• 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.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.248-248
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• 2017

최근 가뭄 모니터링을 위해 과거에 비하여 고해상도의, 물리적으로 기반을 두는 정보가 요구되고 있다. 기존에 주로 활용하고 있는 통계적 방법론 기반의 가뭄지수들은 지니고 있는 한계에 대해 여러 개선과정을 거치고 있으나, 기상변수로부터 지표상의 식생 관련 변수로의 전파 과정에 대한 개별 통계적 가뭄지수 간의 관계 설명이 매우 어렵다. 이와 같은 관계로, 국내 유역에서의 물리적 기반을 둔 고해상도 가뭄 판단방법에 대한 시도가 필요한 시점이다. Brown et al. (2008)은 위성기반 식생정보, 기상학적 가뭄지수, 지형학적 조건을 고려한 식생가뭄반응지수(Vegetation Drought Response Index; 이하 VegDRI)를 개발하였다. 학습자료에 대해 CART 기반의 경험적 모델을 구축하여, 격자마다 근-실시간 자료를 적용한 VegDRI를 산출하여 고해상도의 지도를 산출하는 방식을 제시하였다. VegDRI는 NCDC의 U.S. Drought Monitoring에 활용되고 있으며, NOAA의 Drought Task Force Assessment Protocol에서는 가뭄 모니터링의 기준으로 설정되어 있다. 본 연구에서는 국내에 VegDRI를 적용하고자 필요한 자료수집 및 전처리 과정을 거쳐 결과를 도출하였다. 기상청 ASOS 기상관측소에서 얻은 기상변수, MODIS 위성으로부터 추출된 정규식생지수(Normalized Difference Vegetation Index; NDVI), 지형학적 정보와 기상학적 가뭄지수(SPI, PDSI)를 기계학습으로 모델링하여 VegDRI를 산출하였다. 산출된 VegDRI 공간분포도에 대하여 기존에 활용되던 유관기관의 가뭄 판단방법과의 유사성과 차이점을 비교 검토하여 적용성을 평가하였다.

• Korean Journal of Environmental Agriculture
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• v.42 no.4
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• pp.311-323
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• 2023

Miscanthus sinensis Andersson (Poaceae) cultivars exhibit excellent visual appeal as ornamental grasses and adapt well to diverse environmental conditions. This study focused on assessing the growth response and landscape durability of seven popular Miscanthus cultivars ('Gold Breeze', 'Strictus', 'Morning Light', 'Variegatus', 'Gracillimus', 'Kleine Fontäne', 'Common') under drought, rainfall and low temperature condition. The test cultivars were transplanted and cultivated on research plots in 2013, with data collected from June 2017 to February 2018. Plant materials were categorized into three types based on the amount of the water lost; group I ('Kleine Fontäne', 'Variegatus', 'Strictus'), experiencing the most significant water loss; group II ('Common', 'Gracillimus'); and group III ('Gold Breeze', 'Morning Light') where the least water loss occurred. The drought resistance index (DRI) remained low as water shortage conditions persisted. The lodged angle underwent more pronounced changes in reproductive growth stage than in vegetative growth stage, notably decreasing after heading. Discoloration patterns were classified into two types: group I ('Common', 'Gold Breeze', 'Kleine Fontäne', 'Strictus') and group II ('Gracillimus', 'Morning Light', 'Variegatus') based on the periods of peak duration.

