• Journal of Korea Water Resources Association
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• v.50 no.10
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• pp.691-701
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• 2017

The objective of this study is to evaluate the long-term drought outlook information based on long-term forecast data for the 2015 drought event. In order to estimate the Standardized Precipitation Index (SPI) for different durations (3-, 6-, 9-, 12-months), we used the observation precipitation of 59 Automated Synoptic Observing System (ASOS) sites, forecast and hindcast data of GloSea5. The Receiver Operating Characteristic (ROC) analysis and statistical analysis (Correlation Coefficient, CC; Root Mean Square Error, RMSE) were used to evaluate the utilization of drought outlook information for the forecast lead-times (1~6months). As a result of ROC analysis, ROC scores of SPI(3), SPI(6), SPI(9) and SPI(12) were estimated to be over 0.70 until the 2-, 3-, 4- and 5-months. The CC and RMSE values of SPI(3), SPI(6), SPI(9) and SPI(12) for forecast lead-time were estimated as (0.60, 0.87), (0.72, 0.95), (0.75, 0.95) and (0.77, 0.89) until the 2-, 4-, 5- and 6-months respectively.

• Journal of Korean Society on Water Environment
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• v.29 no.1
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• pp.88-96
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• 2013

Much attention has been needed in water resource management at the watershed due to drought and flooding issues caused by climate change in recent years. Increase in air temperature and changes in precipitation patterns due to climate change are affecting hydrologic cycles, such as evaporation and soil moisture. Thus, these phenomena result in increased runoff at the watershed. The Soil and Water Assessment Tool (SWAT) model has been used to evaluate rainfall-runoff at the watershed reflecting effects on hydrology of various weather data such as rainfall, temperature, humidity, solar radiation, wind speed. For bias-correction of RCP data, at least 30 year data are needed. However, for most gaging stations, only precipitation data have been recorded and very little stations have recorded other weather data. In addition, the RCP scenario does not provide all weather data for the SWAT model. In this study, two scenarios were made to evaluate whether it would be possible to estimate streamflow using measured precipitation and long-term average values of other weather data required for running the SWAT. With measured long-term weather data (scenario 1) and with long-term average values of weather data except precipitation (scenario 2), the estimate streamflow values were almost the same with NSE value of 0.99. Increase/decrease by ${\pm}2%$, ${\pm}4%$ in temperature and humidity data did not affect streamflow. Thus, the RCP precipitation data for Hongcheon watershed were bias-corrected with measured long-term precipitation data to evaluate effects of climate change on streamflow. The results revealed that estimated streamflow for 2055s was the greatest among data for 2025s, 2055s, and 2085s. However, estimated streamflow for 2085s decreased by 9%. In addition, streamflow for Spring would be expected to increase compared with current data and streamflow for Summer will be decreased with RCP data. The results obtained in this study indicate that the streamflow could be estimated with long-term precipitation data only and effects of climate change could be evaluated using precipitation data as shown in this study.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.698-701
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• 2007

