• Title/Summary/Keyword: Asan Bay

Search Result 84, Processing Time 0.029 seconds

Estimation of Sediment Yield to Asan Bay Using the USLE and GIS (GIS와 USLE를 이용한 아산만 유입 유사량 추정)

  • Kim, Sang-Min;Park, Seung-Woo;Kang, Moon-Seong
    • Journal of Korea Water Resources Association
    • /
    • v.36 no.6
    • /
    • pp.1059-1068
    • /
    • 2003
  • Geographic Information System (GIS) combined with Universal Soil Loss Equation (USLE) was used to estimate the soil erosion of Asan Bay experiment watershed in Korea. Spatial data for each USLE factors were obtained from the Landsat-5 TM remote sensing images and 1/25,000 scale digital contour maps. Sediment yield to Asan Bay was estimated by the sediment delivery ratio and trap efficiency. The estimated sediment yield was compared with observed on the Asan and Sapgyo estuary sub-watershed within Asan Bay experimental watershed for the period from 1981 to 2000. The calculated total annual sediment yields from Asan and Sapgyo estuary sub-watershed to Asan Bay were 5,665tonnes/yr and 6,766tonnes/yr, respectively. The measured sediment yields were 12,937tonnes/yr and 12,395tonnes/yr, respectively on an average.

Nutrient Budget and Dam Effluence in Asan Bay (아산만 내 방조제 배출수와 영양염의 물질수지)

  • Jeong, Yong Hoon;Cho, Min Kyun;Lee, Dong Gi;Doo, Sun Min;Choi, Hyun Soo;Yang, Jae Sam
    • Journal of the Korean Society of Marine Environment & Safety
    • /
    • v.22 no.5
    • /
    • pp.468-482
    • /
    • 2016
  • To understand variations in the seawater quality of Asan Bay over four seasons form December 2011 to February 2013, we applied two methods: an in-situ observation of water quality and a comparison study of nutrient budgets among three parts (No. 1, 2, and 3) of Asan Bay. We found a significantly high nutrient concentration in the central part of the bay (No. 2) in July 2012 both in the mass balance study and in situ observation. We presumed the source of these nutrients to be both benthic effluence from old dam reservoirs and incompletely-treated municipal waste-water. This elevated nutrient concentration in the central part of Asan Bay (No. 2) expended to off-shore area and eventually triggered an intense Chl-a concentration in Asan Bay. Based on this result, we suggest improved waste-water quality control around the drainage area of Asan Bay.

Bottom sediments of the Asan bay, west coast of Korea (아산만일대(牙山灣一帶) 해저퇴적물(海底堆積物)에 대(對)하여)

  • Kim, Sung-woo;Chang, Jeong-hae;Park, Yong-ahn
    • Economic and Environmental Geology
    • /
    • v.11 no.2
    • /
    • pp.81-88
    • /
    • 1978
  • Nearly 300 bottom sediments and 20 box-cores were sampled from the Asan bay. The central portion of the Asan bay is covered by sand, slightly gravelly sand and gravelly muddy sand. Between the central and marginal zones gravelly mud and slightly gravelly sandy mud are characteristically distributed. The gravel population in the sediments seems to be originated from the rocky bottom on the area near the bay because the gravel is angular and composed of the schist and gneiss. The quartz/feldspar ratio is about 3/2. It is considered to be that the amount of feldspar in this bay is much higher than that of any other areas in the Yellow Sea. This is considerd to be comparatively short distance of transport ion of these sediment from the provenance.

  • PDF

Benthic Polychate Community in the Southern Area of Kyeonggi Bay, Korea (경기만 남부 해역의 저서다모류 군집)

  • SHIN, HYUN-CHOOL;KANG, SEONG-GIL;KOH, CHUL-HWAN
    • 한국해양학회지
    • /
    • v.27 no.2
    • /
    • pp.164-172
    • /
    • 1992
  • This study was carried out to investigate the benthic polchaete community in the southern area of Kyeonggi Bay, Korea. The species composition was examined in Asan Bay in 1985, the coastal area near Yibug in 1987, the area between Daeranjido and Asan Bay for 1988-1989, and the offshore south of Deogjeogdo in 1992. Polychaetes, the dominant faunal group occupying 57.4% in total density, comprised a total of 124 species with a mean density of 211 indiv.m/SUP -2/. The dominant polychaete was Prionospio sp. (28.8%), followed by Nephtys polybranchia (6.0%), Tharyx sp. (4.8%) Stermaspis scutata (4.4%), Lumbrineris longifolia (3.9%). The Number of species and density were higher in the coastal area near Yibug, Asan Bay and the mouth of Namyang Bay, while lower in the channels of offshore region. The cluster analysis revealed that the study area could be divided into 5 regions, which were distributed serially along the coast from Asan Bay to open sea. Each region sustained its specific Bay, Stermaspis-Heteromastus assemblage from Asan Bay to Daeranjido, Hemipodus assemblage in the channels of offshore, Lumbrineris assemblage on the coastal area o Yibug and Prionospio assemblage in the coastal area south of Yibug. Tharyx-Chone assemblage had the highest species number of 75 spp. and Prionospio assemblage had the highest density of 3,695 indiv.m/SUP -2/ due to the predominance of prionospio sp.. Hemipodus assemblage with the lowest density occupied the largest area in offshore region. The southern Kyeonggi Bay showed higher species number and lower density than the northern Kyeonggi Bay. But the dominant Polychaetes were similar between the southern Bay and the channel regions of the northern Bay.

