• Journal of Korea Water Resources Association
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• v.45 no.10
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• pp.1043-1050
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• 2012

In this study, drought Severity-affected Area-drought Duration (SAD) curves are analyzed in order to examine temporal and spatial behavior of drought. A copulas-based joint drought index which is studied recently is applied to express the severity of drought. JDIs across the country with 60 points are calculated monthly basis, and using EOF and Kriging techniques, locational JDIs are spatially extended into gridbased JDIs with spatial resolution of $10{\times}10$ km. JDIs by lattice is analyzed by drought duration and by affected area, and JDI-based SAD curves are created to represent Korean historical drought events. Though created curves, drought events that occurred in the past in our country can be spatially and temporally characterized. In addition, curves are expected to contribute to determine the exact situation on the current drought condition have an impact to some extent.

• KCID journal
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• v.13 no.1
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• pp.72-81
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• 2006

The objictive of this study is to analyze regional drought using agricultural drought indicator. Toforecast and evaluate the drought, the drought indices for agriculture were applied. In the present drought preparedness plans of Ministry of Agriculture and Forestry (MAF), it is prescribed that the preparedness levels should be classified by considering the precipitation, reservoir storage, soil moisture in paddy and upland, and the growing status of crops. There are many drought index to analyze and evaluate the drought. However, these indices do not exactly explain all drought events. Thus, we select 4 drought indices to evaluate agricultural drought:reservoir storage index, 3-month delayed SPI, mean rainfall index, and dry day index. Using these ineices, six drought stages are classified. The results show that agricultural drought could be apprppriately analyzed and evaluated by agricultural drought stage and four drought indices.

• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.5
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• pp.1-11
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• 2021

Soil moisture plays a critical role in hydrological processes, land-atmosphere interactions and climate variability. It can limit vegetation growth as well as infiltration of rainfall and therefore very important for agriculture sector and food protection. Recently, due to the increased damage from drought caused by climate change, there is a frequent occurrence of shortage of agricultural water, making it difficult to supply and manage stable agricultural water. Efficient water management is necessary to reduce drought damage, and soil moisture management is important in case of upland crops. In this study, soil moisture was calculated based on the water balance model, and the suitability of soil moisture data was verified through the application. The regional soil moisture was calculated based on the meteorological data collected by the meteorological station, and applied the Runs theory. We analyzed the spatiotemporal variability of soil moisture and drought impacts, and analyzed the correlation between actual drought impacts and drought damage through correlation analysis of Standardized Precipitation Index (SPI). The soil moisture steadily decreased and increased until the rainy season, while the drought size steadily increased and decreased until the rainy season. The regional magnitude of the drought was large in Gyeonggi-do and Gyeongsang-do, and in winter, severe drought occurred in areas of Gangwon-do. As a result of comparative analysis with actual drought events, it was confirmed that there is a high correlation with SPI by each time scale drought events with a correlation coefficient.

• Journal of Korea Water Resources Association
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• v.49 no.3
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• pp.217-225
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• 2016

The drought is generally characterized by duration and severity, thus it is required to conduct the bivariate frequency analysis simultaneously considering the drought duration and severity. However, since a bivariate joint probability distribution function (JPDF) has a 3-dimensional space, it is difficult to interpret the results in practice. In order to suggest the technical solution, this study employed copula functions to estimate an JPDF, then developed conditional JPDFs on various drought durations and estimated the critical severity corresponding to non-exceedance probability. Based on the historical severe drought events, the hydrologic risks were investigated for various extreme droughts with 95% non-exceedance probability. For the drought events with 10-month duration, the most hazardous areas were decided to Gwangju, Inje, and Uljin, which have 1.3-2.0 times higher drought occurrence probabilities compared with the national average. In addition, it was observed that southern regions were much higher drought prone areas than northern and central areas.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.6
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• pp.89-97
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• 2010

In this study, the impact of climate change on the spatio-temporal behavior of extreme drought events is investigated by comparing drought severity-area-duration curves under present and future climate conditions. In our climate-change impact experiments, the future climate is based on two GCMs(CGCM3.1-T63 and CSIRO-MK3.0). As a result, in the case of CGCM3.1-T63 future drought events are similar to the present, but in the case of CSIRO-MK3.0 future drought risk is likely to increase. Such results indicate that a climate change vulnerability assessment for present water resources supply system is urgent.

• 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.

• Proceedings of the KSRS Conference
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• v.2
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• pp.563-566
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• 2006

In order for the evaluation and analysis of the spring drought which has been periodically occurring in Korean peninsula since 2000, the use of satellite image data is increasing to investigate temporal and spatial characteristics of the drought areas. The recent spring droughts in south Korea have some characteristics. It last for short period in spring when the activity of vegetation is not lively and it have large areal deviation in the severity of drought. In this study, considering the characteristics of the spring drought in Korean peninsular, the MODIS satellite image data which has superior spatial and radiometric resolutions was used for the analysis of the spring drought. In two basins having different spatial characteristics, the drought events were selected and their severities were analyzed using the MODIS NDVI, LSWI, and daily rainfall data since 2000, and the spatial characteristics of the drought area were analyzed using the DEM, land cover, and digital forest map of the study areas.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.124-124
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• 2020

This study proposes a framework to evaluate extreme drought using the natural drought index and hot spot analysis. The study area was South Korea. Data were used from 59 automatic synoptic observing system stations. The variable infiltration capacity model was used for the period from 1981 to 2016. The natural drought index was constructed from precipitation, runoff and soil moisture data, which reflect the water cycle. The average interval, duration and severity of extreme drought events were determined following Run theory. The most extreme drought period occurred in 2014-2016, with 46 of 59 weather stations exhibition drought conditions and 78% exhibition extreme drought conditions. The Inje and Seosan station exhibited the longest drought duration of 6 months, and the most severe drought was 5 times higher than the extreme drought severity threshold. The hot spot analysis was used to explore the extreme drought conditions and showed an increasing trend in the middle and northeastern parts of South Korea. Overall, this study provides water resource managers with essential information about locations and significant trends of extreme drought.

• Journal of Korea Water Resources Association
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• v.39 no.4 s.165
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• pp.373-382
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• 2006

In this study a theoretical drought severity-duration-frequency analysis is performed based on a simple Rectangular Pulses Poisson Process Model(RPPM). Data set with various durations are prepared for a given truncation level, whose statistics are then derived to be used for parameter estimation. These parameters are then used for the theoretical drought severity-duration-frequency analysis. The analysis is considered for two cases; one is to consider the overlap probability and the other is not. The drought severity of considering the overlap probability increases more as the return period increases. However, the overlap probability itself decreases as the duration increases, which is because the occurrence probability of events decreases as the duration increases. Also, if the duration increases, the events rarely or even not occur, since parameters of the model cannot be estimated in those cases, so the drought severity may not be computed. This is an obvious limitation of the simple RPPM. In this study the return periods of the important drought events occurred in Seoul are estimated using the results of the study. If the return period of an event is assumed to be the longest one among those with various durations, the return periods of some important event in Seoul are estimated to be between 14 and 35 years. These return periods are not so long to indicate that these droughts can occur frequently.