DensityinOⅥraSel箋ay MasahiroNAKAGAWA；IIKazuharuKu王そ肌那＊＊，KoushiNoDA＊＊＊，

Bull．F弧Bioresources，MieU11iv．  

No．12：1S7−207   March31．1994  

VerticalDistributionsofTemperature，Salinityand   DensityinOⅥraSel箋ay  

MasahiroNAKAGAWA；IIKazuharuKu王そ肌那＊＊，KoushiNoDA＊＊＊，  

YoshihiroTAKASHIBA締＊andYoshihikoSEKINE＊  

＊FacultyofBioresources，MieUniversity  

＊輌EnvironmentCountermeasureSection，OwaseCityO琉ce  

Abstract  

HydrographicconditionsofOwaseBayarecharacterizedbytwoe軌IentSOfthermalwaterfrom   thermalelectricpowerp‡antandfreshwaterh・omhydroelectricpowerplant・Constractionofthethird   thermalelectricpowerplantinJune1987inducedtotalvolumeofthemalwateref餌enttoincreasefrom   lesstha1131．6m3sec￣1to53−55m3secMl，Whiletheef鮎entoffreshwatervarieswitharangeofO−25   m3sec…luptonow，Verticaldistributionsoftemperature，SalinityanddensityinOwaseBayaiongthree   observationallinesarepresentedinthispapcrbyuslngObservationaldatainthirteenperiodsfromAprii   1986toSeptember1991．Itis shown thatthereexist signi負cantchangesinhydrographic structure  

depcndirlgOntidalperiods：C漁1entSOfthermalandfreshwaterspreadtoacenterofthebayortoa  

baymouthduringtheperiodsofebbandlowwater．However，tWOemuentSareCOn蝕edtoaninnermost   ofthebayandthee敗IentSeXpandverticallyduringtheperiodso川00dandhighwater・ThistenderlCylS  

mostprominentalongsouther】mOStObservationailine・Itisalsoshownthatthedifferenceintemperature   distributionoccurreddependingonthevolumeofemuentoffreshwater：e漁1entOfthermalwaterspreads   inupperlayerhperiodorweakfreshwatere軌1e吼Whileitintmdesbelowthelesssalinewaterinperiod   Oflarge打eshwatere約uent．  

11IltllOduぐtion  

LocationandgeometryofOwaseBayinKiiPeninsulaareshownFig・1・Hydrographicconditionsof   OwaseBayarecharactedzedbytwoefnuentsofthermalandfreshwater．Themalwaterisdischargedintothe   rivermouthofYano−River，WhiiefreshwaterisdischargedalongNaka−River（Fig．1）．Horizontaldistributions   oftemperatureandsalinityinOwaseBayhavebeenstudiedinPartlofthisstudyl〉− MainresultsofPartlリare  

summarizedasbliows：   

（1）Hydrographicconditioninthelayershailowerthan3msign壇cantlychangeswithtidalperiods・In   periodofconstantefnuentoffteshwater，lesssalinewaterexpandsinrelativelylargeareainebbandlowwater   periods，andexpansiontendstobecon蝕edtoaninnermostofthebayintheperiodsofnoodandhighwater・In   periodofvariablee用uentof＆eshwater，eXpanSiono‖esssalinewaterdependsonthevo‡umeofe漁1entOf  

打eshwater．  

AcceptedOctober27，1993   

ユ88  

M；lSahiroNAKAGAWA，KazuharuKu肝Ⅶ王，KoushiNoDA，Yoshihiro′rAIくAS川BAa11dYoshihikoSEK】パE  

1340E   1360E   1380 E 

38q卜J  

360 N 

340 N 

320 N 

136013′∈   136016′E  

Fig．l．LocationandgeometryofthcwesternpartofOwaseBayanditsdepthcontours（inmeter），Opcn   largesquarene；lrinnermostofthebaymeanstllelocationo川1ermaleまectdcpower由比 Openand  

ClosedtrianglesatrivermouthofNaka−RiverandYano−Rivermeanthe10Cationofinflowandouttlowof  

Sea Water uSedin thermalelectric power plant．Closed circle shows thelocation of Owase Tide  

