• 한국농공학회논문집
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• 제65권6호
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• pp.1-13
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• 2023

Irrigation return flow plays an important role in river flow forecasting, basin water supply planning, and determining irrigation water use. Therefore, accurate calculation of irrigation return flow rate is essential for the rational use and management of water resources. In this study, EPA-SWMM (Environmental Protection Agency-Storm Water Management Model) modeling was used to analyze the irrigation return flow and return flow rate of each intake work using irrigation canal network. As a result of the EPA-SWMM, we tried to estimate the quick return flow and delayed return flow using the water supply, paddy field, drainage, infiltration, precipitation, and evapotranspiration. We selected 9 districts, including pumping stations and weirs, to reflect various characteristics of irrigation water, focusing on the four major rivers (Hangang, Geumgang, Nakdonggang, Yeongsangang, and Seomjingang). We analyzed the irrigation period from May 1, 2021 to September 10, 2021. As a result of estimating the irrigation return flow rate, it varied from approximately 44 to 56%. In the case of the Gokseong Guseong area with the highest return flow rate, it was estimated that the quick return flow was 4,677 10³ m³ and the delayed return flow was 1,473 10³ m³ , with a quick return flow rate of 42.6% and a delayed return flow rate of 13.4%.

• 한국유기농업학회지
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• 제24권4호
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• pp.787-795
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• 2016

The purpose of this study was to assess drought tolerance of groundcover plants for extensive green roof. Form July to November 2013, plant height, chlorophyll content, soil moisture, evapotranspiration and survival rate was measured. As results, after unirrigation started, Aster koraiensis reached 0% of soil moisture earliest followed by Sedum kamtschaticum, Hemerocallis fulva, Hylotelephium spectabile, Iris sanguinea, Hosta longipes and control. Among the plants, A. koraiensis withered earliest on 19th day of unirrigation experiment, followed by H. longipes and H. fulva (27th day); and I. sanguinea (29th day). S. kamtschaticum and H. spectabile survived even after 120th day of the experiment. As for chlorophyll content, I. sanguinea showed constant values in early stage than rapidly decreased right before its withering. Chlorophyll content of A. koraiensis and H. fulva showed rapid decrease from the beginning, while that of H. spectabile and S. kamtschaticum showed continuous reduction for first 30 days and the reduction was slowed down since then. In conclusion, H. longipes, I. sanguinea and H. fulva were found most applicable for extensive green roof considering scenic aspect.

• 한국농공학회논문집
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• 제61권1호
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• pp.21-29
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• 2019

This study analyzed the variability of drought risk based on trend analysis of dry-seasonal dam inflow located in upper river basins. To this, we used areal averaged precipitation and dam inflow of three upper river dams such as Soyang dam, Chungju dam, and Andong dam. We employed Mann-Kendall trend analysis and change point detection method to identify the significant trends and changing point in time series. Our results showed that significant decreasing trends (95% confidence interval) in dry-seasonal runoff rates (= dam inflow/precipitation) in three-dam basins. We investigated potential causes of decreasing runoff rates trends using changes in potential evapotranspiration (PET) and precipitation indices. However, there were no clear relation among changes in runoff rates, PET, and precipitation indices. Runoff rate reduction in the three dams may increase the risk of dam operational management and long-term water resource planning. Therefore, it will be necessary to perform a multilateral analysis to better understand decreasing runoff rates.

• 한국물환경학회지
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• 제25권6호
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• pp.886-895
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• 2009

The guideline of selection of Integrated Management Practices (IMPs), such as wood, green roof, lawn, and porous pavement, for Low Impact Development (LID) design was proposed by ranking the reduction rate of surface runoff using LIDMOD1.0. Based on the guideline, LID was designed with several scenarios at two apartment complexes located at Songpa-gu, Seoul, Korea, and the effect of LID on surface runoff was evaluated during last 10 years. The effect of runoff reduction of IMP by land use change was highly dependent on the kind of hydrologic soil group. The wood planting is the best IMPs for reduction of surfac runoff for all hydrologic soil groups. Lawn planting is an excellent IMP for hydrologic soil group A, but reduction rate is low where soil doesn't effectively drains precipitation. The green roof shows constant reduction rate of surface runoff because it is not influenced by hydrologic soil group. Compared to the rate of other IMPs, the green roof is less effect the surface runoff reduction for hydrologic soil group A and is more effect for hydrologic soil group C and D followed to planing wood. The porous pavement for the impervious area is IMPs which is last selected for LID design because of the lowest reduction rate for all hydrologic soil group. As a result of LID application at study areas, we could conclude that the first step of the strategy of LID design at apartment complex is precuring pervious land as many area as possible, second step is selecting the kind of plant as more interception and evapotranspiration as possible, last step is replacing impervious land with porous pavement.

