• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.121-121
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• 2022

한국과 미국은 2018년 8월에 발표한 메콩우호국(Friends of the Lower Mekong, FLM) "메콩지역 수자원 데이터 관리 및 정보공유 강화에 관한 공동성명"을 계기로 메콩유역의 실시간 수자원 변동 모니터링 및 분석과 수자원 데이터 공동활용 역량을 강화하여 효율적이고 과학적인 수자원관리 지원과 함께 한국의 신남방정책과 미국의 인도-태평양 전략 시너지효과를 극대화하고자 메콩 주변국 재해경감 및 수자원 데이터 활용 역량강화를 위한 글로벌 위성기반 수문자료의 생산·활용 및 홍수·가뭄 등의 수재해 분석기술을 개발하고 있다. 여기에는 한국 K-water의 물관리 기술과 미국 NASA, USACE의 위성활용 및 수자원분석 기술을 접목하여 메콩지역의 체계적인 물관리 및 재해로부터 안전성 확보 기여에 목표를 두고 연구를 진행 중에 있다. 본 연구에서는 전 세계적으로 광범위하게 활용되고 있는 미공병단(USACE, U.S. Army Corps of Engineers)의 HEC software 프로그램을 메콩 시범지역(pilot area)에 적용하여 수리/수문모델 구축을 진행하고 있다. 구축되는 모형은 유역 상류 댐의 연계 모의운영 및 하류 홍수분석이 동시 가능한 HEC-RTS(Real-Time Simulation)로 이는 HEC-HMS, -ResSim, -RAS와 -FIA 모형이 순차적으로 결합된 수리/수문 모델링 시스템이다. 모형의 시범적용 지역은 현지 메콩위원회(MRC, Mekong River Comission)의 의견 등을 반영, 메콩강 하류지역(Lower Mekong) 본류 유역에 위성자료 활용 및 준실시간(near real-time)으로 댐 모의운영 등을 고려할 수 있는 JingHong댐(중국 란창강 최하류)에서 라오스 Xayaburi댐(메콩강 최상류)까지의 구간을 선정하였으며, 전년도에는HEC-RTS 중 HMS(Hydrologic Modeling System) 모형 적용을 중심으로 가용한 위성자료(GPM IMERG)를 활용하여 과거 홍수사상에 대한 모의를 고려한 강우-유출모형의 구축을 완료하였다. 이에 연속하여 금년도에는 동일유역 내 하천 단면 등이 확보된 Chiang Saen 지점에서 Xayaburi 댐까지의 구간에 대해 RAS(River Analysis System)을 구축할 예정으로 구축된 RAS 모형은 HEC-RTS에 포함되어 메콩 시범지역의 종합적 수리/수문분석에 적용될 예정이다.

• Korean Journal of Ecology and Environment
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• v.56 no.4
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• pp.406-413
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• 2023

Captive breeding and reintroduction are crucial strategies for conserving endangered species populations. However, fish raised in predator-free environments, show a lack of recognition of predationrelated stimuli such as chemical and visual signals. It is critical to recognize chemical signals from injured conspecifics, also known as alarm signals, and the order or shape of predators to indicate the spread of predation risk in the habitat. We conducted a laboratory experiment to determine and adjust the optimal exposure period to induce appropriate anti-predator behavior response to different types of stimuli (Chemical, Visual and Chemical+Visual) for the endangered species Microphysogobio rapidus. Our results demonstrate that predator avoidance behavior varies depending on the types of stimuli and the duration of predation risk exposure. First, the results showed captive-breed M. rapidus show lack of response against conspecific alarm signal (Chemical cue) before the predation risk exposure period and tend to increase response over predation risk exposure time. Second, response to predator (visual cue) tend to peak at 48 hours cumulative exposure, but show dramatic decrease after 72 hours cumulative exposure. Finally, response to the mixed cue (Chemical+visual) tend to peak prior to the predation risk exposure period and show reduced response during subsequent exposure periods. This experiment confirms the lack of responsiveness to conspecific alarm signals in captive-bred M. rapidus and the need for an optimal nature behavior enhancement program prior to release of endangered species. Furthermore, responsiveness to predator visual signal peak at 48 hours cumulative exposure, suggest an optimal predation risk exposure period of up to 48 hours.

• Journal of Korea Water Resources Association
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• v.55 no.1
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• pp.1-10
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• 2022

Irrigation water supplied to the paddy field is consumed in the amount of evapotranspiration, underground infiltration, and natural and artificial drainage from the paddy field. Irrigation return flow is defined as the excess of irrigation water that is not consumed by evapotranspiration and crop, and which returns to an aquifer by infiltration or drainage. The research on estimating the return flow play an important part in water circulation management of agricultural watershed. However, the return flow rate calculations are needs because the result of calculating return flow is different depending on irrigation channel water loss, analysis methods, and local characteristics. In this study, the irrigation return flow rate of agricultural watershed was estimated using the monitoring and SWMM (Storm Water Management Model) modeling from 2017 to 2020 for the Heungeop reservoir located in Wonju, Gangwon-do. SWMM modeling was performed by weather data and observation data, water of supply and drainage were estimated as the result of SWMM model analysis. The applicability of the SWMM model was verified using RMSE and R-square values. The result of analysis from 2017 to 2020, the average annual quick return flow rate was 53.1%. Based on these results, the analysis of water circulation characteristics can perform, it can be provided as basic data for integrated water management.

