• 대기
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• 제26권1호
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• pp.141-158
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• 2016

The objective of this study is to examine the impact of urban canopy and the horizontal resolution on simulated meteorological variables such as 10-m wind speed, 2-m temperature and precipitation using WRF model for a local, convective rainfall case. We performed four sensitivity tests by varying the use of urban canopy model (UCM) and the horizontal resolution, then compared the model results with observations of AWS network. The focus of our study is over the Seoul metropolitan area for a convective rainfall that occurred on 16 August 16 2015. The analysis shows that mean diurnal variation of temperature is better simulated by the model runs with UCM before the convective rainfall. However, after rainfall, model shows significant difference in air temperature among sensitivity tests depending on the simulated rainfall amount. The rainfall amount is significantly underestimated in 0.5 km resolution model run compared to 1.5 km resolution, particularly over the urban areas. This is due to earlier occurrence of light rainfall in 0.5 km resolution model. Earlier light rainfall in the afternoon eliminates convective instability significantly, which prevents occurrence of rainfall later in the evening. The use of UCM results in a higher maximum rainfall in the domain, which is due to higher temperature in model runs with urban canopy. Earlier occurrence of rainfall in 0.5 km resolution model is related to rapid growth of PBL. Enhanced mixing and higher temperature result in rapid growth of PBL, which provides more favorable conditions for convection in the 0.5 km resolution run with urban canopy. All sensitivity tests show dry bias, which also contributes to the occurrence of light precipitation throughout the simulation period.

• 대한교통학회지
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• 제33권1호
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• pp.90-99
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• 2015

우리나라는 지리적으로 중위도 온대성 기후대에 해당하며, 초여름부터 초가을까지 집중호우가 발생한다. 집중호우는 도로의 용량 및 서비스 수준에 직접적인 영향을 미치며, 이에 대한 분석의 필요성이 대두되었다. 본 연구는 신호교차로에서의 강우에 따른 포화교통류율 변화를 측정하여 강우가 도로용량에 미치는 영향을 분석하였다. 이를 위해 영상자료를 구축하였고, 영상의 프레임분석을 시행하여 차두간격을 조사하였으며, 조사된 결과를 바탕으로 포화교통류율을 산정하였다. 분석결과에 따르면 일반적인 기상상황에 비해 강우상황에는 포화차두시간이 증가하는 것을 확인하였으며 시간당 강우량이 증가함에 따라 포화교통류율이 점차 감소하는 것을 통계적으로 검정하였다. 통계적 검정 결과 일정 시간당 강우량 범위 내에서는 포화교통류율의 변화가 크지 않으므로 각 시간당 강우량의 범위에 따라 세 영역으로 분류하였으며 각 영역에 따라 포화교통류율은 약 7%, 17%, 21% 감소하는 것으로 나타났다.

• Environmental Engineering Research
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• 제13권4호
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• pp.184-191
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• 2008

Long term monitoring was conducted to investigate a surface runoff of pollution from urban highway. The monitoring data was collected for 18 rainfall events and was used to correlate pollution load to various parameters, such as rainfall intensity, antecedent dry days and total discharge flow. Runoff coefficient and seasonal variation were also evaluated. The mean runoff coefficient of the highway was 0.823(range; $0.4687{\sim}0.9884$), and wash-off ratio for $COD_{Mn}$ and SS loads was 72.6% and 64.3%, respectively. For the initial rainfall event, the runoff EMC of $COD_{Mn}$ was high in summer and the EMC of SS was high in autumn season. However the seasonal variation of T-N and T-P was not significant. The discharged $COD_{Mn}$-EMC was $147.6\;mg/L{\sim}9.0\;mg/L$ on the generated $COD_{Mn}$-EMC of $98.8\;mg/L{\sim}8.9\;mg/L$. While the generated EMC of SS was in $285.7\;mg/L{\sim}20.0\;mg/L$ and its discharged EMC was in $190.4\;mg/L{\sim}8.0\;mg/L$. EMC of pollutants was not directly related to the first flush rainfall intensity and the antecedent dry days. But the correlation was relatively high between EMC and cumulative runoff flow volume. The trend of EMC was reduced with the cumulative runoff flow volume.

