Temporal and Spatial Variation in the Freshwater Region in Noksan Bay with the Passage of Typhoons Using the POM

(1)

59 서 론

매년하계에는북태평양에서약

25

개정도의태풍이발생하

는데

(Fig. 1)

이중약

2.4

개정도가한반도주변을통과하며

(Hong and Sohn, 2004),

^이로^인해^한반도^주변^{연안내만의}^해 수성질이시공간적으로크게변동한다

. Lee and Niiler (2003)

은태풍

Rusa

^통과시^나루도^앞바다^수심^약

25m

^인^해역에서

연직적으로거의균일한수온혼합역이형성되는것을보고하 였다

.

^이는^{태풍통과시}^{표층에서의}^강한^난류^혼합과^용승현상

등에의해발생한것과관련될것이다

(Hong, 2008).

진해만에

서

3D

원시방정식모델을이용하여태풍통과시만내해수유동

을조사한

Hong (1998)

^의^{수치실험결과는}^이러한^가능성을^뒷

받침한다

.

한편

,

^낙동강^하구역^근해는^해수

ㆍ

담수의혼합역이형성되 어물리

,

생물

,

화학적으로그변동성이매우크다

(Sin et al., 2005; Shin et al., 2007).

^특히^근년에^들어^하구역에^각종^댐^건

설로방출담수량이인위적으로조절됨에따라기존하구역의 물리적해수변동을야기하고

,

^이^해역의^생태계에^또^다른^변동 요인이되고있다

.

^더구나^{태풍통과시}^급격히^증가된^강수를^댐 에서일시적으로방류함으로써저염분확산과관련하여비록 일시적이나마생태계에큰변동을초래할수도있을것이다

.

Article history;

Received 2 January 2013; Revised 10 January 2013; Accepted 25 January 2013

*Corresponding author: Tel: +82. 51. 629. 5890 Fax: +82. 51. 629. 5889 E-mail address: [email protected]

Kor J Fish Aquat Sci 46(1) 059-069, February 2013 http://dx.doi.org/10.5657/KFAS.2013.0059 pISSN:0374-8111, eISSN:2287-8815

ⓒ The Korean Society of Fishereis and Aquatic Science. All rights reserved

Temporal and spatial variation in the freshwater region, created by river runoff, of a small bay, caused by the passage of typhoons was examined using a three-dimensional primitive equation model (the Princeton Ocean Model, POM). Numerical experiments were implemented focusing on temporal evolution in the freshwater region in as- sociation with typhoon tracks. The model domain covered most of the estuary around the Nakdong River, including Noksan Bay, where river water is periodically released from upstream (Noksan dam). The model showed that the extension of the freshwater region outside of the bay depended strongly on the tracks of typhoons, specifically the associated wind directions and inner flow fields that are accompanied by new clockwise eddies. The model also showed that entrainment from typhoon passage frequently creates salt wedges in the estuary, indicating that organ- isms in the bay are biologically and chemically influenced with variation in the freshwater region

Key words: Typhoon, Freshwater, River runoff, Clockwise eddy, POM

태풍통과시 3차원 원시모델을 이용한 녹산만 담수역의 시공간 변화특성

부경대학교 해양생산시스템관리학부

Chul-Hoon Hong ^* and Se-Young Park 홍철훈*ㆍ박세영

Temporal and Spatial Variation in the Freshwater Region in Noksan Bay with the Passage of Typhoons Using the POM

Division of Marine Production System Management, Pukyong National University, Busan, 608-737, Korea

Fig. 1. A number of typhoons generated in the North Pacific during 1970-2010.

Total numbers

Year

Total numbers of typhoon during 1970-2010 40

35 30 25 20 15 10 5

070 75 80 85 90 95 0 5 10

(2)

한반도주변하구역에서담수변동과관련하여

,

^예를^들면

,

담수확산에미치는조석효과

(Park, 1988),

^{하천공사와의}^관계

(Han et al., 1993),

^댐에서의^방수량

(Kim et al., 1996)

^또는^바 람과의관계

(Lee et al., 1995)

^등에^대한^연구들이^있었으나

,

태풍통과시댐에서방출된담수가하구역에서어떻게시공간 적으로변동하는지에대한연구는거의없다

.

