• 한국농공학회논문집
• /
• 제57권6호
• /
• pp.173-183
• /
• 2015

The aim of this study was to develop a soil moisture simulation model equipped with meteorological data enhanced by WRF (Weather Research and Forecast) model, and this soil moisture model was applied for quantifying soil moisture content and irrigation requirement. The WRF model can provide grid based meteorological data at various resolutions. For applicability assessment, comparative analyses were conducted using WRF data and weather data obtained from weather station located close to test bed. Water balance of each upland grid was assessed for soils represented with four layers. The soil moisture contents simulated using the soil moisture model were compared with observed data to evaluate the capacity of the model qualitatively and quantitatively with performance statistics such as correlation coefficient (R), coefficient of determination (R2) and root mean squared error (RMSE). As a result, R is 0.76, $R^2$ is 0.58 and RMSE 5.45 mm in soil layer 1 and R 0.61, $R^2$ 0.37 and RMSE 6.73 mm in soil layer 2 and R 0.52, $R^2$ 0.27 and RMSE 8.64 mm in soil layer 3 and R 0.68, $R^2$ 0.45 and RMSE 5.29 mm in soil layer 4. The estimated soil moisture contents and irrigation requirements of each soil layer showed spatiotemporally varied distributions depending on weather and soil texture data incorporated. The estimated soil moisture contents using weather station data showed uniform distribution about all grids. However the estimated soil moisture contents from WRF data showed spatially varied distribution. Also, the estimated irrigation requirements applied WRF data showed spatial variabilities reflecting regional differences of weather conditions.

• 자원환경지질
• /
• 제42권6호
• /
• pp.561-574
• /
• 2009

본 연구에서는 농업지역에서의 양수, 관개, 탈질작용을 고려한 불포화대 및 포화대 지하수 흐름 및 용질이동 모델인 VSFRT2D(Variably Saturated Flow and Reactive Transport model)를 개발하였다. VSFRT2D는 Richards equation을 지하수 흐름 지배방정식으로 이용하며, Thornthwaite 방법을 이용하여 강수가 일어나지 않을 때 지표면 증발산량 계산 절차를 포함하는 새로운 모델을 개발함으로써 기존의 불포화대 모델을 개선하였다. 또한 Monod kinetics에 기반한 생분해 기작을 네 개의 비선형 오염물 거동식과 세 종류의 미생물 거동식을 이용함으로서 탈질작용을 이 모델에 반영하였다. 개발된 모델을 질산성질소로 오염된 홍성 지역의 현장 관측 자료에 적용하였다. 본 연구에서는 강수, 양수, 증발산, 관개, 비료 투여 및 다양한 생분해 과정들이 지하수 흐름 및 오염물 거동에 미치는 효과들을 확인하기 위하여 각각의 과정을 개별적으로 나누어서 수치 모의한 후 각각의 결과를 상호 비교하였다. 수치 모의 결과 이 지역에서의 질산성 질소 농도 변화는 생분해에 의한 영향은 매우 미미하게 나타났다. 반면에 관개에 의한 양수, 강수, 질소 비료 시비에 의해서는 크게 영향을 받았다.

• 한국농공학회논문집
• /
• 제54권2호
• /
• pp.77-86
• /
• 2012

This study was aim to predict future land-cover changes and to analyze regional land-cover changes in irrigation areas and agricultural reservoir watersheds under climate change scenario. To simulate the future land-cover under climate change scenario - A1B of the SRES (Special Report on Emissions Scenarios), Dyna-CLUE (Conversion of Land Use Change and its Effects) was applied for modeling of competition among land-use types in relation to socioeconomic and biophysical driving factors. For the study areas, 8 agricultural reservoirs were selected from 8 different provinces covering all around nation. The simulation results from 2010 to 2100 suggested future land-cover changes under the scenario conditions. For Madun reservoir in Gyeonggi-do, total decrease amount of paddy area was a similar amount of 'Base demand scenario' of Water Vision 2020 published by MLTMA (Ministry of Land, Transport and Maritime Affairs), while the decrease amounts of paddy areas in other sites were less than the amount of 'High demand scenario' of Water Vision 2020. Under A1B scenario, all the land-cover results showed only slight changes in irrigation areas of agricultural reservoirs and most of agricultural reservoir watersheds will be increased continuously for forest areas. This approach could be useful for evaluating and simulating agricultural water demand in relation to land-use changes.