Station．   

VerticaiHydrographicVariationsinOwaseBay   189   

（2）Expansionoftwoe私Iluentsismainlycon鮎edtoalayershauowerthan3m．Onthewhoie，itis   COnCludedthatthehydrographicconditionsofOwaseBaydependonthevolumeofthermalandfreshwater  

efaue‡1tSandontlletida王period＄．   

However．sincethediscussionisbasedonhorizontaidistrbutionsoftemperatureandsal血ty，detailsof   verticaidistributionshavenotbeenweildiscussedinPartll）・Therefore，VerticalstructureinOwaseBayis   presentedillthepresentstudy．  

2 0bservations  

LocatiorlSOfobservationalpointsoftemperatureandsaunityareshowninFig．2．Threeobservational   lines，A−，B−andC−iines，WereSetヒOSeetheverticaidistribution，Detailsoftheobservationsare由veninTable   l，inwhichvolumeofe軌IentSOfthermalandfreshwateraveragedoverthreehoursbeforeeachobservationare   alsoshown・SealevelchangesatOwaseTideStation（Fig．1）areshowninFig．3．Largersealevelchangeof   l・5misobservedinspringtidesandsealevelchangeisrelativelysmau（0．5m）inneaptides．  

34005 N  

34004′N   

136D16■E  

Fig−2・Locationsofobservationalstationsぬrtemperatureandsaunity．  

Asforeachobservationa！period．fourtimesobservationsoftemperatureandsatinityhavebeencarriedout   indifferenttida王periods・TemperatureandsaiinityareobservedbyEILSa血ometer（MC5／2）．Density（ort）  

iscalculatedfrorntemperatureandsaunitydata．Sa最nityatallstationson25Apri11986（86APトIV）andsalinity   OneaStemhaほofth托eObservationa1日neson20and28August1990（90AGトⅤⅠⅠ王）werenotobserved．   

SameasinPartll），WeClassifYtheobservationalconditionsintofourcasesbasedonthedi触enceinseason  

andvolumeofeftluentsofthermalandfreshwater（Table2）．Wedonotshowtheresultson25Apri11986．   

KuRl‡㌻肌KoushiNoDA，Yos仙roTAKAS王−1】まAandYoshil−ikoS‡こKIN】；  

MasahiroNAKAGAWA，Kazuharu  

ユ90  

簑 ⊥苫こ︻  

軍TAびくト00  

浣望ふ思慮罠＝儀で暑  

宏竺．冨呵琵  

嗟r−AUく浣  

ト宗−．冨吠  

一己−ⅠぴVト∞   芸耶−．警戒琵  ♭H・叫u葺二撼  

霊芝 ﹂首  

己・I dS霊  

冨巴．冨鴫∞  已∴u＜富   冨雲．買ペ誓  己・l Uくの￠  買 J馬巴  己・lJ﹁∽の   

￠  く＞  ◎  l＝ゝ  亡｝  ○  

l■ヽ   ○   椚  l≡■   ∽  

（呵車り＝明  

く■  ○  白  t∋  ○  く⊇  

．．′サ   ta   の   ⇔   ゝ（  

tヽ■   M   ▲−   ■●￣  

舛け…ト呵    p  ぶ  ○  凸  0  0  

）7   ￠   uり   申  】ヽ   r・．1   tヽJ   −   ￣￣  

†呵ヤ‖ト呵  

VerticalHydrographicVariationsinOwaseBay   191   

でablel．Detailsofobservations．N．D．meansnodata．   

Ol）SerVations   Date   Tide   E臥1ent（m3sec肌肋1）  

Tilermdwater Freshwater  

D D D D N N N N  

25Apr．1986   Ebb   Lowwater  

F】00d  

Highwater  

ハU 3 0 3 八U 4 8 1 ハリ 3 AT OO＋ハU 3 4 2 0 0 4 3 700 7 nO 6 7 7 ハ8 09 0 0 9 ハU O 1 6 6 5 5 nU 5 9 6 1 1 8 9 8象U 7 8 30 ハU ハU 八U6 68 八UハU 仁U4 086 40 ハリ8ごU 44 4 4 3 333 0564 34 44 4 4．4A． O qV37 d．d．3 3 d．メq．A．4  2   りん n∠ 2 2 2 りん 2 りん  1 22 2 2 2 2 2 2   1 1 2 2 2 2 2 2 2 2 2  1 1  1 2  1 2  1  

