• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.6
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• pp.73-83
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• 2020

Agricultural drought is a natural phenomenon that is difficult to observe and quantitatively express, and agricultural water use is high and usage patterns are diverse, so even if there is a lack of rainfall. The frequency and severity of agricultural drought are increased during the irrigation period where the demand for agricultural water is generated, and reasonable and efficient management of agricultural water for stable water supply is required. As one method to solve the water shortage of agricultural water in an unstructured method, it is necessary to analyze the appropriate supply amount and supply method through simulation from the intake works to the canals organization and paddy field. In this study, irrigation efficiency was analyzed for irrigation systems from April to September over the past three years from the Musu Reservoir located in Jincheon-gun, Chungcheongbuk-do and Pungjeon Reservoir located in Seosan-si, Chungcheongnam-do. SWMM (Storm Water Management Model) was used to collect agricultural water, and irrigation efficiency analysis was conducted using adequacy indicators, and water supply vulnerability. The results of the agricultural water distribution simulation, irrigation efficiency and water supply vulnerability assessment are thought to help the overall understanding of the agricultural water supply and the efficient water management through preliminary analysis of the methods of agricultural water supply in case of drought events.

• Journal of Korea Water Resources Association
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• v.35 no.3
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• pp.285-294
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• 2002

Infiltration is one of the important processes of the hydrologic cycle determining the distribution of water and has been studied extensively. Various theories and models proposed for this process are usually applicable only when the rainfall intensity is higher than the infiltration capacity. The study by Diskin and Nazimov (1995, 1996) suggested a conceptual infiltration model that comprises two elements. The model can make an reasonable approach to the infiltration process, instead of representing the infiltration as a function of time. The study presented herein improved the existing conceptual infiltration model by an additional consideration of the initial moisture contents. The analysis results for the variation of the infiltration capacity curries for various initial moisture contents demonstrate that the model is more reasonable for the approach to the infiltration process. In addition, the results for the relationship of stormwater events-ponding time are compared with the literature values of that for a number of soil types. The agreement is rather good, leading to the conclusion that the improved model is vapid for describing the infiltration process.

• Journal of Korean Society on Water Environment
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• v.23 no.4
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• pp.490-497
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• 2007

A Combined sewer overflows (CSOs) are themselves a significant source of water pollution. Therefore, the control of urban drainage for CSOs reduction and receiving water quality protection is needed. Examples in combined sewer systems include downstream storage facilities that detain runoff during periods of high flow and allow the detained water to be conveyed by an interceptor sewer to a centralized treatment plant during periods of low flow. The design of such facilities as stormwater detention storage is highly dependant on the temporal variability of storage capacity available (which is influenced by the duration of interevent dry periods) as well as the infiltration capacity of soil and recovery of depression storage. As a result, a continuous approach is required to adequately size such facilities. This study for the continuous long-term analysis of urban drainage system used analytical probabilistic model based on derived probability distribution theory. As an alternative to the modeling of urban drainage system for planning or screening level analysis of runoff control alternatives, this model have evolved that offer much ease and flexibility in terms of computation while considering long-term meteorology. This study presented rainfall and runoff characteristics of the subject area using analytical probabilistic model. This study presented the average annual COSs and number of COSs when the interceptor capacity is in the range $3{\times}DWF$ (dry weather flow). Also, calculated the average annual mass of pollutant lost in CSOs using Event Mean Concentration. Finally, this study presented a decision of storage volume for CSOs reduction and water quality protection.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.5
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• pp.93-102
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• 2009

A prediction of streamflow based on multi-objective function is presented to check the performance of Probability Distributed Model(PDM) in Miho stream basin, Chungcheongbuk-do, Korea. PDM is a lumped conceptual rainfall runoff model which has been widely used for flood prevention activities in UK Environmental Agency. The Monte Carlo Analysis Toolkit(MCAT) is a numerical analysis tools based on population sampling, which allows evaluation of performance, identifiability, regional sensitivity and etc. PDM is calibrated for five model parameters by using MCAT. The results show that the performance of model parameters(cmax and k(q)) indicates high identifiability and the others obtain equifinality. In addition, the multi-objective function is applied to PDM for seeking suitable model parameters. The solution of the multi-objective function consists of the Pareto solution accounting to various trade-offs between the different objective functions considering properties of hydrograph. The result indicated the performance of model and simulated hydrograph are acceptable in terms on Nash Sutcliffe Effciency*(=0.035), FSB(=0.161), and FDBH(=0.809) to calibration periods, validation periods as well.