본연구에서는

3D

^{원시방정식모델}

(Princeton Ocean Model, POM)

^을^이용하여^{태풍통과시}^낙동강^하구역

(Fig. 2)

^내만^및 외양연안역을중심으로상류에서방출된담수의시공간적변 동을조사하였다

.

재료 및 방법 수치모델

본연구에사용된모델은

Blumberg and Mellor (1987)

^가^개 발한

POM

^이며

,

^{북태평양에서의}^{태풍영향을}^조사한

Hong and Yoon (2003)

과기본적으로같다

.

다만

,

본연구목적에맞 게모델태풍

,

^연직^레벨수^또는^해저지형^등은^변형하여^사용 하였다

.

^그^다른^부분을^간략히^정리하면

,

^연직^레벨^수는

6

^개 의시그마층

, x, y

^방향^{격자간격은}^각각

80 m

^이며

,

^모델영역

(128°50′~128°57.5′E, 35°0′~35°07′N)

^은^해역^중앙부에^위치

한반폐쇄적녹산내만

(Fig. 2,

녹산과하신사이북부내만

)

을중

심으로낙동강하구서측해역대다수를포함한다

.

^특히^녹산내 만북부에설치된댐에서는낙동강상류담수를주기적으로방 류하므로태풍내습시이내만을통해방출되는담수역의시공 간변화를조사하기에적절한해역이라볼수있다

.

^한편

,

^녹산 만남쪽경계외측에는가덕도

,

진우도

,

장자도등이동서방향 으로위치하고있어태풍내습시동서방향의경계층으로작용 하게되므로외양으로부터남북방향으로의운동량전달효과 를상대적으로감소시키고

,

^{동서방향으로는}^일정^부분^흐름을 강화시키는역할을할것으로예상된다

.

모델영역의해저수심은

1-5 m

범위로서 극히천해이며

,

개 방경계는서쪽

,

^동쪽^및^남쪽으로^{설정하였다}

(Fig. 2

^의^점선내 역

).

^다만

,

^최근^부산신항^건설과^관련하여^가덕도^{동서해역을}

잇는해협

(Fig. 2

^의^서측

^개방경계^상단부분

)

^이^거의^폐쇄된

상태이나본연구에서는편의상개방경계로설정하였다

.

^이^점 에대해서는나중고찰에서논의한다

.

모델외력개방경계조건

으로는

KORDI(1996)

^에서^발간된

‘

^한반도^주변^조석^조화상수

자료집

’

을참고하여제공하였다

.

^본^{모델해역은}

M

2 분조가전

체의

60%

^이상을^차지하고

(KORDI, 1996),

^또^{태풍통과시의}

정성적해수변동에주목하므로편의상

M

2분조만고려하였다

.

모델결과는수치적안정성을고려하여

10

주기조석계산후얻 어진결과를사용하였다

.

^{열염경계조건에서}

,

^{담수확산과}^관련 한염분변동에주목하여

,

^수온은

25℃

^로^일정한^값을^유지시켜 열변화효과는무시하였다

.

^염분은^전^해역에^대해^일정한^초

기조건

(26 psu)

^하에서

,

^녹산내만^북부^경계를^통해^방출된^담

수에의해변동하는염분변화의시공간변동을조사하였다

.

담 수방출은녹산댐관리본수댐담수방출량을참고하여북쪽경 계에서

1,640 m

³

/s

^의^담수가^{방출되도록}^{설정하였다}

.

