• Structural Engineering and Mechanics
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• v.69 no.5
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• pp.557-566
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• 2019

The reservoir basin bedrock produced significant impact on the long-term service safety of super-high arch dams. It was important for accurately identifying geomechanical parameters and its evolution process of reservoir basin bedrock. The deformation modulus mechanism research methods of reservoir basin bedrock deformation modulus for super-high arch dams was carried out by finite element numerical calculation of the reservoir basin bedrock deformation and in-situ monitoring data analysis. The deformation modulus inversion principle of reservoir basin bedrock in a wide range was studied. The convergence criteria for determining the calculation range of reservoir basin of super-high arch dams was put forward. The implementation method was proposed for different layers and zones of reservoir basin bedrock. A practical engineering of a super-high arch dam was taken as the example.

• Korean Journal of Ecology and Environment
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• v.46 no.1
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• pp.103-115
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• 2013

The purpose of this study was to analyze fish fauna and species compositions along with trophic guilds, tolerance indicators, and fish community conditions before weir construction (BWC) and after weir construction (AWC) in the Yeongsan River watershed. Total 45 and 44 fish species were sampled in BWC and AWC, respectively without any distinct differences through weir constructions. Fish fauna analysis revealed that the dominant species was the same, Zacco platypus with 24.3% and 20.8% in BWC and AWC, respectively. However, the subdominant species were Carassius auratus with 8.9% in BWC but Opsarichthys uncirostris amurensis with 20.3%, almost identical that of the dominant species AWC. This phenomenon showed the distinct modification of species composition in the watershed. We sampled the $1^{st}$ class endangered species, Liobagrus obesus in tributary stream as previously reported. Also Culter brevicauda was sampled in the mainstream of Yeongsan River watershed and this was the first sampled record in this watershed. One of the most important features were an increase of exotic species, such as Micropterus salmoides and Lepomis macrochirus, with 3.2% BWC vs. 10.2% AWC as well as the increase in tolerant species with 49.2% BWC vs. 73.7% AWC, indicating ecological degradation through weir construction. Overall, our results indicated that fish fauna and composition analyses showed distinct ecological degradations related to increases of exotic and tolerant species AWC. Further long-term studies of fish monitoring should be conducted in the future to configure existent status of river conditions and to provide key information in order to conserve the healthy ecosystem.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.1
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• pp.114-127
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• 2010

The purpose of this study is to find out cold and fresh air producing areas using climate-ecological functions in Changwon city, Gyeongsangnam-do, South Korea. The evaluation of climate-ecological functions were composed of the six factors: patch size with cold air generation and inflow functions, farmland and grassland ratio, mean slope degree, cross section types, mean slope length and roughness of bottom in valley. The analysis results of each evaluation factor in the study area were divided into 5 grades according to the capacity of cold air generation. The first-grade area with the highest factor values for cold air generation was take up 3.51% of the total study area, second grade was 13.48%, third grade was 31.65%, fourth grade was 27.28%, and fifth grade was 24.09%. According to the spatial distribution of cold air producing areas, the valleys around Mt. Bongnim, Changwon tunnel, and Anmin tunnel had higher evaluation grade. It will require the future research to establish the climate-ecological conservation areas and to construct the wind corridor based on the long-term microclimatic monitoring.

• Environmental Engineering Research
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• v.11 no.5
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• pp.277-284
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• 2006

The genetic toxicity of environmental pollutants, namely, nonylphenol (NP), bisphenol A (BPA) and chloropyriphos (CP) was investigated in aquatic sentinel species, freshwater crustacean, Daphnia magna, and larva of aquatic midge, Chironomus tentans, using Comet assay. Physiological effect of such pollutants was also investigated by studying the specimens' rates of reproduction, growth and survival. Acute toxicity results showed that, as expected, Daphnia was more sensitive than Chironomus to chemical exposure. The order of acute toxicity was CP > NP > BPA in D. magna and NP > CP > BPA in C. tentans. BPA may exert a genotoxic effect on D. magna and C. tentans, given that DNA strand breaks increased in both species exposed to this compound, whereas NP- and CP-induced DNA damage occurred only in C. tentans. In vivo genotoxic data obtained in aquatic sentinel species could provide valuable information for freshwater quality monitoring. The experiments with NP-exposed D. magna showed that the pollutant has long-term effects on reproduction, whereas no short-term effect on DNA integrity was found, being an example of a false-negative result from the biomarkers perspective. This result could be interpreted that other mechanism than genetic alteration might be involved in NP-induced reproduction failure in D. magna. False-positive results from the genotoxic biomarker obtained in BPA-exposed D. magna and in NP-exposed C. tentans make it difficult to use DNA integrity as an early warning biomarker. However, as the mere presence of genotoxic compounds, which are potentially carcinogenic, is of high concern to human and ecosystem health, it could also be important to rapidly and effectively detect genotoxic compounds in the aquatic system in ways that do not necessarily accompany a higher level of alteration. Considering the potential of D. magna and C. tentans as bioindicator species, and the importance of genotoxic biomarkers in ecotoxicity monitoring, DNA damage in these species could provide useful information for environmental risk assessment.

