• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.13 no.3
• /
• pp.46-62
• /
• 2010

This study was conducted to understand the water and soil properties to propose the promotion of vegetation environment at farm pond depression. We selected 8 palustrine wetlands from agricultural area after consideration of human interference, surround land use, and size of area. Water quality analysis showed that the average SS, T-N, T-P were over the limit of agricultural water quality standard level at some sites. The cause for deterioration of water quality is supposed by the long-term stagnation of water in palustrine wetland. The recommended measures to improve water quality are as follows; improving water circulation by connecting with nearby natural water, preventing oxygen depletion by dredging deposit, lowering down T-N and T-P by removing autumn plants, preventing inflow of phosphorus in fertilizer ingredients which is the main cause for high T-P. The soil contamination of the surveyed area was about the same level of average heavy metal contents in soils from 2,010 paddy fields in Korea, which was much lower than soil contamination standards. As for soil texture, sand content was 40~90% and clay content was less than 20%. The content of silt and clay in soil from community of floating-leaved:submerged hydrophytes and community of emergent hydrophytes was higher that of soil from community of hygrophytes, and the content of sand in soil from community of hygrophytes was 10% higher than underwater soil. In terms of bulk density, the average was 0.24~0.96g/$cm^3$, which was quite low, because of high content of peat and organic matter in soil of the surveyed area. As for the average content of organic matter, community of floating-leaved:submerged hydrophytes was 18.25g/kg, community of emergent hydrophytes was 16.88g/kg, and community of hydrophytes was 25.63g/kg. The range of content of T-N in soil of community of floating-leaved；submerged hydrophytes was 0.022~0.307%, and that of community of emergent hydrophytes was 0.029~0.681% and that of community of hydrophytes was 0.088~0.325%. Apart from three sites in the surveyed area, most parts were over the standards or below the standard. After this study, we will conduct and discuss the relationship between vegetation characteristics and environments, which will be used of the best practical management and restoration of wetland.

• Journal of Wetlands Research
• /
• v.12 no.3
• /
• pp.129-144
• /
• 2010

We have studied the changes of the environmental and vegetational factors according to the hydro-seral stages in the shoreline of the lagoons, Korea. We have divided seral stages into 7 stages from open water stage to the stratified forest stage considering as the characteristics of water body, dominance of submerged and emergent plant, and development of the shrub, subtree and tree layer. According to the successional stage, water depth gradually decreased and water quality changed from seawater to brackish water and from brackish water to fresh water, organic matter in a soil layer gradually increased, and the litter layer grew up. As the development of the vegetation structure, the life-form of the vascular plants changed as follows; open water ${\rightarrow}$ submerged plant and floating-leaved plant ${\rightarrow}$ emergent plant and submerged plant ${\rightarrow}$ emergent plant ${\rightarrow}$ emergent plant, mesophyte and scrub ${\rightarrow}$ mesophyte. In the late seral stage, the 3 different forest types were established by the water retention or drainage and nutrient accumulation of the soil layer. Salix dominant forest developed in the wetted sites, the forest type dominated by Pinus thunbergii, Carex pumila and mesophytes developed in the well drained sites causing by sand substrate, and the forest type dominated by the planted or ruderals such as Pinus densiflora, Robinia psedo-acacia, Festuca ovina, Setaria viridis ect. developed in the sites composed of forest soil introduced by artificial reclamation.

• Journal of Korea Water Resources Association
• /
• v.33 no.5
• /
• pp.581-592
• /
• 2000

Turbulence structure and suspended sediment transport capacity in vegetated open-channel flows are investigated numerically in the present paper. The $\textsc{k}-\;\varepsilon$ model is employed for the turbulence closure. Mean velocity and turbulence characteristics including turbulence intensity, Reynolds stress, and production and dissipation of turbulence kinetic energy are evaluated and compared with measurement data available in the literature. The numerical results show that mean velocity is diminished due to the drag provided by vegetation, which results in the reduction of turbulence intensity and Reynolds stress. For submerged vegetation, the shear at the top of vegetation dominates turbulence production, and the turbulence production within vegetation is characterized by wakes. For emergent condition, it is observed that the turbulence generation is dominated by wakes within vegetation. In general, simulated profiles compares favorably to measured data. Computed values of eddy viscosity are used to solve the conservation equation for suspended sediment, yielding sediment concentration more uniform over the depth compared with the one in the plain channel. The simulation reveals that the suspended load decreases as the vegetation density increases and the suspended load increases as the particle diameter decreases for the same vegetation density.

