When an agricultural soil dam collapses, the extent of inundation and the rate of diffusion vary depending on where the collapse occurs in the dam body. In this study, a dam collapse scenario was established and a two-dimensional numerical model FLO-2D was used to closely examine the inundation pattern of the downstream residential area according to the dam collapse point. The results were presented as a flood risk map showing the changes and patterns of the extent of inundation spread. The flood level and the time to reach the maximum water level vary depending on the point of collapse, and the inundation of the downstream area proceeds rapidly in the order of the midpoint, left point, and right point collapse. In the left collapse point, the submergence appeared about 0.5 hour slower than the middle point, and the right collapse point appeared about 1 hour slower than the middle point. Since the relative damage pattern is different depending on the dam collapse point, insurance and disaster countermeasures will have to be established differently.
This field experiment aimed to identify the optimal planting density for establishing a management plan for ground-cover plants under roadside trees. Liriope platyphylla and Hosta longipes both widely used for planting under trees were selected as the plant materials and planted under Prunus serrulata var. spontanea at different planting densities. Based on the distance between each plant, 4 planting densities were used: 11%, 25%, 49%, and 83% with three replications. To estimate plant growth, plant height, number of leaves and tillers, fresh and dry weight, and visual quality were investigated. Liriope platyphylla exhibited relatively better growth at the highest planting density of 83%. For Hosta longipes, however, the lower growth was positively correlated with high planting density. Therefore, the optimal planting density for Liriope platyphylla is 83% and for Hosta longipes is 11%.
This study was to evaluate the utilization of terrestrial light detection and ranging for forest inventory in coniferous forests. Heights and diameter of the stand trees were measured manually using the traditional measurement method and the method using terrestrial LiDAR. The results of two methods were compared and analyzed to evaluate accuracy and feasibility. The terrestrial LiDAR used fixed and handy types to compare the accuracy between different operational methods. Comparative analyses used a paired t-test and Bland-Altman plot analysis. In the case of tree heights, the average of difference between the traditional method and terrestrial LiDAR for each plot was 0.81 m, -0.07 m, and 0.13 m for fixed type; 2.88 m, 1.19 m, and 0.93 m for the handy type. In the case of tree diameter at breast height, the average value of the difference between traditional methods and terrestrial LiDAR for each plot was 0.13 cm, -0.66 cm, and –0.03 cm for fixed type; 2.36 cm, 2.13 cm, and 1.92 cm for the handy type. The values from the method using the fixed type was highly consistent with that using the traditional measurement methods; the average difference was closer to zero. The crown density influences the precision of the height measurement using terrestrial LiDAR in coniferous forests. Therefore, future studies should focus on verifying the a
This study evaluated the contamination levels of inland pollution sources flowing into Taeanhaean National Park. The nutritional status of influents was assessed by analyzing water quality and trophic status index (TRIX) at 52 stations, and the contamination levels of sediments were evaluated by analyzing eutrophication cleanup index (CIET) and heavy metals at 36 stations. The results of the TRIX analysis showed that 26 of the 52 stations had influents with a TRIX value of 6-10 (poor water quality/very high trophic level), indicating atrocious water quality and high eutrophication levels. The results of the CIET analysis showed that 4 out of the 36 stations were highly contaminated with organic matter. Analysis of heavy metals showed that the copper (Cu) and zinc (Zn) levels exceeded the threshold effects level (TEL) and probable effects levels (PEL) at several stations. In addition, the arsenic (As) level exceeded the threshold effects level at one station, and the levels of the other heavy metals (Cd, Cr6+, Ni, Pb, and Hg) were lower. Most inland pollution sources have been identified as small-scale, but long-term and continuous exposure can negatively affect the marine ecosystem; therefore, it necessary to prepare inland pollution source management standards and measures suitable for the characteristics of the coastal area.