• Journal of Wetlands Research
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• v.22 no.3
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• pp.217-224
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• 2020

Waterlogging and unintended lake formation become the main problem in some parts of the world. Starting from 1989, the waterlogging problem was observed in the farmland of the Jarso community of Konso Woreda adjacent to the Segen River in Ethiopia. Therefore, the objectives are determining the extent and causes of unintended lake formation using GIS/RS in addition to a preliminary field survey to mitigate the problem. The analysis of satellite images revealed that over the years invasion of the irrigable land by unwanted water had increased, as, in 1989, the size of the wetland area was about 8 Km²; in 2000 the size of the un-intended lake was only 8.23 ㎢. Alarmingly the size of the lake increased to 19.68 Km² in 2014. Silting up of Weir and changing the flow of River Segen and Human Intervention and changing the natural flow of River Yanda were the main causes of this unwanted prolonged water-logging. The ecological and social environment has been degrading as the people of the waterlogged area have been experiencing some settlement and losing their land. Another problem encountered was flooding from River Barka and invasion of the farmland. Sediment control best management practices (BMPs) i.e, Removal of sediment, providing sandbags and well-scheduled maintenance; Changing the junction point of Yanda and Segen River were suggested for the long-term and short term possible remedial measures. Gabion retaining wall on the bank of the Segen River to the face of Barka River was suggested to protect the farmland from flooding.

• Journal of Ecology and Environment
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• v.46 no.4
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• pp.324-333
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• 2022

Background: The Korean scarlet dwarf, Nannophya koreana Bae (Odonata: Libellulidae), is anendangered dragonfly with an increasing risk of extinction owing to rapid climate changes and human activities. To prevent extinction, the N. koreana population and their habitat should be protected. Therefore, suitable habitat evaluation is important to build the N. koreana restoration project. The habitat suitability index model (HSI) has been widely used for habitat evaluation in diverse organisms. Results: To build a suitable HSI model for N. koreana, 16 factors were examined by seven experienced researchers. A field survey for N. koreana observed sites and spatial analysis were conducted to improve the model. Five factors were finally selected by this procedure (crown density, open water surface, water depth, pioneer plant cover, and type of water source). Finally, the N. koreana HSI model was generated with the five adjusted factors based on interview, field survey, and spatial analysis. This model was validated by a current N. koreana habitat in 2021. With this model, 46 sites in Uljin-gun, Korea, were surveyed for N. koreana habitats; five sites were identified as core habitats and seven as potential core habitats. Conclusions: This model will serve as a strong foundation for the N. koreana restoration project and as a reference for future studies on N. koreana and other endangered insect populations. Further analysis and long-term data will improve the efficacy of this model and restore endangered wildlife.

• Journal of Ecology and Environment
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• v.41 no.4
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• pp.125-131
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• 2017

The ground beetles collected during the investigation period were nine subfamilies, 24 genera, 51 species, and 3504 ground beetles. Species richness was high in Pterostichinae has 24 species (47%), Harpalinae nine species (17.6%), Carabinae six species (11.8%), and Lebiinae three species (5.9%). Overall dominant species was Synuchus agonus, and dominance index was 0.361. Synuchus agonus was investigated as the dominant species in both Namcheon Valley and Geumseon Valley. Regarding subdominant species, it was Synuchus nitidus (52 individuals, 12.6%) and Synuchus cycloderus (52 individuals, 12.6%) in the order in Namcheon Valley, and it was Pterostichus orientalis orientalis (660 individuals, 21.3%) and Pterostichus audax (378 individuals, 12.2%) in the order in Geumseon Valley. Total species diversity index of ground beetles in Sobaeksan National Park was 2.917. By area, the number of collected ground beetles was smaller in Namcheon Valley than in Geumseon Valley. Sobaeksan National Park is located at the boundary of northern and southern parts in Korea and is a very important place in terms of geography and climate. Sobaeksan has been designated as a national park, and its ecosystem is relatively preserved well. If continuous investigation of basic data for ground beetles is conducted through long-term monitoring, the data can be used as key data to research mutual relationship with organisms, effects by climate change, and ecosystem change depending on human activities.

