1idal-Flow, Circulation, and

Flushing Changes Caused -

by Dredge and Fi II •

In

-r ....... r-I • I

I dlTlfJd oay, rlorlaa

R" rARI I} rnnn\A/II\..I I - .. _- • ........ '--" '--" L..o' .. ... "

Prepared in cooperation with the

u.s. Army Corps of Engineers

and the Tampa Port Authority

U . S. G EO lOG I CAL 5 U RV EY W ATE R-S U PPLY PAP ER 2282
DEPARTMENT OF THE INTERIOR ~~~ ~~." l~~~

DONALD PAUL HODEL, Secretary !:.,,"y . -. i .~~ -r-'" , -

.'~ ;/1' "':U . \~'. ., : U 0 ,... ,... .... ,..... ,.....,....~ .. ,... I I .... , ...... I \\~ . .., .-. 1bJ

U.,:). \...II:V LV\...I I Lf'\L ,:) U '" V I: , ~~!. '".Ll."~

Dallas L. Peck Director . ~~.':."d:~h3W

UNITED STATES GOVERNMENT PRINTING OFFICE: 1987

For sale by the Books and Open-File Reports Section, U.S. Geological Survey,

Federal Center, Box 25425, Denver, CO 80225

Ubrary of Congress Cataloging in Publication Data

Goodwin, Carl R. ~. 10. _:._••I~"_~ ~ft"" 4l, ,~h:~~ ,,,., 'cArl h" nrArln.. ",nn fill in , Tampa Bay, Florida.

(U.S. Geological SUNey water-supply paper; 2282)

Bibliography: p. c,,~. "f nn"" nn' I 1 1~:2282

1. Tides-Florida-Tampa Bay-Data proc/*lsing. 2. Tides-Florida-Tampa

Bay-Mathematical models. 3. OCeanic circulation-Florida-Tampa

Bay-Data processing. 4. OCeanic circulation-Florida-Tampa BayMathematical models. 5. Dredging-Florida-Tampa Bay. 6. Fills _.' T___ I:t;', I I Ift:.<W'l c......'; Ar""''' r",rfte. nf

Engineer~:' II. Tampa Port Auth()'rity. III. Title. IV. Series.

GC334.G66 1987 551.46'34 84-600408
CONTENTS

Abstract 1

Introduction 1

t'urpose ana scope 2

Methodology 2 - .C "+.. A •• ,~~~ ., OJ -.-- - Previous studies 9

Acknowledgments 10

Description of computer simulation system 10

uovemmg equations lU

Numerical procedures 11

Tnnllt 1" .

QDerations 13

Model development and application 13

Bottom configuration 13

DounDary conDItions !()

Bottom boundary 16

Shorelines and tributary streams 16

Seaward boundarv 17

Water-surface boundary 19

Initial conditions 21

UDal sIage ana tIaat current :.H ,.., ......

.... Calibration and verification 22

Tidal stalle 22

Tidal current 23

Dispersion 28

Application to 1880, 1972, and 1985 levels of development 32 A. ... ...

J"

Boundary conditions 32

Initial conditions 32

Model results and analysis 35

Methods 35

Vector computations 35 .... ..... a. - lIlCl",,, JJ

Longitudinal summary 35

Water transport 37

Flood and ebb water transport 37

1'100a and ebb water-transport differences for 1880, 1972,

and 1985 46 D 'A .1 ...'" ....". ,. ..,""

Residual water-transport differences for 1880, 1972, and 1985 51

Constituent transport 63

Flood and ebb constituent transport 64

t'Jooa and ebb constituent-transport differences for 1880,

1972, and 1985 71 n '..I. .,If

Resirlll::ll - fnr 1RRfl 1Q7'

and 1985 77

Contents III
Summary 84

Selected references 86

Glossary of selected terms 87

Abbreviations and conversion factors 88

FIGURES

1. Location map of Tampa Bay study area 3

" r...",nh "nrl .. nf tun;""1 t;rI.." -. -~ .. in Tampa Bay 4

3. Map showing locations where physical changes were made to Tampa

Bay between 1880 and 1972 5

4. Map snowmg lOCatIOnS 01 major suoareas ana areas 01 pnyslcal cnange

projected for Tampa Bay between 1972 and 1985 6

"_7 .....

5. Finite-difference scheme for computer simulation model 12

6. Relation of programs, files, input, and output for the simulation

modeling system 14

I. ~al1oralion ana verhicadon SLepS in mOUel uevelopmem 1;'

8. Map showing location of tidal stage and tidal current measuring sites

<Inri <Inri Inn17-t..rm s.itl"S in ,,1 nnH

Bay 18

9-12. Graphs showing:

9. Comparison of observed tidal stage in the Gulf of Mexico and at

ron ue "OLO insiue me mouLII 01 1 ampa Day 1::1

10. Comparison of observed tidal stage in the Gulf of Mexico with

tirl",1 d",.... h" ,,<:in.. ,...n",,_ ., .,n -~ " -~ . 11. Comparison of computed tidal stage in the Gulf of Mexico with

observed tides at Fort De Soto during model calibration and

verification periods 21

w ina speea ana .. U:. aunng anu

periods 22

13-15. Graphs of observed and computed tidal stage at selected sites in Tampa

Bay:

13. During calibration period 24

14. During first verification period 25

1 :>. uuring seconu verhicadon pcriou .u ,r ~. ". ,. .v. v. .... ...... ..".. 17. Graphs of observed and computed tidal current speed and direction at

selected sites in Tampa Bay during first verification period 29

18. Graphs of observed and computed tidal current speed and direction at

selected sites in Tampa Bay during second verification period 30 , .. 1::1. 11l1i:l~l; Ul .... "'...,.)' lJ1Ull1l; 111 .l i:lll1lJi:l Di:lY i:lllU Ul

:~nnA n~r1 • ., ~1"~A 't1 ..". OJ ..

