• Journal of Environmental Science International
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• v.19 no.10
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• pp.1219-1227
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• 2010

In this study, the sensitivity analysis of bed changes due to the various sediment transport equations have been conducted for 80 km reach of the Lower Nakdong River using the HEC-6 which is one dimensional numerical model. The bed elevation changes according to the different sediment transport formulas were compared and analyzed quantitatively. As a result of the numerical simulation, the final bed elevation calculated by Engelund and Hansen(1967), Ackers and White(1973), and Yang(1979) formulas was similar to one another in configuration. The bed change simulated by Engelund and Hansen(1967) were greatest among them, for example, 5.5 m deposition and 2.9 m erosion for 100 years. Also, in the case of Toffaleti (1969) equation, the maximum bed deposition of 8.04 m after 100 years was induced at the 73 km location upstream of the Nakdong River Estuary Barrage. Meyer-Peter-M$\ddot{u}$ller(1948) and Wilcock(2001) formulas produced the deposition only at the upstream end and there was little bed change in the downstream area. The unreal bed configuration of continuously up and down pattern was simulated by Laursen(1958) transport equation.

• Journal of Environmental Science International
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• v.24 no.11
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• pp.1417-1430
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• 2015

In this study we were to explore the seasonal variation of water temperature distributions before and after weir construction at Gumi, Chilgok, Gangjung(Goryung), Dalsung in the Nakdong River using Landsat satellite images. Relationship between in-situ water temperature and radiance values of Landsat-5, 7, 8 satellite images showed high correlation. Seasonal variation of water temperature in Nakdong River showed that the fluctuation ranges of water temperature before weir construction were larger than those after weir construction. This indicated that the variation of water temperature is due to the difference of heat storage volume by weir construction and dredging work. In particular, the water temperature after weirs construction in autumn was 4-8 times lower than that before weirs construction. Water temperature after weir construction decreased in spring and summer at the downstream of Gumi weir and Gangjung(Goryung) weir, and the upstream of Dalsung weir. In autumn and winter, the water temperature after weir construction increased in the upstream and downstream of the whole weirs except upstream of Gumi weir. Relationship between water temperature and meteorological elements (air temperature, wind speed, sunshine, radiation) showed high correlation of above 94% in air temperature, and then radiation was high correlation before and after 65%.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.4
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• pp.531-538
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• 2020

Objective: Evidence from previous reports indicates that pig domestication in East Asia mainly occurred in the Mekong region and the middle and downstream regions of the Yangtze River. Further research identified two new origin centers for domestic pigs in the Tibetan Plateau and the islands of Southeast Asia. However, due to the small sample size of Tibetan pigs, details of the origin and spread of Tibetan pigs has not yet been established. Methods: We analyzed mitochondrial DNA control region (D-loop) variation in 1,201 individuals from nine Tibetan pig populations across five provinces. Comprehensive Tibetan pig samples were taken to perform the most detailed analysis of Tibetan pigs to date. Results: The result indicate that Rkaze pigs had the lowest level of diversity, while Changdu pigs had the highest diversity. Interestingly, these two populations were both in the Tibetan Plateau area. If we calculate diversity in terms of each province, the Tibetan Plateau area had the lowest diversity, while the Chinese province of Gansu had the highest diversity. Diversity gradient analysis of major haplotypes suggested three domestication centers of Tibetan pigs in the Tibetan Plateau and the Chinese provinces of Gansu and Yunnan. Conclusion: We found two new domestication centers for Tibetan pigs. One is in the Chinese province of Gansu, which lies in the upstream region of the Yellow River, and the other is in the Chinese province of Yunnan.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.1
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• pp.67-75
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• 2011

The purpose of this study is to evaluate the flow duration characteristics of Nakdong, Seomjin and Geum river due to environmental change. The water level gauging stations of Nakdong, Seomjin and Geum river were selected to analyze the change of flow duration. The construction period of multipurpose dam was considered to analyze flow duration characteristics. As the result of this study, it show that ninety-five day flow, normal flow, low flow and drought flow were increased by multipurpose dam construction at all stations except a Jukpo gauging station. Especially, improved effect of flow duration in downstream part was bigger than that in upstream and midstream part. The coefficients of river regime of Nakdong, Seomjin and Geum river were decreased and also coefficients of flow duration were decreased after the multipurpose dam construction. However decline of coefficient of flow duration was smaller than coefficient of river regime because coefficient of flow duration is less affected by maximum discharge and minimum discharge than coefficient of river regime, It was confirmed that multipurpose dam on upstream and midstream has a useful effect for improving the flow duration characteristics.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.2
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• pp.198-203
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• 2020

In this paper, we propose an artificial water level prediction system for small river flood prediction. River level prediction can be a measure to reduce flood damage. However, it is difficult to build a flood model in river because of the inherent nature of the river or rainfall that affects river flooding. In general, the downstream water level is affected by the water level at adjacent upstream. Therefore, in this study, we constructed an artificial intelligence model using Recurrent Neural Network(LSTM) that predicts the water level of downstream with the water level of two upstream points. The proposed artificial intelligence system designed a water level meter and built a server using Nodejs. The proposed neural network hardware system can predict the water level every 6 hours in the real river.

