• Korean Journal of Ecology and Environment
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• v.35 no.3 s.99
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• pp.160-171
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• 2002

The impact of summer monsoon on water quality of the lower Nakdong River was evaluated during the summer (June-August) in 1997. Several limnological variables were measured in the interval of $1{\sim}3$ day using an automatic monitoring system (Hydrolab $Recorder^{TM}$) to detect water quality changes caused by rainfall on onehour basis. During the monsoon period (from late June to mid July), 5 times of major rainfall events of >50 mm were recorded in the river basin. Dynamic changes of water quality were observed during the monsoon, and the first rainfall event (June$25{\sim}27$) had a significant influence on the water quality at the lower part of the river. All Parameters were largely changed due to the first rain event, and the changed level was maintained until the end of monsoon period. Nutrient concentrations and turbidity increased and values of the other parameters were declined as a result of water dilution. This rainfall event, Changma, is a meteorological phenomenon caused by the East-Asian monsoon climate. The magnitude and frequency of the rainfall during the early monsoon play an important role in change of water quality and ecosystem characteristics of large river systems.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.334-337
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• 2003

The results of this numerical model is usable to analysis for the phenomena of precipitation during the periods of a rainy season in the Northeastern Asia. Case l(start of rainy season) dominates over precipitation by the processing of convection from the equator region through the East China region, and then the most of water vapor is transported by the processing of advection from the India-monsoon region to this study region. Case 2(heavy rainy season) faints precipitation by the processing of convection in the Korean peninsula, but dominates precipitation by the processing of microphysics. the water vapor originates from the India-monsoon region.

• 한국지구과학회:학술대회논문집
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• 2010.04a
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• pp.92-94
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• 2010

최근 대류권과 성층권 사이에서 매우 빠른 속도로 부는 제트류(jet stream)가 장마 전선에 유입되면서 다량의 수증기 공급으로 인한 집중호우의 발생빈도가 증가하고 있다. 집중 호우는 상, 하층 제트류 사이에서 주로 발생하며, 상층 제트류는 제트류의 남쪽과 하층에서 상승기류를 유발하는 역할을 하고 하층 제트류는 남쪽 및 남서쪽에서 따뜻하고 습윤한 공기를 북쪽 및 북동쪽으로 수송하는 중요한 역할을 한다. 상, 하층 제트류가 교차되거나 근접할수록 상하층의 온위차가 커지고, 연직시어도 증가되며, 또한 두 제트류가 중첩되는 경우에는 2차 순환이 강화되어 호우가능성이 높아진다. 한반도의 경우는 지리적으로 경압성이 강한 동아시아에 위치하여 전반적으로 잘 구조화된 하층제트를 형성하여 호우의 제반 여건을 형성하므로, 하층제트의 영향에 직접적으로 관계한 집중호우의 사례를 분석하였다.

• Journal of the Korean Geographical Society
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• v.28 no.2
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• pp.112-122
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• 1993