20. Graph of tidal stage and tidal current used during turbidity plume

simulation 32

21. Diagrams of shape of simulated turbidity plume at selected times

following start of turbidity generation 33

22. Graph of repeating, 24-hour tide used as boundary condition for model .. 'tLl . 23. Map showing phosphorus distribution in Tampa Bay, July 1975 36

24. Diagram showing computations for vector addition and subtraction 37

25. Diagram showing computations for average flood- or ebb-transport vector ana tor reslaual-transport vector 38

26. Map showing longitudinal summary lines and circulation zones of

D",,, 'to -r -.

IV Contents
27-29. Maps showinp; water-transport pattern durintl tvnical floodtide in

Tampa Bay for:

27. 1880 level of development 40

28. 1972 level of development 41 ..,n I no~ 1~.._1 _J.' •

~-"" 30-32. Maps showing water-transport pattern during typical ebbtide in Tampa

Bay for:

30. 1880 level of development 43

31. 1972 level of development 44

32. 1985 level of development 45

'l'L'l1;; l\Jf"n~" ;n ul"t"r ;~ - Dn 4'~ •• -or -~ -r 0" OJ

33. Tvnical floodtide between 1880 and 1972 Ipvpl~ nf

development 47

34. Typical floodtide between 1972 and 1985 levels of

oevelOpmem ,,~

35. Typical ebbtide between 1880 and 1972 levels of development 50

'll;; - 107.., n~r1 10Q~ 1~..ol~ ~4' C1 r

37. Graph showinp; water transport alom~ lontlitudinal summarY lines durintl

typical floodtide and ebbtide in Tampa Bay for 1880, 1972, and 1985

levels of development 52 - lVlaps snowing resioual waler-IranSport pattern m 1ampa lSay ror: ",o,-,+u.

38. 1880 level of development 54

39. 1972 level of development 55

40. 1985 level of development 56

41. Map showing representative residual water-transport pattern at the entrance to Tampa Bay for 1972 level of development 57

"'ZJZ. Map snowmg cnanges m resIaua! water transport m Tampa Bay 1001\ ._-1 1 ""''''l 1.J.' ~n. . .~ ~oo~ •• .~~.~ ~. ~~ "'7

43. Map showing changes in residual water transport in Tampa Bay between 1972 and 1985 levels of develonment 60

44. Graph of average tributary streamflow and tide-induced circulation in

Tampa Bay along longitudinal summary lines for 1880, 1972, and 1985

levels of development 62 A~ A.., .. ,,-- ••• M .., '~p~ "0 r ~L)'}JI""U HI

Tampa Bay for:

45. 1880 level of development 65

46. 1972 level of development 66

47. 1985 level of development 67

48-50. Maps showing constituent-transport pattern during typical ebbtide in D_. J.'••

'p~ 'J .~••

48. 1880 level of development 68

49. 1972 level of development 69

50. 1985 level of development 70

5 I-54. Maps showmg Changes m constItuent transport m Tampa Bay for:

51. Typical floodtide between 1880 and 1972 levels of . . .,,,

52. Typical floodtide between 1972 and 1985 levels of

development 73

53. Typical ebbtide between 1880 and 1972 levels of development 75

'4. TypIcal ebbtIae between I ~7:l ana 1985 levels of development 76

55. Graph showing constituent transport along longitudinal summary lines r1..r;nlT ......;,..,,1 ., "nrl '.I'~ 'T'n __n D __ 4'~_ 1001\ In..,.., n~-I '0 ·r ... OJ , , 1985 levels of develonment 77

56-58. Maps showing residual constituent-transport pattern in Tampa Bay for:

56. 1880 level of development 78

'I. I ~'j:l level or development 79

Contents V
58. 1985 level of development 80

59. Map showing changes in residual constituent transport in Tampa Bay

between 1880 anCfT97ZTevers ot C1evelopment 81

60. Map showing changes in residual constituent transport in Tampa Bay • n""" _ .oJ • no~ ,_. __, ~~ , 01 £J'_ ....... £J ,oJ

61. Graph showing tide-induced and streamflow flushing of example constituent along longitudinal summary line from lower Tampa Bay to

Hillsborough Bay for 1880, 1972, and 1985 levels of development 84

TABLES

1. Physical changes made in Tampa Bay since 1880 7

2. Physical characteristics of major subareas of Tampa Bay and of Tampa

Bay overall for 1880, 1972, and projected 1985 levels of development 8

- "., .. n ....

;J. ".," i1UUUi11 vI .~ £ ......y .. ...... ...

4. Calibration and verification time periods and field data availability for

tidal sta2e and current observations in Tampa Bay, 1972 22

5. Information summary for tidal stage stations in Tampa Bay 23

6. Standard error of tidal stage in Tampa Bay for calibration and verification

periods 23

- .. " .~., • 'T". n. "'.. I. VI uu.... ..~~ ... £ .....1'.. ~"J -

8. Standard error of tidal current speed and direction in Tampa Bay for

verification periods 31

9. Stage, first difference, and second difference of repeating, 24-hour tide in

Tampa Bay used as boundary condition for model application 34

10. Water transport and direction during typical floodtide at selected sites in " Inn'" ,,_,. • no~ ,. .," "L J "IUy" u .. IVI JUUV, .........., .JU-' .~ ,~.~ v. .v

11 W!ltpr !Inti··· ti'lrinl1 tvni~al • .• at l:itf"l: in

Tampa Bay for 1880, 1972, and 1985 levels of development 49

12. Flood and ebb water transport and percentage changes in Tampa Bay for

1880, 1972, and 1985 levels of development 53

13. Residual water transport and direction at selected sites in Tampa Bay for

1880, 1972, and 1985 levels of development 58 1A A"...."n...:...1 .._' !Inti fnr P!lt"h t";rt"111!1_ -., . tion zone in Tampa Bay for 1880, 1972, and 1985 levels of

development 62

15. Constituent transport and directIOn dunng typical tlooC1tiC1e at selected sites

Inl ampa Hay lor Tl5'W, T':ITZ', ana 1'-0;,) levelS or 0'1

16. Constituent transport and direction during typical ebbtide at selected sites

;n R!lU fnr 1SHUl 107') !Inti 1QRIii If"Vf"Il: nf ' , '71 -.

