• 생태와환경
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• 제48권1호
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• pp.68-76
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• 2015

화산섬 제주도 하천에는 버드나무류 (Salix spp.) 연목림 식생은 존재하지 않는다. 대신에 일부 하천 구간에서 유전적 고립개체군으로서 중대가리나무 식생이 발달한다. 그럼에도 획일적인 하천정비사업으로 중대가리나무의 현존 서식처 및 잠재 서식 공간이 크게 위협받고 있다. 본 연구는 중대가리나무 식생에 대한 군락분류 및 군락생태를 규명하였다. 중대가리나무가 분포하는 전역에 대하여 전통적인 식물사회학적 방법으로 전수조사를 실시하였다. 총 91개 지점에서 11개 식생조사표(phytosociological relev$\acute{e}$)를 획득하였고, 기발표 자료 (식생조사표 총 16개)를 수합하여 비교분석하였다. 종조성의 질적 양적 유의성 분석은 PCoA (Principal coordinates analysis)를 이용한 좌표결정을 수행했다. 본 연구에서는 산철쭉에 대한 군락분류 및 군락지리를 근거로 산철쭉-중대가리나무군집 (Adino-Rhododendretum poukhanensae Itow et al., 1993)을 폐기하고, 중대가리나무-교래잠자리피군집 (Tripogono-Adinetum rubellae ass. nova hoc loco), 중대가리나무군단 (Adinion rubella all. nova hoc loco)을 새로이 기재하였다. 본 단위식생은 제주도 서귀포생태역의 간헐천(間歇川, ephemeral stream) 물길구간내에서 지하수와 완전 격리된 하천식생형(partly ombrotrophic vegetation in ephemeral stream)으로 규정되었다. 한반도 내에서의 대응식생형으로 산철쭉군단 (Rhododendrion poukhanensae Lee, 2004 ex. hoc loco)을 기재하고, 갯버들-달뿌리풀군단 (Phragmito-Salicion)과의 명백한 상이성을 기재했다. 중대가리나무 식생은 제주도 고유의 식생자원으로 절대감시 1급 국가식생자원의 절대(absolute)감시 보존 대상으로 보호대책이 요청되었다.

• 한국환경과학회지
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• 제22권5호
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• pp.515-522
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• 2013

To investigate groundwater variation characteristics in the Hancheon watershed, Jeju Island, an integrated hydrologic component analysis was carried out. For this purpose, SWAT-MODFLOW which is an integrated surface-groundwater model was applied to the watershed for continuous watershed hydrologic analysis as well as groundwater modeling. First, ephemeral stream characteristics of Hancheon watershed can be clearly simulated which is unlikely to be shown by a general watershed hydrologic model. Second, the temporally varied groundwater recharge can be properly obtained from SWAT and then spatially distributed groundwater recharge can be made by MODFLOW. Finally, the groundwater level variation was simulated with distributed groundwater pumping data. Since accurate recharge as well as abstraction can be reflected into the groundwater modeling, more realistic hydrologic component analysis and groundwater modeling could be possible.

• 한국환경과학회지
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• 제20권10호
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• pp.1347-1355
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• 2011

In Jeju island, runoff has frequently happened when the rainfall depth is over a threshold value. To simulated this characteristic rainfall-runoff model structure has to be modified. In this study, the TRSM (Threshold Runoff Simulation Method) was developed to overcome the limitations of SWAT in applying to the hydrologic characteristics of Jeju island. When the precipitation and soil water are less than threshold value, we revised the SWAT routine not to make surface/lateral or groundwater discharge. For Hancheon watershed, the threshold value was set as 80% of soil water through the analysis of rainfall-runoff relationship. Through the simulation of test watershed, it was proven that TRSM performed much better in simulating pulse type stream flow for the Hancheon watershed.