86API   86APII   86APII1   86APIV   8尉LI  

8尉L王Ⅰ  

8尉LII王  

8尉L王V   86AGI   86AGII   86AGII工   86AGiV   87AGI  

87AG王Ⅰ  

87AGII王   87AG王V   87AGV   87AGVI   87AGVII   87AGVlII   88AGI   88AGII   88AGIII   88AGIV   88SPI   88SPI1   88SPII王  

＄8SPIV    89APi  

89A王⊃iI  

89APII王   89APIV    89AGI   89AGI王  

89AGlV   89AGV   S9AGVI   89AGVI1   89AGVIiI    90AG王   90AGI王   90AGIII   90AGIV   90AGV   90AGVI   90AGVII  

90AGVI王Ⅰ   

91SPI   91SPII   91SPIII   91SPIV  

29Jul．1986   Flood  

． 

Highwater   Ebb   Low water  8Aug．1986  日ighwater  

Ebb   Lowwater  

Flood   llAug−1967  王H晦hwater   Ebb   Lowwater  

Flood   19At唱，1987   Ebb  

Lowwater  

lTlロー）（l  

Highwater   Ebb   26Aug．1988  

Lowwater   Flood   High water  2Sep．1988  をIighwater  

Ebb   Lowwater  

Flood   Flood   HigllWater   

Ebb   I−OWWater  

Flood   HigllWater   

Ebb   Lowwater   

Ebb   Lowwater   

Flood   HigllWater   

Ebb   Lowwater   

Flood   H泌1Water   

Flood   HigllWa【er   

Ebb   Lowwater   

I;lood  liigllWater   

lミbb   Lowwater   13Apr．1989  

5 5 3 5 6 6 6 6 6 6 6 6 6 6 6 6  0 3 d一3 4 4 4 4  4 4・4 4 4 4 4 4  5 5 5 5 5 5 5 5  5 5 5 5 5 5 5 5  

25Aug，1989  

31At唱．1989  

20Aug．1990  

28At喝．1990  

n∵n‖  

N N N N  

2Sep．1991  

192  

Masa圭一iroNAKAGAIVA，KazullaruKuliIFUJl，KousはNo勒Yoslliilirol、AKASf＝摘andYoshihikoS王三重くINE  

Table2．Cla＄Sificationofobservatiorlhviewofwateref軋1enCe  

Obsenratiollal   Wateremuence   

SeaSOn  

′rherm扇water FresllWater   。bses）  

Sprii唱  

No data  No data 

Sunl】Ⅵer   S111al】  

Variable  

89APト王Ⅴ  

（Fig．4）  

8村L＝Ⅴ   （Fig．5）  

66AGl−ⅠⅤ  

（Fig．6）  

87AGトⅠⅤ   （Fig．7）  

87AGV・VlII   

90AGト王V   （Fig．9）  

88AGトⅠⅤ   （Fig．10）  

88SPトIV   （Fig．11）  

89AGトIV   （Fig，12）  

89AGV・ⅤⅠⅠ王  （Fig．13）  

90AGV−ⅤⅠⅠⅠ （Fig．14）  

91SPトⅠⅤ  

（Fig．15）  

Summer   Large   Vadable  

Summer   Large   Constant  

becausenoobservationofsalinitywascarriedout．Becauseoftheconstractionofthirdthermalelectricpower   planthJune1987，thee軌1entOfthermalwaterincreasedfromlessthan31・6m3sec血1to53−55m3sec…l・  

ObservationsonllAugust1987werecarriedoutaftertheconstractionofthirdthermalelectricpowerplant，  

effluentofthermalwaterislessthan50m3sec…1（Tablel）．Therefore，thisobservationisclassi6edintoGroup  

（王Ⅰ）．  

3 Results  

Verticaidistributionsoftemperature，Salinityanddensitya重ongA・，B−andC−1inesareshowninFigs．4−15．  

