• The Korean Journal of Quaternary Research
• /
• v.12 no.1
• /
• pp.1-8
• /
• 1998

동해안의 강원도 양양읍 남대천 하구에 발달한 spit beach의 지형적변화(1979∼ 1996) 는 outlet의 위치변화와 해안선 모습의 변화로 규명되었는바 일차적인 변화는 해안에 평행한 spit의 성장이며 이차적인 변화는 spit폭의 변화(overwash across sedimentation)라 고 밝혀졌다. 해빈환경의 소환경(subenvironment)으로서 swash zone과 berm crest는 각각 의 특징적 퇴적상(조직매개변수)으로 구분되는바 이에 관한 분석결과가 기술되었다.

• River and Culture
• /
• v.8 no.4
• /
• pp.100-105
• /
• 2012

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.15 no.3
• /
• pp.115-123
• /
• 2010

The occurrence and variation of oxygen deficient water mass (ODW) in Namdae stream estuary, Yangyang were studied. Field observations for water properties and sediment environments were conducted at 5 stations of the estuary from April 2008 to November 2008. The coastal sandbar is developed at the estuary mouth, and there is a pool between the estuary mouth and about 2.3 km upstream of the estuary. The pool is relatively deep and narrow compared to riverbed of the estuary. The ODW was observed continuously in the pool from May to October. The ODW extends vertically up to 2 m depth in August, and maximum length of the ODW were about 2.3 km. Mean concentration of ignition loss (IL) and acid volatile sulfide (AVS) of sediment was 7.5~9.0%, $0.282{\sim}1.106\;mg/g{\cdot}dry$ wt, respectively. Ammonium concentration in the bottom layer during formation period of the halocline and the ODW was 4~23 times higher than that of surface layer. ODW was initiated by the introduction of seawater into bottom of the estuary pool to make a strong halocline, and then decomposition of organic matter within sediment accelerated the formation of the ODW.

• Journal of Korea Water Resources Association
• /
• v.30 no.2
• /
• pp.165-175
• /
• 1997

This is to study the characteristics of available water resources (AWR) of the eastern coastal area in Korea. A rating curve was suggested at Yangyang water level station of the Yangyangnamdai river. Annual mean precipitation of this area is 1365.8mm. Annual mean precipitation in central and northern area of eastern coastal area is more than that of southern area because of orographic precipitation occurred by the north-easterly air flow from the East sea. By the correlation analysis of monthly rainfall depths between rainfall gauging stations it is presented that the rainfall gauging stations located in coastal region have the regional representativity, but the rainfall gauging stations located in the westward of mountains have a strong locality. AWR of eastern coastal area by the application of runoff coefficient 0.665 is 1134.5X106m3 and 28.6 percentage for total water resources. In each watershed AWR is 193.7X106m3 in the Yangyangnamdai river, 109X106m3 in the Kangnungnamdai river, and 146.0X106m3 in the Samcheokosip river. The seasonal changes of 30/3% in summer and 19.1% in water, and those of the AWR to total water resources are 86.3% in winter, 60.1% in spring, 50.1% in autumn, and 25.7% in summer. The results of this study may be used to establish the water resources planning of eastern coastal area.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.33 no.3
• /
• pp.230-237
• /
• 2000

An ecological study of the benthic macrofauna was carried out using a modified van Veen grab in September 1997, in Namdaechon estuary, Yangyang, Korea. A total of 17 macro-invertebrates was collected and examined from eleven stations in the study area, including 3,795 individuals and 738.63 g wet weight. Arthropods, annelids and molluscs were most abundant and occupied more than $95{\%}$ of the total number of species, individuals and biomass. Namdaechon estuary in Yangyang was very poor in macrobenthic biodiversity, and numerically dominated and characterized by the polychaetes Heteromastus filiformis, Hediste japonica, Eteone longa, an unidentified oligochaete Oligochaeta sp., a corbulid bivalve Corbicula japonica, and an estuarine isopod Cyathura higoensis. Species composition, species dominance, density, and species evenness were compared among stations. The macrofaunal azoic zone appeared in the bottom of 7 m in depth nearby the artificial bank to catch the salmons to return to the livers for spawning. It probably resulted from the oxygen depletion following strong stratification in summer, which can cause major effect on the ecological conditions and then finally kill bottom macro-invertebrates in this area. Moreover, some opportunistic species thrived in nearby another station and this is of vital importance in terms of the ecological succession in a benthic polluted area.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.42 no.5
• /
• pp.70-77
• /
• 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 Aquaculture
• /
• v.15 no.1
• /
• pp.1-6
• /
• 2002

Hydrological factors prevailing in the Namdae stream were as follows : temperature = -0.2~$26.8^{\circ}C$, salinity = 0.50~3.21$\textperthousand$, DO = 5.21~8.13 ppm, $PO_{4}-P$ = ND~1.37 ppm, $NO_{2-}$ = 0.10~0.81 ppm, COD = 1.53~2.82 ppm, $H_2 S$ = ND~0.0012 ppm and IL = 0.85~1.36 %. Sediment was typical, gravelly sand or sand with very good sorting value ranging from 0.53 to 1.77$\varphi$. Population density of the clam C. japonica ranged from 2 to 464/$m^2$. The clams were divided into four size classes, based on shell length of small (0~10 mm), medium (10~20 mm), large (20~30 mm) and largest (>30 mm), and were encountered at the frequency of 3.2, 50.4, 43.3 and 3.1 %, respectively.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2011.05a
• /
• pp.474-478
• /
• 2011

