• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.3
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• pp.127-137
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• 1992

For the real-time control of a multi-purpose reservoir in case of a storm, it is absolutely necessary to forecast accurate flood inflows through a good rainfall-runoff model by calibrating the parameters with the on-line rainfall and water level data transmitted by the telemetering systems. To calibrate the parameters of a runoff model. the trial and error method of manual calibration has been adopted from the subjective view point of a model user. The object of this study is to develop a automatic calibration method using an optimization technique. The pattern-search algorithm was applied as an optimization technique because of the stability of the solution under various conditions. The object function was selected as the sum of the squares of differences between observed and fitted ordinates of the hydrograph. Two historical flood events were applied to verify the developed technique for the automatic calibration of the parameters of the storage-function rainfall-runoff model which has been used for the flood control of the Soyanggang multi-purpose reservoir by the Korea Water Resources Corporation. The developed method was verified to be much more suitable than the manual method in flood forecasting and real-time reservoir controlling because it saves calibration time and efforts in addition to the better flood forecasting capability.

• Journal of the Korean Association of Geographic Information Studies
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• v.11 no.2
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• pp.61-72
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• 2008

Leaf area index (LAI) is a key biophysical variable influencing land surface processes such as photosynthesis, transpiration and energy balance, and is a required input to estimate evapotranspiration in various ecological and hydrological models. The development of more correct and useful LAIs estimation techniques is required by these importance, but LAIs had been assumed in most LAI research through simple relations with the normalized difference vegetation index (NDVI) because the field measurement is difficult on wide area. This paper is to evaluate the MODIS LAI Product's practical use by comparing with LAIs that is derived from NOAA AVHRR NDVIs and the 2 years (2003-2004) measured LAIs of Korea Forest Research Institute in Gyeongancheon watershed (561.12 $Km^2$). As a result, the MODIS LAIs of deciduous forests showed higher values about 14 % and 15~30 % than the measured LAIs and NOAA LAIs. In the year of 2003, the MODIS LAIs in coniferous forests were 5 % higher than the measured LAIs, and showed about 7 % differences comparing with the NOAA LAIs except April. These differences come from the insufficient field data measured in partial points of the target area, and the extracted reference data from MODIS LAIs include the limits of spatial resolution and the error of incorrect land cover classification. Thus, using the MODIS data by the proper correction with the measured data can be useful as an input data for ecological and hydrological models which offers the vegetation information and simulates the water balance of a given watershed.

• Journal of Soil and Groundwater Environment
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• v.10 no.2
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• pp.12-19
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• 2005

Jeju island is one of the highest rainfall areas in the Korean peninsular. However, variation in rainfall amount is much great with years, which resulted in substantial variation in annual groundwater recharge and sustainable yield. Therefore, to cope with groundwater hazard including sea water intrusion and water level decline in accordance with successive extreme drought, Jeju province established a stepwise action system, in which management of representative monitoring wells and corresponding actions to water level conditions was enforced. In this study, rainfall and groundwater monitoring data were analyzed to determine management groundwater level on Jeju island. First, rainfall data for last 30 years were analyzed, which yielded a lower limit of rainfall at a confidence level of 99% as a basis rainfall. Only when the rainfall less than the basis rainfall was sustained over 3 months, the water levels were targeted for the analysis. For the water level data selected using the above criteria, the lower limit of 99% confidence interval was determined as a reference groundwater level. Finally, some ratios of reference groundwater level was determined as stepwise management groundwater level on Jeju island.

• Journal of Wetlands Research
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• v.14 no.2
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• pp.159-168
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• 2012

Stormwater runoff affects the quality of surface water and groundwater due to the nonpoint sources (NPSs) of pollutants that it carries during storm events. Typically, urbanized areas experience high pollutant mass emission because of paved roads and other areas which are all highly impervious. For this reason, proper identification of the levels of pollutants from the watershed area is important to pass the Ministry of Environment of the Republic of Korea's water quality standards in rivers and streams. This research was conducted in order to determine and quantify the different constituents present in stormwater runoff generated from highly impervious areas in Cheonan City, Korea. Also, the average event mean concentration (EMC) of stormwater runoff from paved areas was compared with EMCs of other countries to determine the possible causes of its occurrence. In addition, the occurrence of first flush phenomenon was studied in order to find the first flush criteria to be used on the design of best management practices. The results show the pollutant concentration of stormwater runoff was higher than other countries due its landuse and relatively small size of catchment area. During the first 30 minutes of the rainfall events, occurrence of first flush phenomenon was highly evident. Several factors affected the pollutant concentrations in the stormwater such as landuse type, geographic and topographic characteristics,catchment area and amount of rainfall. This research can provide guidance in achieving an effective NPS pollution management applicable to highly urbanized areas in the future.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1665-1669
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• 2007

