• Journal of Korea Water Resources Association
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• v.47 no.5
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• pp.491-500
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• 2014

To estimate the severity of streamflow drought, this study introduced the concept of streamflow drought index based on threshold level method and Seomjingang Dam inflow was applied. Threshold levels used in this study are fixed, monthly and daily threshold, The $1^{st}{\sim}3^{rd}$ analysis results of annual drought, the severe hydrological droughts were occurred in 1984, 1988 and 1995 and the drought lasted for a long time. Annual compared to extreme values of total water deficit and duration, the drought occurred in 1984, 1988, 1995 and 2001 was serious level. In the results of study, because a fixed threshold level is not reflect seasonal variability, at least the threshold under seasonal level was required. Threshold levels determined by the monthly and daily were appropriate. The proposed methodology in this study can be used to forecast low-flow and determine reservoirs capacity.

• Journal of Wetlands Research
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• v.18 no.4
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• pp.432-447
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• 2016

The increased frequency of drought and flood due to climate change was a global problem. In particular, drought was recognized as a serious environmental, ecological, social, and economic disaster. Therefore, it is necessary to study the measures to prevent it. In this study, we will estimate the meteorological drought index in the Han River Basin and analyze the impact of climate change on drought. The change of the meteorological drought occurrence due to climate change in the Han River separated by the common drought and severe drought was analyzed using the Representative Concentration Pathways (RCPs) scenarios provided by the Intergovernmental Panel on Climate Change (IPCC). The years 1973 - 2010 were selected for analysis in the current period. Using the scenario, we separated the future period (Target I: 2011 - 2039, Target II: 2040 - 2069, Target III : 2070 - 2099). The number of occurrences of less than -1.0 and -1.5 standard precipitation index were analyzed by SPI 3, 6, 12. Looking at the results, trends in rainfall in the Han River was expected to increase from the current figures, the occurrence of drought is predicted to decline in the future. However, the number of drought occurrence was analyzed to increase toward long-term drought. The number of severe drought occurrences was usually larger than the common drought estimated. Additional studies may be considered in addition to the agricultural drought, hydrological drought, socio-economic drought. This will be done by using efficient water management. The results can be used as a basis for future drought analysis of the Han River.

• Journal of Korea Water Resources Association
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• v.41 no.10
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• pp.1045-1058
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• 2008

Drought is a natural phenomena caused by long time lack of precipitation causing varying damages in several regions which increases yearly. Specifically, in 1994$\sim$1995 and 2001 severe drought occurred in almost every region of Korea. Small and medium sized water supply reservoirs exposed their bottoms and also raised considerable economic losses. In spite of this fact, damages and impacts from the drought can still be minimized by well defined drought management plans with optimal management of water supply facilities. Throughout this research, integrated drought information system is proposed to used in monitoring the drought of Korea in real time. And the expert system for the management of water supply facilities has developed using Shared Vision Model (SVM) to enable the Virtual Drought Exercise (VDE). To find a better way to manage water during drought and to develop the enhanced abilities to respond to drought, virtual drought exercise is the most effective approach and process. The proposed process of virtual drought exercise using integrated drought information system can be used as an effective tool to prepare the optimal water supply plans during the drought.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.303-305
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• 2022

In Korea, due to the geographical and hydrological characteristics of the country, the water cycle has a large variation throughout the year. Therefore, in order to quickly identify and prepare for hydrological phenomena such as floods and droughts, the need for scientific water management incorporating the latest ICT technologies is growing. Accordingly, K-water operates a real-time Hydrological Data Acquisition and Processing System (HDAPS) that can check the situation of the site more intuitionally by linking the hydrological data collected in real time through satellite, GIS, and CCTV. and prepared for flood and drought. In this paper, we will introduce K-water's real-time hydrological information system and consider its application to protect people's lives and property.