• 한국농공학회논문집
• /
• 제54권2호
• /
• pp.37-46
• /
• 2012

The change of rainfall pattern and hydrologic factors due to climate change increases the occurrence probability of agricultural reservoir water shortage. Water supply assessment of reservoir is usually performed current reservoir level compared to historical water levels or the simulation of reservoir operation based on the water budget analysis. Since each reservoir has the native property for watershed, irrigation district and irrigation water requirement, it is necessary to improve the assessment methods of agricultural reservoir water capability about water resources system. This study proposed a practical methods that water supply vulnerability assessment for an agricultural reservoir based on a concept of probabilistic reliability. The vulnerability assessment of water supply is calculated from probability distribution of water demand condition and water supply condition that influences on water resources management and reservoir operations. The water supply vulnerability indices are estimated to evaluate the performance of water supply on agricultural reservoir system, and thus it is recommended a more objective method to evaluate water supply reliability.

• 한국농공학회논문집
• /
• 제65권5호
• /
• pp.37-49
• /
• 2023

The drought risk has been increasing recently due to climate change causing the extreme climate to be more frequent. In order to supply agricultural water stably under drought, it is necessary to operate an agricultural reservoir in response to drought. To this end, it is crucial to establish appropriate drought response operation rules considering weather conditions and reservoir status. In the reservoir operation simulation, the supply amount differs from the actual reservoir supply for many reasons, including maintaining water levels for supply and accommodating farmers' requests. So, for a more realistic reservoir operation simulation, it is necessary to reflect the reservoir operation rules of the actual water management site. Therefore, in this study, through a survey, the standards for limitation of agricultural water supply applied to agricultural reservoirs in Korea were investigated, and the criteria for drought response reservoir operation (DRO) were established based on the survey. Then, the DRO was applied to the irrigation period for nine subject reservoirs. The applicability was evaluated by comparing the DRO result to the operation result of HOMWRS (Hydrological Operation Model for Water Resources System). The reservoir drought index, storage rate, and daily supply were compared for evaluation. From the result, DRO showed more stable operation results in most cases against drought as it has fewer days of water supply limitation and a somewhat reservoir storage rate which can be utilized for prolonged drought.

• 생태와환경
• /
• 제43권3호
• /
• pp.349-355
• /
• 2010

본 연구에서는 유역의 효율적인 물관리를 위해 이수적인 측면에서 입력되는 농업용수를 수요측면에서 산정된 계획량에서 실 이용량에 근사하게 보정하는 방법을 제시하고 장기유출모형을 활용하여 실용성이 높은 결과를 도출하고자 하였다. 본 연구의 내용을 요약하면 다음과 같다. 1) 농업용 수리시설물들이 하천유량에 끼치는 영향을 분석하여 농업용수 이용량을 고려한 장기유출을 모의하였다. 그 결과 하천수 의존도가 낮은 지점에서 관측값과 차이가 큰 불량한 모의가 주로 발생하였다. 2) 연강우량과 유출오차와의 상관관계를 분석한 결과 2001년이나 2008년과 같은 가뭄년에 실제 용수이용을 충족시키지 못하여 유출모의시 오차가 커짐을 확인하였다. 3) 장기유출량 모의분석을 통해 논농사가 본격적으로 시작되는 5월부터 유출량이 음의 값으로 모의되고 있음을 확인하였다. 소규모 수리시설물을 고려하여 보정한 용수량을 이용한 결과 상관계수가 보정전 0.580에서 보정후 0.788로 보정전 모의보다 관측값과 상관성이 높아짐을 정량적으로 확인하였다. 4) 주요지점의 불일치율($R_D$) 분석결과 전반적으로 보정을 통한 모의가 적은 불일치 범위에 다수 포함됨을 정량적으로 확인하였다. 특히 대청지점의 불일치율 분석결과 -2에서 -2.5사이의 저유량 오차구간에 전체오차의 3% 차지하는 75개의 불일치율 나타났다. 이는 소규모수리시설물을 고려하지 못하고 용수량이 과다 산정되어 나타나는 오차로 본 연구에서 제시한 방법을 통해 모두 개선되었다. 5) 잔차분석을 통해 대청지점의 보정 전/후로 모의타당성 검정을 실시하였다. 잔차의 정규성 및 독립성을 분석한 결과 보정을 통해 모의의 타당성이 개선됨을 확인하였다.

