• Journal of Climate Change Research
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• v.9 no.1
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• pp.31-45
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• 2018

This study implemented the prediction of drought properties (number of drought events, intensity, duration) using the user-oriented systematical procedures of downscaling climate change scenarios based the multiple global climate models (GCMs), AIMS (APCC Integrated Modeling Solution) program. The drought properties were defined and estimated with Effective Drought Index (EDI). The optimal 10 models among 29 GCMs were selected, by the estimation of the spatial and temporal reproducibility about the five climate change indices related with precipitation. In addition, Simple Quantile Mapping (SQM) as the downscaling technique is much better in describing the observed precipitation events than Spatial Disaggregation Quantile Delta Mapping (SDQDM). Even though the procedure was systematically applied, there are still limitations in describing the observed spatial precipitation properties well due to the offset of spatial variability in multi-model ensemble (MME) analysis. As a result, the farther into the future, the duration and the number of drought generation will be decreased, while the intensity of drought will be increased. Regionally, the drought at the central regions of the Korean Peninsula is expected to be mitigated, while that at the southern regions are expected to be severe.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.6
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• pp.3-13
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• 2006

Although the drought impacts are comparably not catastrophic, the results from the drought are fatal in various social and economical aspects. Different from other natural hazards including floods, drought advances slowly and spreads widely, so that the preparedness is quite important and effective to mitigate the impacts from drought. Soil moisture depletion directly resulted from rainfall shortage is highly related with drought, especially for crops and vegetations, therefore a drought can be evaluated using soil moisture conditions. In this study, SMI (Soil Moisture Index) was developed to measure a drought condition using soil moisture model and frequency analysis for return periods. Runs theory was applied to quantify the soil moisture depletions for the drought condition in terms of severity, magnitude and duration. In 1994, 1995, 2000, and 2001, Korea had experienced several severe droughts, so the SMI developed was applied to evaluate applicability in the mid-range hydrologic unit watershed scale. From the results, SMI demonstrated the drought conditions with a quite sensitive manner and can be used as an indicator to measure a drought condition.

• Journal of Environmental Science International
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• v.4 no.1
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• pp.1-12
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• 1995

The assessment for a degree of drought has been carried out based on the soil moisture index in Korea. The soil moisture index(Im) was calculated assuming of constant evapotranspiration until wilting point as Im = w2/wf $.$100. The soil moisture content(W2) at the final of a period is obtained from W2 : Pe + Wl - E, here the effective precipitation amount is Pe, evapotranspiration E, and the soil moisture content at the beginning of a period is Wl. The filed capacity(Wf), as a mean value of fine sandy loams, was reduced to 92 mm/ft when we accept the wilting point and the available soil moisture content of 42 mm/ft, respectively. The drought begins in Korea when the soil moisture index drops to less than 50%. The value coincides the isoline of 11 or more consecutive days without measureable precipitation. The soil moisture index frequently drops in the northern part of Youngnam area and Honam area so that both areas are well known as the areas of drought. Key word : Droughts, Soil Moisture Index.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.4
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• pp.65-74
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• 2017

North Korea is one of the high vulnerable countries facing the threat of natural disaster and has experienced more frequent disasters in recent years. These disasters have significantly led to food shortages and large reductions in crop yields. In 2015, both North Korean officials and international agencies had identified the extreme drought event, the worst in one hundred years according to the North Korean government. The objective of this study was an assessment of the extreme drought events in 2014~2015, and to apply climatic drought indices for drought monitoring in North Korea. Characteristics of the extreme drought in North Korea are examined by using the weekly-based Standardized Precipitation Evapotranspiration Index (SPEI). The drought characteristics illustrated by the SPEI results are compared with a Standardized Precipitation Index (SPI) results and drought impact information to understand how these indices can explain the drought conditions within the country. These results demonstrated that the SPEI could be an effective tool to provide improved spatial and temporal drought conditions to inform management decisions for drought policy.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1775-1779
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• 2010