• Journal of Environmental Science International
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• v.25 no.1
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• pp.99-105
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• 2016

In this paper, a groundwater hydrological study of the Gyeongju well during the Silla period is conducted to investigate how sufficiently the Gyeongju well supplied water demand at the time. It is assumed that the current geology and soil condition in Gyeongju remain similar to the Silla period. Also, the land use and land coverage during the Silla period is estimated based on the current land condition in Gyeongju. Precipitation during the Silla period is analyzed using precipitation data from 1984 to 2014 provided by Gyeonju weather station. Precipitation analysis is applied based on 3 different scenarios; precipitation intensity during the Silla period was Case (1) the same as, Case (2) 30% more, and Case (3) 30% less than the precipitation intensity of the last decade (2005~2014). Furthermore, to observe the use of the well in Gyeongju during droughts, the following condition(Case (4)) is also considered; ten year drought during the Silla period was the same as the ten year drought from 1984 to 2014. Available amount of groundwater development is analyzed using NRCS-CN method. The results show that the potential amount of groundwater in Gyeongju during Silla era was for Case (1) $62,825,272m^3/year$, Case (2) $93,606,567m^3/year$, Case (3) $32,277,298m^3/year$, and Case (4)$32,870,896m^3/year$. Also, it has been shown that $45,260,000m^3$ of groundwater were required to supply to all households in Gyeongju during Silla era. Therefore, if the precipitation intensity during Silla era was similar with the last decade, the groundwater would provide enough supply to all households in Gyeongju. However, in the case that the precipitation intensity during Silla era was 30% less than the last decade or a ten year drought happened, it is predicted that the water use in Gyeongju would have been limited.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.321-321
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• 2023

가뭄은 수개월 혹은 수년간 지속적이며, 점진적으로 광범위하게 피해를 미치는 자연재해이다. 강수 부족과 같은 비정상적 기상환경으로 인해 발생하는 기상학적 가뭄이 지속되어 토양 수분량 감소 및 식생에 영향을 미치는 농업적 가뭄을 발생시킬 수 있으며, 하천유출량 및 가용수자원이 감소하는 수문학적 가뭄으로까지 진행된다. 이처럼 분야별 가뭄이 장시간 지속됨에 따라 다른 종류의 가뭄을 발생시키는 현상을 가뭄 전이라고 하며, 가뭄이 전이되지 않은 비전이 사상보다 지역에 큰 피해를 야기한다. 최근 우리나라에서도 가뭄 전이와 관련된 연구들이 진행되고 있다. 하지만 기상학적, 농업적 및 수문학적 가뭄에 대한 가뭄 전이를 모두 고려하여 가뭄의 전이 및 비전이사상간의 피해 양상을 비교하는 연구는 부족한 실정이다. 따라서, 본 연구에서는 전국 단위의 시군구별 SPI(Standardized Precipitation Index), SGI(Standardized Groundwater level Index) 및 PHDI(Palmer Hydrological Drought Index)를 사용하여 각각 기상학적, 농업적 및 수문학적 가뭄을 판단하였다. 각 분야별 가뭄간의 시간적 중복여부를 통해 가뭄의 전이 여부를 판단하고, 가뭄의 전이 특성(풀링, 감쇠, 지체, 연장) 분석을 수행하였다. 또한, 가뭄 전이 사상과 비전이 사상이 발생한 시기의 가뭄 피해 관련 자료를 수집하여, 지역별 가뭄 전이 사상 및 비전이 사상간의 피해 양상을 비교 및 분석하였다. 과거 충청북도 충주시는 2011년의 기상학적 가뭄(비전이 사상) 발생시 피해 인구가 없었으나, 2019년의 기상학적 가뭄에서 수문학적 가뭄으로 전이가 발생하여 999명의 피해 인구가 발생하였다. 즉, 동일한 지역에서 다른 시기에 발생한 가뭄 피해 및 동일한 연도에서 인접한 지역의 가뭄 피해를 분석한 결과, 비전이된 가뭄 사상에 비해 전이된 가뭄 사상에서 더욱 큰 피해를 가지는 것을 확인하였다.

• Economic and Environmental Geology
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• v.54 no.6
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• pp.649-657
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• 2021

This paper aims to study the impact of natural disasters on per capita income in Vietnam both the short and long-term, specifically impact loss of income caused by the extreme drought 2013 for agriculture, forestry and fishery in Phu Yen Province, Central Vietnam. The study valued economic damage by applying the synthetic control method (SCM), which is a statistical method to evaluate the effect of an intervention (e.g. natural disasters) in different case studies. It estimates what would have happened to the treatment group if it had not received the treatment by constructing a weighted combination of control units (e.g. control provinces). The results showed that the 2013 drought caused a decrease in income per capita, mainly in the agriculture, forestry, and fishery sector in Phu Yen. The reduced income was estimated to be VND 160,000 (1 USD = 23,500 VND (2021)) for one person per month, accounting for 11% of total income per capita and continued to affect the income 6 years later. Therefore, authorities need to invest in preventive solutions such as early and accurate warnings to help people to be more proactive in disaster prevention.