하천의 만곡부는 원심력으로 만곡 내측의 수면이 낮아지고 만곡 외측의 수면이 높아지는 수면 경사가 발생되며, 2차류 등의 발달로 흐름이 매우 복잡해진다. 특히 산지가 89%를 차지하는 강원도는 하천과 도로가 근접 발달되어 있어서 하천 만곡부의 편수위에 의한 수면상승과 세굴은 하천제방을 파괴시키고 도로 피해로 이어진다. 산지하천 만곡부 곳곳에 많이 노출되어 있는 암초는 홍수시 유수의 원활한 소통을 막고, 편수위 상승을 더욱 가중시키고 있다. 만곡부의 편수위에 대해서는 이론적으로나 실험적으로 많은 연구가 이루어지고 있으나 암초와 같은 장애물이 많고 경사가 급한 산지하천을 대상으로 편수위를 연구는 사례는 미흡한 실정이다. 따라서 본 연구에서는 양양남대천 중상류의 법수치리 면옥치천 합류 전 만곡부에서 홍수시 편수위를 측정하고, 내린천의 인제군 미산리와 홍천군 광원리 각 만곡부에 수위측정장치를 설치해 편수위를 조사하였다. 양양남대천 법수치 만곡부는 그림 1과 같이 하도 내에 있는 암반의 영향으로 편수위가 2.145m를 나타내었고, 내린천은 광원지점에서 최대 1.15m, 미산지점에서는 1.18m로 관측되었다. 특히 내리천 미산지점의 만곡접근부에서는 하도 내에 있는 암초장애물의 영향으로 편수위가 2.17m로 기록되었다. 산지하천 만곡부 수충부에 존재하는 암초 장애물은 편수위를 더욱 가중시킬 수도 있고 계방천 송전교와 같이 저감시키는 역할을 할수 있다는 것이 본 조사연구에서 확인되었다. 하도 내 암초 장애물은 산지하천 만곡부에서 매우 흔하게 발견되는 특성이므로 자연장애물이 편수위에 미치는 영향에 대하여 향후 지속적으로 연구하고자 한다.

• Korean Journal of Remote Sensing
• /
• v.33 no.5_1
• /
• pp.481-493
• /
• 2017

Estuary sand bar of Namdaecheon Stream is located in Yangyang-gun, Gangwon-do in Korea. This unique place is situated between end of Namdaecheon Stream and East Sea. It is an important environment area of the global ecosystem from the transition zone of land and marine environments by forming a variety of coastal circumstance. Some endemic species should be protected which is appearing in the Namdaecheon Stream because of preservation for future generations. Especially, the salmon return to this stream as adults in order to breed which is more than 70 % of the salmon in Korea peninsular. The monitoring of estuary sand bar is need to analyze ecological environment and sustainable development with time. First of all we represents a different shape of estuary sand bar of Namdaecheon Stream from 1984 to 2015 using Landsat satellite imagery series. Particularly movement of the "tidal inlet" is most important factor to investigate the condition of the change for estuary sand bar. The location of tidal inlet is compared with precipitation, height of tide and oceanic current data according to time variation.

• Korean Journal of Environment and Ecology
• /
• v.31 no.5
• /
• pp.461-471
• /
• 2017

Population genetic studies of 10 groups of Iksookimia pacifica were conducted to investigate the genetic diversity and population genetic structure across its known range in South Korea. Population DNA sequences of one mitochondrial gene (mtCOI) and three nuclear genes (IRBP, EGR2B, RAG1) were examined in samples collected from ten streams that flow into the East Sea. Both mitochondrial and nuclear sequences exhibited significant differentiation among populations except a few cases. The Bayesian analysis of the multi-locus genotypes inferred from the DNA sequences of nuclear genes clustered the individual fish largely into two geographical groups: a northern group (from Baebong stream to Cheonjin stream) and a southern group (Yangyangnamdae stream to Gangneungnamdae stream). Given that the streams flowing into the East Sea are geographically isolated water systems, such separation of genotypes can be interpreted by the geographical separation of common ancestors into north and south that had colonized South Korea. Since the initial geographical separation of the ancestral population by north and south, the ancestral groups seem to have experienced further differentiation into the current genetic clusters through the physical isolation of streams by the East Sea in each region. It is notable that many individuals in the Jasan stream formed a genetic cluster with those of Yangyangnamdae and Gangneungnamdae streams which are distant from each other. In addition, mitochondrial gene showed low genetic differentiation between some neighboring populations and very low level of genetic diversity in several populations. The present population genetic study will provide valuable information for the conservation and management of the Korean endemic fish species, I. paicifica.