• Ecology and Resilient Infrastructure
• /
• 제5권4호
• /
• pp.229-245
• /
• 2018

This study aims to investigate the changes in the riparian vegetated area in the Naeseong stream, an unregulated river, in order to analyze the main factors leading to these changes. For this purpose, the land surface cover in the channel area of the Naeseong stream was classified into 9 categories using past aerial photographs collected between 1970 and 2016, which recorded the long-term changes of the Naeseong stream. The increase or decrease in the vegetated area was calculated for each category using a pair of before and after images. The changes in the vegetated area were divided into 6 periods: the unvegetated channel period (1970 - 1980), the first rapid increase (1980 - 1986), the period of decrease due to flood (1986 - 1988), the period of repetitive man-induced disturbance and vegetation increase (1988 - 2008), the period of gradual vegetation increase (2008 - 2013), and the period of second rapid increase (2013 - 2016). Multiple regression analysis was performed using independent variables representing hydrology, climate, and geomorphology. The major variables found to be involved in the changes in the vegetated area of the Naeseong stream were the discharge during June - July, channel width, and temperature during April - June. Among the three variables, discharge and temperature were respectively the main independent variables in the downstream and the upstream reaches as per a single variable model. Channel width was the variable that distinguished the upstream and downstream reaches of the stream. The implication of the long-term increase in the vegetated area in the Naeseong stream was discussed based on the result of this study.

• 한국대기환경학회지
• /
• 제16권5호
• /
• pp.539-544
• /
• 2000

A simple analytic model is proposed here to analyze the concentration deficit field caused by a large area of vegetated area. With non-dimensional deposition velocity chosen as small parameter, the regular perturbation method is exploited to derive the mass balance equation and the dynamic equations for the concentration deficit field, Analytic solutions to those equations are obtained in a closed form for several cases of interest, assuming that the concentration field is stationary and the plume can be nicely approximated as Gaussian for a point source. The results suggest that quite a negligible fraction (less than 1%) of the gaseous air pollutants emitted into the air is removed by the vegetated area of which width is 4 km in wind-wise direction, the typical dimension of the Restricted Development Zones around the metropolitan regions in South Korea.

• 한국해양공학회지
• /
• 제20권1호
• /
• pp.63-68
• /
• 2006

Recently, it has been widely recognized that coastal vegetations may have great value in supporting fisheries, protecting from wave attack, stabilizing the sea bed and maintaining good scenery. Hydrodynamic factors play a major role in the functions of water quality and ecosystems. However, the studies on physical and numerical process of wave propagation are few and far behind compared to those on the hydrodynamic roles of coastal vegetations. In general, Vegetation flourishing along the coastal areas attenuates the incident waves, through momentum exchange between stagnated water mass in the vegetated area and rapid mass in the un-vegetated area. This study develops a numerical model for describing the wave attenuation rate in the complex topography with the vegetation area. Based on the numerical results, the physical properties of the wave attenuation are examined under various wave, geometric and vegetation conditions. Through the comparisons of these results, the effects of the vegetation properties, wave properties and model parameters such ac the momentum exchange coefficient have been clarified.

• 아시안잔디학회지
• /
• 제16권2호
• /
• pp.107-114
• /
• 2002

본 연구는 토지피복현황과 식재의 계층구조가 다양한 도시녹지를 대상으로 기온저감효과에 미치는 영향을 파악하기 위해 녹지 내의 기온을 관측하였다. 그 테이터를 바탕으로 녹지내의 토지피복현황과 기온분포, 식재지율(식재의 면적비율)과 기온, 식재의 계층구조비율과 기온, 수목그루 및 녹적량(수목의 체적)과 기온 저감효과와의 관련성을 회귀분석 등에 의해 해석하였다. 그 결과, 고온역은 인공구조물과 나지 주변에서, 저온역은 식재지와 수면 주변에서 형성되었다. 또한, 식재의 계층구조가 2, 3층으로 덮여있는 구역과 수면을 핵으로 그 주변이 식재로 둘러싸인 구역이 상대적으로 낮은 기온을 나타냈다. 수목그루 및 녹적량의 증가는 어떤 수고라도 기온저감에 효과적이고 그 효율은 교목, 소교목, 관목의 순이다.

• 대한토목학회논문집
• /
• 제30권5B호
• /
• pp.509-518
• /
• 2010

본 연구는 하천의 유역면적 또는 계획홍수량에 따라 하천 규모를 대 중 소하천으로 구분하고, 이들 하천에 대한 식생모델을 구축하여 수치모형을 이용해 제방고 여유율(CSR)을 기준으로 홍수위를 검토하였다. 식생모델 구축전 1차원 HEC-RAS와 2차원 RMA-2 모형을 이용하여 분석한 결과와 기본계획홍수위와 비교한 결과, 1차원의 경우 제방고 여유율은 대하천 모든 단면과 중하천 상류부 2개 단면 외에는 100% 이상이었으나, 소하천은 평균 46.0% 정도로 나타났다. 2차원 대하천의 경우는 평균 101.5%, 중하천은 96.7%, 소하천은 평균 71.1%로 나타났는데, 이는 하천기본계획수립 시 주로 1차원 모형을 사용하기 때문인 것으로 판단된다. 그러나 식생모델 적용 시 1차원에서는 대하천의 경우 평균 제방고 여유율은 91.8%, 중 소하천은 각각 74.2%, 38.3%로 나타났고, 2차원에서 대하천은 95.5%, 중 소하천은 각각 86.7%, 37.0%로 나타났다. 이는 대하천이 중 소하천 보다 유수단면적이 커 식생모델 적용 시 제방고 여유율의 영향을 적게 받기 때문인 것으로 판단된다.

