Hung-Soo Kim

Impact Assessment of Climate Change on Extreme Rainfall and I-D-F Analysis

Recently, extreme precipitation events beyond design capacity of hydraulic system have been occurred and this is the causes of failure of hydraulic structure for flood prevention and of severe flood damage. Therefore it is very important to understand temporal and spatial characteristics of extreme precipitation events as well as expected changes in extreme precipitation events and distributional characteristics during design period under future climate change. In this paper, climate change scenarios were used to assess the impacts of future climate change on extreme precipitation. Furthermore, analysis of future extreme precipitation characteristics and I-D-F analysis were carried out. This study used SRES B2 greenhouse gas scenario and YONU CGCM to simulate climatic conditions from 2031 to 2050 and statistical downscaling method was applied to establish weather data from each of observation sites operated by the Korean Meteorological Administration. Then quantile mapping of bias correction methods was carried out by comparing the simulated data with observations for bias correction. In addition Modified Bartlett Lewis Rectangular Pulse(MBLRP) model (Onof and Wheater, 1993; Onof 2000) and adjust method were applied to transform daily precipitation time series data into hourly time series data. Finally, rainfall intensity, duration, and frequency were calculated to draw I-D-F curve. Although there are 66 observation sites in Korea, we consider here the results from only Seoul, Daegu, Jeonju, and Gwangju sites in this paper. From the results we found that the rainfall intensity will be increased and the bigger intensity will be occurred for longer rainfall duration when we compare the climate conditions of 2030s with present conditions.

Estimation of the Flash Flood Severity using Runoff hydrograph and Flash flood index

The flash flood has been studied in the climatological aspect which considers temporal and spatial characteristics of rainfall. However, we have not interested in runoff hydrograph for flash flood study. Therefore, our objectives of this study are to apply a work of Bhaskar et. al (2000) which studied runoff hydrograph to represent the flash flood to Korea and also to distinguish flash flood event from general flood event. That is, we quantified the severity of flash flood by estimation of flash flood index using runoff hydrograph. This study estimated the flash flood index for investigating the relative severity of flash flood in Han river basin with 101 flood events. Also we quantified the flash flood severity for flood event by heavy rainfall occurred in July of 2006. As a result, Kangwon-do province showed more severe flash flood than other areas in Han river basin and urban area such as Jungrang cheon stream also showed severe flash flood. We analyzed a flash flood of July of 2006 by dividing July into 1st to 3rd terms. From the analysis we knew that the 1st term of July showed the severe flash flood was occurred in Seoul area and the 2nd term showed it was occurred in Kangwon-do province.

Sensitivity Assessment on Daecheong Dam Basin Streamflows According to the Change of Climate Components - Based on the 4th IPCC Report -

Climate change and global warming are prevalent all over the world in this century and many researchers including hydrologists have studied on the climate change. This study also studied the impact of climate change on streamflows of a basin in Korea. The SWAT model was used to assess the impacts of potential future climate change on the streamflows of the Daecheong Dam Basin. Calibration and validation of SWAT were performed on a monthly basis for the year of 1982-1995 and 1996-2005, respectively. The impact of seven 15-year(1988-2002) scenarios were then analyzed for comparing it to the baseline scenario. Among them, scenario 1 was set to show the result of doubling , scenario 2-6 were set to show the results of temperature and precipitation change, and scenario 7 was set to show the result of the combination of climatologic components. A doubling of atmospheric concentration is predicted to result in an maximum monthly flow increase of 11 percent. Non-linear impacts were predicted among precipitation change scenarios of -42, -17, 17, and 42 percent, which resulted in average annual flow changes in Daecheong Dam Basin of -55, -24, 25, and 64 percent. The changes in streamflow indicate that the Daecheong Dam Basin is very sensitive to potential future climate changes and that these changes could stimulate the increased period or severity of flood or drought events.

An impact assessment of climate and landuse change on water resources in the Han river.