IncaseoftheGroup（Ⅰ），Verticaltemperaturechangeon13Aprii1989isweakexceptforaninnermostofthebay  

（Fig．4）．Awaterwarmerthan18Ocexpandsgraduallyasthelapseoftime．Tl扇stendencyisrelativelydear   inA−andB−1ines．Thereissigniticantdifferenceofsalinitydistributionsineachtidalperiod：lesssalinewater   than33psuspreadstoabaymouthinthelayershaliowerthan2mduringtheperiodso用00dandhighwater■  

However，lesssalinewaterexl）andsverticallytoadepthof3minanirmermostofthebayduringtheperiodsof   el）bandlowwater．Althoughaneffluentoffreshwaterstartedduringhighwaterperiod（Tablel），lesssaline   waterthan30psuappearsinebbperiod．Thelesssalinewaterspreadsinthe】ayershallowerthan2milllow   waterperiod．ThistendencylSrelativelyprominentinC−1ine．   

IncaseoftheGroup（ll），aWaterWarmerthan260cspreadstoacenteroftheunesinthelayersha1lower   than2mintheperiodofnoodon29July1986（Fig．5）．However，aWarmWatereXPandsvertica11ytoadepthof   4monandafterhighwaterperiod．Sirnilarchangeisalsodetectedinsalinkydistribution・Lesssalinewater   than31psuspreadstoabaymouthinthelayersha1lowerthan3min鮎odperiod．Althoughfreshwatereffluent   beganduringtheobservationinhighwaterperiod（Tablel），1esssalinewaterisconfinedtorelativelyinnerarea   Ofthebaylntheperiodofebbandlowwater．Sma11expansionoflesssalinewaterissupposedtobeduetoneap  

tidesinthisobservationalperiod（Fig．3）．Lesssalinewaterthan28psuisobservedinyロIelayerdeeperthan2   mofstn．40nCJineinebbperiod，detailsofthislesssalinewaterisunclear．  

Becausetidalchangeshaveacommonphasein8August1986（Fig．6）andllAugust1987（Fig．7），Similar   

VerticalHydrograpl壷Val■iationsbiOwaseIきay  

d   

Fig． 霊．（a）Verticaldis血butionsoftemperature（top），Salinity（middle）anddensity（qt）（bottom），alongA−1inc  

（‡e軋B−】ine（ce11ter）andC−】i】1e（dg壬1t）kl鮎odpel・iodoI113A画＝989．（b）S；l‡11eaS（；l）btlt払rhigll  

waterperiod．（c）Sameas（a）butforebbperiod．（d）Sameas（a）butforlowwaterpcriod．   

Mas融血oNAKAGAWA，KazuhanlKuR肝ⅦⅠ，KoushiNom，Yoshi量血0′rAl仏Slll王与AalldYoshillikoSEiく王州；  

194  

b   l  

Fig．5．（a）SameasFig．4（a）butbriniioodperiodon29Ju】y1986．  

（b）Sameas（a）butforhighwatefperiod．  

（c）SanleaS（a）butわrebbpedod．  

（d）Sameas（a）butforlowwaterperiod．   

VerticalHydrographicVariationsinOwaseBay   j95  

⊂  

l      l   

Fig・．6．（a）SameasFig．4くa）butk〉rinI扇ghwaterpedodon8August1986．  

（b）Sameas（a）butぬrebbperiod．  

（c）Sameas（a）butわrlowwaterperiod．  

（d）Sameas（a）butbr800dperiod．   

MasahiroNAl仏GAWA，KazuharuKulミl王Tt3）l，lくoushiNoI）＾，Yosh血iroTAlくAS111iうAandYoshihikoSEKINlミ  