• Journal of Soil and Groundwater Environment
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• v.26 no.1
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• pp.76-87
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• 2021

Groundwater is considered to be the best water resource to solve water shortage problems during drought periods. Even though excessive pumping (overdraft) during short-period may give an unprofitable effect on groundwater hydrology, it has a primary role to solve a lack of water resources and to maintain incomes of farmers. This study evaluated maximum irrigation amounts of groundwater to each local-government and province during drought periods. Maximum irrigation amounts of groundwater were evaluated using cumulative groundwater usage data of each local-government during normal and drought years. Maximum irrigation amounts of groundwater during drought periods would be roughly identified as approximately 1.3 times more than the exploitable amounts of groundwater resources for each local-government. Drawdown-limitation depth on groundwater levels at each monitoring well was determined by transforming the maximum irrigating amounts into degree of change on levels. Universal limitation depth of drawdown on groundwater levels was evaluated to be approximately three times of annual fluctuating range on groundwater levels for each monitoring well. Systematic response on groundwater demands with abiding by drawdown-limitation depth can attain an optimal irrigation of groundwater resources during short-term drought.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.293-293
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• 2022

This study is to develop new wheat breeding material through wide hybridization with wild species harboring useful characteristics such as salt, heat, and drought tolerance. Leymus mollis, wild rye was used to improve wheat genetic quality. L. mollis, is a perennial plant harboring tolerance against salt, heat, and drought because L. mollis distributes on the seaside. The F₁ hybrids were produced by crossing between common wheat (Triticum aestivum L., Chinese Spring) and L. mollis. Genomic in situ hybridization revealed that the F₁ hybrids have L. mollis genome. For the evaluation of salt and drought tolerance, seeds from the F₂ were used. Under 2% NaCl solution, the F₃ wheat-Leymus addition plants with salt tolerance showed more tillering and longer roots than other F₃ plants without salt tolerance. Also, the F₃ plants with salt tolerance showed better shallow-rooted than other F₃ plants without salt tolerance. Finally, the F₃ plants with salt tolerance made seed-setting under 2% NaCl condition, but other F₃ plants without salt tolerance were not. Under drought conditions, the F₃ plants with drought tolerance showed longer culm and spike length than other F₃ plants without drought tolerance and even those of Chinese Spring under well-water conditions. We evaluated and selected the F₃ plants with salt or drought tolerance for generation advancement.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.1
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• pp.31-43
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• 2017

Recent studies about irrigation water use have focused on agricultural reservoir operation in irrigation period. At the same time, it is significant to store water resource in reservoir during non-irrigation period in order to secure sufficient water in early growing season. In this study, Representative Concentration Pathways (RCP) 4.5, 8.5 scenarios with the Global Climate Model (GCM) of The Second Generation Earth System Model (CanESM2) were downscaled with bias correlation method. Cumulative precipitation during non-irrigation season, October to March, was analyzed. Interaction between cumulative precipitation and carry-over storage was analyzed with linear regression model for ten study reservoirs. Using the regression model, reservoir drought response ability was evaluated with expression of excess and deficiency. The results showed that future droughts will be more severe than past droughts. Especially in case of non-exceedance probability of 10%, drought in southern region seemed to be serious. Nine study reservoirs showed deficiency range from 10% to 55%, which turned out to be vulnerable for future drought. Only Jang-Chan reservoir was secure for early growing season in spite of drought with deficiency of 8% and -2%. The results of this study represents current agricultural reservoirs have vulnerability for the upcoming drought.

• Journal of Korea Water Resources Association
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• v.57 no.1
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• pp.45-58
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• 2024

Drought risk is expected to increase as the frequency, intensity, and duration of droughts increase due to climate change. Drought risk is related to not only hydro-meteorological factors, but also water supply and demand. Recently, along with climate change, socioeconomic factors have also been recognized to increase drought risk. Therefore, it is necessary to outlook the drought risk considering various conditions for coping with future extreme droughts in a timely manner. In addition, considering various drought scenarios help reduce the uncertainty in future drought outlook. In this study, drought scenarios considering climate change scenarios, population, and water demand were created to outlook drought risk for 160 administrative districts in Korea, then new levels of drought risk were assigned based on the results of drought risk outlook to suggest drought management measures. The results showed that the drought risk will increase in the future in 2020, 2025, and 2030, compared to past. Especially the drought risk is likely twice as high in 2030 under the baseline and high scenarios. Applying the drought outlook results from this study to the new methodology for setting the risk levels shows that most regions are in Response (V) in 2020 and 2030 for baseline and high scenarios.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.231-231
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• 2017