• 한국환경과학회지
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• 제22권5호
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• pp.543-554
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• 2013

Acoustic Doppler Current Profilers (ADCPs) are increasingly popular in the river research and management communities being primarily used for estimation of stream flows. ADCPs capabilities, however, entail additional features that are not fully explored, such as morphological representation of river or reservoir bed based upon multi-beam depth measurements. In addition to flow velocity, ADCP measurements include river bathymetry information through the depth measurements acquired in individual 4 or 5 beams with a given oblique angle. Such sounding capability indicates that multi-beam ADCPs can be utilized as an efficient depth-sounder to be more capable than the conventional single-beam eco-sounders. The paper introduces the post-processing algorithms required to deal with raw ADCP bathymetry measurements including the following aspects: a) correcting the individual beam depths for tilt (pitch and roll); b) filtering outliers using SMART filters; d) transforming the corrected depths into geographical coordinates by UTM conversion; and, e) tag the beam detecting locations with the concurrent GPS information; f) spatial representation in a GIS package. The developed algorithms are applied for the ADCP bathymetric dataset acquired from Han-Cheon in Jeju Island to validate themselves applicability.

• 한국환경과학회지
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• 제24권4호
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• pp.403-414
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• 2015

This study is daytime and nighttime runoff image data caused by heavy rain on May 27, 2013 at Oedo Water Treatment Plant of Oedo-Stream, Jeju to compute runoff by applying Surface image velocimeter (SIV) and analyzing correlation according to current. At the same time, current was comparatively analyzed using ADCP observation data and fixed electromagnetic surface current meter (Kalesto) observed at the runoff site. As a result of comparison on resolutions of daytime and nighttime runoff images collected, correlation coefficient corresponding to the range of 0.6~0.7 was 6.8% higher for nighttime runoff image compared to daytime runoff image. On the contrary, correlation coefficient corresponding to the range of 0.9~1.0 was 17% lower. This result implies that nighttime runoff image has lower image quality than daytime runoff image. In the process of computing current using SIV, a rational filtering process for correlation coefficient is needed according to images obtained.

• 한국환경과학회지
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• 제24권4호
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• pp.359-369
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• 2015

This study analyzed the velocimetry of runoff and measured the flood discharge by applying the SIV (Surface Image Velocimetrer) to the daytime and nighttime flow image data with special reference to Seong-eup Bridge at Cheonmi stream of Jeju during the flow by the severe rainstorm on May 27, 2013. A 1000W lighting apparatus with more than 150 lux was installed in order to collect proper nighttime flow image applied to the SIV. Its value was compared and analyzed with the velocity value of the fixed electromagnetic wave surface velocimetry (Kalesto) at the same point to check the accuracy and applicability of the measured velocity of flow. As a result, determination coefficient $R^2$ values were 0.891 and 0.848 respectively in line with the velocity distribution of the daytime and nighttime image and the flow volume measured with Kalesto was approximately 18.2% larger than the value measured with the SIV.

• 한국환경과학회지
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• 제25권8호
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• pp.1165-1176
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• 2016

The accuracy of digital elevation models (DEMs) is crucial for properly estimating flood inundation area. DEM pixel size is especially important when generating flood inundation maps of small streams with a channel width of less than 50 m. In Korea, DEMs with large spatial resolutions of 30 m have been widely applied to generate flood inundation maps, even for small streams. Additionally, when making river master plans, field observations of stream cross-sections, as well as reference points in the middle of the river, have not previously been used to enhance the DEM. In this study, it was graphically demonstrated that high-resolution DEMs can increase the accuracy of flood inundation mapping, especially for small streams. Also, a methodology was proposed to modify the existing low-resolution DEMs by adding additional survey reference points, including river cross-sections, and interpolating them into a high spatial resolution DEM using the inverse distance weighting method. For verification purposes, the modified DEM was applied to Han stream on Jeju Island. The modified DEM showed much better accuracy when describing morphological features near the stream. Moreover, the flood inundation maps were formulated with the original 30 m pixel DEM and the modified 0.1 m pixel DEM using HEC-RAS modeling of the actual flood event of Typhoon Nari, and then compared with the flood history map of Nari. The results clearly indicated that the modified DEM generated a similar inundation area, but a very poor estimate of inundation area was derived from the original low-resolution DEM.

