• Proceedings of the Korea Water Resources Association Conference
• /
• 2009.05a
• /
• pp.1301-1305
• /
• 2009

본 연구의 목적은 금강권역에 속하는 무주 남대천유역의 유량변화가 유역의 대표어종인 피라미 서식환경에 미치는 영향을 분석하는 것이다. 유량변화를 분석하기 위해 미국의 Nature Conservency에서 개발한 수문변화지표법(Indicators of Hydrologic Alteration)을 사용하여 무주 남대천유역의 1966년${\sim}$2001년의 유량변화를 분석하였다. 유황특성이 바뀌는 1984년을 기준으로 1966년${\sim}$1983년과 1984년${\sim}$2001년의 두 기간으로 나누어 유량변화를 분석한 결과 유량은 증가하는 추세임을 확인할 수 있었다. 따라서 무주 남대천유역의 유량변화가 대표 어종인 피라미의 산란기인 4월${\sim}$5월과 치어기인 6월${\sim}$10월의 하천 서식환경에 큰 영향을 미칠 것으로 판단된다. 본 연구에서 무주 남대천유역의 산란기에 영향을 미치는 4월${\sim}$5월과 치어기에 영향을 미치는 6월${\sim}$10월의 월 평균 유량을 구분하고 수리모형인 HEC-GeoRAS를 이용하여 하도구간의 유속과 수위를 산정함으로써 피라미가 선호하는 생태적 요구조건을 만족하는 서식처 조건의 변화정도를 검토하였다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2009.05a
• /
• pp.134-138
• /
• 2009

물 순환과정의 핵심요소로 설명되는 유출량은 용수 공급과 가뭄재해에 대한 이수, 홍수 대비 및 관리는 물론, 하천생태계 유지를 위한 환경에 영향을 미치게 된다. 특히, 유출량의 규모(quantity)와 시간(timing)은 용수공급, 수질과 하천 시스템의 생태학적 교류에 중요한 요소로(Poff 등, 1997) 하천 유황의 5가지 요소(규모, 빈도, 지속시간, 시간과 변화율)는 수중 생태계에 직 간접적인 영향을 미친다(Karr, 1991; Poff 등, 1997). 최근 기후변화 현실화로 강우 발생 시기와 패턴이 변화하면서 유역에 따라 유황이 변화하고 있는 실정이다. 이에 본 논문은 기후변화가 향후 하천 유황과 수생태계에 미치는 영향을 분석하기 위하여 한강 유역을 대상유역으로 선정하고 기상청(Korea Meterological Administration, KMA)에서 제공하는 A2 기반의 고해상도 RCM 모형($27km{\times}27km$)으로부터 일(daily)단위의 기후변화시나리오를 작성하였다. 그리고 준분포형 모형인 SLURP 모형으로부터 유출 변화를 모의한 후 수문변화지표(indicator of Hydrologic Alteration, IHA)를 이용하여 기후변화에 따른 하천 유황과 수생태계에 미치는 영향을 정량화하였다.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.53 no.6
• /
• pp.171-183
• /
• 2011

Temporal and spatical surface runoff by heavy rainfall during 25~28 July, 2011 causing urban flooding at Seoul were analyzed using Long-Term Hydrologic Impact Assessment (L-THIA). L-THIA was calibrated for 1988~1997 and validated for 1998~2007 using monthly observed data at Hangangseoul watershed which covers 90 % of Seoul city. As a results of calibration and validation of L-THIA at Hangangseoul watershed, Nash-Sutcliffe coefficients were 0.99 for calibration and 0.99 for validation. The simulated values were good agreement with observed data and both calibrated and validated levels were "very good" based on calibration criteria. The calibrated curve number (CN) values of residential and other urban area represented 87 % and 93 % of impervious area, respectively, which were maximum percentage of impervious area. As a result of L-THIA application at Seoul city during 25~28 July, 2011, most of rainfall (54 %, 287.49 mm) and surface runoff (65 %, 247.32) were generated at 27 July, 2011 and a significant amount of rainfall and surface runoff were occurred at southeastern Seoul city. As a result of bi-hourly spatial and temporal analysis during 27 July, 2011, surface runoff during 2:00~4:00 and 8:00~10:00 were much higher than those during other times and surface runoff located at Seocho-gu during 6:00~8:00 represented maximum value with maximum rainfall intensity which caused landslide from Umyun mountain.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.65 no.6
• /
• pp.37-49
• /
• 2023