17. Flood and ebb constituent transport and percentage changes for 1880,

1972, and 1985 levels of development 74

18. Residual constituent transport anC1 C1lrectlon at selecteC1 SItes In Tampa Hay

lor 100U, l'-f~, ana 1'-0;) levelS vi OJ

19. Tide-induced flushing and percentage changes in Tampa Bay for 1880,

1Q7? !Inti 1QR'ii lpv"l" nf H4

VI Contents
Tidal-Flow, Circulation, and Flushing Changes

r""",r"rJ ho.I r'\ .."rJ"." ........ ,J c:II :_ ,""UUJ'-'U uy L.",--u5'-- allu I III III

Tampa Bav, Florida

By Carl R. Goodwi n

Abstract Model results show that the bay can be functionally sub- .J: '.J .J . . .~.. T~ .L

physical '0' . .J•

Tampa Bay, Florida, underwent extensive -'

trances to Tamoa Bav and the maior bav subunits HillsboroUl~h cnanges oeTweenr tstsU and I'::J/ L oecause ot construction ot Bay and Old Tampa Bay, have several times greater average causeways, islands, channels, and shoreline fills. These changes circulation than do adjacent and more landward zones. Cir- resulted in a progressive reduction in the auantitv of tidal water • ,-. .L •

that enters and leaves the bay. Dredging and filling also changed o",,~,a"T 'v L"" '-' U .~ LV '" head of Hillsborough and Old Tampa Bays, with a striking ex- the magnitude and direction of tidal flows in large parts of the ception in zone 3 in mid-Tampa Bay. This lO-mile section of bay. the bay has significantly lower average circulation than that

A two-dimen~ion;ll finitp- ' . ,

VI ,LV' ,<::~, Iy Ivr ,~VUV. II<::~<::V model was used to simulate flood, ebb, and residual transport tion is thought to be a circulation constriction that reduces the of both water and a dissolved constituent for the physical con- potential transport of dissolved and suspended constituents. V;L;V'~ L"aL ",,;,,"u' lelllIl-'eI VelY VU';1I5 IOOU drlU 1:1/, dilU Circulation in the constricted section was computed as for the ";thAt ;lrp likpl\' to pxiq in 1QRI; Tl . IIdV "5 U1-'<::' ,,<:: " I UI<::U5<:: ellIU lill Lurl~UULand verified model was used to hindcast water- and constituent- tion between 1880 and 1972. An additional increase of 21 per- transport changes caused by construction in the bay between cent, due to the Federal dredging project, is calculated. With VVVelliV I :7i .... l~ IIvuel Wd~ u~eu ell~V TO these increases, this zone acts as less of a constriction than it

that can be expected to occur as a result of a major Federal did in 1880. This and other circulation increases may have con- dredging project scheduled for completion in 1985. tributed to increased bay salinity and to more rapid flushing The model forecasted transport changes caused by the of constituents from the bav to the Gulf of Mexico.

reaeral areaging project to oe mucn less areally extensive man

the corresponding transport changes caused by construction

in Tampa Bay between 1880 and 1972. Dredging-caused

changes of more than 50 percent in flood and ebb transport 11"1 I .11'-'1"1

were computea to occur over onlY ts or '::J square miles ot tne

Dredge, fill, and other construction activities have bay's 390-square-mile surface area between 1972 and 1985.

The model com outed that construction between 1880 and 1972 created many physical features in Tampa Bay that were

caused changes of similar magnitude over 58 square miles of not present before about 1880. These features include tens

the bay. Dredging-caused changes of more than 50 percent of miles of ship channels, many square miles of islands :~ . ~o . . . .- J~ J'1~~'- i:l,UU - .' ' ~HC~, luur lUi:l,-

miles of the bav between 1972 and 1985. According: to the ~~. "",A +1,,,+ N""'" .. t.~ 1..~. ~",r1 J .." -" OJ'

model simulation, construction between 1880 and 1972 caused numerous residential and commercial shoreline landfills.

changes of similar magnitude over 167 square miles. ,-. Most construction occurred between 1880 and 1972, and

peak activity occurred in the 1950's and 1960's. Before v,~w "~LV' ,~~. LOU' - 'vu"""

patterns. The patterns consist of a series of about 20 interconthis study, the cumulative impacts of these features on nected circulatory features that range in diameter from 1 to

movement of water and waterborne constituents in the 6 miles. Dredging- and construction-caused changes in size, " ..,.. h"" ","'r'" nnt \11",11 • "",A' ~f' I-'V~"'V ""al-''', elIIU "~""LT VI ",<:: 'y leellUle~ " tide-induced circulation and flushing throughout most of the future physical changes could not be anticipated or combay. As a result of past and projected physical changes, the pared with past changes.

bay can and will more rapidly transfer waterborne constituents A Federal dredging project to widen and deepen the

lIlell rlelve lelllUWara ~uurces IO me UUII OT Mexico. Lonverse- mam smp cnannel m lampa liay was startea m l'J/o. liy

Iy, the bay can and will more rapidly transfer constituents that 1985, the anticipated end of the project, approximately

have their source in the Gulf into the upper parts of the bay. '7{\ •• "A 3 nf h,,,, • ",HI h""", 1.. ,n ..... ~,,"'A "",A

" ."

Introduction 1
adverse environmental effects. A need for predictive and

comparative information on flow, circulation, and

flushing was recognized.

on the overall health and ecological stability of estuaries.