최근의 지구온난화에 따른 기후변화로 인하여 홍수와 가뭄과 같은 극한 사상의 발생 빈도가 증가하고 있는 추세이다. 특히, 가뭄은 장기간에 걸쳐 피해를 유발시키는 대표적인 자연재해 중의 하나이다. 따라서 본 연구에서는 가뭄의 크기와 정도를 정량화 할 수 있는 가뭄빈도해석을 수행하였다. 가뭄빈도해석을 위하여 우리나라의 61개 지점을 대상으로 EDI 가뭄지수를 산정하였다. 일별로 산정된 EDI 지수를 이용하여 연도별로 최저값을 추출하였다. 추출된 EDI 자료를 이용하여 빈도해석을 수행하였다. 빈도해석은 복합 확률 분포형 등의 장점을 갖고 있는 경계핵밀도함수를 이용하여 수행하였다. 분석 결과에서 재현기간 5년 내지 10년에서 극단적으로 건조함을 나타내는 가뭄지수인 -2.0 이하의 값을 갖는 것으로 나타났다. 따라서 가뭄은 평균적으로 재현기간 5년에서 10년 사이에 반복적으로 발생할 수 있다. 그러므로 가뭄에 대한 지속적인 모니터링 시스템의 구축과 가뭄피해를 최소화 할 수 있도록 해야 한다.

• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.5
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• pp.95-105
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• 2021

Drought is a disaster that causes prolonged and wide scale damage. Recently, the severity and frequency of drought occurrences, and drought damage have been increased significantly due to climate change. As a result, a quantitative study of drought factors is needed to better understand and prevent future droughts. In the case of agricultural drought, several existing studies examine the economic damage caused by droughts and their causes, but these studies are not well suited to estimating crop-oriented agricultural drought damage and the factors that absolutely affect agricultural drought. This study determines which factors most affect agricultural drought. It examines meteorological factors and those related to agricultural water supplied by irrigation facilities. Rice paddy production per unit area is lower than the average from the last two years where agricultural drought occurred. We compare the relative frequency of agricultural drought impacts with irrigation facilities, effective reservoir storage, the number of water supply facilities, and the meteorological drought index such as Standardized Precipitation Index (SPI). To identify factors that affect agricultural drought, we correlate rice paddy production anomalies with irrigation water supply for the past two years. There was a high positive correlation between rice paddy production and irrigation water usage, and there was a low or moderate negative correlation between rice paddy production anomalies compared to the average of the past two years and SPI. As a result, agricultural water supply by irrigation facilities was judged to be more influential than meteorological factors in rice paddy production. This study is expected to help local governments establish policies related to agricultural drought response.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.158-158
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• 2018

Drought is a recurrent natural hazard in Bangladesh. It has significant impacts on agriculture, environment, and society. Well-timed information on the onset, extent, intensity, duration, and impacts of drought can mitigate the potential drought-related losses. Thus, drought characteristics need to be explained in terms of frequency, severity, and duration. This paper aims to characterize the spatial and temporal pattern of meteorological drought using EDI and illustrated drought severity over Bangladesh. Twenty-seven (27) station-based daily rainfall data for the study period of 1981-2015 were used to calculate the EDI values over Bangladesh. The evaluation of EDI is conducted for 4 sub-regions over the country to confirm the historical drought record-developed at the regional scale. The finding shows that on average, the frequency of severe to extreme drought is approximately 0.7 events per year. As a result of the regional analysis, most of the recorded historical drought events were successfully detected during the study period. Additionally, the seasonal analysis showed that the extreme droughts were frequently hit in northwestern, middle portion of the eastern and small portion of central parts of Bangladesh during the Kharif(wet) and Rabi(dry) seasons. The severe drought was affected recurrently in the central and northern regions of the country during all cropping seasons. The study also points out that the northern, south-western and central regions in Bangladesh are comparatively vulnerable to both extreme and severe drought event. The study showed that EDI would be a useful tool to identify the drought-prone area and time and potentially applicable to the climate change-induced drought evolution monitoring at regional to the national level in Bangladesh. The outcome of the present study can be used in taking anticipatory strategies to mitigate the drought damages on agricultural production as well as human sufferings in drought-prone areas of Bangladesh.