• Journal of Environmental Impact Assessment
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• v.29 no.6
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• pp.441-452
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• 2020

The assessment of the river environment is widely applied as a method to establish the purpose and direction of river rehabilitation projects. This includes surveying and assessing the current state of the river environment and determining whether a previous river project was properly executed. The city of Seoul executed ecological river rehabilitation activities for the tributaries of the Han River from the 2000s following a masterplan to recover the physical shape and ecological functionality of damaged rivers. After the rehabilitation activities, the river environment had been changed substantially. In this study, physical properties, water quality properties, and ecological properties were assessed for 28 tributaries underthe control of the city of Seoul, and then those 3 properties were synthetically reassessed. From the result of the study on the physical properties, it was found that mostrivers had II-III grades. As for water quality properties, rivers had III-IV grades. The damaged rivers showed low grades of D-E based on the Aquatic Ecosystem Health evaluation. Accordingly, we concluded that all rivers of Seoul City have an unhealthy environment in terms of water quality and Aquatic Ecosystem Health, therefore it is regarded that long-term and systematic improvements are required.

• Journal of Wetlands Research
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• v.15 no.4
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• pp.567-572
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• 2013

Mammals act as an important role in maintaining ecosystem, but direct observation is very difficult. Nevertheless, in order to understand the impact of various changes about a sudden environment, long-term monitoring through direct investigation is essential. This study investigated home range analysis using GPS tracking device and behavioral ecology of Korean waterdeer (Hydropotes inermis), indigenous and native species in Korea. Studies on ecological characteristics and home range of Korean waterdeer are insufficient. Therefore, we studied home range using the GPS technique for critical point of existing research. Data showed the active movement in daytime ($44.1km^2$) than night ($30.0km^2$) and large area of activity in winter ($3.7km^2$) and spring ($44.1km^2$) than summer($0.04km^2$) and autumn ($0.01km^2$). The most used area of Korean waterdeer was forested area and wetland, agricultural area, waters in order of frequency based on the land coverage map. Our research represents overall characteristics of Korean water deer due to measurement of area of activity. However, this research signified behavioral ecology for Korean waterdeer, and further investigation in necessary.

• Journal of Ecology and Environment
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• v.33 no.4
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• pp.333-341
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• 2010

The objective of our study was to investigate the major reasons for the different growth and visible injury on the needles of black pine growing in Ulsan and Yeocheon industrial complex areas, South Korea. After 12 years of growth, we collected climatic and air pollutant data, and analyzed soil properties and the physiological characteristics of black pine needles. Annual and minimum temperatures in Ulsan were higher than those in Yeocheon from 1996 to 2008. Ozone ($O_3$) was the pollutant in greatest concentration in Yeocheon, and whereas the $SO_2$ concentration in most areas decreased gradually during the whole period of growth, $SO_2$ concentration in Yeocheon has increased continuously since 1999, where it was the highest out of four areas since 2005. Total nitrogen and cation exchange capacity in Yeocheon soil were significantly lower than those of Ulsan. The average growth of black pine in Yeocheon was significantly smaller than that in Ulsan, and the growth of damaged trees represented a significant difference between the two sites. Photosynthetic pigment and malondialdehyde content and antioxidative enzyme activity in the current needles of black pine in Yeocheon were not significantly different between damaged and healthy trees, but in 1-year-old needles, there were significant differences between damaged and healthy trees. In conclusion, needle damage in Yeocheon black pine can be considered the result of long-term exposure to oxidative stress by such as $O_3$ or $SO_2$, rather than a difference in climatic condition or soil properties, and the additional expense of photosynthate needed to overcome damage or alleviate oxidative stress may cause growth retardation.