• 한국토양비료학회지
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• 제46권4호
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• pp.281-287
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• 2013

Due to its high salt content and poor physical properties in reclaimed tidal lands, it is important to ameliorate soil physical properties to improve the efficiency of desalination. The objective of this study was to evaluate the changes of soil properties at Saemangeum reclaimed tidal saline soil with various soil amendments. Field experiment was conducted at Saemangeum reclaimed tidal land in Korea and the dominant soil series was Munpo series (coarse loamy, mixed, nonacid, Mesic, Typic, Fluvaquents). Woodchips, crushed-stone, oyster shell, coal bottom ash, and rice hull were added as soil amendments and mixed into surface soil to improve soil physical properties. There was large variability in soil hardness, but oyster shell treatment was significantly lower soil hardness at surface layer. Soil hardness was not significantly different below 15 cm depth. Infiltration rate was also significantly greater at oyster shell treatment. This may be due to the leaching of Ca ions from oyster shell and improved soil properties. However, there was no statistical significant difference of the soil bulk density, moisture content, and porosity. Improved physical properties increased desalinization rate in soil and retarded the resalinization rate when evapotranspiration rate was high. Although soil salinity was significantly decreased with oyster shell amendment, soil pH was increased that should be made up as a soil amendment. Our results indicated that oyster shell application increased infiltration rate and improved soil hardness, and thus oyster shell could be used to improve soil salinity level at Saemangeum reclaimed tidal saline soil.

• 생물환경조절학회지
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• 제10권4호
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• pp.232-236
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• 2001

광합성유효광량지속이 50 $\mu$mol.m$^{-2}$ .s$^{-1}$로 유지되는 인공광하에서 수박 접목묘의 증발산속도와 활착에 미치는 포차의 영향을 정량적으로 구명하고자 기온 4수준(23$^{\circ}C$, $25^{\circ}C$, 29$^{\circ}C$), 상대습도 3수준(85%, 90%, 95%)으로 처리된 조건에서 접목과 활착 실험을 수행하였다. 상대습도가 95%로 높게 유지될 때 기온이 증가할수록 접목묘의 증발산속도는 높게 나타났다. 이것은 기온의 증가에 따라 엽온이 상승하면서 엽의 수증기압이 높아져 증발산속도가 높게 나타난 것으로 판단된다. 상대습도가 85%로서 상대적으로 낮게 유지될 때 증발산속도가 높게 나타났으나, 접목 후 경과된 시간에 따라 증발산속도는 감소하면서, 접수의 위조가 관찰되었다. 이것은 대목과 접수가 완전하게 결합되지 않아 접수의 유관속으로 수분의 공급이 충분하게 이루어지지 않았기 때문인 것으로 판단된다. 한편 상대습도가 90%와 95%를 유지하는 조건에서 증발산속도의 차이는 미약하게 나타났다. 상대습도가 높을수록 접목묘의 활착율은 높았으며, 90% 이상으로 상대습도가 유지되는 조건에서 활착율은 기온과 무관하게 90% 이상으로 높게 나타났다. 그러므로 접목묘의 활착율에 미치는 상대습도의 영향은 기온에 비해서 큰 것으로 판단된다. 포차가 작을수록 접목묘의 활착율은 높게 나타났다. 포차가 0.4kPa 이하를 유지하는 조건, 즉 상대습도가 90% 이상으로 유지될 때, 90% 이상의 높은 활착율을 얻을수 있었다. 따라서 수박의 접목 초기에 증발산속도를 억제하여 접수의 위조를 방지하고, 활착율을 높이려면 상대습도를 최소한 90% 이상으로 조절해주는 것이 효과적이다.

• 한국수자원학회논문집
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• 제46권5호
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• pp.519-530
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• 2013

본 연구에서는 미계측 유역인 저수지 상류 유역의 유출을 모의하기 위하여 Tank 모형의 구성성분을 개선하고 매개변수를 지역화하였으며, 모형의 적용성을 평가하였다. 저수지 상류 유역의 유출특성을 고려하여 3단 Tank 모형을 선정하였다. 유역 물수지를 고려하여 세 번째 Tank의 지하배수과정을 제외하였으며, 증발산성분은 국내의 기상관측 상황을 반영하여 개선하였다. 모형의 민감도 분석결과는 매개변수${\alpha}$의 변화에 따라 모형이 합리적으로 반응한다는 것을 제시하였다. 유역의 유역특성인자와 토지이용상태를 변수로 사용하여 모형의 매개변수 지역화식을 결정하였다. 3개 유역의 유출 모의와 1개 저수지의 저수위 모의에 대하여 모형 성능을 검증하였으며, 실측치와 모의치가 유사한 경향을 나타냈다. 24개 저수지 유입량 모의에 모형을 적용한 결과, 대상 저수지 상류 유역의 평균 증발산율은 42.8%, 평균 유출률은 56.6%이었다. 결론적으로 매개변수가 지역화된 Tank 모형은 저수지 상류 유역의 유출 모의에 적용이 가능하며, 모의된 유입량 자료는 저수지 계획, 설계, 운영에 유용하게 활용될 수 있을 것으로 사료된다.