In eneral increases in estuarine circulation result in more

rapid net movement of dissolved and suspended constituents from regions of high concentration to regions of low

concentration. Changes in circulation in an estuary,

tion and concentration levels of all waterborne material.

Lon -term chan es in man h sical chemical and

biological properties of estuarine water can induce

ecological shifts that may destroy natural checks and

balances within estuaries that have evolved over many

estuaries and 2 tidal-flow, circulation, and flushing

changes in Tampa Bay due to dredge and fill.

(2) conditions that existed in 1972 before start of the reThe levels represent (1) conditions that existed in 1880

To meet study objectives, detailed hydrodynamic

simulation models ofwater and constituent motion were

the U.S. Geological Survey, initially in cooperation with

the Tampa Port Authority and subsequently in cooperaimpact of dredge and fill projects on water circulation,

as a means to help forecast the ecological shifts that might

result, led to this study. The study was undertaken by

Purpose and Scope

cent ship-channel dredging, and (3) conditions that are

expected to exist in 1985 after completion of ship-channel

This study addresses the effects of dredge and fill

on tidal flow, circulation, and flushing in Tampa Bay.

prior to a large Federal dredging project to widen

and deepen the main ship channel in Tampa Bay);

3. to determine tidal-flow, circulation, and flushing

c anges etween an cause Y e

Federal dredging project; and

and flushing changes caused by the Federal dredging project and all prior construction in Tampa Bay.

The circulation mechanism investigated in this

compared by using vector maps, vector-change maps, and

circulation and flushing summary diagrams to determine

the nature and degree of changes in tidal flow, circulation, and flushing among the 1880, 1972, and 1985 levels

of development.

Bay, effort was directed to develop a close match between

(1) measured physical dimensions of the bay and their

numerical representation in the model and (2) other

measurable phenomena and corresponding model comof water levels were made at many sites along the bay's

shoreline. The magnitude and direction of tidal currents

were measured at several sites within the bay. Constituent

motion, in the form of turbidity plumes, was obtained

from satellite imagery.

report is a tidal "pumpmg" action cause y mteractlOn

between tidal flow and an irregular bottom configura- . .

at the start of the cycle if tidal inflow (flood) and tidal

outflow (ebb) patterns in an estuary are exactly the same

and if other flow-in ucmg mec anlsms are not operatmg.

Descri ption of Study Area

2 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
..-_._••~.__-- ""<\ \J \

TAMPA T HIGGIN~ \ ~~~~~TIONAL \ '-- TAMPA 5\ ,/

.,,, Or'\A' - \ oJ>. • HifjStwrou9h\.. ('( , J

....... 0 __ I

V<.. oJV

--v.1._ - .. \ -J ."'7 ,...... \ "- ('

~T."'pETERSBURG- ./ \ MaeDILL ...........

INTERNATIONAL ~WEEDON I1l AIR ~RCE '\ ..7

\

\

~~_AI:\ 1,\ f!/ BEND

... TAMPA /--

SA Y

ST. PETERSBURG t!= AIRFIELDI L....Liffle

~tT ~\ 'I // R • ~irports IV

\ \\ ;- _ 0 Powerplants

I\KEY / I~ )

~"'- y~

,~ f'\.RBRADENTON17 I I I I 7.. 11

~C:\ ~'II'~' ~..L.-..L.-....I...-...L.-....J SARASOTA-~ADENTON \

_ '.4 Mil E~

?7· ":1\(\'

Figure 1. Location of Tampa Bay study area.

Introduction 3
n Th

o ulation of the three-county area in 1982 was approximately 1.6 million, with a growth rate of about 42,000

residents yearly since 1970 (Thompson, 1980).

mp

mil (Lewis and Whitman, 1985) and is the largest estuary

in Florida. Its average depth is about 12 f1. The maximum

depth, about 90 ft, is off the northern tip of Egmont Key

at the mouth of Tampa Bay.

The Tampa Bay area has a subtropical climate that

Water motion is dominated b tides that t icall

convey about 21, 3, and 5 billion ft3 of water during each

flood and ebb cycle at the mouths of Tampa Bay,

Hillsborough Bay, and Old Tampa Bay, respectively. The . .,

to the effects of the sun (diurnal)-one high and one low

tide per day-and moon (semidiurnal)-two equal high

and low tides per day- is approximately equal. The result

is a highly variable tide that exhibits predominantly diurnal characteristics on some days and semidiurnal charand Conover, 1981). More than half of the rainfall occurs from June through September, primarily from

thunderstorms.

Tributary inflow to Tampa Bay averages about

unequal low tides each day (fig. 2).

The physical dimensions of Tampa Bay have been

altered many times since the late 1800's. Most changes

have resulted from man's desire to develop and expand

for motor vehicle transportation across the bay, to build

waterfront residences, to construct power generating stamodified from Lewis and Whitman (1985), Goetz and

00 win , p.

subareas ofTampa Bay (lower Tampa Bay, middle Tampa Bay, Old Tampa Bay, and Hillsborough Bay), as

tions, and to develop recreational areas. Table 1 presents

a summary of many of the physical changes that have

occurred in the bay. Locations ofthe changes are shown

and biological processes before being flushed into the

u 0 eX1CO.

a variety of dissolved and suspended organic and inorganic constituents. Many constituents settle to the bottom of the bay. These constituents are subject to benthic . .

These are distributed by water circulation throughout the

bay. The dissolved constituents undergo various chemical

, municipal and industrial discharge, and runoff from adjacent urban and agricultural basins into the bay contain

Seasonal variations in freshwater runoff cause p.4).

w ter-surface area

of salinity and other constituents in bay waters (Goetz

and Goodwin, 1980, p. 20). However, tide and wind actions combine to inhibit formation of salinity differences

volume, and average depth of each major subarea for

physical conditions in 1880, 1972, and 1985. The values

are for a water-surface altitude equal to the National GeoWlt ept un er mos con 1 lons. e ay IS

predominantly well mixed vertically and has little densie lC e lca a um

area of Tampa Bay shown in table 2 differs from that

. ause ofsmall difFigure 2. Diurnal and semidiurnal characteristics of typical tides in Tampa Bay.