  • PDF

Organophosphorous Pesticide Distribution in Seawater from Asan Bay, Korea in 2008 (2008년도 아산만 해수 중 유기인계 농약 분포)

  • Choi, Jin-Young;Yang, Dong-Beom;Lee, Sung-Gyu;Bang, Jae-Hyun;Hong, Gi-Hoon;Shin, Kyoung-Hoon
    • Ocean and Polar Research
    • /
    • v.32 no.3
    • /
    • pp.203-212
    • /
    • 2010
  • Distribution of organophosphorous pesticides (OPs) was studied from February to September 2008 in the seawater of Asan Bay, Korea. Among the 29 types of OPs detected during the study period, IBP(S-benzyl O,O-diisopropyl phosphorothioate), ranging from <1 ng/l to 377 ng/l, was the most abundant. Other commonly observed OPs concentrations in the study area included diazinon (Diethyl 2-isopropyl-4-methyl-6-pyrimidinyl phosphorothionate; <1~307 ng/l), azinphos ethyl (3,4-Dihydro-4-oxo-3-benzotriazinylmethyl O,O-diethyl phosphorodithioate; <1~1997 ng/l), malathion (1,2-Di(ethoxycarbonyl)ethyl O,Odimethyl phosphordithioates; <1~3013 ng/l), demeton-O (Diethyl 2-(ethylthio)ethyl phosphorothionate; <1~2403 ng/l), and DDVP (2,2-dichlorovinyl dimethyl phosphate; <1~283 ng/l). Seasonal distribution of OPs in seawater is dependent on the OP application period. In August, OPs concentrations were generally decreased with the increased salinity of seawater, implying progressive dilution of pesticides in the estuarine system. OPs were deposited into Asan Bay from Asan and Sabkyo Lakes as well as surrounding tributaries. Ten OPs, including diazinon, were detected in the suspended particles of Asan Bay.

Distribution characteristics of organophosphorous pesticides in Asan Bay, Korea (아산만 해역의 유기인계농약 분포특성)

  • Choi Jin-Young;Yang Dong-Beom;Ju Hyo-Jung;Kim Kyung-Tae;Hong Gi-Hoon;Shin Kyoung-Hoon
    • Journal of the Korean Society for Marine Environment & Energy
    • /
    • v.9 no.3
    • /
    • pp.176-186
    • /
    • 2006
  • Distribution characteristics of organophosphorous pesticides(OPs) in water and suspended particles were studied in Asan Bay, Korea, from June 2004 to October 2005. 28 organophosphorous pesticides could be detected in Asan Bay during this study. The most commonly and abundantly measured OPs in the surface waters were IBP (max=$6,343.7ng\;l^{-1}$). DDVP, diazionon, ethoprophos and methidathion were also observed at relatively high concentrations. Their maximum concentrations exceeded $100ng\;l^{-1}$ in almost every month. Malathion, mevinphos, ph orate and chlorfenvinphos were also detected at relatively high concentrations. Many OPs more frequently appeared in summer than in winter due to the intensive application of pesticides in summer months. The concentration of OPs generally decreased with increasing distance from the mouth of Asan Bay. This result implies progressive dilution of these pesticides in the marine environment. Measured concentrations of diazinon were well below $20,000ng\;l^{-1}$ which is a limit set by the seawater quality standard of Korea. The concentrations of malathion and parathion in the surface waters of Asan Bay did not exceed the seawater quality standard of Korea($250,000\;and\;60,000ng\;l^{-1}$ respectively). OPs adsorbed on suspended particles were also studied. DDVP, phorate, stirofos, EPN, azinphos-methyl and IBP had higher adsorption capacity onto suspended particles than other pesticides. Calculated pesticide-particle adsorption coefficient($K_d-particle$) for samples collected in Asan Bay were closely related to the reported pesticides-soil adsorption coefficient ($K_d-soil$).