• Fisheries and Aquatic Sciences
• /
• v.7 no.3
• /
• pp.148-162
• /
• 2004

The monitoring activities at the National Fisheries Research and Development Institute (NFRDI) in Korea have been extended to include all the coastal waters of Korea after the outbreak of Cochlodinium polykrikoides blooms in 1995. We used several alternative methods including climatological analysis, spectral and optical methods which may offer potential detection of the major species of red tide in Korean waters. In the climatological analysis, NOAA, SeaWiFS, OCM satellite data was chosen using the known C. polykrikoides red tide bloom data and the area was mapped by helicopter reconnaissance and ground observation. The relationship between the distribution of sea surface temperature to C. polykrikoides bloom areas was studied. The anomalies of SeaWiFS chlorophyll a imageries against the imageries of non-occurring red tide for August, 2001 showed where the C. polykrikoides occurred. The anomalies of chlorophyll a concentrations from the satellite data during red tide outbreaks showed a similar distribution of C. polykrikoides in the red tide in August, 2001. The distribution between differences in sea surface temperatures during the day and at night also showed a possibility for red tide detection. We used a corrected vegetation index (CVI) to detect floating vegetation and submerged vegetation containing algal blooms. The results of from the optical absorption of C. polykrikoides in the ultraviolet band (340 nm) showed that if we use the optical characteristics from each red tide, we will be able to establish the feasibility of red tide detection.

• Proceedings of the KSRS Conference
• /
• 2003.11a
• /
• pp.654-655
• /
• 2003

Korea has experienced 10 a Cochlodinium polykrikoides red tide outbreaks during the last 10 years (1993-2002). The monitoring activities at National Fisheries Research and Development Institute (NFRDI) in Korea have been extended to all the coastal waters after the worst of fish killing by C. polykrikoides blooms in 1995. NFRDI is looking forward to finding out the feasibility of red tide detection around Korean waters using satellite remote sensing of NOAA/AVHRR, Orbview-2/SeaWiFS, IRS-P4/OCM and Terra/MODIS on real time base. In this study, we used several alternative methods including climatological analysis, spectral and optical methods which may offer a potential detection of the major species of red tide in Korean waters. The relationship between the distribution of SST and C. polykrikoides bloom areas was studied. In climatological analysis, NOAA, SeaWiFS, OCM satellite data in 20th and 26th August 2001 were chosen using the known C. polykrikoides red tide bloom area mapped by helicopter reconnaissance and ground observation. The 26th August, 2001 SeaWiFS chlorophyll a anomaly imageries against the imageries of non-occurring red tide for August 20, 2001 showed the areas C. polykrikoides occurred. The anomalies of chlorophyll a concentration from satellite data between before and after red tide outbreaks showed the similar distribution of C. polykrikoides red tide in 26th August, 2001. The distribution of the difference in SST between daytime and nighttime also showed the possibility of red tide detection. We used corrected vegetation index (CVI) to detect floating vegetation and submerged vegetation containing algal blooms. The simple result of optical absorption from C. polykrikoides showed that if we use the optical characteristics of each red tide we will be able to get the feasibility of the red tide detection.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2006.05a
• /
• pp.1275-1280
• /
• 2006

자연 저항체인 식생은 유체역학적으로 하천의 평균흐름과 난류량을 변화시키며, 이와 관련하여 유사, 영양 물질, 용존 산소, 그리고 서식 동물 등에 많은 영향을 미치는 것으로 알려져 있다. 과거에는 식생된 수로의 흐름을 식생에 의해 항력이 증가된 경계층 흐름으로 단순하게 보아 왔으나, 근래의 실험유체역학적 연구는 식생된 하천 흐름에 대한 미시적인 구조를 규명하였다. 본 연구는 식생수로에서 평균흐름 및 난류량에 관한 수리특성을 분석하고자 하며, 부유사의 퇴적, 유입, 이송 등의 거동에 큰 영향을 미치는 것으로 알려진 고유구조를 파악하였다. 식생된 개수로 흐름의 일반적인 평균흐름 및 난류구조는 기존의 연구결과와 동일하였으며, 본 연구에서 중점을 둔 고유구조의 경우, 식생높이를 기준으로 하여 상 하부의 흐름특성이 서로 상이한 것을 확인하였다. 식생높이 상부에서는 유속이 수면방향을 향하는 분출현상이 지배적으로 나타났으며, 식생높이 하부에서는 이와는 반대로 유속의 변동성분이 하상으로 향하는 쓸기현상이 지배적으로 나타났다. 이는 개수로에 식생이 존재할 경우 부유사의 농도분포가 수심에 따라 일정해지는 것에 대한 물리적인 근거로 파악된다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2009.05a
• /
• pp.400-404
• /
• 2009