• 한국환경과학회지
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• 제11권12호
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• pp.1205-1215
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• 2002

To evaluate the change for water quality after the water gate operation in Shiwha lake, in situ survey were conducted on september in 2000 and January, march, jane in 2001. Chemical characteristics and eutrophication level was estimated from the survey data. The water quality of the Shihwa lake was greatly affected by pollutant load from rainfall, and formation of stratification in summer and winter was increased to effect on nutrient release from sediment. Especially, high concentration of chlorophyll-a was occurred in autumn, due to increased nutrient, high water temperature and low salinity after rainfall runoff. The mean concentration of DIN, DIP were 0.346mg/L, 0.0217mg/L in surface water and 0.826mg/L, 0.0415mg/L in bottom water, respectively, which were over III grade of seawater standard. Also high percentage of ammonia nitrogen to DIN in bottom water for autumn and winter was affected by released nutrient from sediment. Correlation analysis of chlorophyll-a versus TSS was shown that organic matter was affected by autochthonous organic matter stem from the algae, these factor showed reverse correlation about salinity. Closely correlations among to the water quality constituent in continuity survey was appeared. The results of eutrophication index estimation showed the high potentiality of red tide occurrence in Shiwha lake, particularity in summer or fall. Overall water quality was greatly improve to compared with measuring data during 1997~1998 at the beginning water gate operation, which reported by KORDI. Therefore, to improve of water quality in Shiwha lake, we need to establish of management plan about nutrient release from sediment, rainfall runoff, maximum of seawater exchange.

• Journal of Ecology and Environment
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• 제32권4호
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• pp.221-227
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• 2009

This study describes time lag responses between hydrological variables and phytoplankton biomass in a regulated river system, the lower Nakdong River in South Korea. The lower Nakdong is a typical flow-controlled lotic system, and its limnological characteristics are influenced by climatic variation such as monsoons and summer typhoons. Mean rainfall in the area during summer is about 1,200 mm, which comprises >60% of annual rainfall. Our results show that the regulation of flow in the Nakdong by multi-purpose dams from 1995 to 2004 affected phytoplankton dynamics. Diatom blooms occurred in winter, when the limited discharge allowed for proliferation of the phytoplankton community. Using multiple regression analysis, we detected significant time-delayed relationships between hydrological variables and phytoplankton biomass. These results may be useful for water resource managers, and suggest that 'smart flow' control would improve water quality in large regulated river systems of the Republic of Korea.

• 한국지구과학회지
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• 제31권7호
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• pp.749-761
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• 2010

본 연구에서는 2006-2007년 여름(6-8월)동안의 기상청 낙뢰 관측자료와 자동관측소 강우량 자료를 사용하여 여름철 낙뢰와 강우의 관계에 대해 분석하였다. 대부분의 부극성 낙뢰는 대류가 활발한 중심에 집중되어 발생하고 낙뢰빈도가 높고 강한 강우를 동반하였다. 반면 대부분의 정극성 낙뢰는 구름의 가장자리 또는 모루운에서 발생하고 낙뢰빈도는 낮으며, 약한 강우를 동반하였다. 일반적으로 강우강도는 부극성과 정극성이 함께 발생했을 경우 가장 강하고 부극성 낙뢰, 정극성 낙뢰, 그리고 낙뢰가 발생하지 않은 순으로 나타나고 있다. 여름철 전체 낙뢰 중 정극성 낙뢰의 비율은 평균 10% 이하이며 강우를 유발하지 않는 낙뢰의 비율은 평균 34%이다. 강우강도는 특히 부극성 낙뢰빈도와 높은양의 상관을 보였고, 낙뢰는 강우와 동시에 발생하거나 약 10분정도 선행하는 경향을 보였다. 낙뢰를 동반한 강우를 대류성 강우로 정의하여 분석한 결과 우리나라 여름철 강우 중 적어도 20% 이상은 대류성 강우이며 6, 7월보다는 8월에 대류성 강우가 많이 발생하고 있다. 또한 강우 및 낙뢰와 같이 대류성 강우의 비율도 오후에 최대치를 보이는 일변동을 보인다.

• Water Engineering Research
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• 제1권2호
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• pp.147-158
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• 2000

In this study, we characterized the seasonal variation of rainrate fields in the Han river basin using the WGR multi-dimensional precipitation model (Waymire, Gupta, and Rodriguez-Iturbe, 1984) by estimating and comparing the parameters derived for each month and for the plain area, the mountain area and overall basin, respectively. The first-and second-order statistics derived from observed point gauge data were used to estimate the model parameters based on the Davidon-Fletcher-Powell algorithm of optimization. As a result of the study, we can find that the higher rainfall amount during summer is mainly due to the arrival rate of rain bands, mean number of cells per cluster potential center, and raincell intensity. However, other parameters controlling the mean number of rain cells per cluster, the cellular birth rate, and the mean cell age are found invariant to the rainfall amounts. In the application to the downstream plain area and upstream mountain area of the Han river basin, we found that the number of storms in the mountain area was estimated a little higher than that in the plain area, but the cell intensity in the mountain area a little lower than that in the plain area. Thus, in the mountain area more frequent but less intense storms can be expected due to the orographic effect, but the total amount of rainfall in a given period seems to remain the same.

