• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.759-763
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• 2010

본 연구는 격자기반의 지표면 유출 및 도시 유역 우수관거 유출해석모형으로서 유역을 관거 유입구를 기준으로 다수의 소유역들로 구분하고 각 소유역내 지표면 흐름을 비선형저류방정식으로 표현하여 유출량을 산정하는 방법 및 유역을 일정한 크기의 격자로 분할한 상태에서 각 격자의 유입 유출을 계산함으로써 주어진 시간 간격별로 유역 전체에 대한 물수지를 파악하는 격자 물수지식을 이용하는 방법을 결합하여 도시유역의 지표면 유출량을 산정하기 위한 격자기반의 분포형 지표면 유출해석 모형을 개발하는 것을 연구의 목적으로 하였다. 즉, 본 연구에서 개발한 유출모형은 지표면 유출의 메카니즘을 비선형저류방정식으로 표현한다는 점에서 SWMM의 방법을, 격자기반으로 유출량을 계산 추적한다는 것이다. 또한 도시지역의 침수형태 및 원인을 파악함과 동시에 기존의 도시유출 해석모형을 일부 수정 및 보완하여 집중호우발생시의 지표이동류 흐름, 폐합형 우수관거, 하류부의 배수영향 등을 고려한 우수관거 유출모델을 개발하였다. 본 모형을 이용하여 가상 및 실제 유역에 대한 유출모의를 수행함으로써 모형의 적용성을 평가하였다. 본 연구에서 제시하는 격자기반 도시유출해석모형은 대상유역을 일정한 크기의 격자로 구성하고 개개의 격자마다 유출해석을 위한 지형정보와 수문정보를 입력하여 격자별 유출량을 계산 추적함으로써 유역의 임의의 위치에서의 유출량, 유출심의 시간적 변화와 공간적인 분포를 모의할 수 있다. 가상 및 실제 유역에 대한 유출해석을 통하여 본 연구에서 개발한 모형은 이동강우나 국지적인 집중호우 등 시공간적으로 변하는 수문 특성을 반영할 수 있고, 폐합형 우수관망 해석 및 하류부 배수효과를 검토하여 도시유역의 홍수방재관리에 유용하게 활용될 수 있을 것으로 기대된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.424-424
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• 2019

수질오염 저감을 위한 유기물질의 처리를 위해 생물학적 처리에 중점을 둔 하 폐수 처리시설의 증가에 따라 BOD로 대표되는 생분해성 유기물질은 꾸준히 감소하였으나, COD농도의 경우 뚜렷한 감소를 보이지 않고 있다. 유기물질 중 특히 난분해성 물질의 증가는 상수원으로 사용되는 하천의 경우 조류 증식 등을 유발하고 여과공정에 영향을 미쳐 상수처리의 효율을 떨어뜨리는 등의 환경적인 문제를 야기할 수 있다. 기존 BOD, COD로 대표되는 유기물질의 경우 각 유기물질별 상관관계 및 유출특성 등에 대한 연구는 많이 이루어졌으나, 난분해성 물질에 대한 조사는 상대적으로 미진한 실정이다. 특히 동진강수계는 '새만금 제2단계 수질개선종합대책' 등 장기적인 수질개선 대책들이 추진되면서 하천의 BOD5 및 TP는 감소추세를 보이고 있으나, COD는 개선되지 않고 증가하는 추세를 보이고 있다. 동진강의 말단부의 경우 COD/BOD5의 비율이 지속적으로 증가하는 추세를 보이고 있어 상대적으로 난분해성 유기물질에 대한 관리의 중요성이 대두되고 있다. 이러한 COD 및 COD/BOD5의 증가 추세는 국내 4대강에서 전반적으로 나타나고 있는 추세로서, 정부는 2013년부터 하천 및 호소의 생활환경기준에 TOC 항목을 도입하여 2016년부터 호소환경기준의 대표항목을 COD에서 TOC로 대체하였으며, 폐수배출시설에 대해서도 점차적으로 확대 적용할 계획으로, 난분해성물질을 포함하는 총유기물질 관리를 위해서 수질 및 수생태계 환경기준에서 유기물질에 대한 환경기준을 BOD5와 COD에서 TOC로 변경하는 정책을 추진 중에 있다. 본 연구에서는 동진강 유역의 본류 및 지류에서 TOC등 유기물질의 시공간적인 분포와 오염원별 배출특성을 현장조사를 통해 조사 분석하였다. 조사 시기는 건기시, 강우시로 구분하여 수행하였으며 조사항목은 일반수질항목, 유기물질 항목, 유기물질 성상 분석 등에 대하여 수행하였다. 난분해성물질 관리를 위한 기초자료확보를 통하여 새만금호의 수질개선 및 목표수질 달성에 기여 할 것으로 판단된다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1B
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• pp.69-78
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• 2006

