• Korean Journal of Agricultural and Forest Meteorology
• /
• v.19 no.4
• /
• pp.293-303
• /
• 2017

The purpose of this study is to measure the effects of droughts and public investments in irrigation facilities on rice production. We estimated the effects of droughts and the fraction of irrigated paddy fields with irrigation facilities on rice yields through a panel regression model. The results showed that the effect of drought on rice yield was negative but modest. Also, we found that increases in the ratio of irrigated paddy fields to total paddy fields by 1% enhance rice yields by 0.025-0.035%. However, the ratio of irrigated paddy fields to total paddy fields has insignificant effects on reducing harmful droughts effects regardless of the conditions of irrigated paddy fields.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.61 no.2
• /
• pp.105-115
• /
• 2019

For 159 administrative areas, SPI(Standardized Precipitation Index), ARDI(Agricultural Reservoir Drought Index) and ARDIs(Agricultural Reservoir Drought Index Simulated) were developed and applied to analyze the characteristics of agricultural drought index and agricultural droughts. In order to identify hydrometeorological characteristics of agricultural droughts, SPI, ARDI and ARDIs were calculated nationwide, and the applicability was compared and examined. SPI and ARDI showed significant differences in time and depth of drought in both spatial and temporal. ARDI and ARDIs showed similar tendency of change, and ARDIs were considered to be more representative of agricultural drought characteristics. The results of this study suggest that agricultural drought is a problem to be solved in the medium and long term rather than short term due to various forms of development, complexity of development, and difficulty in forecasting. Therefore, it is concluded that a preliminary and systematic approach is needed in consideration of meteorological, hydrological and hydrometeorological characteristics rather than a fragmentary approach, and that an agricultural drought index is needed to quantitatively evaluate agricultural drought.

• Journal of the Korean association of regional geographers
• /
• v.11 no.4
• /
• pp.429-439
• /
• 2005

The propose of this study is to identify distributional characteristics of winter droughts through occurrence frequencies and to analyze synoptic characteristics on the sea level pressure fields and 500hPa levels in Korea. The regional distributions of winter droughts in occurrence frequency vary according to the monthly regional distributions of the variabilities of precipitation in Korea. In January and December, the eastern parts of Korea where the variabilities of precipitation show high, have high rate of drought frequencies, while the western parts have low rate of it. It means that the regional distribution of the drought frequencies in January and December shows the east-high and west-low pattern, In February the frequencies show the north-high and south-low pattern. In the distributions of the sea-level pressure and 500hPa level height anomalies, the positive anomalies appear around Korean Peninsula and Siberian high area, the negative anomalies on the Aleutian low area and the western parts of North Pacific Ocean during the drought period in January and February. The droughts appear when the inflow of warm and humid air from the south eastern parts blocked by the prevailing pressure patterns of the west-high and east-low. Therefore, the zonal wind of the Korean Peninsula is strong. The droughts of December reflect not only low frequencies of cyclone occurrence, also small inflow of warm and humid air from the southern parts stemming from positive anomalies over whole middle latitude of eastern parts of Asia including Korean Peninsula.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.2B
• /
• pp.87-98
• /
• 2011

Recently, occurrence frequency of extreme events like flood and drought is increasing due to climate change by global warming. Especially, a drought is more severer than other hydrologic disasters because it causes continuous damage through long period. But, ironically, it is difficult to recognize the importance and seriousness of droughts because droughts occur for a long stretch of time unlike flood. So as to analyze occurrence of droughts and prepare a countermeasure, this study analyzed a meteorologic drought among many kinds of drought that it is closely related with precipitation. Palmer Drought Severity Index, Standard Precipitation and Effective Drought Index are computed using precipitation and temperature material observed by Korean Meteorological Administration. With the result of comparative analysis of computed drought indices, Effective Drought Index is selected to execute frequency analysis because it is accordant to past droughts and has advantage to compute daily indices. A Frequency analysis of Effective Drought Index was executed using boundary kernel density function. In the result of analysis, occurrence periods of spring showed about between 10 year and 20 year, it implies that droughts of spring are more frequent than other seasons. And severity and occurrence period of droughts varied in different regions as occurrence periods of the Youngnam region and the southern coast of Korea are relatively shorter than other regions.

• Journal of Korea Water Resources Association
• /
• v.54 no.7
• /
• pp.523-534
• /
• 2021

Meteorological drought originates from a precipitation deficiency and propagates to agricultural and hydrological droughts through the hydrological cycle. Comparing with the meteorological drought, agricultural and hydrological droughts have more direct impacts on human society. Thus, understanding how meteorological drought evolves to agricultural and hydrological droughts is necessary for efficient drought preparedness and response. In this study, meteorological and hydrological droughts were defined based on the observed precipitation and the synthesized streamflow by the land surface model. The Bayesian network model was applied for probabilistic analysis of the propagation relationship between meteorological and hydrological droughts. The copula function was used to estimate the joint probability in the Bayesian network. The results indicated that the propagation probabilities from the moderate and extreme meteorological droughts were ranged from 0.41 to 0.63 and from 0.83 to 0.98, respectively. In addition, the propagation probabilities were highest in autumn (0.71 ~ 0.89) and lowest in winter (0.41 ~ 0.62). The propagation probability increases as the meteorological drought evolved from summer to autumn, and the severe hydrological drought could be prevented by appropriate mitigation during that time.

