• Journal of Korean Society on Water Environment
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• v.25 no.2
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• pp.235-244
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• 2009

The purpose of this study is to offer information about the current river conditions and basic data of streams in Busan city, by selecting 20 underground streams and evaluating their multilateral stream assessment. Concerning the evaluation of streams, 4 sections including the general index, the bank index, the river characteristic index, and the ecological environment characteristic index were evaluated. Ahead of the evaluation, the study divided Busan city into 4 zone for a systematic river investigation. Then, the study allocated code names to each river, and conducted literature research and a field survey of streams. Based on this, the study applied the evaluation of multilateral stream assessment. As a result, out of 4 entire grades, there was no grade 1 or grade 2. Instead, 35% were grade 3, 60% were grade 4, and 5% were grade 5. When looking into the evaluation results by Zone, the Dongbusan Zone showed the highest index, and the Suyeonggang Zone, the Jungbusan Zone, and the Nakdonggang Zone followed, in order.

• Journal of Environmental Science International
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• v.27 no.2
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• pp.63-74
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• 2018

As part of the Four Major Rivers Restoration Project, multifunctional weirs have been constructed in the rivers and operated for river-level management. As the weirs play a role in draining water from tributaries, the aim of this study was to determine the influence of the weirs on the water level of the Nam River, which is one of the Nakdong River's tributaries. Self-organizing maps (SOMs) and a locally weighted scatterplot smoothing (LOWESS) technique were applied to analyze the patterns and trends of water level and quality of the Nakdong River, considering the operation of the Changnyeong-Haman weir, which is located where the Nam River flows into the Nakdong River. The software program HEC-RAS was used to find the boundary points where the water is well drained. Per the study results at the monitoring points ranging between the junction of the two rivers and 17.5 km upstream toward the Nam River, the multifunctional weir influenced the water level at the Geoyrong and Daesan observation stations on the Nam River and the water quality based on automatic monitoring at the Chilseo station on the Nakdong River was affected strongly by the Nakdong River and partly by the Nam River.

• Journal of the Korean Association of Geographic Information Studies
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• v.18 no.2
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• pp.135-148
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• 2015

This research is carried out for the land cover change detection in the Nakdong River basin before and after the 4 major rivers restoration project using the LiDAR DEM(Digital Elevation Model) and the multi-temporal Landsat imagery. Firstly the river basin polygon is generated by using the levee boundaries extracted from the LiDAR DEM, and the four river basin imagery are generated from the multi-temporal Landsat-5 TM(Thematic Mapper) and Landsat-8 OLI(Operational Land Imager) imagery by using the generated river basin polygon. Then the main land covers such as river, grass and bare soil are separately generated from the generated river basin imagery by using the image classification method, and the ratio of each land cover in the entire area is calculated. The calculated land cover changes show that the areas of grass and bare soil in the entire area have been significantly changed because of the seasonal change, while the area of the river has been significantly increased because of the increase of the water storage. This paper contributes to proposing an efficient methodology for the land cover change detection in the Nakdong River basin using the LiDAR DEM and the multi-temporal satellite imagery taken before and after the 4 major rivers restoration project.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.15 no.2
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• pp.19-29
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• 2012