ユ96  

l  

Fig．7．（a）SameasFig．4くa）butforimhigtlWaterperiodonllAugust1987・  

（b）Sameas（a）butforebbperiod．  

（c）Sameas（a）butわrlowwaterperiod．  

（d）Sameas（a）butわr鮎odperiod．   

Vertica＝iydrograpllicVariationshOwaseIきay  

一L   

3   きi鼻  

・ 一−■  

熟   ‖  

粧短．8．（a）SameasFig．4（a）butforinebbperiodon19August1987．  

（b）Sameas（a）butbrloww8terperiod．  

（C）Sameas（a）but払ー鮎odperiぬ  

（d）Sameas（a）butforl扇ghwaterperiod．   

MasalliroNAKÅGAWA，KazuharuKulそIl〜肪Kous】扇NoDA，Yos最hiroTAKASl川うAandYos紬玩oS】ミⅠくINE  

b  

ダig．9．（a）SameasFig．4（a）butforinebbperiodo1120August1990・  

（b）Sameas（a）butforlowwaterperiod．  

（c）Sameas（a）butfor鮎odperiod．  

（d）Sameas（a）butforhighwaterperiod．   

VerticalHydrograpbicVaぬtionsinOwaseBay   199  

a  

Fig．10．（a）SameasFig・4（a）butわrinebbpedodon26August1988・  

（b）Sameas（a）butforlowwaterperiod・  

（c）Sameas（a）butfor鮎odperiod一  

（d）Sameas（a）butforhighwaterperiod・   

Masah鉦oNAKAGAWA，KazullaruKuR膵肌KousI扇Nol）A，YosはhimTA】くASⅢBAandYoshjhilくOSIミKINE   200  

l  

Fig．11・（a）SameasF主g，4（a）butforinhighwaterperiodon2Scptember1988．  

（b）Sameas（a）butforebbpedod．  

（c）Sameas（a）butforlowwaterperiod．  

（d）Sameas（a）butbrnoodperiod．   

VerticalHy（1rographicVadationsinOwaseBay   201  

Fig・．12．（a）SalneaSFig．4（a）butfori11鮎odperiod（m25Au卯St1989．  

（b）Sameasくa）butforhighwaterperiod．  

（C）SaiⅥeaS（a）butforebbperiod．  

（d）Sameas（a）butforlowwaterperiod．   

Masal壷oNAlくAGAWA，KazuhanlKulモIFU）！，Kousl厄NoDA，Yosl扇hiroTAKAS11IBAandYos王1ihikoSEKINE  

202  

・・・一一イ        ′  

Fig．13．（a）SameasFig．4（a）butforinebbperiodon31August1989．  

（b）Sameas（a）butforlowwaterperiod．  

（C）Sameas（a）butぬー鮎odperiod．  

（d）Sameas（a）butforhighwaterperiod．   

Vertica‖†ydrographicVariationsinOwaseBay   203  

l  

yig．14．（a）SanleaSFig．4（a）butぬrin800dperiodon28August1990．  

（b）Sameas（a）butbrhighwaterl）eriod．  

（c）Sameas（a）butforebbperiod．  

（d）SalneaS（a）butk〉rlowwaterperiod．   

MasalliroNAKAGA勒Kazu！1amIくUlミIF肌KousはNo彿Yosh抽oTA】くASll】bAan〔iYoshitlikoSE‡く！N】三  

Fig．15．（a）SameasFig・4（a）butぬrinnoodpehodon2September1991・  

（b）Sameas（a）btlt如llig壬1Waterperiod・  

（c）Sameas（a）butforebbperiod，  

（d）Same；lS（a）butbrlowwaterperiod・   

Vertica】ⅠイydrographicVariationshOwase王きay   205  

temperatureandsalinitychangeareobserved‥OnA−andB−1ines，aWaterWarmerthan260cspreadstoacenter   Ofthelinesinthelayershauowerthan2minebbperiod，andwarmwaterexpa11dsverticallyin鮎odperiod．  