경상북도 지역에서 낙동강에 위치한 안동의 하회마을, 내성천에 위치한 예천의 회룡포와 영주의 무섬마을 등은 마을 앞에 위치한 깨끗한 백사장으로 널리 알려진 관광명소이다. 하회마을의 점사주의 경우 낙동강 상류에 안동 및 임하 다목적댐이 건설되면서, 수량이 조절됨에 따라 토사수리학적 특성이 상당히 변화되었으며, 식생이 발생하는 등 옛 모습을 상실해 가고 있는 지역이다. 이 연구는 낙동강의 중상류 구간인 안동조정지댐 직하류부터 하회마을 직하류에 위치한 광덕교 지점까지의 하도구간에 일차원 하상변동 수치모형인 HEC6 모형을 적용하여 하회마을 앞의 점사주에 영향을 미치는 토사수리학적 특성 변화를 규명할 목적으로 수행하였다. 수치모형 적용구간의 하상변동을 예측하기 위해 적절한 일차원 준정상 상태 하상변동모형으로 HEC-6 모형을 선정하였으며, 모형적용을 위한 현황분석으로 하상토 특성 자료를 수집 분석하였다. 지형자료에 대한 분석 결과, 다목적댐 건설 이후 하회구간의 하천 지형 변화의 특징으로 저수로 쪽의 하상저하가 두드러지게 나타남을 발견할 수 있었다. 모형의 적용영역 내에 위치한 각 수위표 지점의 수리 수문자료를 수집하여 분석하였다. HEC-6 모형의 보정은 고정상 및 이동상 수리모형 실험결과를 사용하여, 고정상 보정과 이동상 보정으로 구분하여 수행하였다. 이동상 보정 결과 Ackers and White 공식이 다른 공식에 비하여 전반적으로 우수한 결과를 제공함을 알 수 있었다. 하천망 유사이동 수치모형인 HEC-6 모형을 사용하여 장기 하상변동을 예측하였으며, 댐 건설이 하류 하천의 지형변화에 미치는 영향을 분석하였다.ppm)인 시료에 적합한 여과법을 이용하여 분석하였으며, 유사 입경분포 분석방법으로는 BW관 방법을 이용하여 분석하였다. 현재까지 국내 외적으로 하천 유사량 산정과 관련된 많은 경험식들이 제시되고 있다. 하지만, 외국의 충적하천에 기초하여 개발되어진 유사량 공식들을 우리나라 하천에 무분별하게 적용하는 것은 위험스러우며, 유사량 산정 결과의 신뢰성을 높이기 위해서는 무엇보다 우리나라 하천의 지형, 수리, 수문학적 요소들이 유사 특성에 미치는 영향을 알아야 한다. 그러므로, 본 연구에서는 실측을 통한 유사량 값을 하천의 지형, 수리, 수문학적 요소들과 비교 분석하여우리나라 하천에 맞는 유사특성을 알아보고, 기타 총유사량산정 공식을 이용하여 실측한 유사량과 비교 분석하고자 한다.호강유역의 급격한 수질개선을 알 수 있다.世宗實錄) $\ulcorner$지리지$\lrcorner$(地理志)와 동년대에 동일한 목적으로 찬술되었음을 알 수 있다. $\ulcorner$경상도실록지리지$\lrcorner$(慶尙道實錄地理志)에는 $\ulcorner$세종실록$\lrcorner$(世宗實錄) $\ulcorner$지리지$\lrcorner$(地理志)와의 비교를 해보면 상 중 하품의 통합 9개소가 삭제되어 있고, $\ulcorner$동국여지승람$\lrcorner$(東國與地勝覽) 에서는 자기소와 도기소의 위치가 완전히 삭제되어 있다. 이러한 현상은 첫째, 15세기 중

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.236-240
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• 2007