• Economic and Environmental Geology
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• v.56 no.1
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• pp.87-101
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• 2023

The purpose of this study identifies the production of aggregate every year, and is to understand the supply and demend prospects. In 2021, the total of 135 million m³ of of aggregates was produced in Korea, a slightly increase from the total production of 2020. Of these, about 47 million m³ of sand and about 88 million m³ of gravel were produced. About 46% of total quantity of aggregates were produced with permission and the rest were aggregates produced after declaration. It estimated that of the 135 million m³ of aggregates in Korea in 2020, about 49.6% was produced by screening crushed aggregate, by 36.8% by forest aggregate, 2.6% by land aggregate, 6.8% by sea aggregate and 2.6% by washing each other, and 0.2% by river aggregate. This indicates that screening crushed aggregate and forest aggregate are the main product as in 2021. Leading producing metropolitan governments were Gyeonggi-do, Chungcheongnam-do, Incheon, Gyeongsangnam-do, Chungcheongbuk-do, Gangwon-do, Jeollanam-do, Gyeongsangbuk-do in order decreasing volume. In 2021, aggregates were produced in 148 local governments, and The 10 leading producing local governments were, in descending order of volume, Hwaseong, Ongjin, Paju, Pocheon, Gwangju, Youngin, Cheongju, Gimhae, Anseong, west EEZ. The combined production of the 10 leading local governments accounted for 30% of the national total, and. 47 local governments have produced aggregates of more than 1 million m³ each other. In 148 local governments that produced aggregate, a total of 805 active operations produced aggregate with 372 operations by river, land and forest aggregate, 433 operations by selective crushed and washing aggregate.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.65-65
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• 2016

Various types of flow conditions are developed in the region just downstream of hydraulic structures such as weir and drop structures. One of distinct flow conditions occurred downstream of drop structures is the wave type flow with undular hydraulic jump formation. We present three-dimensional numerical simulations of a wave type flow formed downstream of a stepped weir which were experimentally investigated by Kang et al. (2010). The turbulent flow over the weir structure is modeling using the unsteady Reynolds-averaged Navier-Stokes (URANS) simulation employing the Spalart-Allmaras one equation model and the detached eddy simulation. Numerical modeling and the performance of turbulence modeling approaches are evaluated by comparing with the experimental measurements in terms of the free surface variation, the shapes and sizes of undular wave, roller near at free surface, recirculation zone near the channel bottom downstream of the structures, and streamwise velocity profiles at selected longitudinal locations.

• Journal of Convergence for Information Technology
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• v.10 no.12
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• pp.236-244
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• 2020

In this research a suspended solid transport experiment was conducted in the river experiment center to find the characteristics and dispersion of the material. Modeling by the particle dispersion model was also executed to reproduce the suspended solid transport. The suspended solid was consisted of a mixture of silica and water using a mixing equipment, which was then introduced into a real-scale flume and measured with the laser-diffraction based particle size analyzer(LISST) to find the concentration of the material. The comparison between the measured suspended solid concentration using drone images and particle size analyzers, with the model showed a good match overall, which proved the applicability of the model. Along with finding the model applicability, the research showed the potential for suspended solid estimation in high flow situations with high rainfall.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.258-258
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• 2022

