• 한국농공학회논문집
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• 제53권4호
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• pp.29-37
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• 2011

Effect of rice straw mat and wood shaves on the reduction of runoff and nonpoint source (NPS) pollution loads from field plots were experimentally studied. Three runoff plots of $5{\times}22$ m in size and 3 % in slope were prepared on a loamy sand field. Each plot was equipped with a flume to measure runoff and collect water samples. Experimental treatments of surface cover were bare, wood shaves (1,000 kg/ha) and rice straw mat cover (3,000 kg/ha). Under radish was cultivation. During the growing season of the radish, three rainfall-runoff events were monitored. Effect of wood shaves and straw mat cover on runoff reduction was 4~30 % and 33~75 % respectively compared to control. The effect on NPS pollution reduction was 36.8 and 64.3 % in BOD, 41.1 and 80.8 % in SS, 34.0 and 56.1 % in TP and 28.0 and 56.6 % in TN respectively. It was analyzed that the reduction of runoff and NPS pollution were mainly contributed by the decrease of rainfall energy impact and flow velocity and the increase of infiltration due to the surface cover materials. Rice straw mat showed very stable soil cover while large portion of wood shaves were lost during heavy storm events. It was concluded that straw mat was an efficient cover material to reduce NPS pollution from upland fields.

• Applied Biological Chemistry
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• 제40권4호
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• pp.323-328
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• 1997

토양살충제인 phorate를 포장에 살포한 후, 토성이 다른 두 지역의 소형시험구$(120\;cm{\times}120\;cm)$에서 호우(20 mm/hour) 및 세우(5 mm/hour) 조건의 인공강우에 의한 유출농도와 유출율을 측정하였으며, phorate의 유출 농도가 수서생물에 미치는 영향을 파악하기 위하여 유출수를 이용한 송사리에 대한 급성독성실험을 수행하였다. Phorate의 유출정도는 호우 및 세우조건에 따른 차이가 크지 않았고, 양토 및 사양토에서의 평균 유출농도는 각각 11.3 ppb 및 4.8 ppb였으며, 평균유출율은 0.50%이었는데, 양토지역에서 호우시 1.31%, 세우시 0.18%, 사양토지역에서 호우시 0.48%, 세우시 0.012%였으며, 양토지역에서 phorate 유출수를 54.4%로 희석하였을 때 송사리에 대한 급성독성치(96시간 $LC_{50}$)가 관찰되었고, 사양토지역의 유출수는 그 자체로도 50% 이상의 치사가 나타나지 않을 정도로 양토지역보다 독성이 낮았다.

• 한국농공학회논문집
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• 제57권5호
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• pp.123-128
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• 2015

This study conducted a series of field experiments using soil conditioners, Polyacrylamide(PAM) and gypsum, to evaluate their effects in reducing sediment loss and surface runoff. In addition, the correction factors (K-alpha) for the erodibility factor (K) were determined to reflect the effects of PAM and PAM+gypsum in applying the USLE equation. Experimental erosion plots individually sized $10m^2$ (5 m long, 2 m wide and 1 m deep) have different slopes (10, 20 and 30%). Erosion plots were prepared for one control (C; no PAM and gypsum) and two treatments (P; PAM 20 kg/ha, PG; PAM 20 kg/ha+gypsum 3,000 kg/ha). The amounts of soil eroded and runoff were continuously monitored from July $1^{st}$ to Oct. $31^{st}$ in 2010 and compared to each other. The amount of sediment loss from a control plot was 399.2 ton/ha and the relative reduction of sediment loss were 11.4% and 33.4% for PAM-treated and PAM+gypsum treated plots, respectively. This study also determined the K-alpha factors in the USLE equation to account for the erosion control effectiveness of PAM and gypsum application. The K-alpha factors were calculated as 0.92 for PAM-treated plot and 0.69 for PAM+gypsum-treated plot. The findings of this study revealed that soil conditioners (PAM and gypsum) could play a significant role in controlling soil erosion. In addition, the modified USLE equation using the K-alpha could provide valuable information to make better decision on establishment of best management practice for soil erosion control in agriculture.

