• Entomological Research
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• v.48 no.6
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• pp.540-549
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• 2018

Climate change due to global warming and changes in land use increase the development time and distribution, as well as the abundance, of mosquitoes, thereby negatively affecting human life and health. In this study, we investigated the habitat characteristics of mosquito occurrence sites in Danwon-gu, Ansan city, Korea, based on a daily record of civil pest complaints lodged at the Danwon-gu Community Health Center. We considered two types of factors (natural and artificial) known to affect mosquito occurrence. We confirmed a total of 554 cases of mosquito occurrence from March 2014 to August 2017. The total study area was $49.11km^2$, with urban areas constituting the largest proportion. Additionally, we investigated habitat preferences of mosquitoes in terms of terrain factors; generally, mosquitoes occurred at low elevations and on low slopes. Regarding the preference of oviposition sites, mosquitoes occurred at higher rates near streams and crops lands. The rate of mosquito occurrence tended to increase in areas with dense human populations. Regarding climatic factors, the rate of mosquito occurrence increased in areas with high temperature and low precipitation.

• Korean Journal of Environment and Ecology
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• v.24 no.2
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• pp.147-156
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• 2010

This study was conducted from April, 2002 to March 2006, using three urban streams(Gap Stream, Yudeung Stream and Daejeon Stream) in Daejeon Metropolitan City. 12,027 individual birds summed by the peak count in 126 species, 34 families, and 13 orders were observed from three stream sites. Dominant species were of Anas poecilorhyncha, Anas crecca, Columba livia, Passer montanus, and Egretta garzetta(in that order). The groups of birds were classified into six types. The most frequent group were the arbor birds(54 species), while the smallest group was the diving ducks(7 species). As for the number of individuals, the shrub bird group had 721 individuals while the dabbling ducks observed had 4,974 individuals. Regarding the distribution of birds appeareing in each stream, 14,885 individual numbers in 114 species were observed at Gap Stream, 6,642 individuals in 90 species at Yudeung Stream and 4,202 individuals in 69 species at Daejeon Stream. Various indices of the birds were analyzed with respects to the similarities between streams. Gap Stream had similar characteristics to Yudeung Stream, and the latter was similar to Daejeon Stream. However, Gap Stream and Daejeon Stream showed different characteristics. The dominance index of each section was calculated using ten dominant bird species top-down. Subsequently, the birds and their preferred environment were analyzed. The results showed that shrub birds and arbor birds preferred the upper stream of every stream, while herons and dabbling ducks inhabited the midstream. Dabbling ducks and some diving ducks appeared downstream.

• Journal of Wetlands Research
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• v.10 no.3
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• pp.111-124
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• 2008

The changes in flora and distribution and structure of vegetation were monitored for seven years at a restored reach of an urban stream, the Yangjae Stream, southeast of Seoul, Korea. In the restored reach, diverse kinds of the close-to-nature stream restoration techniques were adapted and implemented in the winter of 1998-1999. The species numbers and diversity indices of riparian plants at the restored reach were higher than those at the unrestored reach seven years after the restoration implementation. But plant diversity was decreased from the early restoration stage of 1999 - 2001 to seven years after the implementation. The dominant species changed from a ruderal annual, Humulus japonicus, to a perennial, Phragmites australis. The floral structure was distinctly different between in the early stage and seven years later on the results of principal component analysis (PCA) because of decreasing in numbers of exotic or ruderal species and planted or introduced plants in newly disturbed habitats. The distribution areas of communities of Humulus japonicus and Erigeron annuus were decreased and those of communities Phragmites australis and Miscanthus sacchariflorus were increased after the restoration implementation. The results of detrended correspondence analysis (DCA) of plant communities revealed that the community structure were changed from the disturbed vegetations to the stable and natural vegetation after the restoration implementation. Total seven species of willows were found at the restored reach, of which two species were planted and the others were naturally introduced. The monitoring results showed that the stream ecosystem of the study reach were successfully recovered in flora and vegetation and could be used as a model site for the stream restoration in urban streams.

• Korean Journal of Ecology and Environment
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• v.43 no.1
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• pp.11-18
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• 2010

The contamination of a suite of heavy metals were evaluated in water and sediments of urban stream, Tancheon down the stream. Tancheon is a urban stream which goes all the way across the urban area where various pollution sources are present. The sixteen study sites from seven different areas were designated down the stream. The heavy metal levels of the streams were detected in the order of Zn>Cu>Ni>Pb>Cd>Cr>Sb. There was a difference in the relative order of the concentration ranking in lake sediments. There is a trend that the heavy metal levels are higher at the sites where the construction causes inflow of soil particles to stream. Toxicity tests using pore-water in sediments were conducted for samples collected in some study sites, and pore-water in one site was proven to be toxic to Japanes medaka (Oryzias latipes). The reason may be the fecal pollution rather than heavy metal effect. Strong odor was detected in the sediment whose pore-water samples showed ecotoxicity. We did not observed the increasing concentration of heavy metals down to stream since the soil texture varied in the stream area of our study. Further study is needed to find quantitative relations between the level of contamination and its eco-effect.

