonopsis at this slope to reduce soil erosion from this steep slope. As shown in this study, the MUSLE method could be utilized to determine optimum crop type for each field with various slope conditions to minimize soil erosion. This approach utilized in this study could be applied to other agricultural watersheds to evaluate various soil erosion conditions.