• Journal of The Korean Society of Agricultural Engineers
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• v.61 no.6
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• pp.31-40
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• 2019

In order to implement practical alternatives to proactively cope with the agricultural drought, the potential vulnerability of irrigation pumping stations to agricultural drought was quantitatively evaluated. Data for the 124 pumping stations which are correlatable to the three proxy variables, i.e. exposure, sensitivity, and adaptive capacity was collected by the Korea Rural Community Corporation, and then standardized considering distribution of each data set. Finally, the vulnerability index was calculated by multiplying the weights determined by the expert survey. The results showed that the vulnerability index ranged from 0.709 to 0.331 and the most vulnerable pumping stations such as Judam, Wongoo and Jinahn were mostly located in Gyeongbuk province likely because of the climatological characteristics with high temperature and low rainfall around this area. In addition, it was found that the adaptive capacity was a dominant factor comparing to exposure or sensitivity proxy variables in contributing to the vulnerability. It is therefore recommended that more practical alternatives should be employed to effectively reduce the vulnerability of an individual pumping station to agricultural drought. Furthermore, the corresponding data related to adaptive capacity should be systematically organized and managed at a field level to design reliable adaptation strategies.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.405-410
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• 2015

우리나라는 2000년대 이후, 하천 및 수공구조물 계획시 Huff 분포를 지배적으로 사용해 왔다. 그러나 Huff 방법은 호우선정, 평균방법, 지속기간별 동일분포 가정 등 여러 가지 문제를 가지고 있어 극치 호우사상을 적절히 모의하지 못하는 약점이 있다는 의견이 많았다. 본 연구에서는 하천, 수공구조의 계획시 국내에서 주로 사용해 왔던 강우량 시간분포 방법인 Huff 방법이 과연 하수도시설물 계획시 적정한가를 평가하고 중소규모 배수(排水)시설물 설계시 합리적이라고 알려져 있는 ABM 방법의 적용성을 비교, 평가하여 하수도시설물의 계획시 적정한 확률강우량의 시간분포 방법을 제안하고자 한다. 연구대상 지역은 삼척지역이며 기상청 산하 동해관측소 자료를 이용하여 연구를 수행하였다. 삼척지역의 지속기간별 확률강우량을 Huff 방법을 적용하여 시간분포하면 지속기간 2시간, 3시간 호우의 1시간 최대치의 경우 지속기간 1시간 최대치 보다 크게 산정된다. Huff 1분위의 경우 지속기간 1시간 호우는 55.3mm이나 지속기간 2시간, 3시간 호우의 1시간 최대치는 각각 61.8mm, 60.7mm 로 지속기간 1시간 호우보다 더 크게 평가되었다. 이러한 구간별 최다 강우량의 지속기간별 역전현상은 도달시간 1시간이내의 소유역이라 할지라도 지속기간 2, 3시간호우에서 첨두홍수량이 발생할 수 있는 문제점을 내포하고 있다. 지속기간의 개념을 고려하여 빈도별 홍수시 ABM, Huff 방법의 적용성을 검토하였다. ABM 방법의 경우 적용 유역 면적(0.1~2,000ha) 전체에서 지속기간이 길어지면 첨두홍수량 결과가 수렵하는 것으로 검토되었다. 반면, Huff 방법의 경우 유역면적이 커짐에 따라 임계지속기간이 길어진다. 30년 빈도 홍수의 경우 유역면적 0.1~0.5ha 에서는 30분, 1~50ha 에서는 1시간, 80~300ha 에서는 2시간, 500~2,000ha 에서는 3시간이 임계지속기간인 것으로 분석되었다. 소규모 유역에서는 ABM과 Huff 방법의 홍수량 산정결과의 차이가 크지 않았으며 하수도시설물 계획시 적용성이 높은 강우량 시간분포 방법은 유역의 연속성을 고려할 수 있는 ABM 24시간 호우를 이용하는 것이 타당할 것으로 사료된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.188-188
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• 2016

The Mekong which is one of the world's most significant rivers plays an extremely important role to South East Asia. Lying across six riparian countries including China, Myanmar, Thailand, Laos, Cambodia and Vietnam and being a greatly biological and ecological diversity of fishes, the river supports a huge population who living along Mekong Basin River. Therefore, much attention has been focused on the giant Mekong Basin River, particularly, the soil erosion and sedimentation problems which rise critical impacts on irrigation, agriculture, navigation, fisheries and aquatic ecosystem. In fact, there have been many methods to calculate these problems; however, in the case of Mekong, the available data have significant limitations because of large area (about 795 00 km2) and a failure by management agencies to analyze and publish of developing countries in Mekong Basin River. As a result, the Universal Soil Loss Equation (USLE) model in a GIS (Geographic Information System) framework was applied in this study. The USLE factors contain the rainfall erosivity, soil erodibility, slope length, steepness, crop management and conservation practices which are represented by raster layers in GIS environment. In the final step, these factors were multiplied together to estimate the soil erosion rate in the study area by using spatial analyst tool in the ArcGIS 10.2 software. The spatial distribution of soil loss result will be used to support river basin management to find the subtainable management practices by showing the position and amount of soil erosion and sediment load in the dangerous areas during the selected 56- year period from 1952 to 2007.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.358-358
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• 2018