지하수 개발가능량 산정을 위한 함양량의 평가는 수문계의 물리적인 형태나 함수층의 수리성 분석 및 수직인 지질분포를 파악하여 어떤 조건하에서 물이 유입 유출되는가를 파악한 후에만 가능하다. 또한 지하수계의 물리적인 형태를 이해함으로써 조사지역의 지표수계나 지하수계의 양계를 통해서 흐르는 물의 양을 결정짓는 물수지 분석이 수행되어야 한다. 이에 따라 강수량, 증발산량, 지하수 유출량, 지표유출량 그리고 하천유출량 등을 수문학적으로 고려해야만 한다. 본 연구는 지표수-지하수 결합모형을 도입하여 분포형 지하수 함양량의 시공간적인 변동성을 파악하는 데 그 목적이 있다. 이를 위해 지표수-지하수 결합모형인 SWAT-K모형을 미호천 유역에 적용하였으며, 지표수의 총유출량과 지하수위의 공간분포자료를 이용하여 검정과 검증을 수행하였다. 전체유역에 대한 연평균 함양량은 수문총량의 약 19%인 것으로 나타났다. 1999년${\sim}$2004년까지의 소유역별 연간 함양량 결과를 월별로 나타냈으며, HRU(Hydrologic Response Unit)별 함양량의 공간분포를 통해 월별, 계절별 특성을 살펴볼 수 있었다. 소유역 모두 강수가 집중하는 7-9월에 걸쳐 많은 함양이 이루어지며 $1{\sim}3$월에는 상대적으로 함양이 적은 것을 볼 수 있다. 월함양량의 경우 최대 약200mm범위내에서 유역의 토지이용 및 토양특성, 경사등에 따라 매우 비균질하게 분포하는 것을 확인할 수 있었다. 이와같은 함양량의 시공간적 불균일성으로 인해 지하수 관리방안은 소유역별 함양특성을 반영해야 할 것으로 판단된다.의 종분산지수가 일반적인 자연대수층에 비해 9.1배 정도 높다는 것을 의미한다. 이는 시험대수층의 투수성이 매우 높아 염소이온의 용질이송이 매우 빠르게 발생되었기 때문이다. 본 연구에서 추정된 종분산지수를 Gelhar et al.(1992)의 연구 결과와 비교 분석한 결과에서도 시험규모에 비해 매우 높은 수리분산이 발생된 것으로 나타났다. 그리고 염소이온의 확산면적을 추정하기 위해, 수렴흐름 추적자시험에 의한 종분산지수와 시험대수층의 평균선형유속을 이용하여 종분산계수를 구하였다. 현장에서 수행된 양수시험에 의한 평균선형유속 22.44 m/day와 평균 종분산지수 0.4155 m를 적용하여 산정된 종분산계수는 $9.32\;m^2/day$이었다. 따라서, 시험부지 내 충적층에서 일정한 양수율$(2,500\;m^3/day)$로 지하수를 개발할 시에 양수정 주변지역으로 유입되는 염소이온의 확산면적은 1일 $9.32\;m^2$ 정도일 것으로 나타났다.적인 $OH{\cdot}$ 의 생성은 ascorbate가 조직손상에 관여할 가능성을 시사하였다.었다. 정확한 예측치를 얻기 위하여 불균질 조직이 조사야에 포함되는 경우 보정이 요구되며, 골반의 경우 골 조직의 보정이 중요한 요인임을 알 수 있었다. 이를 위하여 불균질 조직에 대한 정확한 정보가 요구되며, 이는 CT 영상을 이용하는 것이 크게 도움이 되리라 생각된다.전시 슬러지층과 상등액의 온도차를 측정하여 대사열량의 발생량을 측정하고 슬러지의 활성을 측정할 수 있는 방법을 개발하였다.enin과 Rhaponticin

• Journal of Korea Water Resources Association
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• v.30 no.4
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• pp.317-326
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• 1997

The Palmer Drought Severity Index has been ectensively used to quantitatively evaluate the drought severity at a location for both agricultural and water resources management purposes. In the present study the Palmer-type formula for drought index is drived for the whole country by analyzing the monthly rainfall and meteorological data at nine stations with a long period of records. The formula is then used to compute the monthly drought severity index at sixty-eight rainfall stations located throughout the country. For the past five significant drought periods the spatial variation of each drought is shown as a nationwide drought index map of a specified duration from which the relative severity of drought throughout the country is identifiable for a specific drought period. A comparative study is made to evaluate the relative severity of the significant droughts occurred in Korea since 1960's. It turned out that '94-'95 drought was one of the worst both in the areal extent and drought severity. It is found that the Palmer-type formula is a very useful tool in quantitatively evaluating the severity of drought over an area as well as at a point. When rainfall and meteorological forecast become feasible on a long-term basis the method could also be utilized as a tool for drought forecasting.