The rainfall depth-area-duration analysis which is used to characterize precipitation extremes for specification of so-called design storms, provides a basis for evaluation of drought severity when storm depth is replaced by an appropriate measure of drought severity. So we propose a method for constructing drought severity-area-duration curves in this study. Monthly precipitation data over the whole Korea are used to compute SPI. Such SPIs are abstracted to several independent spatial components from EOF analysis. Using Kriging method, these spatial components are used to constitute grid-based SPI data set over the whole Korea including Jeju island with $6km{\times}6km$ resolution. After identifying main drought events, the drought severity-area-duration curves for these events over 32-year period of record are finally constructed. As a result, such curves show the similar shape with storm-based curves in the sense that the drought severity (or rainfall depth) is inversely proportional to drought area from the curves, but drought-based curves are different from storm-based curves in the sense that the drought severity decreasing rate with respect to drought area is much less than depth decreasing rate.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1B
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• pp.23-33
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• 2009

Climate change, abnormal weather, and unprecedented extreme weather events have appeared globally. Interest in their size, frequency, and changes in spatial distribution has been heightened. However, the events do not display regional or regular patterns or cycles. Therefore, it is difficult to carry out quantified evaluation of their frequency and tendency. For more objective evaluation of extreme weather events, this study proposed a rainfall extreme weather index (STARDEX, 2005). To compare the present and future spatio-temporal distribution of extreme weather events, each index was calculated from the past data collected from 66 observation points nationwide operated by Korea Meteorological Administration (KMA). Tendencies up to now have been analyzed. Then, using SRES B2 scenario and 2045s (2031-2050) data from YONU CGCM simulation were used to compute differences among each of future extreme weather event indices and their tendencies were spatially expressed.The results shows increased rainfall tendency in the East-West inland direction during the summer. In autumn, rainfall tendency increased in some parts of Gangwon-do and the south coast. In the meanwhile, the analysis of the duration of prolonged dry period, which can be contrasted with the occurrence of rainfall or its concentration, showed that the dryness tendency was more pronounced in autumn rather than summer. Geographically, the tendency was more remarkable in Jeju-do and areas near coastal areas.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.17-22
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• 2009

계절에 따른 토양공극의 수리학적 변화를 파악하기 위해서 설마천 유역의 범륜사 독립사면과 광릉 원두부 소유역의 독립사면을 대상으로 장력침투실험을 실시하였다. 토양수분 확보에 신뢰를 받기위해서 TDR(Time Domain Reflectometry)및 현장에서 토양의 불포화 투수계수 측정이 가능한 장력침투계(Tension infiltrometer)를 이용하였다. 계절에 따른 자료수집을 위해서 2008년 3월 20일 부터 약 6주간격으로 10월 29일까지 5회에서 6회 토양수분 자료 및 토양장력침투 자료를 획득하였다. 획득한 자료를 이용하여 포화 및 불포화 수리전도도, 대공극 유효흐름분율(macropore flow), 대공극 유효부피분율을(effective macroporosity) 나타내었다. 분기별로 자료분석 결과 계절별 특성이 나타남을 알 수 있다. 수리전도도는 3월, 5월, 10월은 유사한 반면 6월과 7월 그리고 9월은 상대적으로 높았다. 이는 여름철에 공극 발달이 활발하다는 것을 의미한다. 선행토양수분은 수리전도도에 영향을 미치는 것으로 나타났다. 대공극의 발달은 삼림과 같은 복잡 경관에서는 강우사상에 따른 토양수분의 공간 분포 및 이송, 유출과정이 물순환에 영향을 미친다. 지형분석을 통한 공극의 흐름특성과 토양수분 유의성에 대하여 논의하였고, 대공극 변화에 밀접한 관계가 있는 식생과 그밖에 계절적으로 발달을 일으키는 요인을 모색 하였다. 본 연구는 계절에 따라 변하는 수리전도도를 기초로 하여 불포화대에서 토양공극의 수리학적 변화와 시공간적으로 침투흐름에 얼마나 영향을 주는가를 보여준다.

• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.1
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• pp.1-13
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• 2023

Various techniques for bias correction and statistical downscaling have been developed to overcome the limitations related to the spatial and temporal resolution and error of climate change scenario data required in various applied research fields including agriculture and water resources. In this study, the characteristics of three different statistical dowscaling methods (i.e., SQM, SDQDM, and BCSA) provided by AIMS were summarized, and climate change scenarios produced by applying each method were comparatively evaluated. In order to compare the average rainfall characteristics of the past period, an index representing the average rainfall characteristics was used, and the reproducibility of extreme weather conditions was evaluated through the abnormal climate-related index. The reproducibility comparison of spatial distribution and variability was compared through variogram and pattern identification of spatial distribution using the average value of the index of the past period. For temporal reproducibility comparison, the raw data and each detailing technique were compared using the transition probability. The results of the study are presented by quantitatively evaluating the strengths and weaknesses of each method. Through comparison of statistical techniques, we expect that the strengths and weaknesses of each detailing technique can be represented, and the most appropriate statistical detailing technique can be advised for the relevant research.

