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Kim J.-A.,University of Pennsylvania | Lee S.-W.,Konkuk University | Hwang G.-S.,Halla Engineering and Construction | Hwang S.-J.,Konkuk University | And 2 more authors.
Paddy and Water Environment | Year: 2015

Urban land use can adversely affect the water quality of adjacent streams through interactions at the edges of the two ecosystems. From a landscape ecological perspective, edges control the flow rate of materials between two adjacent systems. Based on the rationale that the streamline complexity formed between land uses and water bodies may function in this manner, we investigated the potential role of streamline complexity in the relationship between stream ecological communities and urban land use in Korea. Various indices of biological indicators including the diatom assemblage index for organic pollution, the trophic diatom index, the Korean saprobic index, and the index of biotic integrity were applied at 80 sampling sites in the Nakdong River system. We computed the fractal dimensions of the streamlines within 1-km buffers and the proportion of urban land use in the watershed within 5-km buffers around the sampling sites. A moderation model was adopted to investigate the role of streamline complexity in the relationship between urban land use and the biological indices of ecological communities. A comparison between a simple geometry regression model and complex geometry models indicated that streamline complexity may moderate the adverse impacts of urban land use on ecological communities in streams. The moderating effect of streamline complexity was particularly significant for assemblages of macroinvertebrates and fishes. Therefore, to enhance the ecological integrity of streams, we strongly recommend considering streamline complexity when restoring channelized streams in developed areas. © 2015 The International Society of Paddy and Water Environment Engineering and Springer Japan Source


Kim J.,Konkuk University | An K.-J.,Konkuk University | Hwang S.-J.,Konkuk University | Hwang G.,Halla Engineering and Construction | And 3 more authors.
Paddy and Water Environment | Year: 2014

Numerous studies have stated that land use in urbanized areas can adversely affect water quality of streams. Previous studies reported that edges may play important roles in controlling flow rate of material in two systems. In this study, we examined the mediating effects of streamline geometry on the relationships between urban land use and the index of biological integrity (IBI) of the Nakdong River in Korea. Two mediation models with streamline geometry, including the partial mediation effect model and the full mediation effect model, were estimated to explore the mediating effect of streamline geometry. To measure streamline geometry, we calculated the fractal dimension of a streamline within a 1 km buffer from the sampling sites. The proportion of urban land use within a 5 km buffer of the sampling sites was also computed by GIS. We used biological assessment data from the National Aquatic Ecological Monitoring Program in Korea to delineate the IBI at the sampling sites. The results showed that urban land use significantly degraded stream morphology and IBI in the Nakdong River. It was also observed that streamline geometry mediated the influence of urban land use on the IBI. The results of structural equation modeling analysis for the two mediation models with the fractal dimension and IBI suggested that only two paths were significant in the partial mediation model, whereas all paths were significant in the estimated full mediation model. © 2014 The International Society of Paddy and Water Environment Engineering and Springer Japan. Source

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