Drought limits rice production under upland condition. This study quantified the effect of rhizobacteria inoculation on rice root system developmental response to drought and its role in maintaining high soil water use, and dry matter production under drought using NSIC Rc192 (rainfed lowland rice variety). The source of inoculant was Streptomyces mutabilis, a recently isolated rhizobacteria containing plant growth promoting compounds such as ACC deaminase, indole-3-acetic acid and phosphatase (Cruz et al., 2014, 2015). In the first experiment, pre-germination inoculation of seeds with S. mutabilis significantly increased the shoot and root (radicle) length as well as root hair lengths, relative to the non-inoculated control. In the second experiment, rice plants inoculated with S. mutabilis and grown in rootbox with soil generally had greater total root length under drought regardless of the timing of inoculations, relative to the non-inoculated control. Consequently, improved root system development contributed to the increase in soil water uptake under drought and thus, dry matter production. Among inoculation treatments, one-time inoculation of S. mutabilis either at pre-germination or pre-drought stress at 14 days after sowing (DAS), had significantly greater shoot dry matter production than three-time inoculation at pre-germination, at thinning (3 DAS) and at pre-drought (14 DAS). This study demonstrated the effectiveness of rhizobacteria (S. mutabilis) containing growth promoting compounds for enhancing drought dehydration avoidance root traits and improving the growth of rice plants under drought condition.

• Korean Journal of Plant Resources
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• v.31 no.6
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• pp.622-633
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• 2018

Chinese cabbage grown during autumn season is confronted with drought conditions for a certain period, especially during the early growth stage. In this study, we investigated the effects of drought stress on plant growth characteristics, as well as free amino acid, carotenoid, and proline in Chinese cabbage. Chinese cabbage seeds (Bulam Plus) were germinated, and all the seedlings were transplanted into plastic containers (28 cm diameter ${\times}$ 22 cm high) containing a commercial growth medium. The soil water content was measured and maintained at 10% for the drought-stressed plants and at 30% for the control plants, for three weeks. The results revealed that plant growth parameters were lower in the drought-stressed plants than in the control plants. The total free amino acid content tended to decrease in both drought-stressed and control plants with time. The total free amino acid content was found to be lower in the drought-stressed plants than in the control plants and the proline content was unaffected. Moreover, at three weeks after treatment, carotenoid content in drought stressed plants was significantly higher than that in the untreated plants. We believe that our study makes a significant contribution to the literature because the effects of drought stress on plant growth parameters, free amino acid, carotenoids, and proline accumulation in autumn growing cultivar of Chinese cabbage have not been widely studied in Korea, and our study provides valuable information in this regard, as Chinese cabbage is consumed throughout the year in Korea.

• Journal of Environmental Science International
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• v.29 no.11
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• pp.1099-1108
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• 2020

In this study, the capacity of supplying agricultural water to 13 districts was analyzed by calculating the necessary water supply for the arable land of Gunwi-gun and examining the capacity of supplying water to reservoirs, streams, pumping stations, collection sites, and groundwater wells in Gunwi-gun. As a result, among the 13 districts the second district was found to be short of water by 1.2×10⁶ tons/year. In general, local governments establish drought measures by selecting drought disaster risk zones. While selecting drought-risk areas, some water-poor areas that do not have water sources should be selected, even if the entire area has a sufficient water supply. The water-supply evaluation at the regional level was insufficient for locating areas without water sources, but most areas with water sources, such as streams, reservoirs, and pumping stations, were found to have no shortage of water. To locate water shortage areas without water sources, GIS analysis conducted a field survey of areas with a distance of 4 or less than that of water sources analyzed by GIS analysis. Sixty-nine sites in 13 districts were selected for the on-site survey and six areas of water shortage were identified in areas other than the second district.