• Journal of the Korean association of regional geographers
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• v.22 no.1
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• pp.240-250
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• 2016

Monitoring for water quantity and quality was conducted in this study for 2 years (2012~2013) in Oenam Stream which is a tributary of Seomjin River and upstream of Juam Lake. Suspended solid and total phosphorous(TP) were monitored and analyzed, then water quantity and quality as well as their relation with landuses were identified based on the previous study. Flow showed the similar pattern with precipitation but some discrepancies existed due to the distance between weather station(Gwangju) and study area. Watershed was modeled based on observed data using SWAT(Soil and Water Assessment Tool). Model calibration was conducted using data obtained in 2012 and validation was conducted using data in 2013. The coefficient of determination ($R^2$) between observed and modeled showed 0.6644 and 0.5176 for flow and TP, respectively for model calibration period. For validation period, $R^2$ was 0.7529 for flow and 0.7057 for TP, which were higher than calibration period. Hot spots were determined for watershed management by analyzing the amount of sediment and TP outcome from each sub-watershed. TP loading by landuse determined that cropland, of which the area takes only 5% from entire watershed, generated 53.6% of TP and residential and cowshed was responsible for 23.5% of TP loading.

• Journal of the Korean Association of Geographic Information Studies
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• v.19 no.2
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• pp.14-26
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• 2016

This study analyzed the correlation between the standardized precipitation index(SPI) and forest fire occurrences using monthly accumulative rainfall data since 1970 and regional fire occurrence data since 1991. To understand the relationship between the SPI and forest fire occurrences, the correlations among the SPI of nine main observatory weather stations including Seoul, number of fire occurrences, and log of fire occurrences were analyzed. We analyzed the correlation of SPI with fire occurrences in the 1990s and 2000s and found that in the 1990s, the SPI of 3 months showed high correlation in Gyeonggi, Gangwon, and Chungnam, while the SPI of 6 months showed high correlation in Chungbuk, and the SPI of 12 months showed high correlation in Gyeongnam, Gyenongbuk, Jeonnam, and Jeonbuk. In the 2000s, the SPI of 6 months showed high correlation with the fire frequency in Gyeonggi, Chungnam, Chungbuk, Jeonnam, and Jeonbuk, whereas the fire frequency in western Gangwon was highly correlated with the SPI of 3 months and, in eastern Gangwon, Gyeongnam, and Gyenongbuk, with the SPI of 1 month. In the 1990s, distinct differences in the drought condition between the SPI of 3 months and 12 months in the northern and southern regions of Korean Peninsula were found, whereas the differences in both the SPI of 1 month and 6 months were found in the Baekdudaegan region except western Gangwon since the 2000s. Therefore, this study suggests that we can develop a model to predict forest fire occurrences by applying the SPI of 1-month and 6-month data in the future.

• Journal of Korea Water Resources Association
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• v.48 no.6
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• pp.463-477
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• 2015

The recent unusual climate and extreme weather events have frequently given unexpected disaster and damages, facing difficulties in the management of water resources. In particular, climate change could result in intensified typhoons, and this would be the worst case scenario that can happen. The primary objective of this study is to identify the patterns of typhoon-induced precipitation and the associated synoptic pattern. This study focused on analyzing precipitation patterns over the South Korea using historic records as opposed to a specified season or duration, and further investigates the potential connection with heavy rainfall to synoptic patterns. In this study, we used the best track data provided by the Regional Specialized Meteorological Center of Japan for 40 years from 1973 to 2012. The patterns of the typhoon-induced precipitation were categorized into four groups according to a given typhoon track information, and then the associated synoptic climatology patterns were further investigated. The results demonstrate that the typhoon-induced precipitation patterns could be grouped and potentially simulated according to the identified synoptic patterns. Our future work will focus on developing a short-term forecasting model of typhoon-induced precipitation considering the identified climate patterns as inputs.