As climate changes and abnormal climates have drawn research interest recently, many countries utilize the GCM, which is based on SRES suggested by IPCC, to obtain more accurate forecast for future climate changes. Especially, many research attempts have been made to simulate localized geographical characteristics by using RCM with the high resolution data globally. To evaluate the impacts of climate and landuse change on water resources in the Han-river basin, we carried out the procedure consisting of the CA-Markov Chain, the Multi-Regression equation using two independent variables of temperature and rainfall, the downscaling technique based on the RegCM3 RCM, and SLURP. From the CA-Markov Chain, the future landuse change is forecasted and the future NDVI is predicted by the Multi-Regression equation. Also, RegCM3 RCM 50 sets were generated by the downscaling technique based on the RegCM3 RCM provided by KMA. With them, 90 year runoff scenarios whose period is from 2001 to 2090 are simulated for the Han-river basin by SLURP. Finally, the 90-year simulated monthly runoffs are compared with the historical monthly runoffs for each dam in the basin. At Paldang dam, the runoffs in September show higher increase than the ones in August which is due to the change of rainfall pattern in future. Additionally, after exploring the impact of the climate change on the structure of water circulation, we find that water management will become more difficult by the changes in the water circulation factors such as precipitation, evaporation, transpiration, and runoff in the Han-river basin.

Hydraulic and Hydrologic Analysis by Washland Construction

최근에 홍수조절 기능과 비홍수기의 생태적 측면으로써 천변저류지에 대한 관심이 증가하고 있다. 따라서 본 연구에서는 지속가능한 홍수방어 대안으로 천변저류지 조성방안에 대한 검토와 조성된 천변저류지에 대한 습지로의 활용 가능성을 검토하기 위한 수리·수문 분석을 수행하였다. 대상지역은 경상남도 창녕군의 토평천 유역이다. 토평천 유역에 국내 최대 내륙 습지인 우포늪이 포함되어 있으며, 토평천은 낙동강의 지류이다. 천변저류지는 우포늪 상류와 하류에 조성하는 것으로 가정하였으며, 홍수기의 홍수위저감효과를 알아보기 위한 수리분석은 HEC-RAS모형을 이용하였다. 모형의 모의는 천변저류지 조성 시나리오 7가지에 대하여 수행하였다. 그 결과 모의 시나리오 중에서 최대 0.56 m의 홍수위가 감소하는 것으로 나타났다. 또한, SWAT모형을 이용하여 비홍수기에 천변저류지의 물수지 분석을 위한 수문분석을 수행하였으며, 물수지 분석 결과 1년 동안에 천변저류지의 최저수심이 1.3 m(세진지역)정도 유지되는 것을 알 수 있었다. 【Recently, we have a growing interest in the washland construction for the function of flood defense in flood season and also as an ecosystem in non flood season. Therefore this study performed the hydraulic and hydrologic analysis for washland construction plan as sustainable flood defense alternative in flood season and wetland application possibility. The study area is Topyoung-cheon basin in Changnyeong-gun, Gyeongnam. A Topyoung-cheon basin includes a Woopo wetland which is the largest nature wetland in Korea and a Topyoung-cheon is ond of the tributaries of Nakdong river. We assume that the artificial washland is constructed in upperstream and downstream of Woopo wetland, and In flood season, the hydraulic analysis for the investigation of the effectiveness of flood level mitigation is performed by HEC-RAS model. Simulation of model is performed from 7 scenarioes of washland construction. As the result in flood season, the flood level is reduced by maximum 0.56 meter as we construct the washlands by 7 scenarios. Also, we performed hydrologic analysis for the investigation of water balance in washland in non flood season using SWAT model. From the result of water balance analysis, we found that the minimum water level of washland was maintained in about 1.3 meter for one year.】

