• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1166-1171
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• 2006

Drought is defined by differently for the several scientific and technical fields such as hydrological drought, agricultural drought, meteorological drought, climatological drought, atmospheric drought. A lot of drought indices have been developed to quantify drought severity levels. However these drought indices might be expressed differently as the drought conditions for specific period because the drought severity level is using different types of data on each condition. It is necessary for development of quantative drought representation methods by drought index application. In this research, the reaction to the historical droughts is analyzed after estimation of PDSI, SPI and MSWSI(Modified Surface Water Supply Index) in south korean territory. Lastly the drought representation methods were examiner combining the drought indices by drought indices. The arithmetic mean drought indices that include PDSI, SPI, in yearly basis from 1971 to 2001 and MSWSI in yearly basis from 1974 to 2001 were estimated through the whole nation. The applicability of drought indices are examined based on the observed drought data for national and regional droughts. The result shows that PDSI, SPI(3), SPI(6), and MSWSI have proven to be sensitive enough to the historical drought. The correlation analysis of each drought index was conducted whether they could show the long and short term drought equally. The analysis of how appropriately represent for the historical drought was used for determining for the combined drought index. Consequently, PDSI, SPI(3), SPI(6), and MSWSI have been appeared as suitable indices for the development of quantitative drought representation methods. For the decision of weight on combining PDSI, SPI(3), SPI(6), and MSWSI, drought map was made for eighteen alternative to decide weight. The results showed that PDSI(20%), SPI(3)(60%), SPI(6)(10%), and MSWSI(10%) have been the most well matched weights. Using selected weights of each drought indices and by reconstructing the national mean drought severity on yearly basis, the fact that the year of historical drought is in accordance with the verified one for drought representation. In short, the acquired technique using combined drought index can be used for useful and believable quantitative method of drought analysis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.3
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• pp.291-302
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• 2024

Sustained meteorological drought can lead to hydrological drought, known as drought propagation. The propagated droughts cause more damage to the region than the non-propagated droughts. Recent studies on drought propagation have focused on identifying the lag time using correlation analysis. There is a lack of studies comparing damage patterns between propagated and non-propagated droughts. In this study, the overlap and pooling propagation between meteorological and hydrological droughts were analyzed using drought indices in Chungcheong Province to identify drought propagation, and the propagation characteristics such as pooling, attenuation, lag and extension were analyzed. The results showed that although Chungju-si experienced a meteorological drought in 2010, no damage was caused by the drought. However, a meteorological drought in 2017 and 2018 propagated into a hydrological drought of longer duration but less severity, resulting in drought-affected damage. Similarly, Cheongyang-gun experienced a meteorological drought in 2017, but no damage was reported from the drought. However, in the neighboring county of Buyeo-gun, a meteorological drought with a similar magnitude propagated to a hydrological drought during the same period, resulting in drought-affected damage. The overall results indicated that the damage from propagated drought events was more severe than the non-propagated drought events, and these results can be used as basic data for establishing drought response policies suitable for the region.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.3
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• pp.41-49
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• 2013

Drought risk assessment is usually performed qualitatively and quantitatively depending on the definition a drought. The meteorological drought indices have a limit of not being able to consider the hydrological components such as evapotranspiration, soil moisture and runoff, because it does not consider the water demand in paddies and water supply in reservoirs. Agricultural drought was defined as the reservoir storage shortage state that cannot satisfy water requirement from the paddy fields. The objectives of this study were to suggest improved agricultural drought risk assessment in order to evaluate of regional drought vulnerability and severity studied by using Reservoir Drought Index (RDI). The RDI is designed to simulate daily water balance between available water from agricultural reservoir and water requirement in paddies and is calculated with a frequency analysis of monthly water deficit based on water demand and water supply condition. The results indicated that RDI can be used to assess regional drought risk in agricultural perspective by comparing with the historical records of drought in 2012. It can be concluded that the RDI obtained good performance to reflect the historical drought events for both spatially and temporally. In addition, RDI is expected to contribute to determine the exact situation on the current drought condition for evaluating regional drought risk and to assist the effective drought-related decision making.

• KCID journal
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• v.1 no.2
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• pp.22-28
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• 1994

The calculation method for the Drought index based on the principal hydrological factors, such as precipitation, reservoir storage and river discharge, can estimate the duration and intensity of drought. It is not easy to establish an universal criteria o

• KCID journal
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• v.4 no.2
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• pp.48-61
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• 1997

Drought index calculation method using principal hydrological factors, such as precipitation amount and reservoir storage ratio, can estimate the duration and the intensity of drought. It is not easy to establish an universal criteria of drought, since th

• Atmosphere
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• v.22 no.2
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• pp.267-277
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• 2012