최근 집중호우에 의한 피해가 증가함에 따라 도시화에 따른 불투수 면적이 유출량 증가의 주요한 원인으로 지목되고 있으며 도시의 인구집중으로 인한 지하수의 난개발로 지하수 오염 및 고갈이 빠르게 진행되고 있다. 이에 도시의 지속적이고 건전한 물 관리를 위하여 우수유출저감시설이 고려되고 있으며, 정량적인 저감효과의 분석방법이 요구되고 있다. 따라서, 본 연구에서는 호주에서 물관리 및 우수유출저감을 고려한 도시유역계획을 위해 이용되고 있는 모형에 대한 민감도 분석을 실시하였으며, 이러한 결과를 바탕으로 MUSIC 향후 국내 우수유출저감시설에 관한 수문 해석시 MUSIC의 적용이 가능할 것으로 판단된다. MUSIC의 매개변수 중 불투수율과 토양특성이 매우 중요한 매개변수로 고려되고 있으므로, 본 연구에서는 투수지역의 최대저류깊이, Soil storage(mm), 강우초기 최대저류깊이의 포화정도 Initial storage(%), 지하수위에 도달할 수 있는 Field capacity(mm), 최대 침투율에 영향을 미치는 건조토양상태의 침투율을 정의하는 계수 a와 함수비 증가에 따른 최대 침투율 감소를 정의하는 지수 b 등의 매개변수에 대해 초기값을 중심으로 일정비율로 각 매개변수를 10단계로 구분하여 민감도 분석을 실시하였다. 주요 매개변수의 민감도 분석 결과로부터 MUSIC의 모의를 위해서는 불투수율의 민감도 변화 범위가 가장 넓고 첨두유출량과 총유출량 변화가 함께 일어나므로, 이를 가장 우선적으로 조정하고 이와 함께 토양특성을 반영하는 Soil storage와 Initial storage를 고려한다면 MUSIC을 이용하여 개발에 의한 유출변화와 다양한 우수침투시설 설치에 따른 저감효과를 합리적으로 예측할 수 있을 것으로 판단된다. 물 관리를 요구하게 되었다. 우리나라는 현실적으로 매년 홍수 피해가 발생하고 있지만, 다른 한편 인구밀도가 높고 1인당 가용 수자원이 상대적으로 적기 때문에 국지적 물 부족 문제를 경험하고 있다. 최근 국제적으로도 농업용수의 물 낭비 최소화와 절약 노력 및 타 분야 물 수요 증대에 대한 대응 능력 제고가 매우 중요한 과제로 부각되고 있다. 2006년 3월 멕시코에서 개최된 제4차 세계 물 포럼에서 국제 강 네트워크는 "세계 물 위기의 주범은 농경지", "농민들은 모든 물 위기 논의에서 핵심"이라고 주장하고, 전 프랑스 총리 미셀 로카르는 "...관개시설에 큰 문제점이 있고 덜 조방적 농업을 하도록 농민들을 설득해야 한다. 이는 전체 농경법을 바꾸는 문제..."(segye.com, 2006. 3. 19)라고 주장하는 등 세계 물 문제 해결을 위해서는 농업용수의 효율적 이용 관리가 중요함을 강조하였다. 본 연구는 이러한 국내외 여건 및 정책 환경 변화에 적극적으로 대처하고 물 분쟁에 따른 갈등해소 전략 수립과 효율적인 물 배분 및 이용을 위한 기초연구로서 농업용수 수리권과 관련된 법 및 제도를 분석하였다.. 삼요소의 시용 시험결과 그 적량은 10a당 질소 10kg, 인산 5kg, 및 가리 6kg 정도였으며 질소는 8kg 이상의 경우에는 분시할수록 비효가 높았으며 특히 벼의 후기 중점시비에 의하여 1수영화수와 결실율의 증대가 크게 이루어졌다. 3. 파종기와 파종량에 관한 시험결과는 공시품종선단의 파종적기는 4월 25일부터 5월 10일경까지 인데 이 기간중 일찍 파종하는 경우에 파종적량은 10a당 약 8${\ell}$이고 늦은 경우에는 12${\ell}$ 정도였다. 여기서 늦게 파종한 경우 감수의 가장

• Journal of Korea Water Resources Association
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• v.43 no.2
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• pp.211-220
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• 2010