  • PDF

A Numerical Experiment On Tidal Currents In Asan Bay

  • Ahn, Hui Soo;Lee, Suk Woo
    • 한국해양학회지
    • /
    • v.11 no.1
    • /
    • pp.18-24
    • /
    • 1976
  • The distribution of tidal currents in Asan Bay was simulated by a numerical experiment. A homogeneous and single layer model with bottom stress taken into account was used. Although the effective configuration of the bay differs significantly between the high tide and the low tkde, its form is assumed to be fixed as a first approximation. The advective term is particularly large because the tidal range of 810cm is large compared to the depth and the changes of velocities occur abruptly. The results of calculations agree fairly well with the observations. For example, the tidal range at Manhoriis amplified 15cm higher and the phase lag is five minutes later than at the mouth of the bay. It also can generally be said that, with the semidiurnal tide at the mouth of the bay, the tidal range is increased toward the inner corner and that tidal currents are found to be large at the deeper part of the bay.

  • PDF

Distribution and Abundance of Japanese Anchovy Engraulis japonicus and Other Fishes in Asan Bay, Korea, estimated Hydroacoustic Survey (수산음향기법을 이용한 아산만 멸치(Engraulis japonicus)와 기타어군의 분포 및 현존량 추정)

  • Lee, Hyung-Been;Kang, Don-Hyug;Im, Yang-Jae;Lee, Kyoung-Hoon
    • Korean Journal of Fisheries and Aquatic Sciences
    • /
    • v.47 no.5
    • /
    • pp.671-681
    • /
    • 2014
  • The distribution and abundance of coastal fish species in Asan Bay, Korea, were estimated from hydroacoustic survey and net catches. Acoustic data were collected with 38 and 200 kHz from July to October of 2012, and converted to the nautical area scattering coefficient (NASC, $m^2/mile^2$) for $0.25n{\cdot}mile$ along ten transects. Japanese anchovy Engraulis japonicus was the dominant specie in the net catches. The virtual echogram technique was used to distinguish E. japonicus from other species based on the differences in the mean volume backscattering strength (${\Delta}MVBS$) at 38 and 200 kHz. Engraulis japonicus and other fishes are mainly distributed in the center channel and outer part of Asan Bay. E. japonicus tends to move from inner to outer Asan Bay in summer and fall. From NASC data, the target strength and length-weight function of E. japonicus and other fishes were used to estimate the E. japonicus stock at 24.1-93.3 tons, and other fish at 40.6-88.4 tons from July to October 2012. The estimated anchovy biomass compared well with the cumulative catch weight from stow net catches. The hydroacoustic method offers an approach to understanding spatial/temporal structure and estimating the biomass of fish aggregations in coastal areas.

Seasonal Variations in Seawater Quality Due to Freshwater Discharge in Asan Bay (담수유입으로 인한 아산만 해양수질의 계절적인 변동)

  • Jeong, Yong Hoon;Cho, Min Kyun;Lee, Dong Gi;Doo, Sun Min;Choi, Hyun Soo;Yang, Jae Sam
    • Journal of the Korean Society of Marine Environment & Safety
    • /
    • v.22 no.5
    • /
    • pp.454-467
    • /
    • 2016
  • In order to understand the seasonal characteristics of seawater in Asan Bay, the quality of this water was observed over four seasons form December 2011 to February 2013, and correlations between seawater quality variations and freshwater input were analyzed by a statistical method. The results, based on factor analysis, indicate that the two most important factors in understanding variation are freshwater input (37.7 %) and seawater exchange (24.4 %). Asan-ho and Sapgyo-ho are two major freshwater sources that affect inner (eastern) Asan Bay. Discharged freshwater from the inner bay strongly affects the spatial and temporal distribution of seawater in the bay overall during the summer rainy season. On other hand, water re-suspended from the bottom of the bay overwhelmed the water quality during the dry winter season. In conclusion, seasonal freshwater discharge dominated the water quality of the bay, and, consequently, DIP limited the growth of phytoplankton in the bay.

The Circulation and the Submarine Topography in Asan Bay (아산만의 해저지형과 해수유동)

  • 장선덕
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.13 no.1
    • /
    • pp.1-5
    • /
    • 1977
  • A series of echo-sounding and current measurements as well as the drogue and the drift bottle experiments were carried out in Asan Bay since November 1974. Several sand bars or sand flats covered by silts were developed at ebb tide in the bay. Sand waves and sand ripples were seen on the surface of the sand bars, around which sea channels of 8~ 12 meters in depth are formed. The main stream axis of the flood current which is separated into east and west branch flows southward. A cyclonic and an anticyclonic eddy are developed at the early stage of flood tide. They are transformed into a clockwise eddy before the slack water. The maximum tidal current speed observed was 3.1 ~ 3.2 knots at the entrance of the bay, while it was 1.O ~ 2.8 knots in the bay. The location of the main stream axis of the tidal current coincides well with the sea channel. A salt wedge was observed at the estuary of the Sabgyo-cheon River.

  • PDF