• Journal of the Korean Geographical Society
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• v.41 no.4 s.115
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• pp.418-434
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• 2006

The study was investigated to runoff characteristics of non-point pollutants according to rainfall in Kokseong river watershed. The result of which is as follows : First of all, major reason which affect the formation of water quality of Kokseong River is judged to be caused by non-point pollution source which flows out from farmland and residential area. Flow of rainfall effluent in the downstream in which direct flow components of urban district and combined sewer overflows of farmland was intervened faster than that in the upstream reacted more promptly. Generation of pollutants by non-point source shows increasing trend in general in accordance with the increase in the intensity of rainfall but it was affected by SS, BOD, COD and T-P in the upstream part whereas BOD, COD and T-N were significantly affected by beginning period of rainfall in the downstream. EMC in the downstream increased approximately 3-315 times as compared to upstream, particularly the discharge of SS5 and T-P were extremely increased. While surface flow out of rainfall effluent in the upstream was only 4.7%, the surface flow in the downstream took up as much as 29%, which was major reason for the increase of EMC. From the above contents, we can see that the change in water quality according to the increase and decrease of effluent at the time of rainfall showed very complex pattern depending on the type of land use, and it is judged that the most important thing for the administration of non-point pollution source is to come up with the solution for the reduction of effluent at the beginning.

• Journal of Wetlands Research
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• v.14 no.4
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• pp.715-723
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• 2012

The Hoelyongpo in the Naeseong River as tributary basin of the Nakdong River is broadly well-known a tourist attraction, which is made of sandy beach, and is called "Island of Inland". But Construction of the Dam was planned at upstream of river. In other words, an influx of sediment is blocked from upstream of river. In this situation, through sediment discharge coming from tributary of the Naeseong river, the whether to go ahead of sand beach of the Hoelyongpo is analyzed by using 1-D and 2-D model. The sediment discharge is estimated through ratio raw with basin area, and the instream flow requirement of river coming from dam and the flow rate and sediment coming from tributary are inputted for model. The 1-D model uses HEC-6 and the 2-D model uses SMS(RMA2 and SED2D). The analysis using the HEC-6 is performed from cross section data 10 year ago to the present cross section. Consequently, Yang equation presenting similar result to the present cross section data is determined, using this, the prediction is conducted for the cross section after 20 years. The 2-D analysis is conducted for the present cross section data. The value of distinction between a deposition and erosion with the results presented in the 1, 2-D models is occur, however, the appearance between the deposition and the erosion is similar.

• The Korean Journal of Ecology
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• v.28 no.2
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• pp.63-67
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• 2005

The eleven local samples of six species including Corbicula leana examined in this study were collected from the Nam River and the Nakdong River in Korea. Buzas's new formula was used to evaluate the ecological biodiversity among eleven populations and six species. In addition, enzyme electrophoresis was used to genetic diversity within and among populations of C. leana. The upper populations of the river have fewer species than the middle and low populations of this river. The genetic diversity trends to increase from the source of the main river to the mouth. It suggests that the population of downstream might be expanded toward upstream.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.5
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• pp.70-77
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• 2000

The fishways at Namdae-cheon and Osib-cheon were investigated from July 1998 through October 1999. There are three types of fishways on these rivers. those are baffied fishway, fish ladder, and fish ladder with gabion. Namdae-cheon has 7 baffled fishways and 19 fish ladders, and Osib-cheon has 7 gabion fishways. On namdae-cheon, 1,775 fishes of 24 species were collected. Among these fishes, 452 fishes of 11 species were anadromous fishes occupying 46% in species and 25% in number. On Osib-cheon, 1,953 fishes of 24 species were collected. Among these fishes, 483 fishes of 5 species were anadromous fishes occupying 21% in species and 25% in number. On Namdae-cheon the species number and abundance decreased gradually upstream. The poor structure of fishways seems to have worked as an obstacle to the upstream migration of fishes in the Namdae-cheon . On Osib-cheon all the observed fish species except three-spined stickleback(Gasterosteus aculeatus aculeatus) which stay and spawn around downstream of fiver could migrate upstream. The good structure of fishways on this river is thought to have helped upstream fish migration.

• Journal of Environmental Science International
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• v.12 no.3
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• pp.287-297
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• 2003

To investigate water quality and pollution states of rivers in Gwangju city, total of 30 water samples were taken from the main stream of Yeongsan river, Hwangryong river and Gwangju stream in dry and flood seasons. Physico-chemical characteristics of above streams according to pH-Eh and Piper's diagrams we, typically, assigned to natural river water. In the streams, BOD, COD, T-N and T-P indicating water quality mostly increase toward downstream. Notably, water qualities in area near connection between the Gwangju stream and the main stream of Yeongsan river are polluted over V level in rivers and lakes water quality standard. The pollutions are influenced by lift and agricultural foul waters from Gwangju City and farming areas around upstream branches of the Yeongsan river, reasonably. Besides, heavy metals are below the standard in those streams. So, it is considered that the streams are polluted by not industrial but life/agricultural foul waters.