Especia11yon8August1986（Fig．6d），aWarmWaterreaChestoadepthof5m．HoweveronCJine，aWarrn   WatereXpandshorizontauyandverticallyastllelapseof玩me．工tisnotedthattemperatureinversionoccursat  

thesurfaceoftheinnermostofthebayin凸00dperiod．Thisphenomenonseemstoberesultedfromintrusionof   thermalwaterefnuentbelowlesssalinewater．Salinitychangedependingontidalperiodhasacommonphase  

totemperattlre．   

IncaseoftheGroup（ⅠⅠⅠ），thetwoobservations，On19August1987（Fig．8）and20August1990（Fig．9），  

haveacommonchangeintemperature．Awaterwarmerthan270c（Fig．8）or280c（Fig．9）spreadsinthelayer   Shallowerthan2minlowwaterperiod，andthewarmwateronA−1ineexpandsratherverticauytoadepthof3m   inhighwaterper主od．However，thewarmwateronC−1inecontirmestoexpandholizontaiyandverticalyasthe   lapseoftime．TemperatureinversionoccursatthesurfacelayeroftheirulermOStOfthebayinhighwater  

Period（Figs．8dand9d）．Itisfoundthatsalinityisrelativelyhighevenatthesurfaceintheinnermostofthebay   OneaChobservationexceptforhighwaterperiod．   

IncaseofGroup（IV），Signi鮎antdecreaseinsaiinitywascommonlyobservedexceptfor25August1989  

（Fig．12）．Especiauy，lesssalinewaterthan30psuisdetectedevenatadepthof5mon26August1988（Fig．  

10）．Itissuggestedthatnotabledecreaseofsaunityintheupperlayerresultsinintrusionofe蝕IentOfthermal   Water．However，threedifferentchangesintemperatureandsalinityareobserved，dependingonthetida王   Period．Firstly，thetwoobservations，On26August1988（Fig．10）and2September1988（Fig．11），havea   COmmOnChangeinsalinity：lesssalinewaterthan24psu（Fig．10）or29．5psu（Fig．11）spreadstoacenterof   eachtineortoabaymouthinperiodsofebbandlowwater，butlesssalinewaterissuppressedtoaninnermostof  

tllebayintloodperiod．ThisphenomenonisratherconspICuOuSJ）nA−andBpunes．However，itisdetected   thattemperaturedistributionisindependentontida壬periods，Asigniticantcoldwaterthan24Ocisobservedata   depth of3−4m ofB−1ine on2September1988（Fig，11d）．As this cold wateris detected at only one   Observationalpoint，detausofthiscoldwaterisunclear．  

Secondly，aSfortheresultsof25August1989（Fig．12）and2september1991（Fig．15），Saunitydistribution   differsfromprevioustwoobseravationsofGroup（lV）．Lesssalinewaterthan32psu（Fig．12）or26psu（Fig．  

15）spreadstoabaymouthintheupperlayerh鮎odperiod，andlesssalinewaterissuppressedtoaninnermost   Ofthebayinebbperiod．Lesssalinewaterexpandsverticauytoadepthof5minaninnermostofthebayon   and after high water period on25August1989（Fig．12）．Simiilar changeis also foundin temperature  

distribution：aWaterWamerthan270cspreadsinthelayershauowerthan2minperiodo用00d，andwarm   WatereXPandsvertica11ytoadepthof4monandafterhighwaterperiod．SincesealeveLchangeon25August   1989isrelativelysmallduetoneaptides（Fig．3），dependenceontidalperiodsisrelativelysma】l．Incontrastto   this，aWaterWarmerthan260cexpandshorizontallyastbelapseoftimeon2september1991（Fig．15）．  

Thirdiy，itshouldbenoticedthattemperattlredistributionson31August1989（Fig．13）on28August1990  

（Fig．14）shownodependenceontidalperiods，althoughtheformer（latter）obserbationa重periodisinspring  

（neap）tides（Fig．3）．Awaterwarmerthan26Oc（Fig．13）or280c（Fig．14）expandshorizontallyandverticauy   asthelapseoftime．Lesssalinewaterthan30psuspreadsinthelayershallowerthan2mtoabaymouthinebb  

Period，andlesssalinewaterisrathersuppressedtoacenterofA−andB−1inesinfloodperiodon31August1989  