Since more than 50${\%}$ of annual precipitation in Korea falls during Changma, the rainy season of early summer, and Late Changma, the rainy season of late summer, forcasting the onset days Changmas, and the amount related rainfalls would be necessary not only for agriculture but also for flood-control. In this study the authors attempted to build a prediction model for the forecast of the onset date of Changmas. The onset data of each Changma was derived out of daily rainfall data of 47 stations for 30 years(1961~1990) and weather maps over East Asia. Each station represent any of the 47 districts of local forecast under the Korea Meteorological Administration. The average onset dates of Changma during the period was from 21 through 26 June. The dates show a tendency to be delayed in El Ni${\~{n}}o years while they come earlier than the average in La Nina years. In 1982, the year of El Ni${\~{n}}o, the date was 9 Julu, two weeks late compared with the average. The relation of sea surface temperature(SST) over Pacific and Northern hemispheric 500mb height to the Changma onset dates was analyzed for the prediction model by polynomial regression. The onset date of Changma over Korea was correlated with SST in May(SST${_(5)}{^\circ}$C) of the district (8${^\circ}$~12${^\circ}S, 136${^\circ}~148${^\circ}W)of equatirial middle Pacific and the 500mb height in March (MB${_(3)}$"\;"m)over the district of the notrhern Hudson Bay. The relation between this two elements can be expressed by the regression: Onset=5.888SST${_5}"\;"+"\;"0.047MB${_(3)}$"\;"-251.241. This equation explains 77${\%}$ of variances at the 0.01${\%}$ singificance level. The onset dates of Late Changma come in accordance with the degeneration of the Subtro-pical High over northern Pacific. They were 18 August in average for the period showing positive correlation(r=0.71) with SST in May(SST)${_(i5)}{^\circ}$C) over district of IndiaN Ocean near west coast of Australia (24${^\circ}$~32${^\circ}$S, 104${^\circ}$~112${^\circ}$E), but negativ e with SST in May(SST${_(p5)}{^\circ}$ over district (12${^\circ}$~20${^\circ}$S,"\;"136${^\circ}$~148${^\circ}$W)of equatorial mid Pacific (r=-0.70) and with the 500mb height over district of northwestern Siberia (r=-0.62). The prediction model for Late Changma can be expressed by the regression: Onset=706.314-0.080 MB-3.972SST${_(p5)}+3.896 SST${_(i5)}, which explains 64${\%}$ of variances at the 0.01${\%}$ singificance level.

• Korean Journal of Environmental Biology
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• v.18 no.2
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• pp.215-226
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• 2000

We evaluated the aquatic ecosystem of Keum-Ho River through applications of the Index of Biological Integrity (IBI) using fish assemblages and Qualitative Habitat Evaluation Index (QHEI) during June-November 1999. Overall IBI values ranged from 13 to 37 with mean of 23 (n=25, Std. error= 1.16), indicating a "Poor" or "Very Poor" condition according to the criteria of Karr (1981) and U.S. EPA (1993). The values of mean IBI declined at the rate of $0.22km^{-1}$(($r^2$=0.91, p< 0.05) along the longitudinal distance from the headwaters to the down-river. Reduced IBI values at down-river (St. 4 and 5) were attributed to the decreases in riffle benthic species and the relative abundance of insectivore and increases in tolerant species, anormalies and exotic species. Spatial pattern in IBI agreed with QHEI values, which showed a linear relation ($r^2$=0.998, p< 0.001) with mean number of species. Field measurements of conductivity and pH, indicators for variation of conservative ions, showed that the river water was diluted up to 30% by summer precipitation and surface run-off from the watershed, resulting in physical and chemical instability during the monsoon. For these reasons, average IBI values during monsoon and postmonsoon decreased more than 20% compared to pre -monsoon. Before the perturbation of the system (i.e., pre-monsoon), values of QHEI were inversely correlated (r=-0.99, p< 0.0001) with realtive abundance of native omnivore and were positively correlated (r=0.87, p=0.05) with relative abundance of native carnivore. These results indicate that spatial degradation of habitat quality modified the species richness and trophic structure, producing decreased IBI values. (Biological integrity, IBI, Monsoon, Habitat, River, Korea)bitat, River, Korea)

• Asian Journal of Turfgrass Science
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• v.26 no.2
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• pp.83-88
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• 2012

When perennial ryegrass was overseeded in bermudagrass fairway, shoot density of perennial ryegrass was gradually increased to $88,000/m^2$ at the end of May, however dramatically decreased to 0 in September over the rainy season. On the other hand, that of bermudagrass increased from $2,000/m^2$ in March to $20,000/m^2$ in early June, and then decreased to $4,000/m^2$ at the end of July, after the rainy season, rapidly increased to $50,000/m^2$ in early September. Overseeding bermudagrass fairway with perennial ryegrass was maintained a good quality from mid-April to mid-June and decreased the quality over the rainy season from late June to July, and then turf quality was decrease to the worst level at the end of July. After the rainy season fairway quality was improved gradually and was the highest-level during September and early October. Trifloxysulfuron-sodium was treated to minimize the deterioration in turf quality due to early bermudgrass transition time in spring. Consequently, transition was started in mid-May and shoot density of bermudagrass treated by trifloxysulfuron-sodium was $70,000/m^2$ in mid-June. Even in the rainy season it was sustained as $30,000/m^2$, approximately three times higher than that of untreated overseeding fairway.