4 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
Fi ure 3. Locations wh

,

o

EXPLANATION

SHORELINE DURING 1880

PHYSICAL CHANGES

THROUGH 1972

------------ SUBMERGED SPOIL DISPOSAL

4 5 MILE

I I

Introduction 5
6 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida

EXPLANATION

- - - - SUBAREA BOUNDARY

67 INDEX NUMBER FOR SITE OF

TABLE 1)

---SHORELINE DURING 1972

LEVEL OF DEVELOPMENT

---PHYSICAL CHANGES

PROJECTED THROUGH 1985

-------SUBMERGED SPOIL DISPOSAL

AREAS
Table 1. Physical changes made in Tampa Bay since 1880

Index no. Approximate Index no. Approximate

(see figs. Description surface area (see figs. Description surface area

3 and 4) (sauare miles) 3 and 4) (sauare miles)

I ------ Causeway ------------------- 0.04 36 ------ Causeway ------------------- .09

2 ------ Causeway and residential ______ .07 37 ------ Commercial __________________ .15

3 ------ Causeway and commercial _____ .13 38 ------ Causeway ------------------- .54

.:1 "nrl ., 1.1 10 .,1\ ---- '. ---- ------------ 5 ------ Causeway ------------------- .22 40 ------ Commercial __________________ .27

o ______ '-.-ommercial ano spoil oisposal _ .I:l 41 ______ KeslOenual ___________________ .12 '7 - .. 1 A" ., ',' - ---- ."" -- - -- ---- - -- ---- ---- .. 8 ------ Residential ___________________ .59 43 ------ Residential ___________________ .10

9 ------ Commercial __________________ .76 44 ------ Commercial __________________ .08

lU ______ ~POlJ Olsposal ________________ .11 4' ______ commerCial __________________ .23

II - Spoil disposal -- --- .06 46 ---- Commercial --- - .03

12 ------ Spoil disposal and bird sanctuary .02 47 ------ Residential ___________________ .09

u ______ :SPOil disposal and bird sanctuary .04 48 ______ Causeway ------------------- .13

14 ------ Spoil disposal ________________ .05 49 ------ Residential ___________________ .43

15 Commercial __ .05 "i0 .:10 --- - - -

16 ------ Commercial and spoil disposal _ .23 51 ------ Causeway and residential ______ .40

17 ------ Commercial and causeway _____ .86 52 ------ Residential ___________________ .39

III :md l"ifl 'i1 1,<;

19 ------ Commercial __________________ .23 54 ------ Causeway and residential ______ .29

20 ------ Residential and commercial ____ .30 55 ------ Residential ___________________ .21

'1 - 1 IS/ '\,<; D I\A

------ -------- --- -- - 22 ------ Military --------------------- .12 57 ------ Causeway and residential ______ .79

23 ------ Spoil disposal ________________ .24 58 ------ Causeway ------------------- .19

"::4 ______ ~POII disposal ________________ .Uj ,~ ______ Causeway ------------------- .19

25 ------ Commercial _________________ .08 60 ------ Submerged spoil disposal ______ 8.59

26 ------ Commercial __________________ .23 61 ------ Ship-channel construction ----- 4.69

2/ ______ Causeway and military ________ .11 62 ______ Spoil disposal and beach

28 ------ Residential ___________________ .18 nourishment --------------- .16

29 --- Residential ___ ------------ .25 63 ---- Snoil disDosal S/I

30 ------ Commercial and residential ____ .03 64 ------ Spoil disposal ________________ .02

65 ------ Spoil disposal ________________ .02

31 ------ Causeway ------------------- .13

32 - Commprri:ll Ofl F.,<; "'n,,;l 011

33 ------ Causeway ------------------- .02 67 ------ Circulation-inducing cuts ______ .47

34 ------ Causeway and beach __________ .19 68 ------ Submerged spoil disposal ______ 3.12 ~~

J"J ---- - ---- ---- .1 U:7 _ ___ ~U1P- wiul:'uiJJg - - .,'+

ferences in the boundary definition of lower Tampa Bay. part of the dredged material became new emergent upland ~. . . . . .. 1111; r 111 I:'a~ll to' oJ <oU,", ·C ...... U". 6<OU' .u " <oL'" v. ~lll; U<oy.

from 1880 to 1972, from 1972 to 1985, and from 1880 Under these conditions, the average depth also increased

to 1985 also are given. The largest percentage changes because larger water volumes are divided by smaller surin surface area, volume, and depth were for Hillsborough face areas.

Bay. Between 1972 and 1985, only Hillsborough Bay and Dredging and filling from 1880 to 1985 will have relower Tampa Bay subareas sustained any changes in the duced the surface area of the entire Tampa Bay system . - , , 'non#' ... .. OJ ~lla~ all:' l;;lVI;U 111 ~aUll; ,(.. uy.:l.u . uy l.7U-', "<0."1 "U1 U<OV"

;n .,,."'., I.",,,, • .,hl", ", r",f'I",.... :n 1:1",,, h" 1 't .,,,,rl .h", ...16_+1. ...:11 -, -r -" -" 0 , -Q. -r

tion of islands, causeways, and other fills. Increases in have increased by 4.4 percent.

water volume occurred because (1) the source of material Changes to the physical characteristics of Tampa Bay

for most fill construction was the bay bottom and (2) only influence the quantity of water that enters and leaves each

Introduction 7
Table 2. Physical characteristics of major subareas of Tampa Bay and of Tampa Bay overall for 1880, 1972, and

projeClea I ~o, levels or aevelopmem 'co. &: &. • & ... "_1,.- . &, - ••,_• ._".&_,••1.:...... ____I ...... - • , V~r.;~~' n~.,,~ nf 10"01 '0 -, "T