^평상시

(

담수방출이없을경우

)

와비교하기위해

11

조석주기

(

즉

,

준정

35°06′

35°04′

35°02′

35°00′

128°51′ 128°53′ 128°55′ 128°57′

N

E

124 126 128 130 132 134°

40°

38

36

34

32

30

N

E

Fig. 2. Map of the western Nakdong River region. The model domain is depicted by a rectangle, and dotted lines represent the open boundaries. Black circles show the observed stations for validating the model results in the case without typhoons.

The locations are 35°06′48″N-128°53′53″E for St. A and 35°05′44″N-128°53′37″E for St. B.

Fig. 3. Tracks of the model typhoons. The dots are 6 hours apart, numerals in the left and right hand sides of the tracks represent hours and atmospheric pressures, respectively.

(3)

상해이후

1

^주기

)

^경과^후^{북쪽경계에서}^담수를^방출하고^그^결 과를비교하였다

.

태풍모델에있어

,

기압분포는종래에흔히사용되어온

Fujita (1952)

^식을

,

^바람에^대해서는

Miyazaki et al. (1961)

^에^의해^주 어진다

(

^상세한^것은

Hong and Yoon, 2003

^참조

).

또담수확산역변동에미치는태풍경로의존성을조사하기 위해

,

^하계^한반도^{주변해역에}^내습하는^태풍^경로를^좌측

(

^서 해진행형

),

중심부

(

녹산내만역

)

및우측

(

동해진입형

)

등으로 구분

(Fig. 3)

^하여

case study

^를^행하였다

.

^이들^태풍은^편의상 큐슈서방역

(124°40′51″E,35°05′12″N)

^을^{발생역으로}^가정하 였으며

,

^{이동속도는}^일정

(

^약

3.7 m/sec)

^하게^유지도록^하였다

.

또중심기압은태풍이모델영역에가장근접했을때최저기압

(970 hpa)

이되도록설정하였으며

,

모델계산시간은

60

시간수 행하였다

.

결 과

관측결과와 비교

Fig. 4

는녹산내만

2

개지점

(Fig. 2)

에서

M

2분조에대한관측 및모델조류타원을나타낸다

.

^{전반적으로}^계산결과

(

^우도

)

^가 지점

A, B

에서공히약

1-2 cm/sec

정도로관측

(

좌도

)

에비해 다소강한경향을보이나북동

-

^남서^방향이^강한^경향은^대체 로잘대응한다

.

Fig. 5

^와

Fig. 6

^에

St.A

^와

St.B

^에서

RCM-9

^을^이용해^얻은^유 속시계열

(

^위

)

^및^{수치실험결과}

(

^아래

)

^를^각각^{나타내었다}

.

^자료 간격은수치계산

(5

분

)

과관측결과

(1

시간

)

가각각상이하나전

반적으로크기나유향에서조류타원결과

(Fig. 4)

^와^같이^좋은

대응을보였다

.

^즉^유향은^남서

-

^북동류

,

^유속은^약

2-4 cm/s

^정 도였다

.

^다만

,

^{조류타원결과}

(Fig. 4)

^를^포함하여^만^안쪽^지점

A

^에서의^흐름이^지점

B

^보다^{상대적으로}^약했다

.

^이것은^수심

이얕은

(

약

0.5 m

이내

)

만안쪽에서해저마찰이상대적으로

크게작용한결과로해석된다

. 조석반응

Fig. 7

은담수방출이조류에미치는효과의한예를보여준

다

.

^댐에서^담수가^방출되면^{낙조시에는}^평상시

(Fig. 7a

^위

)

^보 다조류를녹산만내및외측까지강화시키고

(Fig. 7b

^위

),

^창조 시에는반대로평상시

(Fig. 7a

아래

)

보다더욱약화

(Fig. 7b

아 래

)

^시키는^경향을^보였다

.

^즉^댐에서^담수가^방출

(

^일종의^관성 류

)

됨에따라녹산내만은물론만외측의조류세기에직접적인 영향을미치고있음을확인할수있다

.