Multi-Dimensional Flood Damage Analysis (I): Principle and Procedure

최근 이상홍수로 인한 인명과 재산피해가 급격히 증가하여 홍수피해를 경감시키기 위한 치수사업의 필요성은 인식하고 있으나, 사업타당성을 정확하고 객관적으로 분석할 수 있는 경제성분석 방법이 미진한 실정이다. 본 연구는 기존의 치수경제성분석을 개선하기 위한 것으로 현행 국내에서 사용중인 치수경제성분석의 문제점을 파악하고 외국의 사례와 비교 분석하여 개선방향을 도출하고 이를 바탕으로 다차원 홍수피해산정방법(MD-FDA Multi-Dimensional Flood damage analysis)을 개발하였다 주된 내용은 예상피해지역의 자산조사를 통하여

Assessment of Flood Flow Conveyance for Urban Stream Using XP-SWMM

100\%

Plasma cleaning of carbon species for silicon homoepitaxial growth

피해규모를 산정하고, 침수심 조건에 따라 피해율을 적용하여 예상 홍수피해액을 계산하는 것이다. 여기에서, GIS와 연계하여 침수면적뿐만 아니라 침수심의 공간적 분포를 고려하여 피해액을 보다 정확하게 산정할 수 없다. 본 연구에서 개발한 다차원 흥수피해산정방법은 기존 방법에서 야기되었던 문제점을 개선하고 계속해서 업데이트되는 국가통계자료를 이용함으로써 보다 합리적이고 정확한 피해액을 산정할 수 있으리라 사료된다. 【Recently, the flood damages including losses of human lifes and property have been rapidly increased according to extreme floods. And we know that the flood control project is needed for diminishing flood damages. However, we have had the lacks in a reasonable methodology for the economic analysis of food control project. This study aims to improve the existing economic analysis method for flood control project. So, first of all, we understand the problems of existing economic analysis and investigate the methodologies of foreign countries. Based on that, the Multi-Dimensional Flood Damage Analysis(MD-FDA) is developed in this study. The survey of properties on the floodplain is conducted, then the damage rate obtained by evaluating the monetary values of surveyed property is applied, and the expected flood damage is calculated. Also by considering damage area in the floodplain as well as spatial distribution of inundated depth using GIS, the flood damages are evaluated more accurately than existing method. From the study, we know that the MD-FDA can improve the problems of existing method and evaluate the reasonable flood damages by using updated nation리 statistics.】

Assessment of Future Climate Change Impact on Groundwater recharge, Baseflow and Sediment in Steep Sloping Watershed

최근 급속한 도시화로 인한 유역 내 불투수 면적의 증가는 자연유역에 비해 짧은 도달시간과 높은 첨두 홍수량을 유발하여 도시홍수 피해의 원인이 되고 있다. 따라서 홍수피해를 저감시키고자 구조물적 또는 비구조물적 홍수방어 대책들을 마련하여 시행하고 있다. 본 연구의 대상유역인 굴포천 유역은 유역 내의 유출 특성이 아닌 하류의 한강 외수위 조건에 의해 잦은 침수 피해가 발생하고 있으며, 이를 예방하고자 폭 20m의 임시 방수로를 폭 80m로 확장할 예정이다. 이에 따라 본 연구에서는 대표적인 도시 유출 모형의 하나인 EPA의 SWMM 모형을 근간으로 하는 XP-SWMM모형을 이용해 굴포천 방수로 확장에 따른 홍수소통능력을 분석하였다. 재현기간 100년인 설계 강우와 동일한 조위 조건 하에서 개수전과 후에 대한 수위와 유량을 비교하였으며, 분석결과 개수전 상황이 개수후에 비해 통과 유량이 1/3임에도 불구하고 비슷하거나 더 높은 수위를 나타내었다. 또한 개수후 상태에서 모의한 결과 방수로 분기점에서 자연 분류시킬 경우 최고

Estimation of baseflow considering recession characteristics of hydrograph

300m^3/sec