• 한국물환경학회지
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• 제23권6호
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• pp.897-905
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• 2007

Approximately 70% of Korea is composed of forest areas. Especially 48% of agricultural field is practiced at highland areas over 400 m in elevation in Kangwon province. Over 90% of highland agricultural farming is located at Kangwon province. Runoff characteristics at the mountainous area such as Kangwon province are largely affected by steep slopes, thus runoff estimation considering field slopes needs to be utilized for accurate estimation of direct runoff. Although many methods for runoff estimation are available, the Soil Conservation Service (SCS), now Natural Resource Conservation Service (NRCS), Curve Number (CN)-based method is used in this study. The CN values were obtained from many plot-years dataset obtained from mid-west areas of the United States, where most of the areas have less than 5% in slopes. Thus, the CN method is not suitable for accurate runoff estimation where significant areas are over 5% in slopes. Therefore, the CN values were adjusted based on the average slopes (25.8% at Doam-dam watershed) depending on the 5-day Antecedent Moisture Condition (AMC). In this study, the CN-based Long-Term Hydrologic Impact Assessment (L-THIA) direct runoff estimation model used and the Web-based Hydrograph Analysis Tool (WHAT) was used for direct runoff separation from the stream flow data. The $R^2$ value was 0.65 and the Nash-Sutcliffe coefficient value was 0.60 when no slope adjustment was made in CN method. However, the $R^2$ value was 0.69 and the Nash-Sutcliffe value was 0.69 with slope adjustment. As shown in this study, it is strongly recommended the slope adjustment in the CN direct runoff estimation should be made for accurate direct runoff prediction using the CN-based L-THIA model when applied to steep mountainous areas.

• 한국농공학회논문집
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• 제60권5호
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• pp.41-54
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• 2018

A method to account a detention in a rice paddy field in hydrologic modeling was tested at plot and watershed scales. Hydrologic Simulation Program - Fortran (HSPF) and its one of surface runoff modeling method, i.e Surface-Ftable, were used to simulate a inundated condition in a rice paddy culture for a study plot and basins in Saemangeum watershed. Surface-Ftable in HSPF defines surface runoff ratio with respect to surface water depth in a pervious land segment, which can be implemented to the feature of water management in a rice paddy field. A Surface-Ftable for paddy fields in Saemangeum watershed was developed based on the study paddy field monitoring data from 2013 to 2014, and was applied to Jeonju-chun and Jeongeup-chun basins which comprise 12% and 22% of paddy fields in the basins, respectively. Four gaging stations were used to calibrate and validate the watershed models for the period of 2009 and 2013. Model performed 7.13% and 9.68% in PBIAS, and 0.94 and 0.90 in monthly NSE during model calibrations at Jeonju and Jeongeup stations, respectively, while the models were validated its applicability at Hyoja and Gongpyung stations. The comparison of results with and without considering detention effect of paddy fields confirmed the validity of the Surface-Ftable method in modeling watersheds containing rice paddy fields.

• 한국농공학회논문집
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• 제57권4호
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• pp.51-59
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• 2015

Various Best Management Practices (BMPs) have been suggested to reduce soil erosion and non point source (NPS) pollutant loads from agricultural fields. However, very little research regarding water quality improvement with No-till (NT) has been performed in Korea. Thus, effects of NT were investigated in this study. The objective of the study was to investigate the effect of NT on the surface runoff and sediment discharge in a field. Eight experimental plots of $5{\times}30m$ in size and 3 % or 8 % in slope prepared on gravelly sandy loam soil were treated with Conventional-till (CT) and NT. Runoff and NPS pollution discharge were monitored and compared the treatments. The amounts of rainfall from 13 monitored events ranged from 28.7 mm to 503.5 mm. The runoff amount was reduced by 17.6~59.2 % in 3 % NT and 29.6~53.2 % in 8 % NT. The average NPS pollution loads of the 3 % NT plots and 8 % NT plot were reduced about 45.1~89.2 % and 47.7~98.0 % compared to those of the CT plots, respectively. This research revealed that NT can reduce the NPS pollution loads substantially as well as increase the crop yield. Runoff and NPS pollution loads reduction by NT method could be contribute to improve the water quality of streams in agricultural regions.

• 한국산림과학회지
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• 제96권5호
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• pp.561-566
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• 2007

This study was conducted to clarify runoff production processes in forested catchment through hydrograph separation using three-component mixing model based on the End Member Mixing Analysis (EMMA) model. The study area is located in the coniferous-forested experimental catchment, Gwangneung Gyeonggido near Seoul, Korea (N 37 45', E 127 09'). This catchment is covered by Pinus Korainensis and Abies holophylla planted at stocking rate of 3,000 trees $ha^{-1}$ in 1976. Thinning and pruning were carried out two times in the spring of 1996 and 2004 respectively. We monitored 8 successive events during the periods from June 15 to September 15, 2005. Throughfall, soil water and groundwater were sampled by the bulk sampler. Stream water was sampled every 2-hour through ISCO automatic sampler for 48 hours. The geochemical tracers were determined in the result of principal components analysis. The concentrations of $SO_4{^{2-}$ and $Na^+$ for stream water almost were distributed within the bivariate plot of the end members; throughfall, soil water and groundwater. Average contributions of throughfall, soil water and groundwater on producing stream flow for 8 events were 17%, 25% and 58% respectively. The amount of antecedent precipitation (AAP) plays an important role in determining which end members prevail during the event. It was found that ground water contributed more to produce storm runoff in the event of a small AAP compared with the event of a large AAP. On the other hand, rain water showed opposite tendency to ground water. Rain water in storm runoff may be produced by saturation overland flow occurring in the areas where soil moisture content is near saturation. AAP controls the producing mechanism for storm runoff whether surface or subsurface flow prevails.