• Journal of The Korean Society of Agricultural Engineers
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• v.61 no.3
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• pp.77-88
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• 2019

Drought is the recurrent natural disasters which harshly affect agricultural production and society in various parts in Bangladesh. Information on the spatiotemporal variability of drought events plays a vital role to take necessary action towards drought mitigation and sustainable development. This study aims to analyze the spatial and temporal variation of meteorological drought in Bangladesh during 1981-2015 using Effective Drought Index (EDI). Monthly precipitation data for 36 years (1980-2015) were obtained from 27 meteorological stations. Drought frequency (DF) and areal extent of drought were considered to investigate the spatiotemporal structure of drought. The DF analysis showed that the northern, southwestern and central regions of the country are comparatively vulnerable to meteorological drought. The frequency of drought in all categories has considerably increased during the recent five years from 2011 to 2015. Furthermore, the most significant increasing trend of the drought-affected area was found over the central region especially for pre-monsoon (March-May) season during this period while the decreasing trend of the affected area was found within the eastern region during the study period. To prevent and mitigate the damages of drought disasters in Bangladesh, agricultural and government managers should pay more attention to those regional drought events that occur in pre-monsoon season. The outcome of the present study can be used as explanatory data in building the strategies to drought monitoring and mitigation activities in Bangladesh.

• Atmosphere
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• v.18 no.4
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• pp.249-266
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• 2008

The tendencies for teleconnection with a time lag and other characteristics of Korean summer droughts have been investigated and some clues to predict the drought occurrences several months before have been found. First, the May and June droughts in Korea are simultaneous with those over the northwestern part of Korea owing to the relation with the baroclinic wave. However, the July and August droughts occur over the mid-latitudes or southern part of Korea owing to the relation with the Changma front. Second, several months before the MJJA droughts in Korea, it is found that the effective drought index (EDI) over particular areas (hereafter, referred to as the omen areas) is large. Thailand, Carolina Island, Mongolia, and Central Bengal Bay were selected as the omen areas. Third, when the monthly minimum EDI (MME) of the omen area in winter is more than 0.7, it signifies that the precipitation is above normal, Korea has almost always experienced a summer drought. However, the droughts occurring with this type of relationship only represent half of the MJJA droughts in Korea. Fourth, the relationships between the Korean drought and the precipitation over omen areas in low latitudes are not valid over all the eight precipitation areas in Korea, but only over Areas I, II, and III, where heavy rains occur during spring and summer.

• Journal of Ecology and Environment
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• v.44 no.3
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• pp.115-125
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• 2020

Background: The phenomenon of tree dieback in forest ecosystems around the world, which is known to be associated with high temperatures that occur simultaneously with drought, has received much attention. Korea is experiencing a rapid rise in temperature relative to other regions. Particularly in the growth of evergreen conifers, temperature increases in winter and spring can have great influence. In recent years, there have been reports of group dieback of Pinus densiflora trees in Korea, and many studies are being conducted to identify the causes. However, research on techniques to diagnose and monitor drought stress in forest ecosystems on local and regional scales has been lacking. Results: In this study, we developed and evaluated an index to identify drought and high-temperature vulnerability in Pinus densiflora forests. We found the Drought Stress Index (DSI) that we developed to be effective in generally assessing the drought-reactive physiology of trees. During 2001-2016, in Korea, we refined the index and produced DSI data from a 1 × 1-km unit grid spanning the entire country. We found that the DSI data correlated with the event data of Pinus densiflora mass dieback compiled in this study. The average DSI value at times of occurrence of Pinus densiflora group dieback was 0.6, which was notably higher than during times of nonoccurrence. Conclusions: Our combination of the Standard Precipitation Index and growing degree days evolved and short- and long-term effects into a new index by which we found meaningful results using dieback event data. Topographical and biological factors and climate data should be considered to improve the DSI. This study serves as the first step in developing an even more robust index to monitor the vulnerability of forest ecosystems in Korea.