The objectives of this study are to develop a real-time drought monitoring and prediction system on the East Asia domain and to evaluate the performance of the system by using past historical drought records. The system is mainly composed of two parts: drought monitoring for providing current drought indices with meteorological and hydrological conditions; drought outlooks for suggesting future drought indices and future hydrometeorological conditions. Both parts represent the drought conditions on the East Asia domain (latitude $21.15{\sim}50.15^{\circ}$, longitude $104.40{\sim}149.65^{\circ}$), Korea domain (latitude $30.40{\sim}43.15^{\circ}$, longitude $118.65{\sim}135.65^{\circ}$) and South Korea domain (latitude $30.40{\sim}43.15^{\circ}$, longitude $118.65{\sim}135.65^{\circ}$), respectively. The observed meteorological data from ASOS (Automated Surface Observing System) and AWS (Automatic Weather System) of KMA (Korean Meteorological Administration) and model-driven hydrological data from LSM (Land Surface model) are used for the real-time drought monitoring, while the monthly and seasonal weather forecast information from UM (Unified Model) of KMA are utilized for drought outlooks. For the evaluation of the system, past historical drought records occurred in Korea are surveyed and are compared with the application results of the system. The results demonstrated that the selected drought indices such as KMA drought index, SPI (3), SPI (6), PDSI, SRI and SSI are reasonable, especially, the performance of SRI and SSI provides higher accuracy that the others.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3B
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• pp.253-264
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• 2011

Drought assessment is usually performed qualitatively and/or quantitatively after defining a drought from meteorological, agricultural, hydrological, and socioeconomic perspective. Most of the drought analyses focus on meteorological, agricultural, and hydrological droughts, whereas the socioeconomic drought evaluation has been not actively performed since it needs different aspects. In this study, after defining a socioeconomic drought applicable to assess droughts in Korea, we suggested Water Excess Deficiency Index (WEDI) as an useful tool to evaluate socioeconomic droughts, based on water demand condition and water supply condition. This study verified the validity of WEDI by comparing with other drought indices (SPI, PDSI) and historical drought condition in Gyeongsang-do in 2001. The results indicated that the WEDI can be used to assess regional droughts in a socioeconomic perspective.

• Journal of Korea Water Resources Association
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• v.50 no.11
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• pp.769-779
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• 2017

As the occurrence of drought is recently on the rise, the reliable drought forecasting is required for developing the drought mitigation and proactive management of water resources. This study developed a probabilistic hydrological drought forecasting method using the Bayesian Networks and drought propagation relationship to estimate future drought with the forecast uncertainty, named as the Propagated Bayesian Networks Drought Forecasting (PBNDF) model. The proposed PBNDF model was composed with 4 nodes of past, current, multi-model ensemble (MME) forecasted information and the drought propagation relationship. Using Palmer Hydrological Drought Index (PHDI), the PBNDF model was applied to forecast the hydrological drought condition at 10 gauging stations in Nakdong River basin. The receiver operating characteristics (ROC) curve analysis was applied to measure the forecast skill of the forecast mean values. The root mean squared error (RMSE) and skill score (SS) were employed to compare the forecast performance with previously developed forecast models (persistence forecast, Bayesian network drought forecast). We found that the forecast skill of PBNDF model showed better performance with low RMSE and high SS of 0.1~0.15. The overall results mean the PBNDF model had good potential in probabilistic drought forecasting.

• Atmosphere
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• v.23 no.1
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• pp.113-121
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• 2013

The objective of this study is to develop and evaluate the system to produce the real-time ensemble drought prediction data. Ensemble drought prediction consists of 3 processes (meteorological outlook using the multi-initial conditions, hydrological analysis and drought index calculation) therefore, more processing time and data is required than that of single member. For ensemble drought prediction, data process time is optimized and hardware of existing system is upgraded. Ensemble drought data is estimated for year 2012 and to evaluate the accuracy of drought prediction data by using ROC (Relative Operating Characteristics) analysis. We obtained 5 ensembles as optimal number and predicted drought condition for every tenth day i.e. 5th, 15th and 25th of each month. The drought indices used are SPI (Standard Precipitation Index), SRI (Standard Runoff Index), SSI (Standard Soil moisture Index). Drought conditions were determined based on results obtained for each ensemble member. Overall the results showed higher accuracy using ensemble members as compared to single. The ROC score of SRI and SSI showed significant improvement in drought period however SPI was higher in the demise period. The proposed ensemble drought prediction system can be contributed to drought forecasting techniques in Korea.

• Journal of Korea Water Resources Association
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• v.43 no.1
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• pp.15-24
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• 2010

Regional frequency analysis is often used to overcome the limitation of point frequency analysis to estimate probability rainfall depths. However, point frequency analysis is still used in drought analyses. This study proposed a practical method to categorize the homogeneous regions of drought characteristics for the analyses of regional characteristics of droughts in Korea. Using rainfall data from 58 observation stations managed by the Korea Meteorological Administration, this study calculated drought attributes, i.e., mean drought indices for various durations using the Standardized Precipitation Index (SPI) and drought severities expressed by durations, depth, and intensity. The drought attributes provided useful information for categorizing stations into the hydrological homogeneous regions. This study introduced a cluster analysis with K-means techniques to group observation stations. The cluster analysis grouped observation stations into 6 regions in Korea. The data in the hydrological homogeneous region would be used in spatial analysis of drought characteristics and drought regional frequency analysis.