• 한국농공학회논문집
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• 제55권4호
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• pp.37-44
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• 2013

We have examined the effect of rice straw mat (RSM) on the reduction of non-point source (NPS) pollution loads at soybean cultivations. The slope of the experimental plot was about 3 %. Monitoring was carried out for four years at conventional tillage (CT) in 2008~2009 years and RSM covered tillage in 2010~2011 years. Thirty-two rainfall events were monitored and analyzed during the study period. During the 2 years of 2008 and 2009, 20 rainfall runoff events were monitored. But in 2010 years, only 2 rainfall runoff events could be monitored. And in 2011 years, 10 rainfall runoff events was monitored. It was because the RSM cover enhanced infiltration and reduce runoff in 2010 and 2011. Average NPS pollution load (organic matters) of the RSM covered field was reduced by 72.1~94.2 % compared to that of CT field. NPS pollution load of TN and TP reduced by 67.5 % and 55.7 %, respectively. Especially, SS pollution load was reduced by 97.3 %. Based on the results, rice straw mat cover was considered as a promising best management practices (BMP) to reduce NPS pollution load. However, it was recommended that the results are limited to the field conditions and the same experiments must be performed on different soil textures, slopes, and crops if it is applied to the development of policies.

• 한국토양비료학회지
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• 제48권5호
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• pp.477-484
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• 2015

Environmental effect of water-saving irrigation on the emissions of greenhouse gases (GHGs) has not been well investigated. The objective of this study was to measure the effect of water-saving irrigation on GHGs as well as water use and rice production yield in paddy field condition in Korea. Four experimental runoff plots of 4x35 m in size were prepared at an existing paddy field. GHGs emission was measured during the 2012~2013 growing seasons while a Japonica rice variety was cultivated. Four different water management methods, 1) Continuous Flooding (CF), 2) Intermittent Drainage (ID), 3) Water Saving (WS), and 4) CF+WS, were used during a rice growing season to compare the effects of water management methods on GHGs emission. CF method is flooding all the time, ID method makes paddy water drained 40 days after transplanting for about two weeks, WS method maintains 2~3 cm water-level, which should be refilled when the water-level decreased to about 0 cm, and CF+WS method combines CF method before 30 days after transplanting (DAT) and WS method after 30 DAT. Regardless of water management methods, paddy field water was drained about 30 days before harvest. Amount of GHGs emission from WS plot was reduced by 69.3% compared to that from CF plot and by 59.0% compared to that from ID plot. Amount of GHGs emission from CF+WS plot was reduced by 60.7% compared to that from CF plot and by 47.5% compared to that from ID plot. Weed occurrence in CF+WS plots was reduced to 62.2% in comparison with the WS plot, implying that CF+WS plot showed the best effect to mitigation of the greenhouse gas emission in the atmosphere.

• 지질공학
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• 제19권3호
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• pp.365-371
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• 2009

본 연구에서는 비점오염원의 효율적인 관리방안을 확립하기 위하여 단위재배지로부터의 오염물질 배출특성을 조사하였다. 무강우일수가 상대적으로 길었던 약 20%의 강우사상을 제외한 나머지 강우사상에 대해서는 강우량과 강우에 의한 유출수량의 상관성은 상관계수 0.92로 매우 높았으며, 유출수량이 유출계수에 미치는 영향인자로는 유출직전의 강우강도가 주요인자임을 알 수 있었다. 한편, 유출수로부터 발생하는 오염물질의 EMCs(유량가중평균농도)가 높은 강우사상의 결과로 무강우일수가 길었던 강우사상에서 무강우에 의해 건조된 토양의 영향에 기인한 것임을 알 수 있다. 유출수로부터 발생되는 TSS, BOD, COD, TN 및 TP 등의 부하량은 동일한 강우사상에서 유사한 경향을 나타내므로 부유물질을 제어함으로써 다른 오염물질의 제거도 가능할 것으로 추정된다. 따라서 강우량계급별 유출계수 만을 이용한 오염물질부하량은 많은 오차를 나타낼 것이며, 오염부하 예측시스템을 개발할 때에는 강우량, 무강우일수, 선행강우량 등을 인자로 고려한 재배지토양조건을 충분히 고려하여야 할 것이다.