Percentage change

nl ., ,nn" .n~~ 1CC"

ch~;a~teristic Area 1880 1972 1985 to to to

1972 1985 1985

Approximate __ Lower Tampa Bay __________ 128.4 126.1 125.9 - 1.8 -0.2 - 1.9

~lIrf"r .. Mitltll.. T"m~ R"v III , 1M 'Ii 100 'Ii 1 'Ii 0 1.5

area, Old Tampa Bay ____________ 77.8 74.8 74.8 - 3.8 0 - 3.8

in mF. Hillsborough Bay __________ 42.7 38.8 36.9 - 9.1 -4.9 -13.6 -.- -. , 1 i1l1lpi1 Di1Y \LULilIJ --- ;lOUd ;l'+"7.~ ;l'+ .1 ;l.U .V J.V

Water _______ Lower Tampa Bay __________ 1,572 1,578 1,578 + .4 0 + .4

volume, Middle Tampa Bay _________ 1,475 1,481 1,481 + .4 0 + .4 _ a &. AI..! 'T"n __n Dn ~ll{) ~()C CClC () () a -.. " - -- Hillsborough Bay ___________ 352 373 388 + 6.0 +4.0 + 10.2

Tampa Bay (total) _____ 4,088 4,127 4,142 + 1.0 + .4 + 1.3

Lower Tamna Bav __ 12.2 12.5 12.5 + 2.4 0 + 2.4

depth, Middle Tampa Bay _________ 13.3 13.5 13.5 + 1.5 0 + 1.5

in ft. Old Tampa Bay ____________ 8.9 9.3 9.3 + 4.5 0 + 4.5 U<L] ______ n n, ,n r .- n • "'0 n

--- 0 .... 7.V JV." . J • J ,. ~u.v

Tampa Bay (overall) ___ 11.4 B.8 11.9 + 3.5 + .8 + 4.4

Approximate __ Lower Tampa Bay __________ 248 246 246 - .8 0 - .8

t;A..l 1\.,f;AAI.. T"",n" ll" ')1'7 ')1< ')'t< II 0 II '. prism,1 Old Tampa Bay ____________ 190 187 187 - 1.6 0 - 1.6

in mF-ft. Hillsborough Bay ___________ 99 95 93 - 4.0 -2.1 - 6.1

Tampa Hay (total) _____ 774 7fi5 70T T:Zr .j 1.1

IThe volume of water that enters or leaves a tidal water body between high slack water and low slack water.

...'- '-'.' ., .....L· ." -' .. ,. -'- ..,,,-, '.L'_ .L • •.• ~~_6 1""6 }J<LJ • V J ...... Vel)' " ...........] .............. ................ VJ ...... ..........OV--.uIIIIO .- ,.

the tidal prism and is defined as the volume of water that tween the limits of high tide and low tide altitudes).

enters or leaves a tidal water body between high slack The following sketch shows an extreme example of the

water and low slack water. Tidal prism is approximately impact that reduced surface area can have on tidal prism

equal to the surface area Umes a representative tidal range for hypoilletlillprismatic estuaries havmg the same total

of the water body. Even though the total volume of water water volume at high tide. n, ..! ,••- -_..:I - - n¥6_ 'l Ar "r.." Ar .........p .......]." -~ ~, ..... (;1I;n. ..,

.. th.. t;I'1,,1 nr;orn ;~ -' (OP.. t,,},I.. ,\ T},;o An. TotAl volume ABC Total volume ABC

parent anomaly is explained by the reduced surface area Tidal prism == 2aAC Tidal prism == aAC

I I I A I

." I

/T / -r-

/C// /// A // ///

~I ~// /1 ~~// 8=2A

v-:/ / Ign tlce /

a Lowtide-- - 1------V f----r--- /

/

/

/

,/

8 Tidal·Flow, Circulation, and Flushins Chantes in Tampa Bay, Florida
The tidal rism and associated ercenta e chan es for

Tampa Bay and for each major bay subarea are given

10 ta e .

Tidal prism reductions from 1880 to 1985 are expected

o e wri en commun., une

developed and applied a two-dimensional, hydrodynamic

Hillsborough Bay.

In two master's theses prepared at the University of

Sout Flonda, R. D. Ghioto (written commun., March

two-dimensional, constituent-transport model having 40

segments or cells. Little information was developed during this study regarding tidal circulation and flushing in

gyres or net rotational features existed in the bay that apacteristics. Results from a similar model reported by Ross

(1973) showed a different gyre pattern than that computed by Cote. Such differences confirm that circulation

ists. Modeli results from this stud show, however that

either directly or indirectly concerned with tidal effects

in Tam Ba. As back round and reference information, many of these studies are briefly described and discussed herein.

Studies oftidal motion in Tampa Bay were first underi c ns ruc ion, vera i exc a ge

throughout the bay is marginally reduced, and, conse- .. .

for lower Tampa Bay, 0.8 percent for middle Tampa Bay,

1.6 percent for Old Tampa Bay, and 6.1 percent for Hillsborough Bay. These changes indicate that, as a result of

dredge and fill also cause circulation increases that more

than overcome the effects of reduced flushing potential

U.S. Coast and Geodetic Survey, as part of its mission

to chart the coastline ofthe United States. Because water

depths are measured from a constantly changing water

surface, referencing water-surface altitudes to a meaningful navigational datum, normally mean lower low water

one or more of the following items:

1. choice of hydrodynamic model,

2. sc ematlZatIon 0 ttom con IguratlOn,

3. grid size,

is defined as the average of the lowest low-water height

of each tidal day observed over a tidal epoch of 18.6

years. Shorter periods of observations must be corrected

by comparison with simultaneous observations at a longterm control station. Tidal stage data were first collected

1947.

