• Proceedings of the Korea Water Resources Association Conference
• /
• 2016.05a
• /
• pp.564-564
• /
• 2016

개념적 수문 모형은 탱크의 개수, 탱크 간 관계구조, 그리고 저류량과 유출량 간 선형/비선형 관계 정의 방식 등에 따라 다양한 형태로 개발되어왔으며, 각 모형마다 매개변수 수 및 입력 자료가 상이하다. 모형의 매개변수가 많아지면 결과가 좋게 나타날 수 있으나, 늘어난 매개변수에 대해 물리적 의미를 부여하고 해석하기가 쉽지 않다. 단순한 모형은 보정이 용이하고 그 특성상 실무에서 널리 이용되고 있으나, 물순환 구조가 복잡한 유역에 대해서는 적용성이 떨어질 수 있다. 하지만 매개변수의 수가 많은 모형이 적은 모형에 비해 항상 결과가 좋은 것은 아니다. 복잡한 모형은 부족한 안정성에 의해 보정 기간에서는 결과가 좋았으나, 검정 기간 대해 결과가 안 좋을 수도 있으며 이에 대한 평가가 필요하다. 본 연구에서는 국내에서 주로 이용되는 개념적 모형을 대상으로 모형의 복잡성과의 정확도의 관계를 비교 평가하고자 한다. 대상 모형으로는 수정 3단 Tank 모형, Im's Tank 모형, Two-Parametric Hyperbolic Model (TPHM), 그리고 Daily Watershed Streamflow Model (DAWAST)을 선정하였고, 대상유역으로는 이동저수지 상류에 위치한 2개 유역을 선정하였다. 모형 간 비교를 위한 정량적 통계적 지표로 $R^2$, Nash-Sutcliffe efficiency (NSE), root mean square error-observations standard deviation ratio (RSR), 그리고 percent bias (PBIAS)를 이용하였다. 본 연구 결과는 개념적 수문 모형에 대한 이해를 증진하고, 장기유출 해석을 위한 수문 모형의 선택 시 모형의 복잡도 및 정확도의 관점에서 도움을 줄 수 있는 기초자료로 이용될 수 있을 것이다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2019.05a
• /
• pp.358-358
• /
• 2019

도시화 및 산업화로 인해 불투수면이 지속적으로 증가하고 있으며, 불투수면의 증가로 인해 물순환 구조 왜곡이 발생하고 있으며, 이로 인해 집중 호우시 첨두유량 증가로 인한 도시 침수, 자연적 침투량 감소로 인한 지하수 고갈 및 하천 건천화, 도시 열섬 현상 등 다양한 물 문제가 발생하고 있다. 건강한 물순환 체계 회복을 위해, 환경부에서는 소권역별 불투수면적률에 대한 중장기 물순환 목표를 포함하여 물환경보전법을 개정하였으며, 2020년부터 시행예정이다. 본 연구에서는 안성천 유역을 대상으로 소권역별 불투수면적률을 산정하고 불투수면적률 저감에 따른 유출량 등의 유역 물순환 구조 변화를 분석하고자 한다. 불투수면적률은 연속수치지도, 연속지적도, 용도지역 지구도 3개의 지리정보자료를 중첩하여 최신 불투수면적 정보가 반영되도록 계산하였으며, 물순환 구조는 HSPF 모형을 이용하여 분석하였다. 본 연구의 결과는 향후 불투수면적과 물순환 요소간의 상관관계 분석을 위한 기초자료로 활용될 수 있을 것으로 사료된다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2020.06a
• /
• pp.140-140
• /
• 2020

도암호 유역 위치한 강원도 평창군 대관령면 일대는 고랭지 농업이 주로 이루어지는 곳으로 강우시 토양 유실로 인한 하천의 수질오염이 빈번하게 발생하고 있다. 비점오염원은 강우시 호수와 하천으로 유입되는 특징을 가지고 있으며 불특정 발생원에서 불특정 기상조건과 경로에 의해 발생하여 지속적인 모니터링에는 어려움이 따른다. 이러한 비점오염원 중에서도 농촌지역에서 발생되는 비점오염원은 정확한 기작이 분석되지 않고 있어 수질오염에 큰 문제가 되고 있다. 본 연구는 도암호 유역 송천에서 2019년 7월부터 10월까지 6회 모니터링을 실시하였다. 이후 각 강우사상에서 비점오염물질의 유출에 미치는 강우요인(선행무강우일수, 강우지속시간, 총 강우량, 최대강우량, 평균강우량)을 분석하였다. 또한 강우유출수 분석을 통해 유량가중평균농도(EMC, Event Mean Concentration)을 산정하여 각 강우사상에서 유출된 오염원의 농도를 정량화하였으며, 초기세척비율(MFFn, Mass First Flush ratio)를 산정하여 강우초기에 유출된 오염원의 농도를 알아보았다. 분석결과 강우의 특성과 모니터링 시기별 영농단계에 의해 강우사상별 오염원의 농도와 초기세척비율의 차이를 보인 것으로 판단된다. 추후 지속적인 모니터링과 분석을 통한 강우강도에 따른 효율적인 비점오염원 저감대책과 관리 방안이 필요할 것으로 보인다.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.62 no.4
• /
• pp.1-12
• /
• 2020