만내의해면변위의변동양상

(Fig. 8)

^은^유동^변화

(Fig.7)

^와 잘대응한다

.

즉평상시

(Fig. 8

좌도

)

보다담수방출에따라낙 조시

(Fig. 8b,

^우상도

)

^및^창조시

(Fig. 8b,

^우하도

)

^의^해수면^변 화가공히증가하는경향을보였다

.

특히만안쪽에서이러한 경향이보다뚜렷하게나타났다

.

Fig. 4. Tidal ellipses of the observation (left) and the model (right) at St. A (upper) and B (lower).

25

0

-25

25

0

-25

-25 0 25

M2(St.A)

20 10 0 -10

-20

-20 -10 0 10 20 (cm/s)

M2, St.A

20 10 0 -10

-20

-20 -10 0 10 20 (cm/s)

M2, St.B

M2(St.B)

(4)

Fig. 5. Comparison of tidal currents in the observation (upper) and the model (lower) at St. A. For convenience, time intervals are given in 1 hour and 5 minutes for the observation and the model, respectively.

Fig. 6. Same as Fig. 5 except for St. B.

Stick Diagram M2 + pp, ST.B

20 10 0 -10 -20

20

0

-20

12:00 00:00 12:00 00:00 12:00 tidal

Mar 26 Mar 27 Mar 28

Hours

20

0

-20

12:00 00:00 12:00 00:00 12:00

Stick Diagram M2 + pp, ST.A

20 10 0 -10 -20

tidal

Mar 26 Mar 27 Mar 28

Hours

Stick Diagram M2 + pp, ST.B

20 10 0 -10 -20

20

0

-20

12:00 00:00 12:00 00:00 12:00 tidal

Mar 26 Mar 27 Mar 28

Hours

20

0

-20

12:00 00:00 12:00 00:00 12:00

Stick Diagram M2 + pp, ST.A

20 10 0 -10 -20

tidal

Mar 26 Mar 27 Mar 28

Hours

(5)

Fig. 7. Velocities (a) at M2 tide only, (b) in M2 tide with river discharge. Upper ones show flow fields 5 hours after high tides, and lower ones at 3 hours after low tides.

Fig. 8. Same as Fig. 7 except for elevations.

(6)

담수역의확산범위는저염분역의시공간변동을살펴봄으로 써파악할수있다

. Fig. 9

는담수역확산을보여준다

.

고조후

5

시간뒤

(

^낙조시

)

^담수방출

1

^시간^후부터

2

^시간^간격으로^제시 된염분분포로볼때

,

^방출후^약

5

^시간^뒤에는^내만^{외측경계까} 지담수역이확장되고있음을알수있다

.

^담수역의^시공간변 화를보다상세히살펴보기위해

x-t

^{다이어그램}

(Fig. 10)

^상에

서보면

,

^대략

20 psu

^등염선을^기준할^때

,

^{북쪽경계에서}^녹산 내만외측까지확산하는데약

5

시간소요됨을알수있다

.

내만

의길이가약

4.5 km

^인^점을^감안할^때^담수역의^{확장속도는}

약

0.25 m/sec

^이다

.

^또

15 psu

^등염선의^{시간변동을}^주목해^볼 때

,

^{조석운동에}^따라^약

12

^시간^주기로^내만외측^및^내측

(

^남북 방향

)

^으로^{소장하면서}^진동

(Fig. 10,

^화살표^방향참조

)

^하는^것 을알수있다

.

태풍에 대한 담수역 및 해수유동 반응

태풍통과시해수반응및담수역시공간변동조사와관련하여 담수방출은태풍근접통과시기를고려

,

^고조후

4

^시간^뒤

(

^계산 시간

152

^시간

)

^에^편의상

5

^시간^동안^방류하여^{조사하였다}

.

태풍통과시조사해역에서의바람방향은해수유동변화에직

접적으로영향을미친다

. Fig. 11

는태풍이조사해역의좌측

(Fig. 11a)

^및^우측

(Fig. 11b)

^을^가장^근접^통과할^때

(Fig. 3,

^태 풍경로참조

)

^의^{바람분포를}^보여준다

.

