• Korean Journal of Ecology and Environment
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• v.47 no.4
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• pp.258-272
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• 2014

Bats hibernating in caves and unused mines were surveyed during six hibernation periods (from December to February, 2005 and 2011) in Korea. We recorded 13,288 individuals of 11 species at 140 hibernacula (60 caves and 80 abandoned mines): Rhinolophus ferrumequinum (n=3,509), Eptesicus serotinus (n=6), Hypsugo alaschanicus (n=349), Miniopterus fuliginosus (n=5,919), Murina hilgendorfi (n=417), Myotis aurascens (n=294), Myotis bombinus (n=2), Myotis formosus (n=401), Myotis macrodactylus (M.mac, n=151), Myotis petax (n=2,131) and Plecotus ognevi (n=109). We studied the thermal preference and selection of hibernacula of seven dominant bat species. Four species (Myotis petax, Hypsugo alaschanicus, Plecotus ognevi and Murina hilgendorfi) hibernated mainly at the cold site below than $7^{\circ}C$, while three species (Myotis formosus, Rhinolophus ferrumequinum and Miniopterus fuliginosus) hibernated at warm site above than $7^{\circ}C$. Rhinolophus ferrumequinum had broad-ranged temperature zone for their hibernating site. The mean body temperature of each species was $2.64{\pm}0.98^{\circ}C$ for Murina hilgendorfi, $2.76{\pm}1.68^{\circ}C$ for Hypsugo alaschanicus, $2.78{\pm}0.98^{\circ}C$ for Plecotus ognevi, $4.52{\pm}1.02^{\circ}C$ for Myotis petax, $7.83{\pm}1.94^{\circ}C$ for Miniopterus fuliginosus, $9.19{\pm}2.35^{\circ}C$ for Rhinolophus ferrumequinum and $13.64{\pm}0.76^{\circ}C$ for Myotis formosus, respectively. The body temperatures of hibernating bats were closely related to the rock surface temperatures rather than the ambient temperatures. In conclusion, the diversity of bats community in hibernacula were closely related to the range of inner ambient temperature of hibernacula, and more species of bats were occupied at sites presenting a broad range of ambient temperatures.

• Korean Journal of Ecology and Environment
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• v.46 no.4
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• pp.561-569
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• 2013

This study examines locational environment factors that may affect the vegetation structure in the forests of Naejang National Park. To that end, we selected LAI (Leaf Area Index), diameter at breast height, and tree height as structural variables as well as altitude above sea level, gradient, slope direction, soil moisture, topographic location, and amount of solar radiation as locational environment factors, using the method of canonical correlation analysis in order to find out correlation between them. As to the simple correlation between the locational environment factors and structural variables, the correlation coefficient was relatively low (0.6). The values of LAI, measured along the ridge with higher altitudes, decreased as the soil moisture and solar radiation increased. However, LAI increased as the gradient increased and the slope direction faced the north (farther from the east). In respect of the diameter at breast height, the diameter decreased as the altitude and gradient increased. But the diameter increased as the moisture and solar radiation increased. The tree height decreased as the moisture increased and the site was closer to the ridge. These various correlations show a variety of locational environment factors in the national park, implying that the structural variables are affected by complex locational environment factors. This study conducted a canonical correlation analysis on locational environment factors which may affect the vegetation structure, and the result showed that LAI increased and tree height & diameter at breast height decreased as the solar radiation & moisture decreased and altitude increased. Although more factors that may affect vegetation structure (e.g. climate) should be taken into account, this study is significant in that the vegetation structure, which can adapt to more unfavorable conditions in terms of solar radiation, moisture, and higher altitudes, could be inferred in a statistical way. The results of this study, especially the locational environment factors based on DEM, can be used for assessing diversity of vegetation structure in a forest and for monitoring the structure in a national park on a regular basis so as to establish more effective maintenance plans of a park.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.4
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• pp.425-437
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• 2007