Numerous studies suggested that fish assemblage structure reflects the status of stream ecosystems. The status of streams integrity, including various trophic levels, water quality and habitat degradation, can be assessed by fish assemblages. In this study, we investigated the relationships between fish assemblages and streamline geometry of streams. Previous studies suggested that geomorphologic parameter can be a critical factor of permeability between adjacent two systems. From a landscape ecological perspective, edges may partially control the flow rate of energy between two adjacent systems. Thus, the Streamline geometry can be a geomorphologic parameter that exhibits the integrity of stream. We selected the Nakdong river for study areas, which is one of major rivers and the longest (525 km) River in South Korea. We used the revised IBI representing overall ecological characteristics of Korean fish assemblages and eight sub-assessment criteria of IBI, collected from 82 sampling sites in the Nakdong River. For calculating the Streamline geometry, we measured fractal dimension index that generally used in biology, ecology and landscape ecology. We used the digital land-use/land-cover map and generated a 1-km buffer for each sampling site and refined the shape of the Streamlines. Pearson correlation analyses were performed between Streamline geometry and IBI and sub-assessment criteria of IBI. The results show that IBI and eight sub-assessments of fish are significantly correlated with geometry of Streamline. The fractal dimension of Streamline geometry were related with IBI (r = 0.48) and six sub-assessments of IBI, including total number of native fish and native species, the number of riffle benthic species, sensitive species, tolerant species and native insectivore. Especially, the number of tolerant species(r = -0.52) and native insectivore(r = 0.52) show strong correlation with geometry of Streamline. These results indicate that lower Streamline geometry can result in poor fish assemblages, while higher geometry of Streamline can enhance fish assemblages by potentially supplying insects and better habitat conditions. We expect the results of our study to be useful for stream restoration and management. However, we see the necessity of study investigating the mechanisms how Streamline geometry affect fish assemblages.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.446-446
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• 2018

The urban rivers have unique hydraulic characteristics between natural rivers and artificial canals. These hydraulic characteristics determine the characteristics of urban rivers with small environmental capacity and fragile ecosystems. With the development and utilization of natural resources, the pollutants that have been produced enter the river through different channels, which seriously damages the urban river ecosystem. Therefore, how to restore contaminated water to a normal state and reproduce a natural, self-regulating ecosystem is one of the most concerned issues in recently. Eco-hydraulics is a cross-disciplinary subject of hydraulics biology and ecology. It is closely related to the protection of rivers, wetlands, and ecological self-repair. In this study, The basic principle of eco-hydraulics is concisely described and its approaches to protection and rehabilitation of river are introduced. The conception of establishing gardenesque eco-pond for urban use is suggested. The strategies including changing the hydrodynamic features of rivers, adjusting the breeds and species and constructing the gardenesque eco-pond for improving the exist ing urban rivers are proposed. It provides scientific information and guidance for the restoration of rivers and wetlands by studying the close relationship between river hydraulic characteristics, currents, and rivers and ecosystems.

• Korean Journal of Ecology and Environment
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• v.55 no.4
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• pp.406-414
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• 2022

Bolboschoenus planiculmis has been acknowledged as a key species in whooper swans (Cygnus cygnus) habitat by providing food for this migratory waterfowl. B. planiculmis wetlands are being degraded by water shortages and salinization caused by anthropogenic activities and climate changes. In 2004, the distribution of B. planiculmis in the tidal flats of the Nakdong Estuary was 2,475,568 m², and in 2021, the distribution area was 798,731 m², which decreased by 32.3%. In order to restore the degraded B. planiculmis wetlands, shoot transplantation and seed sowing were tentatively used in three places with different salinity and water levels. The average density per unit area in September at the optimal growth period after planting were A (fresh water level 50 cm) 58±15.65 m^-2, B (brackish water level 0~5 cm) 188±63.83 m^-2, C (brackish water level 0 cm or less) 188±45.13 m^-2. The tubers were observed as A 0 g dw m^-2, B 25.32±2.94 g dw m^-2, and C 13.39±0.91 g dw m^-2. Tubers were distributed in the soil, with only 3.0% at the 10~20 cm depth but 97.0% at the 0~10 cm depth. In contrast, the germination rate of B. planiculmis seeds was observed to be 0%. Results of this study provide technical support for the restoration of B. planiculmis wetland and the improvement in the quality of whooper swans habitat.