대청댐은 준공이후 현재까지 37년의 수문자료가 축적되었으며 총 43회의 수문방류를 하여 연간 1.16회의 수문방류를 시행하였다. 본 연구에서는 그동안 수문방류와 지속적으로 최신화한 K-water 저류함수법을 이용하여 수문방류기간중 총강우량 현황과 강우량에 따른 11개의 강우분포형(증가, 감소, 증가감소, 균일, 감소증가, 증가계단, 감소계단, Huff1, Huff2, Huff3, Huff4)의 현황분석, 강우량별 분포형별 유출율을 분석하여 금년도 및 향후 발생이 예상되는 홍수시 수문방류결정에 활용하기 위함이다. 홍수발생 원인을 살펴보면 홍수기 초반에는 장마전선으로 인한 강우가 원인이며, 장마가 끝난 7월말~8월경에는 태풍의 영향을 받는다. 또한, 최근 엘리뇨 및 라니냐 현상의 출현에 따른 기후변화 및 이상기후의 영향으로 예측이 어려운 국지성 돌발호우의 증가로 홍수관리에 어려움을 겪기도 한다. 그러나 최근 가뭄발생이 잦아 우리나라 전역에 가뭄피해가 발생하고 있으며 또한, 홍수기에도 많은 강우가 내리지 않아 2013년 이후에는 수문방류 실적이 전무한 편이다. 홍수로 인한 재해는 인명피해 및 재산피해를 동반하는 우리나라에서 가장 심각한 재해중의 하나이며, 재해예방을 위한 홍수예보는 강우예측과 유출해석으로 나뉠 수 있다. 강우예측은 정교한 강우모형과 기상전문가의 몫이며, 정확한 유출해석은 수문학자들에 의한 연구과제였다. 우리나라 홍수유출해석에 주로 사용되는 모형은 저류함수법이며, 1961년 일본의 Kimura에 의해 창안된 이래 여러 학자들에 의한 다각도의 모형개선을 통해 수차례 모형 성능 향상이 되었다. 그동안 축적된 홍수수문자료를 바탕으로 대청댐 준공이후 수문방류기간중 강우량-강우분포-유출율 관계를 통해 강우량별, 강우분포별, 매개변수별, 유출율, 홍수조절율에 대한 통계분석 및 상관분석을 시행하여 향후 발생가능한 홍수관련 업무에 활용하고자 한다. 또한, 수문방류기간중 호우원인(장마전선, 태풍, 국지성홍수 등)에 대한 분석을 시행하고 호우사상별 매개변수를 산정하여 해당 호우에 대한 특성을 파악하고자 한다.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.157-163
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• 2011

In this study, after the target basin was divided into both overland and channel grids, the travel time from center of each grid cell to watershed's outlet was calculated based on the manning equation. Through this process, volumetric discharge was calculated according to the isochrones and finally, the direct runoff hydrograph was estimated considering watershed's hydrodynamic characteristics. Sanseong subwatershed located in main stream of Bocheong basin was selected as a target basin. The model parameters are only two: area threshold and channel velocity correction factor; the optimized values were estimated at 3,800 and 3.3, respectively. The developed model based on the tuned parameters led to well-matching results between observed and calculated hydrographs (mean of absolute error of peak discharge: 3.41%, mean of absolute error of peak time: 0.67 hr). Moreover, the analysis results regarding histogram of travel time-contribution area demonstrates that the proposed model characterizes relatively well hydrodynamic characteristics of the catchment due to effective rainfall.

• Journal of Korea Water Resources Association
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• v.54 no.7
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• pp.545-552
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• 2021

The burden of flood control on the dam under frequently flood due to climate change and especially heavy flood in 2020 year are come to the forward and increased. The objective of the study is therefore to establish the method to estimate capacity and target water level for flood control in actual dam management. Frequency matching method was applied to establish a pair of cumulative distribution function (CDF) based on daily dam inflow and discharge records. The relationship between dam storage and discharge volume represented as a percentage of inflow volume was derived and its characteristics was analyzed. As the result, the Soyanggang (45%) and Chungju Dam (39%) contributing to flood control with temporarily storing flood runoff. The method and diagram to estimate flood control capacity and target water level for flood control in the dam were established. The result of the study could be used as a supplementary data for flood control of the dam according to the rainfall prediction on the Korea Meteorological Administration.