The extreme 2017 spring drought affected a large portion of South Korea in the Southern Gyeonggi-do and Chungcheongnam-do districts. This drought event was one of the climatologically driest spring seasons over the 1961-2016 period of record. It was characterized by exceptionally low reservoir water levels, with the average water level being 36% lower over most of western South Korea. In this study, we consider drought response methods to alleviate the shortage of agricultural water in times of drought. It could be to store water from a stream into a reservoir. There is a cyclical method for reusing water supplied from a reservoir into streams through drainage. We intended to present a decision-making plan for water supply based on the calculation of the quantity of water supply and leakage. We compared the rainfall-runoff equation with the TANK model, which is a long-term run-off model. Estimations of reservoir inflow during non-irrigation seasons applied to the Madun, Daesa, and Pungjeon reservoirs. We applied the run-off flow to the last 30 years of rainfall data to estimate reservoir storage. We calculated the available water in the river during the non-irrigation season. The daily average inflow from 2003 to 2018 was calculated from October to April. Simulation results show that an average of 67,000 tons of water is obtained during the non-irrigation season. The report shows that about 53,000 tons of water are available except during the winter season from December to February. The Madun Reservoir began in early October with a 10 percent storage rate. In the starting ratio, a simulated rate of 4 K, 6 K, and 8 K tons is predicted to be 44%, 50%, and 60%. We can estimate the amount of water needed and the timing of water pump operations during the non-irrigation season that focuses on fresh water reservoirs and improve decision making for efficient water supplies.

• Journal of Korea Water Resources Association
• /
• v.38 no.1
• /
• pp.1-9
• /
• 2005

The study shows the possible use of the index flood frequency curves for an estimation of flood quantiles at ungauged locations. Flood frequency analysis were made for the annual maximum flood data series at 9 available stations in the Han river basin. From the flood frquency curve at each station the mean annual flood of 2.33-year return period was determined and the ratios of the flood magnitude of various return period to the mean annual flood at each station were averaged throughout the Han river basin, resulting mean flood ratios of different return periods. A correlation analysis was made between the mean annual flood and physiographic parameters of the watersheds i.e, the watershed area and mean river channel slope, resulting an empirical multiple linear regression equation over the whole Han river basin. For unguaged watershed the flood of a specified return period could be estimated by multiplying the mead flood ratio corresponding the return period with the mean annual flood computed by the empirical formula developed in terms of the watershed area and river channel slope. To verify the applicability of the methodology developed in the present study the floods of various return periods determined for the watershed in the river channel improvement plan formulation by the Ministry of Construction and Transportation(MOCT) were compared with those estimated by the present method. The result proved a resonable agreement up to the watershed area of approximately 2,000k $m^2$. It is suggested that the practice of design flood estimation based on the rainfall-runoff analysis might have to be reevaluated because it involves too much uncertainties in the hydrologic data and rainfall-runoff model calibration.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.10
• /
• pp.403-411
• /
• 2016

Recently, the number of occurrences of inundation and the severity of flood damage has increased rapidly as the frequency of localized heavy rainfall and the ratio of impervious area increased in urban areas. Most local governments focus on employing structural measures (e.g., the construction of detention reservoirs/pump stations, rehabilitation of drainage and sewer pipes) to prevent urban inundation. On the other hand, the effectiveness of implementing such structural measures is being dimished because there are already many inundation prevention facilities. The limitation of structural measures can be overcoming by employing non-structure measures, such as flood alerts and the operation of drainage facilities. This study suggests the pump operation rule (i.e., suggesting pump stop level) for a new detention reservoir operating method, which triggers the operation of a pump based on the water level at the monitoring node in urban drainage system. In the new reservoir operation, a total of 48 rainfall events are generated by the Huff distribution for determining the proper pump stop level. First, the generated rainfall events are distributed as frequencies, quartiles, and durations. The averaged system resilience value was determined to range from 1.2 m to 1.5 m is based on the rainfall-runoff simulation with rainfall generated by the Huff distribution. In this range, 1.2 m was identified considering the safety factor of 1.25 by the Standard on sewer facilities in 2011.