Flow distribution of water and sedimentation rate were investigated to understand the hydrodynamics and settling characteristics of particulate materials in a constructed wetland for treatment of non-point sources pollutants, the Sihwa constructed wetland, Korea. The Sihwa constructed wetland is divided into three sub-wetlands(the Banwol, the Donghwa and the Samhwa wetlands) to treat the polluted water from three streams, the Banwol stream, the Donghwa stream and the Samhwa stream. From the results of water flow experiment using dye(Rhodamine 50WT Red), it was found that the water flow in the wetland was prevailing at the waterway and open water. Dye was spread slowly in the closed water area planted by plants. The mean hydraulic retention time(HRT) at the upper area of high wetland and lower wetland of Banwol, was found to be 34.1 hr at the upper area and 74.6 hr at the lower area respectively, totaling approximately 108.7 hr(4.5 days). The sedimentation rate was higher at lower area(sites of B, C and D) of the wetland than upper area(site of A which is settling zone). Based on the forecast for 20 years as to the amount of sediment that can be deposited in the open water in the future, the sediment depth of each area would be like this: A: 6.3 cm, B: 8.3 cm, C: 7.0 cm, D: 9.5 cm. The contents of organic materials in the sediment deposited within the sediment trap were found to be higher overly in the first investigation period which had much rainfall, and B, C and D areas were found to have an increased COD accumulation than A area. Also, nitrogen and phosphorus were found to increase in the down-stream of the wetland. The results of this study suggest that a sustainable research and management for the characteristics of water flow pattern and sedimentation changeable as time passes is needs to maintain or improve the efficiency of water treatment in the constructed wetland.

• Korean Journal of Environmental Agriculture
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• v.26 no.2
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• pp.99-106
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• 2007

This study was focused on understanding the agricultural non-point sources pollution in 72 rural catchments of Nakdong river watershed from 2001 to 2005 every two year. Also. Pearson correlations between water quality and basin characteristic were computed. Water quality of this study watershed was better in 2003 than any other period. The water quality of upstream was recorded from 0.040 to 0.510 dS/m in EC, from 3.55 to 22.60 mg/L in DO, from 0.32 to 16.64 mg/L in T-N, from 0.00 to 12.21 mg/L in $NO_3-N$, from 0.000 to 0.860 mg/L in T-P, and from 0.000 to 0.640 mg/L in $PO_4-P$. A the downstream, EC was measured from 0.030 to 0.520 dS/m, DO from 4.13 to 18.36 mg/L, T-N from 0.38 to 26.88 mg/L, $NO_3-N$ from 0.10 to 20.12 mg/L, T-P from 0.002 to 0.820 mg/L, $PO_4-P$ from 0.002 to 0.690 mg/L. But there was no difference between upstream and downstream for the water quality. Based on the correlation analysis between water quality and land use, correlation between BOD and residential was the highest positive correlation of 0.541 (p<0.01), and correlation between $PO_4-P$ and forest was the highest negative correlation of -0.451 (p<0.01). Also, T-N, $NO_3-N$, and pH were not correlated with all basin characteristics and basin was not correlated with all water quality parameter. According to the correlation residential was causative of growing worst for water quality, and forest was causative of improving for water quality.

• Journal of Korea Water Resources Association
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• v.46 no.12
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• pp.1193-1207
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• 2013

Increase of impervious area caused by overdevelopment has led to increase of runoff and then the problem of flooding and NPS were brought up. In addition, as decrease of base flow made groundwater level to decline, a stream that dries up is issued. low impact development (LID) method which is possible to mimic hydrological water cycle, minimize the effect of development, and improve water cycle structure is proposed as an alternative. As introduction of LID in domestic increases, the study on small watershed is in process mainly. Also, analysis of property of hydrological runoff and load on midsize watershed, like sewage treatment district, is required, the study on it is still insufficient. So, area applying LID practices from watershed of Dongrae stream is pinpointed and made the ratio and then expand it to watershed of Oncheon stream. Among low impact development practices, Green Roof, Porous Pavement, and Bio- retention are selected for the application considering domestic situations and simulated with SWMM-LID model of each watershed and improvement of water cycle and reduction of non-point pollution loads was analysed. Improvement of water cycle and reduction of non-point pollution loads were analyzed including the property of rainfall and soil over long term simulation. The model was executed according to scenario based on combination of LID as changing conductivity in accordance with soil type of the watershed. Also, this study evaluated area of LID application that meets the efficiency of conventional management as a criteria for area of LID practices applying to sewer treatment district by comparing the efficiency of LID application with that of conventional method.