• Korean Journal of Environmental Biology
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• v.40 no.2
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• pp.172-186
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• 2022

Benthic macroinvertebrates are important ecological and environmental indicators as primary or secondary consumers, and therefore are widely used in the evaluation of aquatic environments. However, there are no comprehensive river ecosystem monitoring surveys that link the major physicochemical water quality items with benthic macroinvertebrates in urban streams. Therefore, this study investigated the distribution characteristics of benthic macroinvertebrates and physicochemical water quality items (17 items) in Yangjaecheon and Yeouicheon from 2019 to 2020. At the same time, by applying Spearman's rank correlation analysis and nonmetric multidimensional scaling (nMDS) analysis in the water quality data and biotic index, we tried to provide basic data for diagnosing the current status of river ecosystems in major urban rivers in Seoul. Based on the study results, a total of 39 species and 3,787 individuals were identified in Yangjaecheon, the water quality(based on BOD, TOC, and TP) of Yangjaecheon was higher than Grade Ib(good), and the BMI using benthic macroinvertebrates appeared as Grade C(normal) at all the sites. In Yeouicheon, a total of 51 species and 4,199 individuals were identified, the water quality(based on BOD, TOC, TP) was higher than Grade Ib(good) similar to Yangjaecheon, and the BMI of both Upstream and Saewon bridge was Grade B(good), while Yeoui bridge was Grade C(normal). Overall, analysis results for the distribution of benthic macroinvertebrates by a nonmetric multidimensional scaling method showed no significant difference between the two streams (p=0.1491). Also, significant environmental variables related to benthic macroinvertebrates distribution were determined as water temperature and DO. On the other hand, the results of the correlation analysis between biotic index and major water quality items confirmed that R1 and BMI could be used for on-site urban river water quality evaluation.

• Journal of the Korean Institute of Landscape Architecture
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• v.37 no.1
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• pp.78-86
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• 2009

Recently, there seems to besome problems in the urban visual landscape as a result of continuous economic growth and industrial development. At the same time, the public has begun to be aware of the importance of visual resources, and the necessity for visual landscape conservation and improvement. Therefore, the development of evaluative indicators for systematic visual landscape planning and design is urgent. The purpose ofthis study is to discover evaluative models and indicators for the diagnosis of urban visual landscapes. This study included the selection of 18 physical indicators(statistical data) by literature reviews, adoption of field and questionnaire surveys at 12 autonomous districts in Seoul and surrounding major mountain valleys and river streams(i.e. Mt. Nam and Han-River). The content of the questionnaire is scenic beauty. Moreover, the linear regression analysis between the scenic beauty mean scores and the physical indicator scores figure out the scenic beauty prediction model. As this study suggests, the most important indicators in urban visual landscapes are 'Greens', 'Park' and 'the number of apartment buildings(higher than 20 stories).' Based on the results, greens and parks should be priority elements to considerin urban landscape planning and design. Moreover, since the number of apartment buildings that are higher than 20 stories has a negative correlation with the scenic beauty score, it can be used as basic data for landscape planning. For the scenic beauty prediction models and evaluative indicators suggest a direction of urban management, each indicator becomes basic data for visual landscape planning and design. In following studies, if physical indicators and case studies are added, the scenic beauty prediction models and evaluative indicators could be more synthetic and systematic. Moreover, the development of physical indicators in three dimensions(3D)(i.e. results from visual district analysis, view surface analysis) could be expected to obtain more general and varied results.

• Journal of the Korean Society for Marine Environment & Energy
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• v.20 no.2
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• pp.76-83
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• 2017

In order to investigate the characteristics of water quality and heavy metals in Shihwa Lake, concentration comparisons according to land use types and mass discharge through streams were carried out. Based on classification for streams according to land use types, the concentration of DO, SS, POC, $NO_3$ and Chl-a showed higher concentrations in agricultural areas than in industrial and urban areas. However, COD, DIN, DIP, TN, TP, DOC, TOC and heavy metal concentrations showed relatively high values in industrial areas. The concentrations of water qualities and heavy metals were relatively high in March to May and the concentration decreased in summer seasons (July-August). The averages of stream discharges of water qualities were 1,172 kg/d for SS, 151 kg/d for TN, 11.1 kg/d for TP and 389 kg/d for TOC, respectively. The agricultural area, Jangjunbo(S8), accounted for 47.5%(TP)~75.1%(SS) in the total stream discharges. Cu, Zn and Cd in stream waters were found to be more than 92% of the total discharges in industrial area, showing descending order of Zn>Cu>Ni>Pb>Co>Cd.