By analyzing tide data in terms of harmonic constituents, the NOS has predicted tides (U.S. Department of

Commerce, 1982a) each year since 1939. Tidal currents . .

designed to extend tidal current predictions to unmeasured locations also have been published (U.S.

epartment 0 Commerce, 1951). e most recent NOS

survey, 1963, of tidal currents in Tampa Bay was described and summarized by Dinardi (1978). His report

grammetrically tracked drogues and foam patches. Data

from Dinardi (1978) were used to confirm tide-induced,

resl ua ve oCltIes compute urmg t IS stu y.

5. choice of tidal boundary function.

It is important to note that there are no fixed patterns

point out that circulation is an ever-changing quantity

that evolv sin res onse to chan in tide wind and oth r

driving forces. Determination of a truly representative

or average circulation pattern must be deferred until exhaustive measurements and computations are under- . . .

conditions will differ because of computational sensitivity

to the above items.

tion Control Administration to determine the source of features.

Introduction 9
Computer studies oftidal mixing in upper Old Tampa

Bay were conducted at the University of South Florida

Earth Resources Observation Systems Data Center is also

appreciated.

by Ross and Anderson (1972). A two-dimensiOnal, hydrodynamic model having a grid size of 14 mile was de- T1.__.~..l_1 .1.~.' ..... .. ~"

DESCRIPTION OF COMPUTER SIMULATION _.._--

simulated InfOrmatIOn IS desued. These equatiOns are

cal procedures, Input requuements, ana operatIOnal

ing location in the real system.

The following sections describe the equations, numeriphysical laws governing water and constituent motion in

two dimensions are applied between every location where

. -

or tne SYSlem.

Water motion in estuaries is governed by the physical

laws of conservation of momentum and conservation of

mass. The two-dimensional estuarine simulation system

The model used in this study can simulate water and

constituent motion in well-mixed estuaries, embayments,

"nrl nth.... "n"ct,,! 0 ...."" - th::lt • thE>

r:,

sOlveo at small ume :SLCV:S LV r i:l I,;Jv:SC

approximation of the time history of water level, water

::Inn . at each ndHigh and low uniform constItuent concentratIOns were

initially assigned to the water on the landward and ~;..l~ ~".1.~ • T1.~ ~ft~~ ~"

-r

the bay. An effective method was used to determine

changes in flushing characteristics caused by various

alteration options to the Courtney Campbell Causeway.

as a basis for flushing comparison between alternatives.

Goodwin (1977) compared computed residual tidal curtsay. t'rellmmary CUCUlauon results rrom a aetauea moael

of Hillsborough Bay (Goodwin, 1980) showed complex

net tidal currents that had not been previously detected.

Comoarisons were made between comouted flow and cirbut that little potential existed for improving overall circulation between waters of Hillsborough Bay and Tampa

, -r

nt trlln~ferred durin~ one tidal cycle was used

rents In HIllsborough Hay tor ISlan<1S ot vanous configurations constructed from materials dredged from the ~h;n • U.. •• th"t' -r •

could be modified bv chan~es in island confi~urations

culation patterns for conditions both before and after the

Federal dredging project begun in 1976.

(SIMSYS2D) applied in this study uses vertically integrated forms of equations that describe conservation of

UIOvannelll (1~!S1) usea the results ot Uoo<1WIn (l~!SU) . ._. a" UIV'''' LV a "au- -r UIV"'''I LV -r "VUductance changes in Hillsborough Bay off the mouth of

the Alafia River. He found that a 17-fold increase in river

discharge (40-680 ft3 Is) produced a 25-percent reduction

in the specific conductance (40,000-30,000 ILmho/cm) of

bay water near the river mouth. Specific conductance at .. .. ... .._n

mass anl:fmOmenTum, as given-o-yLeenoense ana urinun ,.~.... n'

\"7 ", v. UJ.

(1)

at ax oy

au au au ar U(U 2+ V 2)O.5

-:::-+ U --;:-+ v --;:- - f V+g -:::-+g ro, r..T

U1C llYCI JJ1UUUI wa" uy JJ1V1C Luau 'U r

This reduction in specific conductance indicates significant mixin2 of river water with HilIsboroue:h Bay water

1 -- 7/=0 (2)

near the Alafia River.

Acknowled2ments

We are grateful to the Tampa Port Authority, particularly Delmar Drawdy for initiation and coooerative

financing of this study from 1971 to 1973. We are also

U u .... UJ' UJ ~~.

I -- 7/=0 (3)

en

grateful to the U.S. Army Corps of Engineers, Jacksonville District, for continuation of the study and financial • , ...n

:SUVVUlL _"" 1:70~.

Large computer simulation runs that culminated this

study were made possible by the Defense Communications Agency (DCA) Hybrid Simulation Facility at

Reston, Va. Without assistance from DCA, a full-scale

study could not have been made. T .• '.' ••• • 1. T T .1: .1._ D __..l

Survey research staff on a precursor of the models described in this report is gratefully acknowledged. Enhancement of satellite imagery by Gerald Moore of the

where

f=the Coriolis parameter, 2w sin¢ (S-I), where

-• . ".L"'" W 'LUC VI "I" ...,.... L"

its axis (radians per second) and cP = geographical latitude (degrees);

g = acceleration of gravity, in foot per second

squared;

e= water density, in pound·second2 per foot4 ;

. .. . - waLCI-IC 'Cl flUI -r .~ ...

nlftn~ ;~ " ....t. r

H = h (distance from the reference plane to the embayment bottom, in feet) + r= water depth,

in feet;

10 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
C=Chezy roughness coefficient, in footo. 5 per where

st:conu, V. ;OlsperslOn COet1Iclent, How In the x OlreCtlOn, . . , . . . .~ .......~~ .. 