• Journal of Korea Water Resources Association
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• v.56 no.11
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• pp.823-835
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• 2023

Recently, due to the increase in abnormal climate, rainfall intensity is increasing and drought periods are continuing. These environmental changes lead to prolonged drought conditions and difficulties in real-time recognition. In general, drought can be judged by the amount of precipitation and the number of days without rainfall. In determining the impact of drought, it is divided into meteorological drought, agricultural drought, and hydrological drought and evaluation is made using the drought index, but environmental drought evaluation is insufficient. The river water quality managed through the total water pollution cap system is vulnerable to the effects of such drought. In this study, we aim to determine the drought impact on river water quality and quantify the impact of prolonged drought on water quality. The impact of rain-free days and accumulated precipitation on river water quality was quantitatively evaluated. The Load Duration Curve (LDC), which is used to evaluate the water quality of rivers, was used to evaluate water pollution occurring at specific times. It has been observed that when the number of consecutive rainless days exceeds 14 days, the target water quality in the mid-basin is exceeded in over 60% of cases. The cumulative rainfall is set at 28 days as the criteria, with an annual average rainfall of 3%, which is 32.1 mm or less. It has been noted that changes in water quality in rivers occur when there are 14 or more rainless days and the cumulative rainfall over 28 days is 32.1 mm or less in the Gamcheon Mid-basin. Based on the results of this study, it aims to quantify the drought impact and contribute to the development of a drought water quality index for future environmental droughts.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.1
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• pp.155-163
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• 2019

The knowledge about drought propagation is very important in accurate estimation of hydrological drought characteristics and efficient development of early warning system. This study investigated a probabilistic relationship of drought propagation based on Bayesian network model for historic period and for future projection under climate change scenario RCP 8.5 over the Han River basin. The results revealed that the propagation rate and lag time have increasing and decreasing trends from the historic period of 1967-2013 to the future periods of 2014-2053 and 2054-2100 under climate change, respectively. The probabilistic results of Bayesian model revealed that the probability of occurrence of lag time varied spatially and decreased when the intensity of meteorological drought changed from moderate to severe and extreme condition during 1967-2013. The values of probability increased in the first future period of 2014-2053 in several sub-basins and slight decreased in the second period of 2054-2100. The proposed probabilistic results will be useful for the decision makers to develop related policies with an appropriate insight toward the future drought status.

• Journal of Korea Water Resources Association
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• v.35 no.4 s.129
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• pp.397-410
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• 2002

In order to quantitatively identify historical drought conditions and to evaluate their variability, drought indices commonly used. The calculation method for the drought index based on the principal hydrological factors, such as precipitation and reservoir storage, can estimate the duration and intensity of a drought. In this study the Palmer-type formula for drought index is derived for the Nakdong River basin by analyzing the monthly rainfall and meteorological data at 21 stations. The Palmer Drought Severity Index(PDSI) is used for dry land sectors to evaluate the meteorological anomaly in terms of an index which permits time and space comparisons of drought severity. The Surface Water Supply Index(SWSI) is devised for the use in conjunction with the Palmer index to provide an objective indicator of water supply conditions in Nakdong River basin. The SWSI was designed to quantify surface water supply capability of a watershed which depends on river and reservoir water The Standardized Precipitation Index(SPI) is evaluated for various time periods of 1 to 12 months in Nakdong River basin. For the purpose of comparison between drought indices correlation coefficient was calculated between indices and appropriate SPI time period was selected as 10 months for Nakdong River basin. A comparative study is made to evaluate the relative severity of the significant droughts occurred in Nakdong River basin since 1976. It turned out that $'94{\sim}'97$ drought was the worst drought in it's severity. It is found that drought indices are very useful tools in quantitatively evaluating the severity of a drought over a river basin.