• 한국농공학회논문집
• /
• 제47권7호
• /
• pp.49-56
• /
• 2005

Contamination in the drainage channels and creeks with pesticides used in agriculture is of a major concern in many countries. In this study the stream pesticide model RIVWQ (chemical transport model for riverine environments) was assessed for its applicability in simulating pesticide fate in drainage channels. The model was successfully calibrated against field data collected on flows and pesticide concentrations for a drainage channel from a small catchment in the Murrumbidgee Irrigation Area of southwestern New South Wales. The effects of different pesticide loading scenarios from farm fields on channel water quality were analysed by the calibrated model. The model simulated the flow rates and the pesticide concentrations in the drainage channel well. The results of the model simulation suggest that the RIVWQ model can be effectively used for predicting pesticide fate in the drainage channels and exposure assessment of pesticide in the agricultural environment.

• 한국농공학회지
• /
• 제32권3호
• /
• pp.47-55
• /
• 1990

An adaptive algorithm was applied to forecast daily stream flows in real time using rainfall data. A three-component tank model was selected to simulate the flows and its time-variant parameters were self-calibrated with updated data using a parameter optimization scheme, golden section search method. The resulting adaptive model, APTANK, was applied to six watersheds, ranging from 0.47 to 33.62 km$^2$ size and the simulated daily streamflows were compared with the measured. The simulation results were in good agreement with the field data. APTANK is found to be applied to real-time flow simulation purposes such as a tool for irrigation water resources management and operations. The model is particularly good to simulate streamflows on dry days as compared to wet days having runoff-induced precipitation.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
• /
• pp.274-276
• /
• 2003

The traditional crop productivity simulations based on crop models are normally site-specific. To simulate regional crop productivity, the spatial crop model is developed in this study by integrating Geographical Information System (GIS) with Erosion Productivity Impact Calculator (EPIC) model. The integration applied a loose coupling approach. Data are exchanged using ASCII or binary data format between GIS and EPIC model without a common user interface. The spatial EPIC model is conducted to simulate the average corn and wheat productivity of 1980s in North China. The results show that the simulation accuracy of the spatial EPIC model is acceptable. The simulation accuracy can be improved by using the detailed crop management information, such as irrigation, fertilizer and tillage schedule.

• Applied Biological Chemistry
• /
• 제43권2호
• /
• pp.116-123
• /
• 2000

작물이 자라는 토양에서 점적 관개에 의해 일어나는 토양 수분의 분포와 이동을 3차원 직교 좌표계로 예측할 수 있는 수학적 모델을 개발하였다. 모델은 지면 증발과 증산을 고려하였으며, 이들의 계절적 현화와 하루 중의 시간변화 뿐 아니라 작물 뿌리의 성장 및 뿌리의 토양 중 분포형태도 고려하였다. 모델의 해는 block centered grid system등을 적용하여 Crank-Nicolson법과 Gauss-Seidel 반복법을 사용하여 구하였다. 모델은 실험을 통해 검증하였으며, 점적 관개의 특성을 알기 위하여 모델을 이용한 컴퓨터 모사를 실시하였고, 본 연구의 조건으로부터 다음의 결과를 얻었다. (1) 관수된 물은 점적기에서 멀어짐에 따라 그 유속이 크게 감소하였고, 관수 시간이 증가함에 따라 습윤구역의 크기가 증가하는 속도도 급격히 감소하였다. (2) 1점 관수의 경우 습윤구역은 수평 방향보다는 수직 방향으로 더 깊이까지 도달하였다. (3) 본 연구조건에서 물이용 효율은 지하 25cm지점의 4점 관수가 가장 좋았으며, 지표면 1점 관수보다 증산량은 10% 증가, 지면 증발량은 20% 감소하였다. (4) disk tension infiltrometer에 의한 토양의 수분보유도 함수는 토양수분 압출에 의한 젖음 곡선과는 상당한 차이를 나타내는 것도 알 수 있었다.