본 연구에서는 곧은 식생과 유연한 식생 및 다양한 수심비를 갖는 개수로 흐름 조건에 대한 수리실험을 실시하였다. 레이저 도플러 유속계를 이용하여 수로 전체 단면의 유속을 측정함으로써, 이차흐름이 평균유속 및 난류량에 미치는 영향을 분석할 수 있도록 하였다. 평균유속의 경우, 수치모의결과와 동일하게 측벽근처에서 최대 유속이 발생하였다. 유속측정자료를 이용하여 침수식생 개수로 흐름의 벡터도를 살펴본 결과, 침수식생 개수로의 경우 일반 개수로 흐름과는 달리 바닥 와 (bottom vortex)가 측벽 근처에서 매우 활발한 것으로 나타났으며, 이로 인해 수로 중앙의 높은 운동량을 가진 유체가 측벽방향으로 이동하고 있음을 확인하였다. 또한 측벽에서 이차흐름으로 인해 발생하는 강한 하강류가 레이놀즈응력 및 난류 강도의 수직방향 분포 형태에 영향을 미치는 것을 확인하였다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2008.05a
• /
• pp.669-673
• /
• 2008

본 연구에서는 식생 하층 및 상층영역의 층평균 유속 및 유속 분포에 관련한 모형을 제시하였다. 제안된 모형을 정상류 흐름에 적용할 경우, 수심, 경사, 식생밀도, 식생높이와 같은 기본조건만을 이용하여, 각 층의 평균유속 뿐만 아니라 유속 분포를 산정할 수 있다. 모의 식생 및 레이저 도플러 유속계를 이용한 실내 수리실험을 수행하여 제안식의 적용성 및 정확성을 파악하였고, 기존 문헌 자료의 유속 및 식생 자료를 이용하여 범용성을 확인하였다. 분석 결과 본 연구에서 제시된 제안식이 비교적 정확하게 각 식생층의 평균유속을 산정하는 것으로 나타났으며, 식생조건 및 흐름조건의 변화에 따른 조도계수의 변화 양상에 대해 살펴보았다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2011.05a
• /
• pp.241-241
• /
• 2011

일반적으로 식생흐름의 층 적분 모형은 층의 수에 따라 2층 및 3층 모형으로 구분한다. 즉, 전체 수심을 식생영역과 상부영역으로 구분하는 2층 모형과 식생영역을 바닥 조도의 영향 유무에 따라 내부 및 외부 식생영역으로 구분하는 3층 모형으로 나뉜다. 본 연구에 사용된 수리실험 자료는 기존의 연세대학교에서 수행한 실험결과를 이용하여 각 모형의 정확성을 예측해 보았다. 다양한 실험조건에 적용한 결과, 3층 모형이 식생영역에서 유속의 변화를 고려할 수 있지만 레이놀즈응력의 영향에 민감하고, 적분된 유속은 2층 모형에 의한 예측 결과가 더욱 정확하였다. 3층 모형에서는 내부 식생영역의 결과는 전체흐름구조에 미미한 영향을 미치므로 무시할 수 있으며, 이를 바탕으로 식생영역에서 유속 변화가 고려되는 수정 2층 모형을 제시하였다. 본 연구를 통하여 기존의 2층 모형과 3층 모형의 장점을 취합하여 수정된 2층 모형의 방정식을 바탕으로 모형의 정확성을 평가하기 위하여 2층 모형, 3층 모형, 수정 2층 모형의 유속 분포를 비교 분석하여 모형을 검증하였다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2007.05a
• /
• pp.930-934
• /
• 2007

본 논문은 수리실험을 통해 침수식생 개수로의 단면특성을 살펴보고자 하는 실험논문이다. 레이저 도플러 유속계를 이용하여 측벽으로부터의 거리에 따른 침수식생 개수로의 2차원 순간속도를 측정하였다. 측정된 유속자료를 이용하여, 평균유속, 레이놀즈응력, 난류강도를 살펴보았으며, 침수식생 개수로 흐름의 단면특성을 살펴보았다. 실험결과 침수식생 개수로는 기존의 일반적인 개수로흐름과는 다른 단면 흐름특성을 보이는 것을 확인하였다. 특히 최대유속 발생지점이 수로 중앙이 아닌 측벽 근처로 이동하였으며, 이차흐름의 영향으로 인하여 흐름방향 등유속선의 물결형태와 레이놀즈응력 및 난류강도의 최대값 발생위치 이동과 같은 현상이 발생하는 것을 확인하였다.