^협역의^{조사해역이므로} 전해역이거의동일한바람방향및세기를형성하며

,

^좌측통 과태풍의경우는남동풍

,

^우측통과^태풍의^경우는^북동풍이 우세하여태풍위치에따른풍향의차이를잘보여준다

.

다만

,

조사해역의중심을통과하는태풍의경우는태풍중심의통과 와함께북동풍에서남서풍으로급격이바뀌어다소복잡한양 상을보였다

(

^여기서는^그림생략

).

Fig. 9. Low salinity distributions from 5 hours after high tides with river discharge. Time evolution is given in every 2 hour. Note an initial condition of salinity with 25 psu.

Fig. 10. x-t diagram of freshwater region. Note that freshwater regions are oscillated in the south-north direction of the bay.

35.12

35.11

35.1

35.09

35.08

N

0.25 m/s

10 10 10

10 10

10

15

15 15

15 1515

15 15

15 15 1515

15

15 15 15

20 20

20

25 25

15

15 15

10

S

Hours

Laitude

128 130 132 134 136 138 140 142 144

Open ocean

Water

gate

(7)

Fig. 12

^는^{조사해역의}^좌측으로^태풍이^통과시

(Fig. 3),

^담수 방출

1

시간뒤부터

2

시간간격으로제시된염분분포를나타낸 다

.

^평상시

(Fig. 9)

^는^담수방출^후^약

5

^시간^경과한^뒤에^만내외 측까지확장되었던담수역이내만에한정되고있음을알수있 다

.

이는동일시간흐름분포

(Fig. 13)

에서알수있듯이

,

태풍 이조사해역에접근하면서발달된남동풍계열

(Fig. 11a)

^의^바 람이해안에평행한강한서향류를발생시켜만

외측으로확장하려는담수역을만내로억제시킨결과로이해 할수있다

.

^그^결과^만^{외측경계역}^{근처에서는}^{담수방출로}^인 한남향관성류와태풍으로발달된만안쪽으로진입하는북향 Fig. 12. Same as Fig. 9 except for the passage of the left hand side typhoon.

Fig. 11. Wind vectors with the passage of typhoons towards (a) the left hand side and (b) right hand side.

류가서로상쇄되어매우약한흐름장이형성되고

,

^만^안쪽에 는시계방향의와류가형성되는것이흥미롭다

.

이와류는태 풍통과후에는소멸된다

(

^그림생략

).

한편

, Fig. 14

^에서^보여주는^우측통과^태풍^시도^{좌측통과의}

경우

(Fig. 12)

처럼

,

담수역은만내에한정됨을볼수있다

.

다 만

,

^{북동계열의}^바람

(Fig. 11b)

^영향으로^왼쪽통과^태풍에^비 해다소만내외측으로확장된경향을보였다

.

이는북동계열 의바람이이번에는해안선에평행한동향류를발달시키고이 흐름의영향이좌측통과태풍때와유사한영향을미쳤기때문 이다

.

전반적으로약한와류를형성하는것도바람영향에기

(8)

Fig. 13. Same as Fig. 12 except for the velocities.

Fig. 14. Same as Fig. 12 except for the passage of the right hand side typhoon.

(9)

태풍통과시 3D모델에서 내만 담수역 시공간 변동

67

인한것으로해석된다

.

태풍이조사해역중앙부를통과한경우

(

^여기서는^그림^생략함

)

^는^조사해역^통과^전에는^북동풍

,

^통과

후에는남서풍계열의바람을가장근접해영향을받게되므로 담수역의변동도매우복잡하게변동하였다

.

^즉^담수방출^후 약

10

^시간만에^{만외측경계를}^벗어나^해안선을^따라^서쪽으로 광범위하게확산하나태풍통과후에는방향을바꾸어외측연

Fig. 17. Vertical structures of salinity in the levels with passage of (a) LHS, (b) RHS, and (c) the central-passage-type typhoons.