• Journal of the Korean Institute of Landscape Architecture
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• v.50 no.3
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• pp.19-34
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• 2022

This study was conducted to provide basic data that can be used when establishing Net Zero policies and implementation plans for non-urban settlements by quantitatively analyzing the Net Zero contribution to green infrastructure in rural areas corresponding to non-urban settlements. The main purpose is to first, systematize green infrastructure in rural areas, secondly derive basic units for each element of green infrastructure, and thirdly quantify and present the impact on Net Zero in Korea using these. In this study, CVR(Content Validity Ration) analysis was performed to verify the adequacy of green infrastructure elements in rural areas derived through research and analysis of previous studies, is as follows. First, Hubs of Green infrastructure in rural area include village forests, wetlands, farm land, and smart farms with a CVR value of .500 or higher. And Links of Green infrastructure in rural area include streams, village green areas, and LID (rainwater recycling). Second, the basic unit for each green infrastructure element was presented by classifying it into minimum, maximum, and median values using the results of previous studies so that it could be used for spatial planning and design for Net Zero. Third, when Green infrastructure in rural areas is applied to non-urban settlements in Korea, it is analyzed that it has the effect of indirectly reducing CO₂ by at least 70.76 million tons and up to 141.16 million tons. This is 3.4 to 6.7 times the amount of CO₂ emission from the agricultural sector in 2019, and it can be seen that the contribution to Net Zero is very high. It is expected to greatly contribute to the transformation of the ecosystem. This study quantitatively presented the carbon-neutral contribution to settlements located in non-urban areas, and by deriving the carbon reduction unit for each element of green infrastructure in rural areas, it can be used in spatial planning and design for carbon-neutral at the village level. It has significance as a basic research. In particular, the basic unit of carbon reduction for each green infrastructure factors will be usable for Net Zero policy at the village level, presenting a quantitative target when establishing a plan, and checking whether or not it has been achieved. In addition, based on this, it will be possible to expand and apply Net Zero at regional and city units such as cities, counties, and districts.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.3 no.2
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• pp.35-46
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• 2000

Environmental pollution has become more and more serious in urban areas since industrialization as most streams and rivers were developed heavily because of economic opportunism. Recently river restoration techniques, applied in advanced countries, have been introduced to Korea. But the application of river restoration techniques developed in advanced countries, has a lot of limitations in respect of economic loss during construction, suitability for the domestic situation and the problem of flood control. The method of minimizing the problems must take into consideration these issues, including economic considerations. So from these points of view this study intends to plan ecological river restoration and to create a nature friendly river in the case of the Chungrang river. The subject site is the upper part of Chungrang river, from the Nokchun bridge to Sang-kye bridge, where the ecosystem is well preserved in comparison with other parts of the river. The subject site is divided into 10 sections for plant state investigation. The result of plant-state investigation showed pioneer water plants such as Persicaria thunbergii, Oenanthe jaranica, Rumex crispus. appeared very often. On the basis of the existing plant state, this study has planned an appropriate plant state for the river and has planned for bank protection using a method of construction, which is suitable for natural river. In this study, first of all, it is intended to investigate the plant growth state of Chungrang river and try to plan a particular ecosystem for the river for the purpose of the revival of the natural river.

• Journal of Wetlands Research
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• v.17 no.3
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• pp.209-220
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• 2015

This study has improved the existed physical disturbance evaluation assessment technique in a river and analysed its applicability. The improvements are the quantitative evaluation items instead of qualitative one by providing the background and their evaluation equations, corresponding detailed itemization of evaluation score, and the direct input of hydraulic characteristics and geometrical changes by numerical simulation. In order to confirm the applicability of improved disturbance evaluation technique, the comparison and analysis between the evaluation results of existed and improved techniques have been carried out by applying to the 6 cases of natural, urban, and mountainous streams. Direct input of numerical simulation results of HEC-RAS enables the evaluation simple for 8 evaluation items excluding the items of habitat environment and bottom substrate. The improved disturbance evaluation technique, which evaluates the degree of disturbance sensitively by the quantitative and detailed itemized evaluations, has been confirmed the appropriate applicability by applying to river systems.