This research investigated the effect of the eruption of Japan Sakurajima volcano on the concentration of ultrafine particle when the north Pacific high pressure exists in the Busan in summer. As a result of analyzing the forward trajectory using the HYSPLIT model, the air parcel from Sakurajima volcano passed through the sea in front of Busan at 1500 LST on July 17, 24 hours after the volcanic eruption. As a result of analyzing the PM10 and PM2.5 concentrations in the Busan for two days from July 16 to 17, 2018, the Sakurajima eruption in Japan, it can be seen that there was a high increase in PM10 and PM2.5 concentrations compared to the previous day. As a result of analyzing the backward trajectory, the air mass that reached Busan at 1300 LST on July 17, 2018 has moved near the Sakurajima volcano at 1,500 m, 2,000 m, and 3,000 m. The concentration of SO4 2- in PM2.5, the concentration of all three stations in Busan showed a sharp increase from 1000 LST on July 17th. Looking at the NH4 + concentration in PM2.5, it shows a very similar variation trend to SO4 2-, and the correlation coefficient between the two components is 0.96 for Jangrimdong and Yeonsandong, and 0.85 for Busan New Port. Looking at the NO3 - concentration in PM2.5, the same high concentrations as SO4 2- and NH4 + were not observed in the afternoon of July 17th.
This study investigated characteristics of meteorological parameters and ionic components of PM2.5 during Asian dust events on November 28 and 30, 2018 at Busan, Korea. The seasonal occurrence frequencies of Asian dust during 1960∼2019 (60 years) were 81.7% in spring, 12.2% in winter, and 6.1% in autumn. Recently, autumn Asian dust occurrence in Busan has shown an increasing trend. The result of AWS (automatic weather station), surface weather chart, and backward trajectory analyses showed that the first Asian dust of Nov. 28, 2018, in Busan came with rapid speed through inner China and Bohai Bay from Mongolia. The second Asian dust of Nov. 30, 2018, in Busan seems to have resulted from advection and deposition of proximal residual materials. These results indicated that understanding the characteristics of meteorological parameters and ionic components of PM2.5 during Asian dust events could provide insights into establishing a control strategy for urban air quality.
Baengnyeongdo, located within the Asian dust stream, is an ideal place to analyze Asian dust moving into the West Sea due to its low emission of artificial pollutants. Baengnyeongdo is being used to analyze the vertical distribution of dust from the lower atmosphere to the upper layer through remote observation. This study compared the ground concentration of dust between Baengnyeongdo and the metropolitan area, estimated the lag time of transport of Asian dust from Baengnyeongdo to the metropolitan area, and examined the homogeneity of upper winds using the rawinsonde method. The results showed that the cross correlation coefficient was higher and the lag time was shorter for each observation station when the distance from Baengnyeongdo was shorter. The upper wind at Baengnyeongdo is dominated by the west/northwest wind. It is the basis for the correlation of dust concentration between Baengnyeongdo and the metropolitan area located to the east. In the future, upper wind data and Asian dust concentration data over the West Sea and Baengnyeongdo are expected to contribute to research related to the movement and prediction of Asian dust and preparation for Asian dust in the metropolitan area.
This study aimed to investigate the effects of dietary Ptecticus tenebrifer on the fecal microbiomes of bichon frise. A total of 16 bichon frise dogs (average weight, 2 kg) were randomly allotted to 4 dietary treatments (4 dogs/group): general pet food, two types of domestic pet food containing Ptecticus tenebrifer, and one imported pet food containing Ptecticus tenebrifer. In the controls, Firmicutes accounted for the highest proportion (82%) at the phylum level in the fecal microbiomes. The Tax4Fun2's functional prediction program indicated that the control groups showed a relatively high amount of obesity-related microorganisms; the pathways included three types of carbohydrate metabolism. Among the treatments, Firmicutes abundances was the least in the treatments with the two types of domestic pet food containing Ptecticus tenebrifer; this did not affect the functional prediction of Tax4Fun2. In conclusion, the two types of domestic feed with Ptecticus tenebrifer were healthy and suitable for bichon frise; they could be beneficial in terms of obesity.