35.12

35.11

35.1

35.09

35.08

0.08 m/s

15 15

20 20 20 20

20

15 15

15 15 15 15

N

S

Laitude

Hours

155 160 165 170 175 180 185

TP 10

10 25

25

25 25 10

10 10 10

25

Openocean Water gate

35.12

35.11

35.1

35.09

35.08

N

0.16 m/s

15

15 15

15

15 15 1515 20

20 20

20

25 25 25 25 2525

25 25

S

Hours

Openocean

Water gate

Laitude

155 160 165 170 175 180 185

TP

20 20

20

20 20

20 10 10

35.12

35.11

35.1

35.09

35.08

0.18 m/s 15

Laitude

Hours

155 160 165 170 175 180 185

TP

25

25 25

25

25 25

25 25 2525

25 25

25

10 10

20

2020

20

20 20

20

20 20 20 20

20 20

20 15 15

15 15 N

S Openocean Water gate

35.08 35.09 35.1 35.11 35.12 S

Level1

hours 157 Tp left + M2 +wg 2

3

4

5

25 2525 2520 20 2015 10 10

1010 10

15

N

1atitude

1ayer

35.08 35.09 35.1 35.11 35.12 hours 157

Tp left + M2 +wg

25 25 20 20

2020 15 10 10 10

10 10 10 10

15

15 15

1515

25 25

N

1atitude

E Level1

2

3

4

5

1ayer

35.08 35.09 35.1 35.11 35.12 hours 157

Tp left + M2 +wg

S

25 20

202020

20 15

15

15 15202510

10 10

1010

10 30

25 25 25 2525

Level1

2

3

4

5 N

1atitude

1ayer

35.12

35.11

35.1

35.09

35.08

0.08 m/s

15 15

20 20

20

15 15

15 15 15 15

N

S

Laitude

Hours

155 160 165 170 175 180 185

10 TP

10 25

25

25 25 10

10 10 10

25

35.12

35.11

35.1

35.09

35.08

N

0.16 m/s

15

15 15

15

15 15 1515 20

20 20

20

25 25 25 25 2525

25 25

S

Hours

Openocean

Water gate

Laitude

155 160 165 170 175 180 185

TP

20 20

20

20 20

20 10 10

35.12

35.11

35.1

35.09

35.08

0.18 m/s 15

Laitude

Hours

155 160 165 170 175 180 185

TP

25

25 25

25

25 25

25 25 2525

25 25

25

10 10

20

2020

20

20 20

20

20 20 20 20

20 20

20 15 15

15 15 N

35.08 35.09 35.1 35.11 35.12 S

Level1

3

4

5

25 2525 2520 20 2015 10 10

1010 10

15

N

1atitude

1ayer

35.08 35.09 35.1 35.11 35.12 hours 157

Tp left + M2 +wg

25 25 20 20

2020 15 10 10 10

10 10 10 10

15

15 15

1515

25 25

N

1atitude

E Level1

2

3

4

5

1ayer

35.08 35.09 35.1 35.11 35.12 hours 157

Tp left + M2 +wg

S

25 20

202020

20 15

15

15 15202510

10 10

1010

10 30

25 25 25 2525

Level1

2

3

4

5 N

1atitude

1ayer

35.12

35.11

35.1

35.09

35.08

0.08 m/s

15 15

20 20 20 20

20

15 15

15 15 15 15

N

S