• Journal of Korea Water Resources Association
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• v.42 no.3
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• pp.235-246
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• 2009

This study theoretically reviews the basin storage coefficient and concentration time using the Nash model, a simple unit hydrograph theory. First, the storage coefficient and concentration time of Nash instantaneous unit hydrograph (IUH) are derived based on their definitions, whose characteristics as well as their relationship are also reviewed. Additionally, several empirical equations of storage coefficient and concentration time commonly used in Korea are evaluated by comparing them with those for the Nash IUH. Major results of this study are summarized as follows. (1) The concentration time of Nash IUH is approximately linearly proportional to the number of linear reservoirs, but the storage coefficient non-linearly to the square root. That is, if increasing the number of linear reservoirs by four times, the concentration time becomes also increased by about four times, but the storage coefficient only about two times. This result has a special meaning to understand the effect of basin subdivision on the concentration time and storage coefficient. (2) The storage coefficient and concentration time of Nash IUH are not independent each other, so their independent estimation does not make any physical sense. As the concentration time among the two is more sensitive to the number of linear reservoirs, which should be estimated first, then the storage coefficient considering the concentration time estimated. (3) Empirical equations of concentration time can be divided into two groups, one following the linear channel theory and the other not, whose equation forms are also found to be very similar. This result indicates that the characteristic factors dominating the concentration time are very similar, indicating the possibility of its regionalization over a basin with consistent equation forms. (4) Those for storage coefficient like the Russell formulae are found to consider the physical characteristics of a basin, so their unreasonable applications could sufficiently be excluded.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.3
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• pp.139-144
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• 2000

This study was conducted to obtain the basic information to increase the practical use of soil survey data through the subdividing of valley shapes with soil sequences due to different parent rocks, and to study the relationship between the valley shapes and parent rock. The various rocks such as sedimentary(gray shale and sand stone) and igneous rocks(granite, granite gneiss and andesite porphyry) which are the major parent rocks in Yeongnam area were investigated. The characteristics of valleys formed and the kinds of soils derived from different rocks were analysed by using aerial photographs and topographical maps scaled 1:5,000. The rill density in igneous rock area was as high as 40. But the rill bifurcation ratio of first order stream was higher in the sedimentary than the igneous rocks except granite area. The mean slope of valleys in igneous areas was about 8%, which was higher than that of the sedimentary areas. The variability of valley width in the complexly metamorphosed rock, such as granite gneiss, and andesite porphyry, was greater than in sedimentary and in granite rocks. Based on the variability of valley widths and valley slopes, it was possible to classify the valleys into two types. The "Uterus-shaped valleys" had wide variability of valley width and were located in the areas of granite gneiss and andesite porphry rocks. while the "Roots-shaped valleys" had narrow variability of valley width and were located in the sedimentary areas. "Uterus-shaped valleys" were typified by having land forms of mountain foot slopes and alluvial fans, and the soil drainage sequences also had complexities. So that, we concluded that the variability of valley width and valley slopes was associated with kinds of parent rocks and metamorphism which influences soil sequence and characteristics.

• Economic and Environmental Geology
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• v.52 no.1
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• pp.13-28
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• 2019

This study analyzed precipitation environment, heavy metal contamination, and mineral composition of white, reddish brown and mixed precipitates occurring at the Osip stream drainage, Gangwondo. Furthermore, spectral characteristics of the precipitates associated with heavy metal contamination and mineral composition was investigated based on spectroscopic analysis. The pH range of the precipitates was 4.43-6.91 for white precipitates, 7.74-7.94 for reddish brown precipitates, and 7.59-7.9 for the mixed precipitates, respectively. XRF analysis revealed that these precipitates were contaminated with Ni, Cu, Zn, and As. The white precipitates showed high Al concentration compared to reddish brown precipitates as much as 3.3 times, and the reddish brown precipitates showed high Fe concentration compared to white precipitates as much as 15 times. XRD analysis identified that the mineral composition of the white participates was aluminocoquimbite, gibbsite, quartz, saponite, and illite, and that of reddish brown precipitates was aluminum isopropoxide, kaolinite, goethite, dolomite, pyrophyllite, magnetite, quartz, calcite, pyrope. The mineral composition of the mixed precipitates was quartz, albite, and calcite. The spectral characteristics of the precipitates was manifested by gibbsite, saponite, illite for white precipitates, goethite, kaolinite, pyrophyllite for reddish brown precipitates, and albite for the mixed precipitates, respectively. The spectral reflectance of the precipitates decreased with increase in heavy metal contamination, and absorption depth of the precipitates indicated that the heavy metal ions were adsorbed to saponite and illite for white precipitates, and goethite and magnetite for reddish brown precipitates.