• Journal of Korea Water Resources Association
• /
• v.46 no.1
• /
• pp.47-58
• /
• 2013

Recently, an increase in the occurrence of sudden local flooding of great volume and short duration due to global climate changes has occasioned the significant danger and loss of life and property in Korea as well as most parts of the world. Such a local flood that usually occurs as the result of intense rainfall over small regions rises quite quickly with little or no advance warning time to prevent flood damage. To prevent the local flood damage, it is important to quickly predict the flood severity for flood events exceeding a threshold discharge that may cause the flood damage for inland areas. The aim of this study is to develop the NFI (New Flood Index) measuring the severity of floods in small ungauged catchments for use in local flood predictions by the regression analysis between the NFI and rainfall patterns. Flood runoff hydrographs are generated from a rainfall-runoff model using the annual maximum rainfall series of long-term observations for the two study catchments. The flood events above a threshold assumed as the 2-year return period discharge are targeted to estimate the NFI obtained by the geometric mean of the three relative severity factors, such as the flood magnitude ratio, the rising curve gradient, and the flooding duration time. The regression results show that the 3-hour maximum rainfall depths have the highest relationships with the NFI. It is expected that the best-fit regression equation between the NFI and rainfall characteristics can provide the basic database of the preliminary information for predicting the local flood severity in small ungauged catchments.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.8 no.1
• /
• pp.88-96
• /
• 2020

In this study, the effect of cyclic wetting-drying on the self-healing of cementitious materials containing superabsorbent polymers (SAPs) were experimentally evaluated. In each cycle, cracked cement paste specimens containing various SAP dosages were exposed to wet conditions for 1 h, during which the capillary water absorption tests and water flow tests were conducted, and then exposed to dry conditions for 47 h. The capillary water absorption test results showed that the sorptivity values of the specimen without SAPs, SAP 0.5%, SAP 1.0%, and SAP 1.5% specimens were decreased by approximately 22.9%, 36.8%, 42.8%, and 46.3%, respectively, after 8 cycles. In addition, the water flow test results showed that the amount of water runoff through the cracks of all cracked specimens gradually decreased over wet/dry cycles, especially the reduction ratio of the amount of water runoff increased with increasing SAP dosage. Furthermore, the swelling behavior of SAPs in cracks by in gress water was con firmed via X-ray computed tomography (CT) analysis. These results indicate that the effective crack width can be reduced as SAPs absorb water and swell, while the water absorbed in SAPs can be released to crack surfaces under dry conditions, further promoting healing product formation. This study demon strates that the in corporation of SAPs can in crease the water tightness of cracks, thereby improving the self-healing efficiency of cementitious materials.

• Journal of Wetlands Research
• /
• v.20 no.2
• /
• pp.145-154
• /
• 2018

In this study, three pilot-scale wetland systems were built for treating stormwater runoff from asphalt road. Each of the system consists of a settling tank and a vertical flow wetland packed with 25%, 50%, and 75% woodchip as treatment media. According to the analysis of the distributions of particle size, it was found that solids ranging in size $0.52-30{\mu}m$ were predominant in the stormwater runoff. After 24-hours settling, those coarser than $20{\mu}m$ were significantly detained. Further retention, especially for the finer-sized fraction, occurred in the wetland through internal recirculation during the dry day periods. As a primary media of the wetland, woodchip showed a high filtration and attachment capacity for the particulates in pre-settled stormwater, whereas overall amount of solids in the wetland effluent increased due to the detachment of woody elements from the media. This was observed mainly during the initial 75 days of operation, and the size and detachment rate were found to be strongly related with the woodchip packing ratio. The mechanism involving woody particle detachment was modeled as a first-order form. In addition, water quality factors and operational parameters affecting the detachment were analyzed and discussed.

• Journal of Wetlands Research
• /
• v.26 no.1
• /
• pp.1-9
• /
• 2024

In this study, a HSPF model was developed to simulate runoff and water quality in the Haebancheon watershed, which has a high land area ratio and population density among the West Nakdong River watersheds. Various non-point source pollution control strategies were applied, and the reduction in pollutant loads and the exceedance rate of water quality standards were analyzed. The scenarios included basic road cleaning for reducing pollutant loads, runoff reduction measures considering extensive low-impact development techniques, and inflow reduction measures to mitigate non-point source pollution entering the river. In the first step, practical conditions such as the number of vehicles for road cleaning in Kimhae City were considered, while for the second and third steps, it was assumed that 50% of the applicable land use area was used to be applicable for the LID techniques. As a result of applying all three measures, it was analyzed that the BOD pollutant load could be reduced by 58.28%, T-N by 58.49%, and T-P by 51.56%. Furthermore, the 60th percentile of water quality measurements accumulated over 5 years was set as the target water quality, and a flow-duration curve was constructed. The exceedance rate of the flow-duration curve before and after applying non-point source pollution reduction measures was analyzed. As a result, for BOD, the exceedance rate decreased from 41.57% before applying the measures to 16.32% after, showing a 25.25% reduction in the exceedance rate. For T-N, the exceedance rate decreased significantly from 40.31% before the measures to 22.84% after, and for T-P, it decreased significantly from 62.43% to 27.22%.