Laitude

Hours

155 160 165 170 175 180 185

TP 10

10 25

25

25 25 10

10 10 10

25

35.12

35.11

35.1

35.09

35.08

N

0.16 m/s

15

15 15

15

15 15 1515 20

20 20

20

25 25 25 25 2525

25 25

S

Hours

Openocean

Water gate

Laitude

155 160 165 170 175 180 185

TP

20 20

20

20 20

20 10 10

35.12

35.11

35.1

35.09

35.08

0.18 m/s 15

Laitude

Hours

155 160 165 170 175 180 185

TP

25

25 25

25

25 25

25 25 2525

25 25

25

10 10

20

2020

20

20 20

20

20 20 20 20

20 20

20 15 15

15 15 N

35.08 35.09 35.1 35.11 35.12 S

3

4

5

2525 20 20 10

1010 10

15

N

1atitude

1ayer

35.08 35.09 35.1 35.11 35.12 hours 157

Tp left + M2 +wg

25 25 20 20

2020 15 10 10 10

10 10 10 10

15

15 15

1515

25 25

N

1atitude

E Level1

2

3

4

5

1ayer

35.08 35.09 35.1 35.11 35.12 hours 157

Tp left + M2 +wg

S

25 20

202020

20 15

15

15 15202510

10 10

1010

10 30

25 25 25 2525

Level1

2

3

4

5 N

1atitude

1ayer

안을따라동쪽으로확산하였다

.

Fig. 16

^은^태풍의^좌측통과

(Fig. 16a),

^우측통과

(Fig. 16b)

^및 중앙통과

(Fig. 16c)

^의^경우에^대한^담수역^확장을^나타내는

x-t

다이어그램이다

.

^평상시

(Fig. 10)

^담수역^확장속도

(

^약

0.25 m/

sec)

^보다^{좌측통과시}

(

^약

0.08 m/sec)

^약

3

^배^가까이^느리고

,

^태 풍통과전

(

연직선

)

에는만내에한정되다통과이후

(

약

175

시 Fig. 16. Same as Fig. 10 except for typhoons with passages of (a)

LHS, (b) RHS and (c) the central area in the model domain.

(10)

간

)

^에^비로소^만^외측으로^확산되고^있음을^알^수^있다

.

^그러 나태풍경로가우측인경우

(Fig. 16b)

^에는^{확장속도도}^약

2

^배

(0.16 m/sec)

^빠르고^태풍^통과^후에는^곧^만^외측으로^확장되

고있음을알수있다

.

^중앙부를^통과한^경우

(Fig. 16c)

^도^태풍 통과전까지다른태풍의경우처럼확장속도가비교적느리다

(0.18 m/sec).

^한편

,

^태풍^통과^후^만내에서^담수역의^소장과^관

련해진동하는현상은평상시

(Fig. 10)

^와^유사한^경향을^보였

다

.

^다만

,

^평상시의^경우는^{진동주기가}^조석주기

(

^약

12

^시간

)

^에

해당되나태풍통과후의경우는대체로관성주기

(34.5N-

^약

21

시간

)

로진동하였다

.

Fig. 17

^은^{태풍통과시}^각^태풍경로^별^만내의^{연직방향의}^염

분분포를나타낸것이다

.

^{만내외측으로의}^{담수확장역이}^가장 협소했던좌측통과태풍

(Fig. 17a)

^의^경우는^상하층이^거의^균 질한염분구조를보인데반해

,

^만^외측으로^보다^확장된^우측 통과태풍

(Fig. 17b)

및중앙부통과태풍

(Fig. 17c)

의경우공히

만안쪽으로염수쐐기

(salt wedge)

^형태가^발달한^경향을^보여

주었다

.

^이러한^결과는^{태풍통과시}^{태풍경로에}^관련된^담수방 출역의소장에따라염수쐐기침입으로인한만내해수연직분 포가크게변동할수있음을시사한다

.

고 찰

본연구에서는수치실험을바탕으로태풍통과시녹산만내상 류에서방출된담수역의소장변화를조사하였다

.

^{모델유속결}

과는만내

2

^개^지점

(Fig. 2)

^에서^안데라

RCM

^유속계를^이용

해연속관측해얻은유속자료를조화분해한결과

(M

2

)

^와^검증 하여비교적좋은대응결과를얻었다

.