Rainfall data is one of the most important data in hydrologic modeling. In this study, the impacts of spatial resolution of precipitation data on hydrological responses were assessed using SWAT in the Santa Fe River Basin, Florida. High correlations were found between the FAWN and NLDAS rainfall data, which are observed weather data and simulated weather data based on observed data, respectively. FAWN-based scenarios had higher maximum rainfall and more rainfall days and events compared to NLDAS-based scenarios. Downstream areas showed lower correlations between rainfall and peak discharge than upstream areas due to the characteristics of study site. All scenarios did not show significant differences in base flow, and showed less than 5% of differences in high flows among NLDAS-based scenarios. The impact of resolution will appear differently depending on the characteristics of the watershed and topography and the applied model, and thus, is a process that must be considered in advance in runoff simulation research. The study suggests that applying the research method to watersheds in Korea may yield more pronounced results, and highlights the importance of considering data resolution in hydrologic modeling.

• Journal of Korean Society on Water Environment
• /
• v.36 no.3
• /
• pp.206-219
• /
• 2020

As urbanization and impermeable areas have increased, stormwater and non-point pollutants entering the stream have increased. Additionally, in the case of the old town comprising a combined sewer pipe system, there is a problem of stream water pollution caused by the combined sewer overflow. To resolve this problem, many cities globally are pursuing an environmentally friendly low impact development strategy that can infiltrate, evaporate, and store rainwater. This study analyzed the expected effects and efficiency when the LID facility was installed as a measure to improve hydrologic cycle and water quality in the Oncheon stream in Busan. The EPA-SWMM, previously calibrated for hydrological and water quality parameters, was used, and standard parameters of the LID facilities supported by the EPA-SWMM were set. Benchmarking the green infrastructure plan in New York City, USA, has created various installation scenarios for the LID facilities in the Oncheon stream drainage area. The installation and maintenance cost of the LID facility for scenarios were estimated, and the effect of each LID facility was analyzed through a long-term EPA-SWMM simulation. Among the applied LID facilities, the infiltration trench showed the best effect, and the bio-retention cell and permeable pavement system followed. Conversely, in terms of cost-efficiency, the permeable pavement systems showed the best efficiency, followed by the infiltration trenches and bio-retention cells.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2005.05b
• /
• pp.143-148
• /
• 2005

The main purpose of this study is to suggest and evaluate an operational method for assessing the potential impact of climate change on hydrologic components and water resources of regional scale river basins. The method, which uses large scale climate change information provided by a state of the art general circulation model(GCM) comprises a statistical downscaling approach and a spatially distributed hydrological model applied to a river basin located in Korea. First, we construct global climate change scenarios using the YONU GCM control run and transient experiments, then transform the YONU GCM grid-box predictions with coarse resolution of climate change into the site-specific values by statistical downscaling techniques. The values are used to modify the parameters of the stochastic weather generator model for the simulation of the site-specific daily weather time series. The weather series fed into a semi-distributed hydrological model called SLURP to simulate the streamflows associated with other water resources for the condition of $2CO_2$. This approach is applied to the Yongdam dam basin in southern part of Korea. The results show that under the condition of $2CO_2$, about $7.6\% of annual mean streamflow is reduced when it is compared with the observed one. And while Seasonal streamflows in the winter and autumn are increased, a streamflow in the summer is decreased. However, the seasonality of the simulated series is similar to the observed pattern and the analysis of the duration cure shows the mean of averaged low flow is increased while the averaged wet and normal flow are decreased for the climate change.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.56 no.3
• /
• pp.19-29
• /
• 2014