• Journal of the Korean association of regional geographers
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• v.20 no.4
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• pp.393-408
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• 2014

In this study, the spatio-temporal characteristics of summer extreme precipitation events in the Republic of Korea are examined based on the daily precipitation data observed at approximately 360 sites of both Automatic Weather Station (AWS) and Automated Synoptic Observation System (ASOS) networks by the Korea Meteorological Administration for the recent decade(2002~2011). During the summer Changma period(late June~mid July), both the frequency of extreme precipitation events exceeding 80mm of daily precipitation and their decadal maximum values are greatest at most of weather stations. In contrast, during the Changma pause period (late July~early August), these patterns are observed only in the northern regions of Geyeonggi province and western Kangwon province as such patterns are detected around Mt. Sobaek and Mt. Halla as well as in the southern regions of Geyeonggi province and western Kangwon province during the late Changma period (mid August~early September) due to north-south oscillation of the Changma front. Investigation of their regional patterns confirms that not only migration of the Changma front but also topological components in response to the advection of moistures such as elevation and aspect of major mountain ridges are detrimental to spatio-temporal patterns of extreme precipitation events. These results indicate that each local administration needs differentiated strategies to mitigate the potential damages by extreme precipitation events due to the spatiotemporal heterogeneity of their frequency and intensity during each Changma period.

• Ecology and Resilient Infrastructure
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• v.8 no.1
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• pp.54-63
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• 2021

This study aimed to investigate changes in benthic macroinvertebrate communities caused by erosion control dams using data obtained from three erosion control dams in Wonju, Gangwon Province, before and after the rainy season. Surveys were conducted four times from March to September 2019, and survey points were continuously selected during the installation of closed-type and open-type dams. A total of eight points from the upstream and downstream regions of each dam type were selected. The flow velocity of both the closed and open types increased, but the closed type exhibited a relatively higher flow velocity than the open type. Benthic macroinvertebrate species and individuals mostly decreased after the rainy season. A relatively large number of species and individuals were found upstream of the closed-type dam. An analysis of the ephemeroptera-plecoptera-trichoptera groups showed relatively reduced ephemeroptera in the closed-type dam and reduced trichoptera in the open-type dam. The periods before and after the rainy season could be divided based on the results of a similarity analysis. The open type showed relatively minimal changes before and after the rainy season.

• The Korea Beekeeping Bulletin
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• s.331
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• pp.18-23
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• 2008

강원도 고랭지 지역과 서해안 해안이나 도서 지역에서만 6월 초순경까지 일부 아카시아 꽃이 남아 있어 유밀이되는데 기온이 높을 때는 수분도 많고 꿀 분비도 잘 안되어 밀원으로서의 가치가 별로 없게 된다. 아카시아 채밀도 끝나고 밤꿀 이나 화분, 로얄제리 생산이나 분봉 등을 시키는 시기가 되겠다. 6월에 개화되는 꽃으로는 밤나무, 대추나무, 흑싸리, 찔레, 다래 등이 주요 밀원인데 그 중 밤나무, 대추나무에서는 채밀 할 수 있으나 찔레, 다래등은 화분만으로 만족해야 할 것이다. 만일 밤, 대추에서도 장마가 일찍 오면 채밀은 미지수이다. 이 장마기가 양봉에 있어서 월동 다음으로 어려운 월 하기라 생각한다.

• The Bimonthly Magazine for Agrochemicals and Plant Protection
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• v.8 no.6
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• pp.41-46
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• 1987

금년은 과거 어느 해보다도 과수농사에 어려움이 많았던 한 해였다. 주요 과수의 개화기 전후의 저온과 7,8월의 집중호우를 동반한 긴 장마와 $\ulcorner$셀마$\lrcorner$$\ulcorner$다이너$\lrcorner$태풍의 피해 그리고 9월중순부터 계속되고 있는 오랜 가뭄 등으로 지역에 따라서는 일부 과종들이 병해충의 발생과 한발의 피해로 조기낙엽이 되고 있어 금년 겨울의 동해가 우려되므로 세심한 관리가 요망되고 있다.