^그러나^{태풍통과시의}^경 우는관측자료가없어사실상이론적고찰에머물렀다

.

^그러 나태풍의경로에의존

,

^담수역^소장과^관련된^만내^형성된^와 류

(Fig. 13, Fig. 15)

^및^{염분연직구조변화}

(Fig. 17)

^는^그^발생 개연성이충분히예상된다

.

^더구나^본^연구에서^얻어진^만내의 유동특성등은한반도다른연안내만에서도공통적으로발생 할가능성이크고

,

^만내의^{해수변화에}^영향을^줘^생태계^변동 에도크게영향을미칠수있을것으로예상되어

,

^추후^관측을 통해검증할필요성이요구된다

.

또최근부산신항건설과관련하여가덕도동서해역을잇는

해협

(Fig. 2

^의^서측^개방경계^상단부분

)

^이^거의^폐쇄된^상태이

나본연구에서는편의상개방경계로설정하였다

.

^이를^폐쇄경

계로처리할경우

, Fig. 13

^에서^예상할^수^있듯이

,

^가덕도^동편

과서편을잇던해협을통해진해

ㆍ

마산쪽으로분산유출되었 던해수

(

^서향류

)

^들이^태풍이^{북상하면서}^반시계^방향의^바람 영향으로가덕도동편연안을따라형성되는빠른남향연안제 트류를더욱강화시켜외해흐름장을크게변화시킬것이다

.

그러나이러한외해의흐름변화와는달리녹산만에서방류된 담수역의확산역은본연구결과와크게다르지않을것으로사 료된다

.

본연구에서는편의상

,

^{열적변동이나}^기본류

(

^대마난류^등

)

^및 대기해양간열교환

,

^강수^등을^무시한^매우^간단한^조건에서 실험을수행하였다

.

^특히^조석은

M

2만고려하여각분조별

(

^예 를들면

, S2, O1, K1

^등

)

^{상호영향은}^{무시하였다}

.

^이러한^조건 들은실험결과에일정부분영향을미칠수있을것이다

.

기본 류

(

^대마난류^등

)

^를^{무시함으로써}^{해수유동에}

,

^{강수제외는}^염분 농도에

,

^대기해양^열교환^및^일정수온^조건^등은^경압성^해류 생성에어떤영향을미칠수있을것이다

.

^그러나^이러한^것들 은본실험결과에정량적으로어떤영향은줄지라도정성적인 결과자체를크게바꾸지는않을것이다

.

이런모델의약점은 추후연구를통해보완해야할것이다

.

사 사

이논문은

2010

^학년도^{부경대학교의}^지원을^받아^수행된^연

구임

(PK-2010-

^과제^번호

C-D-2010-0175).

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Temporal and Spatial Variation in the Freshwater Region in Noksan Bay with the Passage of Typhoons Using the POM

59 서 론

25

(Fig. 1)

2.4

(Hong and Sohn, 2004),

. Lee and Niiler (2003)

Rusa

25m

.

(Hong, 2008).

3D

Hong (1998)

.

,

ㆍ

,

,

(Sin et al., 2005; Shin et al., 2007).

,

.

.

Article history;

Received 2 January 2013; Revised 10 January 2013; Accepted 25 January 2013

*Corresponding author: Tel: +82. 51. 629. 5890 Fax: +82. 51. 629. 5889 E-mail address: [email protected]

Kor J Fish Aquat Sci 46(1) 059-069, February 2013 http://dx.doi.org/10.5657/KFAS.2013.0059 pISSN:0374-8111, eISSN:2287-8815

ⓒ The Korean Society of Fishereis and Aquatic Science. All rights reserved

Key words: Typhoon, Freshwater, River runoff, Clockwise eddy, POM

태풍통과시 3차원 원시모델을 이용한 녹산만 담수역의 시공간 변화특성

Chul-Hoon Hong * and Se-Young Park 홍철훈*ㆍ박세영