• Fisheries and Aquatic Sciences
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• v.23 no.6
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• pp.15.1-15.14
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• 2020

Background: Large rivers are ecological treasures with high human value, but most have experienced decades of degradation from industrial and municipal sewage, row-crop agricultural practices, and hydrologic alteration. We reviewed published analyses of long-term fish diversity publications from three intensively managed large river ecosystems to demonstrate the conservation potential of large river ecosystems. Results: We show how the incorporation of recent advances in river concepts will allow a better understanding of river ecosystem functioning and conservation. Lastly, we focus on the Wabash River ecosystem based on high conservation value and provide a list of actions to maintain and support the ecosystem. In the Wabash River, there were originally 66 species of freshwater mussels, but now only 30 species with reproducing populations remain. Although there were multiple stressors over the last century, the largest change in Wabash River fish biodiversity was associated with rapid increases in municipal nutrient loading and invasive bigheaded carps. Conclusions: Like similarly neglected large river systems worldwide, the Wabash River has a surprising amount of ecological resilience and recovery. For instance, of the 151 native fish species found in the 1800s, only three species have experienced local extinctions, making the modern assemblage more intact than many comparable rivers in the Mississippi River basin. However, not all the changes are positive or support the idea of recovery. Primary production underpins the productivity of these ecosystems, and the Wabash River phytoplankton assemblages shifted from high-quality green algae in the 1970s to lower less nutritional blue-green algae as nutrient and invasive species have recently increased. Our recommendations for the Wabash River and other altered rivers include the restoration of natural hydrology for the mainstem and tributaries, nutrient reductions, mechanisms to restore historical hydrologic patterns, additional sediment controls, and improved local hydraulics.

• Journal of Environmental Impact Assessment
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• v.23 no.6
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• pp.417-431
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• 2014

There is a Conjoint Analysis to estimate the environmental value of natural river restoration project of Inchon Metropolitan City's small River: Gong-chon Stream, Gul-po Stream, Seung-gi Stream, Jang-su Stream. In order to find out the optimal expense condition, we tried to estimate the possible payable amount. According to the analysis, almost all people are willing to pay 15,000 Won. In case of the river types, the people liked 10 cm's depth of water and there should be brook trail, convenient facilities and flood plain at the stream edge space. But it is impossible to build these facilities with minimum fare 15,000 Won per a household. If the necessary expenses set high, the tax resistance of the local residents will be increased. So, in consideration of the analytical results of the attribute level, we draw five alternatives. This study is based on the results of Incheon metropolitan City residents' survey, and there is Conjoint Analysis to estimate the environmental value of natural-type river project of Incheon metropolitan City. If it is reflected the special assume factors of this study, and if there is exact environmental value estimation of the various river quality through different analysis, then it will become a study of high utilizing.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.7 no.5
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• pp.26-37
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• 2004

Most domestic small rivers and streams due to industrialization and urbanization have managed by concrete structures. The environmental functions of the river and stream are disappearing and urban streams play only the role of drainage systems. Also, the researches to restore natural streams are something yet to develop and not established the restoration for ecological functions of a small stream. Therefore the researches are required to develop ecological engineering system for watershed management system to handle various pollutants with restoration for ecological functions of a small stream. To develop this, the ecological engineering system for watershed management system could be developed with ecological conservation. In addition, ecological engineering system for watershed management system should be prior to conserve the habitat of biological resources and water conservation and applied to the original shape of streams. Also, it should be designed to restore the micro-topography of stream, the habitat of plant population in watershed. It is needed to develop the integrated researches to restore a small stream ecosystem.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.16 no.2
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• pp.137-153
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• 2013

In order to assess the effects of ecosystem and landscape in around spur dikes, this study had carried out monitoring on the changes of ecosystem and morphologic characteristics in around spur dikes that had been settled in bend of Youngcheon River. The study site was a short reach with length 190m, spur dikes were installed in March, 2008. Monitoring of the site had been started in May 2008 and had been completed September 2011. The results are as follow ; 1) Spur dikes that were installed for channel stabilization are performing effectively hydraulic functions at flooding time. 2) Spur dikes that were installed in water colliding front of river bend brought about sediment deposition between those and formed pools around front of those. Therefore, it was verified to create various physical characteristics in the aspect of channel topography and flow consequently. 3) The survey results that was carried out in October 2008 showed to emerge 25 species of plant, 9 species of fish and 17 species of benthic macroinvertebrates, but the survey results in October 2010 showed to emerge 74 species of plant, 12 species of fish and 19 species of benthic macroinvertebrates. In particular, plant species that emerged in 2011 increased about three times more than those in 2008.