Long-Term Variations of Water Quality and Material Flux in the Nakdong River, Korea

As a result of the construction of a barrage in the estuary of the Nakdong river the size of the estuary will be considerably reduced. In addition, a large river reservoir is created upstream of the barrage. Main points of interest are the effects of the discharge of raw sewage and treated effluent into the Nakdong river on the water quality in the projected reservoir and the water quality forecasts for the remaining part of the estuary, in relation with the existing plans for sewerage and sewage treatment for the city of Busan. In addition, measures to reduce the effects of the barrage and the outline of a water quality management programme are presented. Special consideration is given to the methodological aspects of the water quality study, i.e. the selection and use of mathematical models in a situation where input data are rather uncertain and only very few data for parameter estimation and model verification are available.

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Effects of Weir Construction on Phytoplankton Assemblages and Water Quality in a Large River System

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph15112348 ◽

2018 ◽

Vol 15 (11) ◽

pp. 2348 ◽

Cited By ~ 9

Author(s):

Hae-Jin Lee ◽

Hae-Kyung Park ◽

Se-Uk Cheon

Keyword(s):

Water Quality ◽

Chlorophyll A ◽

River System ◽

Large River ◽

Anthropogenic Factors ◽

Centric Diatom ◽

Nakdong River ◽

Biological Variables ◽

Physical Chemical ◽

The Nakdong River

Flow regulation is one of the most common anthropogenic factors affecting rivers worldwide. In Korea, 16 weirs were constructed along four major rivers from 2009 to 2012. This study aimed to elucidate initial changes in physical, chemical, and biological variables after the construction of consecutive weirs on the Nakdong River, a major large river system. Water quality variables and phytoplankton cell densities were investigated at eight representative sites and compared with the data recorded before the weir construction. There were spatial and temporal changes in the hydraulic retention time (HRT), total phosphorus (TP), and chlorophyll a concentrations among the eight weir sections. HRT increased after the weir construction, while TP and chlorophyll a tended to decrease from the middle to lower section of the Nakdong River. Furthermore, differences were observed in the phytoplankton community composition between 2006–2007 and 2013. There was a marginal decrease in the duration of centric diatom (Stephanodiscus hantzschii) blooms after weir construction. However, Microcystis aeruginosa proliferated more extensively during summer and autumn than it did before the weir construction. Our results suggest that changes in hydrological factors, in response to consecutive weir construction, may contribute to greater physical, chemical, and ecological variability.

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Long-Term Ecological Research in the Nakdong River: Application of Ecological Informatics to Harmful Algal Blooms

Ecological Informatics ◽

10.1007/978-3-319-59928-1_20 ◽

2017 ◽

pp. 435-453 ◽

Cited By ~ 1

Author(s):

Dong-Gyun Hong ◽

Kwang-Seuk Jeong ◽

Dong-Kyun Kim ◽

Gea-Jae Joo

Keyword(s):

Harmful Algal Blooms ◽

Algal Blooms ◽

Ecological Research ◽

Nakdong River ◽

Long Term Ecological Research ◽

The Nakdong River

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Uncertainty Improvement in a Simulation of Channel Evolution

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.212-213.341 ◽

2012 ◽

Vol 212-213 ◽

pp. 341-344

Author(s):

Kwang Ik Son ◽

Taik Jean Hwang ◽

Man Ha Hwang ◽

Young Ho Yoon

Keyword(s):

Nakdong River ◽

Channel Evolution ◽

Alluvial Channel ◽

Longitudinal Slope ◽

Bed Materials ◽

Channel Degradation ◽

The Nakdong River ◽

The Stability ◽

Natural Channel

The Four Major Rivers Restoration Project (4MRRP), one of the largest river rehabilitation projects in Korea, has being carried out during the last three years. 0.57 billion m3 of sediment was dredged to widen and deepen the channel along four major rivers, the Han, Nakdong, Geum, and Youngsan rivers. As a result of reshaping the natural channel to a trapezoidal channel, and the construction of 16 weirs, the change of longitudinal slope of the river was inevitable. The distribution of bed materials was also changed, due to dredging. Therefore, the rivers were totally disturbed, and the stability of the rivers could not be assured. In particular, the Nakdong river, the second largest river in Korea, has the characteristics of an alluvial channel. Degradation of the main channel bed caused bank erosion, and head-cut phenomena in many tributaries. Deformations of the main channels could be observed all along the river. Long-term simulation of the channel evolution and prediction of the stability of the Nakdong river have to be examined, to cope with the instability of the river, which could lead to unexpected river disasters. This study deals with the methodology of uncertainty improvement, in analysis of the simulation and confirmation with field survey data. Methodology of uncertainty improvement in description of weir, whose discharge coefficient is unknown, in a river was suggested.

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