• Journal of Korea Water Resources Association
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• v.54 no.8
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• pp.629-641
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• 2021

In this study, a two-dimensional numerical model (Nays2DH) was applied to analyze the process of morphological changes in the river channel bed depending on the changes in the amount of flooding after fully opening the Sejong weir, which was constructed upstream of the Geum River. For this, numerical simulations were performed by assuming the flow conditions, such as a non-uniform flow (NF), unsteady flows (single flood event, SF), and a continuous flood event (CF). Here, in the cases of the SF and CF, the normalized hydrograph was calculated from real flood events, and then the hydrograph was reconfigured by the peak flow discharge according to the scenario, and then it was employed as the flow discharge at the upstream boundary condition. In this study, to quantitatively evaluate the morphological changes, we analyzed the time changes in the bed deformation the bed relief index (BRI), and we compared the aerial photographs of the study area and the numerical simulation results. As simulation results of the NF, when the steady flow discharge increases, the ratio of lower width to depth decreases and the speed of bar migration increases. The BRI initially increases, but the amount of change decreased with time. In addition, when the steady flow discharge increases, the BRI increased. In the case of SF, the speed of bar migration decreased with the change of the flow discharge. In terms of the morphological response to the peak flood discharge, the time lag also indicated. In other words, in the SF, the change of channel bed indicates a phase lag with respect to the hydraulic condition. In the result of numerical simulation of CF, the speed of bar migration depending on the peak flood discharges decreased exponentially despite the repeated flood occurrences. In addition, as in the result of SF, the phase lag indicated, and the speed of bar migration decreased exponentially. The BRI increased with time changes, but the rate of increase in the BRI was modest despite the continuous peak flooding. Through this study, the morphological changes based on the hydrological characteristics of the river were analyzed numerically, and the methodology suggested that a quantitative prediction for the river bed change according to the flow characteristic can be applied to the field.

• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.35-48
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• 2022

Fish assemblage of total 325 of Korean peninsula estuaries were surveyed to analyze the characteristics of community structure and diversity by sea areas for three years from 2016 to 2018. The scale (stream width) of Korean estuaries were various (14~3,356 m), and 68.9% of all estuaries showed salinity of less than 2 psu. Total 149 species classified into 52 families of fish were identified, and the dominant and sub-dominant species were Tribolodon hakonensis (relative abundance, RA, 12.5%) and Mugil cephalus (RA, 9.5%), respectively. The estuary of the Korean Peninsula had different physical and chemical habitat environments depending on the sea area, and accordingly, fish community structure also showed statistically significant differences (PERMANOVA, Pseudo-F=26.69, P=0.001). In addition, the NMDS (nonmetric multidimensional scaling) results showed the patterns that indicating fish community difference by sea areas, even though low community similarity within sea area (SIMPER, 21.79~26.39%). The estuaries of east sea areas were distinguished from the others in the aspects of which, the higher importance of migratory fishes and endangered species, and that of brackish species were characterized at south sea estuaries. However, the estuaries of west sea showed higher importance of species that have a relation with freshwater (primary freshwater species, exotic species), which is the result that associating with the lower salinity of west sea estuaries because of the high ratio of closed estuaries(78.2%). The SIMPER analysis, scoring the contribution rates of species to community similarity, also showed results corresponding to the tendency of different fish community structures according to each sea area. So far, In Korea, most studies on fish communities in estuaries have been conducted in a single estuary unit, which made it difficult to understand the characteristics of estuaries at the national level, which are prerequisite for policy establishment. In present study, we are providing fish community structure characteristics of Korean estuaries in a national scale, including diversity index, habitat salinity ranges of major species, distribution of migratory species. We are expecting that our results could be utilized as baseline information for establishing management policies or further study of Korean estuaries.