• 한국수자원학회논문집
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• 제55권10호
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• pp.823-833
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• 2022

HSPF (Hydrological Simulation Program-Fortran)는 미국과 우리나라에서 특히 많이 사용하는 유역 수문 및 수질 모델이다. 이 모델은 분산형 모델로서 각 유역의 지형, 지질 및 오염부하특성을 정확하게 반영하는 것이 매우 중요하다. 본 연구에서는 HSPF의 매개변수 중 조도계수(NSUR), 침투(INFILT), 토양 하부의 증발산(LZETP)에 대하여 실제 용담댐 유역의 토지피복과 토양의 종류에 따라 값을 차등 입력함으로써 단일 값을 입력했을 때에 대비하여 유량, 수문 성분 및 수질의 정확도 향상 여부를 분석하였다. 조도계수와 식물의 밀도를 의미하는 토양 하부의 증발산은 토지피복의 종류에 따라 입력하였고, 침투는 유역의 수문학적 토양 그룹의 분포에 따라 입력하였다. 분석 결과 유량과 수질은 단일 값을 입력했을 때보다 각 매개변수를 토지피복과 토양의 종류별로 차등 설정하였을 때 정확도가 향상되는 것으로 나타났다. 또한, 조도계수(NSUR) 입력에 의해 지표유출과 첨두유량이 증가하였고, 침투(INFILT) 입력에 의해 기저유출이 감소하고 지표유출이 증가하였으며, 증발산(LZETP) 차등 입력으로 중간유출과 지표유출이 증가하고 지하수유출이 감소하는 등 각 매개변수의 설정이 유역 말단의 유량뿐 아니라 모든 수문 성분의 구성 비율에 영향을 미친다는 것을 확인하였다. 이러한 결과는 유역의 토지피복 및 토양의 비균질한 특성을 정확하게 표현하는 것이 이 모델을 이용한 유량 및 수질 예측의 정확도 제고에 중요하다는 것을 시사한다.

• 한국농공학회논문집
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• 제63권2호
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• pp.1-10
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• 2021

Agricultural reservoirs have a great influence on the water circulation in the watershed. It is necessary to evaluate the impact on water circulation by the agricultural reservoir. Therefore, in this study, we simulated the agricultural watershed through linkage of Hydrological Simulation Program Fortran (HSPF) and Module-based hydrologic Analysis for Agricultural watershed (MASA) and evaluated the contribution of the agricultural reservoir to water circulation by watershed water circulation index. As a result of simulating the Idong reservoir watershed through the HSPF-MASA linkage model, the model performance during the validation period was R2 0.74 upstream, 0.78 downstream, and 0.76 reservoir water level, respectively. To evaluate the contribution of agricultural reservoirs, three scenarios (baseline, present state, and present state without reservoir) were simulated, and the water balance differences for each scenario were analyzed. In the evaluation through the agricultural water circulation rate in the watershed, it was found that the water circulation rate increased by 1.1%, and the direct flow rate decreased by 13.6 mm due to the agricultural reservoir. In the evaluation through the Budyko curve, the evaporation index increased by 0.01. Agricultural reservoirs reduce direct runoff and increase evapotranspiration, which has a positive effect on the water circulation.

• 한국토양비료학회지
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• 제48권4호
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• pp.246-254
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• 2015

This study explored the effect of rainfall pattern and soil characteristics on water management in rice paddy fields, using a soil water balance model, BUDGET. In two sites with different soil textural group, coarse loamy soil (Gangseo series) and fine soil (Hwadong series), respectively, we have monitored daily decrease of water depth, percolation rate, and groundwater table. The observed evapotranspiration (ET) was obtained from differences between water depth decrease and percolation rate. The root mean square difference values between observed and BUDGET-estimated ET ranged between 10% and 20% of the average observed ET. This is comparable to the measurement uncertainty, suggesting that the BUDGET model can provide reliable ET estimation for rice fields. In BUDGET model of this study, irrigation requirement was determined as minimum water need for maintaining water-saturated soil surface, assuming 100 mm of bund height and no lateral loss of water. The model results showed different water balance and irrigation requirement with the different soil profile and indicated that minimum percolation rate by plow pan could determine the irrigation requirement of rice paddy field. For the condition of different rainfall distribution, the results presented different irrigation period and amounts, representing the importance of securing water for irrigation against different rainfall pattern.