• Journal of Korea Water Resources Association
• /
• v.49 no.2
• /
• pp.145-153
• /
• 2016

Using monthly rainfalls, this study investigated outliers of annual and/or seasonal rainfall for quantitative assessment of historical droughts in Korea. Based on the analysis of annual rainfall, Icheon, Geochang, Jeongeup, Suncheon and Jangheung gaging stations were selected to represent the major river basins, because they had most frequent dry years. The overall results indicated that the years of 1988 and 1994 were the worst dry years. Although the 2001 drought was not severe, it resulted in typical agricultural drought damage mainly in Seomjin and Yeongsan river basin due to the lack of agricultural water. On the other hand, the droughts of 1981-1982 and 1994-1995 were long term nation wide droughts that lasted more than two years resulting in extensive drought damages to parts of the country.

• Journal of the Korean association of regional geographers
• /
• v.19 no.4
• /
• pp.580-599
• /
• 2013

After the unification of Three Kingdoms, Silla Dynasty had been on the prosperity with continuous population growth during approximately 120 years. However, Unified Silla Dynasty experienced 11 times of famine and bad year by frequent droughts during 50 years since the late 8th century, and these caused to political, economic and social changes. It is evident that Silla Dynasty slowly declined by the droughts and famines, although ancient records described as still on glory days. Since then, national power of Unified Silla Dynasty was abruptly weakened by migration of residents, and 9 times of rebellion or revolt occurred during 50 years in the late 9th century. As a result, political and social agitations reached the maximum. These led to the collapse of the Unified Silla Dynasty, and King Gyeongsoon handed over the dynasty to King Wanggeon, a founder of Goryeo Dynasty. These resulted from the 500-year-cycle droughts and human activities that seriously devastated the vegetations by using trees as an energy source for hundreds of thousands people during several centuries. The devastation of vegetation destroyed farm lands and led to large changes in river and groundwater systems, and eventually, increased damages by droughts.

• Journal of the Korean Geographical Society
• /
• v.44 no.4
• /
• pp.497-509
• /
• 2009

Records on natural hazards such as droughts, floods, smallpox and attacks of grasshoppers are classified and analyzed during the Ancient Times(BC 57$\sim$AD 935) based on the Historical Records of the Three Kingdoms Age(Samguksaki main record), and influences on human activities and relationships of each natural hazard are studied. The strongest influences on the agricultural productivity were the drought and the influences of floods were weak. The most floods were not destructive hazards because the cultivated lands were distributed in the valley plains and the towns and villages were constructed in the area free from the floods during the Ancient Times. The attacks of grasshoppers have the high frequencies with the droughts. The smallpox of the Ancient Times has no relationships with the dearth, floods and droughts. This means that the waterborne infections happened periodically and after the unification, the infectious diseases happened continuously due to the urbanization leading the concentration of population on the capital. Two cycles of droughts are recognized, and they happened with the time intervals of approximately 500 years during approximately 1000 years in Shilla dynasty.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.41 no.2
• /
• pp.113-121
• /
• 2021

The occurrence mechanisms of heatwave have been conventionally studied at a synoptic scale. However, the implications of precedent droughts on the following up heatwave occurrences have not been elucidated and are important to address the complex causal mechanisms of heatwaves. Therefore, this study evaluated the causality and implication of the seasonally antecedent droughts to summer heatwaves that occurred for 46 years since 1974 using partial least squares-structural equation modeling (PLS-SEM). The resulting contribution of winter (spring and summer) droughts to summer heatwaves for Seoul-Gyeonggi, Gangwon, and Chungcheong provinces were 37 % (29 % and 22 %), 21 % (18 % and 29 %), and 17 % (8 % and 38 %), respectively. This is due to the regional variability of seasonal drought impacts. Furthermore, Gangwon and Chungcheong provinces, which have a higher level of impacts of summer droughts to summer heatwaves, are more likely to be exposed to the compound drought-heatwave damages compared to Seoul-Gyeonggi province, which has relatively a low-level impact of summer drought.

• Journal of Ecology and Environment
• /
• v.32 no.3
• /
• pp.197-206
• /
• 2009

Benthic macroinvertebrate communities were collected from six different sites in the Dobong Stream in Seoul, Korea to investigate spatial and temporal changes in benthic macroinvertebrate communities in response to natural disturbances such as floods and droughts. We collected samples monthly or semimonthly with a Surber net ($30cm{\times}30cm$), and measured environmental factors, including stream temperature, discharge, width, conductivity, dissolved oxygen and pH at each sampling site. Benthic macro invertebrates were strongly affected by floods as well as droughts. In addition, benthic macroinvertebrate communities displayed different responses to the onset of the rainy season in summer 2006 and 2007, apparently due to differences in the intensity and amount of precipitation. Chironomids were particularly sensitive to heavy rain. Floods and droughts also affected the proportions of functional feeding groups during the survey period: the proportion of scrapers was high right after heavy rains, while the proportion of predators tended to increase in intermittent-type streams as the riffle zone decreased. Finally, although species richness and abundance were strongly influenced by heavy rain, they recovered to background levels for within one month, and varied consistently among stream types, indicating habitat stability.