물넘이 형식에는 수문과 밸브로 조절할 수 있는 조절형식, 개수로 및 관수로 형식의 자연적으로 수위조절이 되는 비조절형식, 레버린스(Labyrinth), 피아노건반(Piano Key Weir), 사이펀(Siphon) 등의 특수형식으로 구분할 수 있다. 이 중에서 피아노건반 물넘이는 레버린스 물넘이를 피아노건반 모양으로 개량한 것으로 2003년 알제리 Biska 대학의 Quamane 교수에 의해 제안되었다. 제한된 물넘이 폭에 물넘이의 길이를 연장하여 방류능력을 증가시키는 효과를 나타내는 물넘이 형식으로 여수로의 월류수심을 낮게 유지하면서 방류량을 증가시킬 수 있다. 피아노건반 물넘이는 2006년에 프랑스에서 최초로 적용되었으며, 현재까지 약 30여 지역(프랑스, 베트남, 호주 등)의 댐에 적용되었다. 본 연구에서는 국내 저수지를 대상으로 여수로에 피아노건반 물넘이를 적용하여 방류능력과 수리적 안정성 검토를 위해 농어촌연구원 국제융합수리시험센터에서 수리모형실험을 수행하였다. 농어촌연구원은 2018년도에 기존 수리모형실험 시설을 확장하여 가로 250m, 세로 102m의 국내 최대규모의 실내 수리모형실험 시설을 준공하였고, 대형유사순환수로, 고정식 급경사수로, PIV 전용실험수로 등 기능별 7종의 실험수로를 갖추고 있다. 수리실험은 Froude 상사에 의한 축척을 적용하여 모형을 제작하였고, 기존의 수리시설과 하류하천까지 포함하여 70m(L)×20(B)×2m(H) 규모이다. 실험은 유량을 다양하게 변화시키면서 수위-방류량을 검토하였고, PMF 홍수위에서 방류량이 배제 가능한지 검토하였다. 또한, 물넘이의 안정성 검토를 위한 접근유속을 게측하였고, 물넘이를 통해 월류하는 흐름의 유황을 분석하여 수리학적으로 안정한 흐름이 발생하는지 검토하였다.

• Ecology and Resilient Infrastructure
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• v.8 no.1
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• pp.9-21
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• 2021

In this study, fish and flow surveys were conducted at 12 survey points to calculate the fish habitat suitability index of Miho Stream in the Geum River Water System. The field surveys were conducted four times from September 2019 to May 2020. The results show the presence of 8 families, 37 species, and 5,754 individuals. The number of water purification species that preferred waters with a low flow rate was the highest. The habitat suitability index was calculated according to the Washington Department of Fish and Wildlife method based on the populations collected at various water depths and flow rate sections and the flow rate survey results. For the dominant species, Zacco platypus and swimming species, the results were compared by calculating at Gasan Bridge and Palgye Bridge at the upper stream. The single species showed no significant difference between the upstream and downstream at water depths of 0.1 - 0.5 m and flow rates of 0.2 - 0.5 m/s. The species swimming ability was similarly calculated at water depths of 0.2 - 0.5 m and flow rates of 0.2 - 0.5 m/s. The dominant species, Pyramid, had a wide range of physical habitats. The habitat suitability index between the swimming species was similarly calculated. These results can be effectively used as basic data for calculating the environmental ecological flow rate and establishing a river restoration plan of the Miho Stream.

• Korean Journal of Ecology and Environment
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• v.56 no.1
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• pp.1-13
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• 2023

Targeting Microcystin (MC), which is most abundantly detected in the North-Han River water area, we analyzed the relationship between the MC biosynthesis gene (mcyA gene), cyanobacteria cell density, and MC concentration, derived an RNA-MC conversion formula, and derived the cyanobacteria. The concentration of MC present in cells was predicted. In the North-Han River waters, the mcyA gene was found mainly at downstream sites of the North-Han River after Muk-Hyeon Stream junction, and higher copy numbers were found on average than other sites. In the Uiam Lake waters upstream of the North-Han River, the mcyA gene copy number increased at the Kong-Ji Stream point, and after September, the mcyA gene copy number decreased throughout the North-Han River waters. The expression of the mcyA gene was concentrated in the short period of summer due to the spatio-temporal difference between upstream and downstream water bodies. The mcyA gene expression level was not only highly correlated with MC concentration, but also correlated with the cell density of Microcystis aeruginosa and Dolichospermum circinale, which are known to biosynthesize MC. Six conversion formulas derived based on the RNA-MC relationship showed statistical significance (p<0.05) and exhibited high correlation coefficients (r) of 0.9 or higher. The expression level of MC biosynthesis gene present in eRNA determines the synthesis of cyanotoxin substances in water, quickly quantifies gene activity, and can be fully utilized for early warning of MC development.

• Korean Journal of Ecology and Environment
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• v.56 no.3
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• pp.250-258
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• 2023

Freshwater jellyfish, a type of jellyfish exclusively found in freshwater, has a limited number of species but is found globally. However, their ecology and causes of occurrence are largely unknown. Therefore, understanding the distribution of polyps, which produce the larvae of freshwater jellyfish, can provide important data for comprehending their ecology. This study aims to explore the COI gene of freshwater jellyfish using environmental DNA from the microbial film in the Miho River system. Among the 12 survey points in the Miho River watershed, genetic material of freshwater jellyfish was detected in 8 points, mainly located upstream near reservoirs. These genetic materials were identified as genes of the well-known freshwater jellyfish species, Craspedacusta sowerbii. Notably, the C. sowerbii genes found in the Miho River watershed survey points were closely related to a species previously discovered in Italy. Consequently, utilizing environmental DNA to explore the genetic traces of freshwater jellyfish enables rapid screening of areas with a high likelihood of freshwater jellyfish occurrence. This approach is deemed to provide crucial information for understanding the distribution and ecology of freshwater jellyfish in Korea.