• 환경생물
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• 제35권1호
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• pp.57-63
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• 2017

본 연구는 제주도에서 외래침입종인 붉은귀거북 (Trachemys scripta elegans)의 지리적 분포와 현황을 살펴보기 위하여 수행되었다. 붉은귀거북의 서식지는 총 32개 지점이었고, 25개의 연못과 5개의 저수지, 1개의 하천과 1개의 웅덩이에서 관찰되었다. 발견된 서식지 중에서 13개 지점은 이번 조사에서 새롭게 확인되었고, 나머지 19개 지점은 기존 연구에서 보고된 지점이었다. 반면, 사전 연구에서 보고된 서식지 중 9개 지점에서는 붉은귀거북이 관찰되지 않았다. 전체적으로 붉은귀거북 133개체가 관찰되었다. 그중에서 39개체의 유체들이 19개 서식지에서 발견되었고, 이는 제주도의 야생생태계에서 붉은귀거북들이 번식활동을 하고 있음을 의미하는 것이다. 바다에 의한 지리적 격리로 19세기까지 제주도에는 담수거북류가 서식하지 않았다. 따라서 붉은귀거북 서식지와 개체수의 증가는 애완용이나 다른 목적으로 도입된 이후 인간에 의한 방류, 자연 상태에서의 번식에 의한 결과로 추정되었다. 본 연구의 결과는 제주도에서 고유 야생 동물에 대한 보존프로그램의 운영과 침입외래종인 붉은귀거북에 대한 관리 계획 수립에 유용하게 활용될 것이다.

• 한국환경과학회지
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• 제21권6호
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• pp.725-738
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• 2012

Recently, a variety of GIS-based tools enabling to generate topographic parameters for hydrologic and hydraulic researches have been developed. However, most of GIS-based tools are usually insufficient to estimate and visualize river channel slopes especially along the river network, which can be possibly utilized for many hydraulic equations such as Manning's formula. Many existing GIS-based tools have simply averaged cell-based slopes for the other advanced level of hydrologic units as likely as the mean watershed slope, thus that the river channel slope from the simple approach resulted in the inaccurate channel slope particularly for the mountain region where the slope varies significantly along the downstream direction. The paper aims to provide several more advanced GIS-based methodologies to assess the river channel slopes along the given river network. The developed algorithms were integrated with a newly developed tool named RiverSlope, which adapted theoretical formulas of river hydraulics to calculate channel slopes. For the study area, Han stream in the Jeju island was selected, where the channel slopes have a tendency to rapidly change the upstream near the Halla mountain and sustain the mild slope adjacent to watershed outlet heading for the ocean. The paper compared the simple slope method from the Arc Hydro, with other more complicated methods. The results are discussed to decide better approaches based on the given conditions.

• 한국수산과학회지
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• 제9권4호
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• pp.251-255
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• 1976

1973년 8월 25일부터 1974년 9월 14일에 걸쳐 제주도 서귀포소재 천지천에서 채집한 총 362미의 은어에 대하여 체장, 체중관계와 비만도를 산란기를 중심으로 검토하여 다음과 같은 결과를 얻었다. 1. 체장, 체중관계에 있어 산란전과 산란기에는 그 관계식이 각각 $W=0.008639\;L^{3.1806}$과 $W=0.01830\;L^{2.7689}$로써 유의성이 인정되었으나 자웅간에는 유의성이 보이지 않았다. 2. 평균체장이 산란기에 감소현상이 나타나는데, 이것은 산란에 참여한 대형어의 폐사에서 온 은어 특유의 현상이라 보았다. 3. 비만도는 산란전인 8월에 평균 $13.45\%_{\circ}$ 였던 것이 9월부터 점차로 감소, 11월 29일에 가서 최저로 평균 $10.25\%_{\circ}$였으며, 다음 해인 2월에는 $11.18\%_{\circ}$로 고복단계에 있었다. 4. 월년어의 대부분은 全전장 $11\~12cm$ 미만의 소형어였다.