（Fig．13）．   

206   MasahiroNAKAGAWA，KazuhamKu】モIFUJ【，KouslliNo帆Yosl−ih如TAKAS‡ハ11日AandYoshihikoSE】くINE  

4 S11mmaryanddiscussion  

AsaninitialphaseofthehydrographicconditionofOwaseBay，theverticaldistributionsoftheobserved   ternperature，Salinityanddensityhavebeenpresentedinthepresentpaper・Themainresuitsaresummrized  

asぬijows．   

（1）ItisdetectedthathydrographicconditionofOwaseBaysignifgicantlydependsontidalperiod：ef臥1entS   ofthermaland魚・e＄hwatertendtospreadtoacenterofthebayortoabaymouthぬebbandiowwaterperiods．  

Incontrasttothis，eXpanSionofe飢uentstendtobecon餌edtoanhnermostofthebay，andef軋1entSeXpand   verticauyinnoodandhighwaterperiods．Thissuggeststhatadvectionoftidalcurrentisimportantforthe   expansionofe軌jenとS．Thistendencyismoresi如艮cantonA一触e．   

（2）Dtlringconstantlargeemuentoffreshwater，lowdensitywaterduetolowsalinityspreadsinasurface   layer．E瑠uentofthermaiwaterintrudesbelowthelesssa血ewater．Fromthisviewpoint，VOlumeoffresh   WaterefauentisimportantforthetotalfeatureofhydrographicconditioninOwaseBay．  

Upliftofsalinewaterneartheout触wofthermalwaterisperceivedinsomeobservations：inlowwater  

Periodor18August1986（Fig．6c），inthreeperiodsonllAugust1987exceptforlowwaterperiod（Fig．7），in   ebbperiodon26August1988（Fig．10a）andinlowwaterperiodonAugust1989（Fig．13姉．Thereisa   possibiiitythattheupiiftiscausedbytheverticalentrainmentofsalinewaterduetothestronge班uent．The   dynamicaldiscussiononthisprocessisneededforthefuturestudy．   

Togetherwiththehorizontaldistributionsoftemperatureandsalinityl），generalf由turesofhydrographic   StruCtureOfOwaseBayhavebeenpresented．HydrographicstructureofOwaseBayassociatedwithe用uents   Ofたeshandthemalwaterandtidalconditionswi艮beexaminedstatisticalyandquantitativelyinasuccedhg  

paper・  

Acknowledgments   

Theauthorswishtoexpresstheirthanl（StOMr．R．Tasakiforhishelpindrawingsome蔦糾reS．  

Re鎚rences   

l）SEKINE，YりM．NAKAGAWA，K．KuRIl〜肪K．NoDAandY．TÅ鮎S‡1IBA．Ho血ontaldistdbutionoftemperatureandsalinity   

hOwaseBay．Bull，F弧Bioresources，MieU王IivりNo．11，pP．113−144（1993）・   

VerticalHydrographicVariationsinOwaseBay   207   

尾鷲湾内部の水温・塩分・密度の鉛直分布について  

中川 勝裕＊・栄藤 和治＊＊・野田 排史＊納  

商芝 芳裕＊摘  ・関根 幾彦＊  

＊ 三蕊大学生物資沫学部  

＊＊馬食市役所水産辣   輌＊尾薯市役所環境対策裸  

尾港湾の海況は火力発電所からの温排水と水力発電研からの淡水の流人により特徴づけられる。1987年7月に火力   発電所3母機が増設され，温排水蕊は散大で31．6m3sec￣1であったのが53m3sec仙lから55m3sec￣1に増加し   た。一方，淡水放水盤は今日までOm3sec￣1から敢大25m3sec】1の問で変化している。本給文では1986年4月から   1991年9月にかけて13桓】行われた3測線におけるデータを月伸一て，水温・塩分・密度の鉛夜分布を示した。全体とし   て潮時に依存する顕著な水温・塩分・密度の変化があることが示された。温排水と淡水の排水は共に下げ潮時と干潮   時において綺中央部から湾口にまで広がる。しかし，上げ潮時と潤潮時には湾奥に閉じ込められ鉛麗方向に広がる。  

この傾向は澄も南寄りの測線において踏著である。また，水力発電研からの淡水放水愈により水温構造が異なること  

が示された。淡水放水盈が少ない場合は温排水は薙蘭を広がるが，多い場合は湾の教奥郵から温排水ほ低塩分水の下  

に常人する。