• 한국해양공학회지
• /
• 제21권5호
• /
• pp.18-24
• /
• 2007

The environmental value of coastal vegetation has been widely recognized. Coastal vegetation such as reed forests and seaweed performs several useful functions, including maintaining water quality, supporting fish (and, thus, fisheries), protecting beaches and land from wave attack, stabilizing sea beds and providing scenic value. However, studies on the physical and numerical process of wave propagation, sediment transport and bathymetric change are few and far between compared to those on the hydrodynamic roles of coastal vegetation. In general, vegetation flourishing along the coastal areas attenuates the incident waves through momentum exchange between stagnated water mass in the vegetated area and rapid mass in the un-vegetated area. This study develops a numerical model for describing the wave attenuation and sediment transport in a wave channel in a vegetation area. By comparing these results, the effects of vegetation properties, wave properties and model parameters are clarified.

• 대한원격탐사학회지
• /
• 제4권1호
• /
• pp.49-60
• /
• 1988

Principal Component Analysis (PCA) was applied for regional geological mapping to a multivariate data set of the Landsat TM data in the heavily vegetated and topographically rugged Chungju area. The multivariate data set selection was made by statistical analysis based on the magnitude of regression of squares in multiple regression, and it includes R1/2/R3/4, R2/3, R5/7/R4/3, R1/2, R3/4. R4/3. AND R4/5. As a result of application of PCA, some of later principal components (in this study PC 3 and PC 5) are geologically more significant than earlier major components, PC 1 and PC 2 herein. The earlier two major components which comprise 96% of the total information of the data set, mainly represent reflectance of vegetation and topographic effects, while though the rest represent 3% of the total information which statistically indicates the information unstable, geological significance of PC3 and PC5 in the study implies that application of the technique in more favorable areas should lead to much better results.

• The Korean Journal of Ecology
• /
• 제28권3호
• /
• pp.141-147
• /
• 2005

조간대 내 칠면초 종자의 분포 및 매토 특성을 파악하기 위해 1999년 3월부터 2000년 10월까지 경기도 시흥시 월곳동에서 매토 종자의 수직 및 수평 분포와 게에 의한 저토의 굴착량을 추정하였다. 칠면조 종자는 94%가 모체의 수관 아래 분포하였으며, 나머지 6%만이 수관밖에 위치하였다. 저질 내 유기물 함량은 칠면초가 있는 지역에서는 6 cm 깊이까지 평균 17%로 높았지만 이것이 없는 지역에서는 8%로 낮았다. 한편, 식생지에서 유기물 함량은 표토(1 cm 깊이)가 19%이었으며 하층으로 갈수록 감소하여 6 cm 깊이에서는 14%이었다. 칠면초 종자는 표면으로부터 2 mm 이내에 45%가 매토되어 있었고 하층으로 갈수륵 급격히 감소하여 12 mm깊이 이후에는 없었다. 갑각류의 서식밀도는 식생지는 비식생지보다 높았으며 특히, 세스랑게류의 겉은 약 8 배이었다. 식생지에서 갑각류가 하층으로부터 파낸 저질의 양을 추정한 결과 2,409 $cm^3{\cdot}m^{-2}$이었으며 이는 저토의 높이를2.4 mm 상승시킬 수 있는 양이었다. 따라서 칠면초 종자는 자신의 고사체와 갑각류가 구멍을 형성하는 동안 파낸 저토에 의해 매토될 수 있는 것으로 판단되었다. 또한 식생지는 비식생지보다 많은 양의 갑각류가 서식하는 결과에 의하면 갑각류는 칠면초로부터 일부 이득을 얻는 것으로 판단되었다.

• 한국지구과학회지
• /
• 제27권7호
• /
• pp.787-803
• /
• 2006

The drought index has been developed, based on a $8.6{\mu}m$ surface emissivity in the $8-12{\mu}m$ MODIS channels over the African Sahel region (10-20 N, 13 W-35 W) and the Seoul Metropolitan Area (SMA: 37.2-37.7 N, 126.6-127.2 E). The emissivity indicates the $SiO_2$ strength and can vary interannually by vegetation, water vapor, and soil moisture, as a potential indicator of drought conditions. In a well-vegetated region close to 10 N of the Sahel, the Normalized Difference Vegetation Index (NDVI) showed high sensitivity, while the emissivity did not. On the other hand, the NDVI experienced negligible variability in a poorly vegetated region near 20 N, while the emissivity reflected sensitively the effects of atmospheric water vapor and soil moisture conditions. Seasonal variations of the emissivity (0.94-0.97) have been examined over the SMA during the 2003-2004 period compared to NDVI (or Enhanced Vegetation Index; EVI). Here, the dryness was more severe in urban area with less vegetation than in suburban area; the two areas corresponded to the north and south of the Han river, respectively. The emissivity exhibiting a significant spatial correlation of ${\sim}0.8$ with the two indices can supplement their information.

• 환경영향평가
• /
• 제19권5호
• /
• pp.511-525
• /
• 2010

Understanding of the hydraulics of flow over vegetation is very important to support the management of fluvial processes. The objective of this study is to assess the effects of hydraulic influence by tree planting in a compound channel with vegetated floodplain. This study analyzes the influence of tree planting on hydraulic features in Young-river in Munkyung city using HEC-RAS and RMA-2 model. The study results showed that there is a rise in water surface elevation and decrease in velocity near vegetated area. It is also ascertained that only negligible effects was seen within the feasible range of freeboard for the existing levees. However, as hydraulic features can vary depending on the aspect of flood inundation during each flood period, it is necessary to accumulate data through continuous data collecting.