• Journal of Korea Water Resources Association
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• v.53 no.3
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• pp.155-166
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• 2020

In this study, we applied the Radar-AWS Rainrates (RAR), weather radar-based quantitative precipitation estimations (QPEs), to the Yongdam study watershed in order to perform the flood runoff simulation and calculate the inflow of the dam during flood events using hydrologic model. Since the Yongdam study watershed is a representative area of the mountainous terrain in South Korea and has a relatively large number of monitoring stations (water level/flow) and data compared to other dam watershed, an accurate analysis of the time and space variability of radar rainfall in the mountainous dam watershed can be examined in the flood modeling. HEC-HMS, which is a relatively simple model for adopting spatially distributed rainfall, was applied to the hydrological simulations using HEC-GeoHMS and ModClark method with a total of eight independent flood events that occurred during the last five years (2014 to 2018). In addition, two NCL and Python script programs are developed to process the radar-based precipitation data for the use of hydrological modeling. The results demonstrate that the RAR QPEs shows rather underestimate trends in larger values for validation against gauged observations (R² 0.86), but is an adequate input to apply flood runoff simulation efficiently for a dam watershed, showing relatively good model performance (E_NS 0.86, R² 0.87, and PBIAS 7.49%) with less requirements for the calibration of transform and routing parameters than the spatially averaged model simulations in HEC-HMS.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.5B
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• pp.487-495
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• 2010

Soil moisture is a crucial factor in hydrological system which influences runoff, energy balance, evaporation, and atmosphere. United States National Aeronautic and Space Administration (NASA) and Department of Agriculture (USDA) have established Soil Moisture Experiment (SMEX) since 2002 for the global observations. SMEX provides useful data for the hydrological science including soil moisture and hydrometeorological variables. The purpose of this study is to investigate the relationship between remotely sensed soil moisture data from aircraft and satellite and ground based experiment. C-band of Polarimetric Scanning Radiometer (PSR) that observed the brightness temperature provides soil moisture data using a retrieval algorithm. It was compared with the In-situ data for 2-30 cm depth at four sites. The most significant depth is 2-10 cm from the correlation analysis. Most of the sites, two data are similar to the mean of data at 10 cm and the median at 7 cm and 10 cm at the 10% significant level using the Rank Sum test and t-test. In general, soil moisture data using the C-band of the PSR was established to fit the Normal, Log-normal and Gumbel distribution. Soil moisture data using the aircraft and satellites will be used in hydrological science as fundamental data. Especially, the C-band of PSR will be used to prove soil moisture at 7-10 cm depths.

• Journal of Korea Water Resources Association
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• v.38 no.8 s.157
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• pp.655-664
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• 2005

A real-time monitoring and modeling system (RTMMS) for rainfall-induced turbidity flow, which is one of the major obstacles for sustainable use of reservoir water resources, is under development. As a prediction model for the RTMMS, a laterally integrated two-dimensional hydrodynamic and water quality model, CE-QUAL-W2 was tested by simulating the temperature stratification, density flow regimes, and temporal and spatial distributions of turbidity in a reservoir. The inflow water temperature and turbidity measured every hour during the flood season of 2004 were used as the boundary conditions. The monitoring data showed that inflow water temperature drop by 5 to $10^{\circ}C$ during rainfall events in summer, and consequently resulted in the development of density flow regimes such as plunge flow and interflow in the reservoir. The model showed relatively satisfactory performance in replicating the water temperature profiles and turbidity distributions, although considerable discrepancies were partially detected between observed and simulated results. The model was either very efficient in computation as the CPU run time to simulate the whole flood season took only 4 minutes with a Pentium 4(CPU 2.0GHz) desktop computer, which is essentially requited for real-time modeling of turbidity plume.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.1
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• pp.66-77
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• 2005

We have investigated microclimatic controls on the spatiotemporal variations of net primary production (NPP) of a rugged forested watershed using the process-based biogeochemical model (BIOME-BGC). To validate the model simulation of water and carbon cycles at the plot scale, we have conducted field survey over deciduous broadleaf forest (DBF) and evergreen needleleaf forest (ENF) since 2000. The modeled values of soil temperature, soil moisture and soil respiration showed high correlation with those from the field measurements. The modeled seasonal changes of NPP showed high correlation with air temperature but no significant correlation with water related parameters. The precipitation frequency turned out to be the best climatic factor to explain the annual variation of NPP. Furthermore, NPP of ENF was more sensitive to precipitation frequency than that of DBF. With changes in vegetation cover and topography, the spatial distribution of NPP was of great heterogeneity, which was negatively correlated with the magnitude of NPP. Despite the annual precipitation of 1,400mm, NPP at the study site was constrained by the amount of water available for the vegetation. Such a modeling result should be verified by the field measurements.