The objective of this paper presents the application of an "integrated urban flood modeling-runoff model, urban flood model and sewer system model-" in a highly urbanized area of Samcheok where is seriously inundated in 2002 and 2003. For this, we demonstrate how couple a 1-D hydrodynamic model of the river, a 2-D hydrodynamic model of the overland (surface) flow, and a sewer network model including each boundary conditions. In order to make data file for the model, topographic information like elevation and share rate of buildings are directly extracted from DEM or topographical source data without data exchange to avoid uncertainty errors. Furthermore, the research is to assess the impacts of Manning n and buildings influences to inundated depth by changing its share ratio from 10 % to 30 % in low-land urban area. As a results, we found out that the urban inundated depth was decreased by Manning n but increased by buildings ratio. The calculated results of inundation was similar with observed one in 2002 and 2003 flooding. Furthermore, the area was also inundated under not riverbank break case in 2002 flooding.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.1
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• pp.1-16
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• 2020

The APEX model has been developed for assessing agricultural management efforts and their effects on soil and water at the field scale as well as more complex multi-subarea landscapes, whole farms, and watersheds. Recently, a key component of APEX application, named APEX-Paddy, has been modified for simulating water quality by considering paddy rice management practices. In this study, the performance of the APEX-Paddy model was evaluated using field data at Iksan experimental paddy sites in Korea. The discharge and pollutant load data during 2013 and 2014 were used to both manually and automatically calibrate the model. The APEX auto-calibration tool (APEX-CUTE 4.1) was used for model calibration and sensitivity analysis. Results indicate that APEX-Paddy reasonably performs in predicting runoff discharge rate and nitrogen yield. However, sediment and phosphorus yield is not correctly predicted due to the limitation of model schemes. With APEX-Paddy, the performance in reproducing the discharge and nitrogen yield is found to be a satisfactory level after manual calibration. The manually calibrated model performed better than the automatically calibrated model in nearly all comparisons. For runoff, manual calibration reduced PBIAS while R² and NSE values of the automatically calibrated model were the same as the manual calibration. For T-N, NSE and PBIAS were reduced when using manual calibration, whereas R² value was the same as manual calibration. The limitation of the APEX-Paddy model for predicting sediment, as well as the phosphorous yield, was discussed in this study.

• Ecology and Resilient Infrastructure
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• v.7 no.2
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• pp.114-125
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• 2020

Despite the various artificial neural networks that have been developed, most of the discharge models in previous studies have been developed using deep neural networks. This study aimed to develop a discharge model using a convolution neural network (CNN), which was used to solve classification problems. Furthermore, the applicability of CNN was evaluated. The photographs (pictures or images) for input data to CNN could not clearly show the characteristics of the study area as well as precipitation. Hence, the model employed in this study had to use numerical images. To solve the problem, the CN of NRCS was used to generate images as input data for the model. The generated images showed a good possibility of applicability as input data. Moreover, a new application of CN, which had been used only for discharge prediction, was proposed in this study. As a result of CNN training, the model was trained and generalized stably. Comparison between the actual and predicted values had an R² of 0.79, which was relatively high. The model showed good performance in terms of the Pearson correlation coefficient (0.84), the Nash-Sutcliffe efficiency (NSE) (0.63), and the root mean square error (24.54 ㎥/s).

• Journal of Korea Water Resources Association
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• v.50 no.12
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• pp.827-836
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• 2017

The most important parameters of the Muskingum method, widely used in hydrologic river routing, are the storage coefficient and the weighting factor. The Muskingum method does not consider the lateral inflow from the upstream to the downstream, but the lateral inflow actually occurs due to the rainfall on the watershed. As a result, it is very difficult to estimate the storage coefficient and the weighting factor by using the actual data of upstream and downstream. In this study, the flow without the lateral inflow was calculated from the river flow through the hydraulic flood routing by using the HEC-RAS one-dimensional unsteady flow model, and the method of the storage coefficient and the weighting factor calculation is presented. Considering that the storage coefficient relates to the travel time, the empirical travel time formulas used in the establishment of the domestic river basin plan were applied as the storage coefficient, and the simulation results were compared and analyzed. Finally, we have developed a formula for calculating the travel time considering the flow rate, and proposed a method to perform flood routing by updating the travel time according to the inflow change. The rise and fall process of the flow rate, the peak flow rate, and the peak time are well simulated when the travel time in consideration of the flow rate is applied as the storage coefficient.