• Journal of Korea Water Resources Association
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• v.43 no.3
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• pp.309-323
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• 2010

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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3469-3476
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• 2015

The Korea Academia-Industrial cooperation Society. The Korea Academia-Industrial cooperation Society. In Korea, the territory has east high west low type and the rainfall is concentrated in the summer season. A nation having these topography and precipitation condition like Korea has to basically needs support of hardware alternatives. However, the right places decrease gradually and the resistance of the public opinion for national water resources policy stiffens gradually. The climate change has an effect in water resources fields and has a close relation. In the present study, therefore, future inflow of Miryang multipurpose dam basin is estimated by using SWAT model applied RCP 4.5 and 8.5 scenarios of "Korea Meteorological Administration" and considering the results, the future direction is purposed to operate the dam. As a result, the rainfall pattern is changed from traditional peak form to flat form. The dam operation rule in accordance with changing precipitation pattern has to be modified from the conventional operation rule and a new plan has to be established to meet a situation.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.608-608
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• 2012

현재 기후변화의 기상변동성이 커짐에 따라 태풍 및 집중호우 등의 이상기후 현상이 전 지구상에 걸쳐 광역적으로 나타나고 있다. IPCC에서는 이러한 기후변화가 기온 상승에 따른 증발산량의 증가, 강수량 및 유출량의 시공간적 분포의 변동 등을 초래하여 수자원의 효율적 관리 및 안정적인 공급에 어려움을 증대시킬 것으로 전망하였다. 뿐만 아니라 현재 국내 전반에 걸쳐 4대강 사업이 진행되고 있고, 낙동강에서도 낙동강 살리기 사업이 실시되어 주변 지형들의 변화가 진행되고 있다. 이러한 지형의 변화는 현재까지 구축되어 있는 기존자료의 대폭적인 변화를 의미하므로 홍수관련 연구결과에도 변화를 의미하고 있다. 이에 따라 4대강 사업 이후의 기후 변화에 따른 낙동강유역에서의 유출량의 증가를 분석하여 극한홍수의 발생가능성을 제시하고 이러한 극한홍수발생에 따른 위험지역도 과거에 의해 변경될 것으로 판단되어 국내외적으로 하천의 수리검토에 널리 사용되고 있는 1차원 수리해석 프로그램인 FLDWAV를 이용하여 취약지점을 분석하고 위험도를 분석하고자 한다. 낙동강 살리기 사업으로 낙동강에 건설된 8개의 보를 고려한 본류 및 지류에서의 제내지 및 제외지 지형데이터를 구축하고 구축된 자료을 이용해 낙동강 본류 및 지류에 대해서 극한홍수시 200년 빈도, 500년 빈도 홍수량 및 홍수위를 FLDWAV를 통해 정상류로 계산해서 예측하고 500년 빈도 홍수량과 홍수위를 부정류로 계산하여 제방고와 홍수위를 비교하여 범람위험지역을 선정하였다. 그리고 그 결과를 통해 GIS를 통하여 범람위험지역 제내지의 주요도심 구간 포함, 범람 범위를 분석함과 동시에 극한홍수에 따른 도심구간, 비도시구간 등의 범람범위를 분석하였다. 또한 선정한 범람위험지역의 범람 피해규모를 산정하고 피해범위의 현황을 파악하였다. 연구의 결과는 다음과 같이 나타났다. 500년 빈도 홍수시 범람위험지역은 낙동강 본류의 하류부에서 각각 154.7km, 123.2km, 12.9km에 위치한 지점이 선정되었으며 각 지점의 피해규모는 제내지에 범람된 유출량의 수위는 각각 21.7m, 24.3m, 2.11m로 계산되었고 이때의 피해면적은 각각 $2.68km^2$, $2.64km^2$, $1.25km^2$로 나타났다. 이 결과는 기후변화로 인한 극한홍수 발생 가능성과 취약지점의 분석을 통한 지역의 홍수피해 저감과 정책개발에 기본 자료로 활용될 것이며 낙동강 살리기 사업으로 인한 하천주변 지형의 변화를 제공함으로서 앞으로 진행될 연구의 기본 자료로서 이용가능 할 것으로 판단된다. 또한 이전의 홍수방어계획을 개선한 새로운 홍수방어계획의 수립을 통하여 향후 발생될 홍수의 예방 및 대응방안 수립의 참고자료로 이용될 것이며 제내지 및 제외지의 공간확보 연구를 통해 해당 지자체의 토지매수계획의 참고자료로 이용 가능할 것으로 기대된다.