This study was to evaluate the potential climate change impact on watershed hydrological components of evapotranspiration, surface runoff, lateral flow, return flow, and streamflow using Soil and Water Assessment Tool (SWAT). For Yongdam dam watershed (930 $km^2$), the SWAT model was calibrated for five years (2002-2006) and validated for three years (2004-2006) using daily streamflow data at three locations and daily soil moisture data at five locations. The Nash-Sutcliffe model efficiency (NSE) and coefficient of determination ($R^2$) were 0.43-0.67 and 0.48-0.70 for streamflow, and 0.16-0.65 and 0.27-0.76 for soil moisture, respectively. For future evaluation, the HadGEM3-RA climate data by Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios were adopted. The biased future data were corrected using 30 years (1982-2011, baseline period) of ground weather data. The HadGEM3-RA 2080s (2060-2099) temperature and precipitation showed increase of $+4.7^{\circ}C$ and +22.5 %, respectively based on the baseline data. The impacts of future climate change on the evapotranspiration, surface runoff, baseflow, and streamflow showed changes of +11.8 %, +36.8 %, +20.5 %, and +29.2 %, respectively. Overall, the future hydrologic results by RCP emission scenarios showed increase patterns due to the overall increase of future temperature and precipitation.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.60 no.6
• /
• pp.65-71
• /
• 2018

The Long-Term Hydrologic Impact Assessment (L-THIA) model is a quick and straightforward analysis tool to estimate direct runoff and nonpoint source pollution. L-THIA was originally implemented as a spreadsheet application. GIS-based versions of L-THIA have been developed in ArcView 3 and upgraded to ArcGIS 9. However, a major upgrade was required for L-THIA to operate in the current version of ArcGIS and to provide more options in runoff and NPS estimation. An updated L-THIA interfaced with ArcGIS 10.0 and 10.1 has been developed in the study as an ArcGIS Desktop Tool. The model provides a user-friendly interface, easy access to the model parameters, and an automated watershed delineation process. The model allows use of precipitation data from multiple gauge locations for the watershed when a watershed is large enough to have more than one precipitation gauge station. The model estimated annual direct runoff well for our study area compared to separated direct runoff in the calibration and validation periods of ten and nine years. The ArcL-THIA, with a user-friendly interface and enhanced functions, is expected to be a decision support model requiring less effort for GIS processes or to be a useful educational hydrology model.

• Journal of Korea Water Resources Association
• /
• v.45 no.6
• /
• pp.517-529
• /
• 2012

Climate change can impact hydrologic processes of a watershed system. The integrated modeling systems need to be built to predict and analyze the possible impacts of climate change on water environment for the optimal water resource operation and management. In this study, Namgang Dam watershed in the Nakdong River basin was selected as a study area. To evaluate the vulnerability of Namgang Dam watershed caused by climate change, the change in hydrologic runoff were predicted using the watershed model, SWAT. The RCM scenario was analyzed and downscaled using the artificial neural network and the dynamic quantile mapping. The results of this study will be utilized for suggesting an effective counterplan for climate change, and finally to propose the optimal water resource management method.

• Journal of Korea Water Resources Association
• /
• v.49 no.10
• /
• pp.863-876
• /
• 2016

Climate change projections for precipitation are in general provided at daily time step. However, sub-daily precipitation data is necessarily required for hydrologic design and management. Thus, a reliable downscaling model is needed to analyze impact of climate change on water resources. While daily downscaling models have been widely developed and applied in hydrologic and climate community, hourly downscaling models have not been properly developed. In this regard, this study aims at developing a hourly downscaling model that can better reproduce sub-daily extreme rainfalls using conditional copula model. The proposed model was applied to generate extreme rainfalls under the RCP 8.5 scenario for weather stations in South Korea, and design rainfalls were then finally provided. We expected that the future design rainfalls can be used for baseline data to evaluate impact of climate change on water resources.