• Journal of Animal Science and Technology
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• 제63권2호
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• pp.339-353
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• 2021

This study aimed to assess the causality of different climate variables on the production of whole crop maize (Zea mays L.; WCM) in the central inland region of the Korea. Furthermore, the effect of these climate variables was also determined by looking at direct and indirect pathways during the stages before and after silking. The WCM metadata (n = 640) were collected from the Rural Development Administration's reports of new variety adaptability from 1985-2011 (27 years). The climate data was collected based on year and location from the Korean Meteorology Administration's weather information system. Causality, in this study, was defined by various cause-and-effect relationships between climatic factors, such as temperature, rainfall amount, sunshine duration, wind speed and relative humidity in the seeding to silking stage and the silking to harvesting stage. All climate variables except wind speed were different before and after the silking stage, which indicates the silking occurred during the period when the Korean season changed from spring to summer. Therefore, the structure of causality was constructed by taking account of the climate variables that were divided by the silking stage. In particular, the indirect effect of rainfall through the appropriate temperature range was different before and after the silking stage. The damage caused by heat-humidity was having effect before the silking stage while the damage caused by night-heat was not affecting WCM production. There was a large variation in soil surface temperature and rainfall before and after the silking stage. Over 350 mm of rainfall affected dry matter yield (DMY) when soil surface temperatures were less than 22℃ before the silking stage. Over 900 mm of rainfall also affected DMY when soil surface temperatures were over 27℃ after the silking stage. For the longitudinal effects of soil surface temperature and rainfall amount, less than 22℃ soil surface temperature and over 300 mm of rainfall before the silking stage affected yield through over 26℃ soil surface temperature and less than 900 mm rainfall after the silking stage, respectively.

• 한국환경보건학회지
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• 제26권2호
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• pp.41-48
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• 2000

This study has been carried out to determine the seasonal characteristics of concentration of various ionic (CI-, NO3-, SO42-, Na+, NH+, K+, Ca2+) and heavy metallic (Pb, Mn, Cu, Ni) species in Pusan from August 1997 to April 1998. The concentrations of CI-, Na+, K+ were higher during summer with 2.98 ${\mu}{\textrm}{m}$/㎥. Seasonal variation of total concentration of but the concentration of NH4+ was higher during winter with 2.46${\mu}{\textrm}{m}$/㎥. Seasonal variation of total concentration of heavy metals(Pb, Cu, Mn, Ni) were 186.0 ng/㎥ in summer, 222.6 ng/㎥ in autumn, and 135.83 ng/㎥ in winter. Over the seasons inspected, the concentration of Mn was higher in coarse particles than fine particles and concentration of Ni was higher in fine particles than coarse particles. during yellow sand period, the concentration of TSP was increased about two times than that of other period. SO42-, Ca2+ concentrations were higher than other ionic components because of soil particles. The concentration of Ni showed 94.62ng/㎥ was increased about 4~5 times than other period. Principal component of the yellow sand, SO42-, Ca2+ could be discreased by rainfall and washout effect of atmospheric aerosol was higher in coarse particles than fine particles. Results from PCA(principal component analysis) showed that major pollutant was NaCl by seasalt particulate and (NH4)2SO4.

• 지질공학
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• 제27권2호
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• pp.125-132
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• 2017

우리나라는 국토의 64% 가량이 산지로 되어 있어 하절기 집중호우 및 태풍으로 인해 지속적인 산지재해(사면붕괴, 산사태, 토석류 등)가 발생하고 있다. 이러한 산지를 중심으로 사회기반시설의 개발 및 확충을 통해 산지 개발이 이루어지고 있으나 체계적인 관리는 미흡한 실정이다. 산지사면을 대상으로 임도시설의 개설은 대상 산지를 인위적으로 변화시킴에 따라 하절기에 집중적으로 산지재해 발생의 원인으로도 작용한다. 이처럼 불안정한 상태의 산지환경에서 재해에 강한 환경을 건설하기 위한 노력이 절실히 요구되는 시점이다. 본 연구는 자연산지와 산지 내 임도 개설 여부를 기준으로 극한강우 조건하에서 강우의 침투특성을 고려하여 토층심도(1~5 m) 및 산지경사($20{\sim}60^{\circ}$) 조건에 따른 산지사면의 안정성을 분석하였다. 그 결과, 산지사면의 안정성은 토층심도와 토층의 포화면적에 따라 안전율의 차이를 갖는 것으로 나타났으며, 산지 내 임도 개설에 따른 산지의 안정성이 자연산지보다 낮은 것으로 분석되었다. 특히, 강우 침투양상의 경우에는 임도 상부측 사면부에서 강우 침투수의 유출이 발생하는데 이는 토층심도가 낮을수록 유출 현상이 뚜렷이 발생하는 것으로 나타났다.