. III U";;A , III"~~,

in pound per square foot; Dy= dispersion coefficient, flow in the y direction,

7/ = surface wind-stress component in the V direction, in sauare feet ner second' and

in pound per square foot; and SA = source and sink function, including the rate

t = time, in seconds. of injection of constituent A.

The variables U and V are the vertically averaged As with the velocities U and V, P is the vertically inte- . . . " .. Vi llVW as~ 51 <.."u _0 111<1"" vi ,",,"

1 t

u dz given by U=- (4) rr 't . ,~

~~ ·h P=~ PA U .. F"J

V=_1 I~ 1'1 -h

v dz (5)

H -h where PA is the local mass concentration of a particular

where u and v are the point-flow velocities in the positive constituent substance, A.

Holley (1969, p. 628) noted that, except in regions of

x and y directions, respectively. and dz is the differential . in the vertical direction. The wind-stress components are ICll !>" , Ill""" -, .. 1.... :~ ~~+~_ •• •• ~_ .11

given by Dronkers (1964, p. 188) as: 'J 'J

with mass transport by advection. Leendertse (1970, p.

7: = (Jea w 2 sin if; (6) 13) reasoned that, if this were true, small errors in assignana 7:= (}eaw2 cos if; (7) ing values to the longitudinal dispersion coefficient would

where not substantially change the solutions obtained. He then

() = wind-stress coefficient =0.0026, from assumed that dispersion could be adequately defined by T . .... - . " (\"" (\\ hlln <>., • .thp .... \'J ", P_ JI' -r -'"

nondimensional, effect of lateral mixing and a directional component apea=air density, in pound·second2 oer foot 4 , proximating longitudinal effects. The dispersion coeffiw = wind velocity, in foot per second, and cients, D. and Dy, used in SIMSYS2D are given by

11' - angle between wind vector and y axis, in Leenoertse {1':l7U, p. 14 ana ~4) as:

.., degrees. D. = dHUgo.sc- 1+Dw (10) ." ". . VIllI""" 111 ...V ,_.

sions. Equations 2 and 3 express continuity of momen- Dy=dHVgo.SC- 1+Dw (11)

tum in the x and y Cartesian coordinate directions, respec- where

tively. These equations assume that water density is con- Dw = a diffusion coefficient reoresenting wave,

stant both hOrIzontally and vertically, that vertical flow wind, and lateral mixing effects, in square

components do not exist, and that horizontal flow com- feet per second, and ..l ~~+ .... .. 'T'L .....1· . - 'J .... "'V~~1 .~ 111 U 'an SUlllliU tV .- tn J:lrpJ:l<: tnJ:lt J:lr.. •• <>.,r1" " .. . ..... " " ,...~,...\ -oJ 111<11 --uy~~.

well mixed. However, this type of model has been successfully applied where gradually varying horizontal density Numerical Procedures

graolents occur_

Transport of dissolved constituents is governed by Partial differential equations 1, 2, 3, and 8 describe

1 .1 '~.' ~~ ...+ __ .. _ .... general relations that exist among the manv forces that -e> 'J control water and solute motion. Because the equations bv fine-scale disner<:ivf" or l'll'tinn l'l'll1<:..ti hv

presence of turbulence superimposed on the average flow_ cannot be solved analytically for most real-world condiTransport of dissolved constituents is governed by the tions, procedures have been devised that provide approxi- . .. . .. conservatIon ot SOlute mass. Transport Incorporates 111<"" vy U"lll!> IV -" 'OJ P~IIVl"l ....

advective and dispersive concepts and allows for consti- enormous quantity of numerical computations.

tuent sources and sinks as given by Leendertse and The numerical procedure used in SIMSYS2D is sumGritton (l971 n. 4) for two- _. flow marized below and is presented in detail by Leendertse

8): and Gritton (1971, p. 15). Equations 1,2,3, and 8 can

a(HP) ..j, (HUP) a(HVP) be approximated over a region in time and space by a 1____ • .." •• -- • n_.'·- ~~

at ax ay '0-

I ill dmilJ:lr in fnrm tn th.. nJ:lr..nt •• _- f"11 IIl'l-

_a{HD. ~~ a{HDy~~ tion but is applicable at only one point in time and space

HSA-O (8) and is separated from all other points by finite time and

ax ay space increments. Such a finite-difference approximation

Description of Computer Simulation System 11
is valuable because, by using the approximation, a differCIllliU IS to ,u~e1. • • • • •

......."'.0 cu.

Each difference equation contains known and unknown terms. As long as the number of equations equals

the number of unknown terms, the system is solvable.

The method of solution for the unknown terms involves

a point-to-point, repeating, stepwise procedure that in- • .•. ...I.

tional elements defined at integer points and midway be- • • -. .., 1:_

Leendertse and Gritton (l971, p. 11) give a complete

description of how equations 1, 2, 3 and 8 are structured

at each (x, y, t) point and how unknowns in each equation are solved. An overview of the solution scheme is

given also by Cheng and Casulli (1982, p. 1655).

Input Requirements

... 'J -r

appropriate.

A space-sta~gered grid scheme (fig. 5) is used in the

I nree categones or input aata cue

SIMSYS2D model. Water levels (n and solute mass denSlty (p) are dehned at mteger values or mana n. I ne

reference water depths (h), measured from the NGVD of

1n"n ~.~ .~. • .. ~~:~ .. o intpapr U~l11P"

SIMSYS2D:

1 ••• nf . .

LU

:mci initi::ll .. '-~'''' - of both m and n. Velocities in the y direction (V) are defined at points midway between integer values of nand

at integer values of m. Velocities in the x direction (ll)

are defined at pomts rniC1way between mteger valUes or

m and at integer values of n. 'T""'~ ~.:...I .. ..hA • ~f" ..hA ::Irp,.

conditions,

2. definition and characteristics of the fixed boundary

(bay bottom and land surface), and

j. aenmuon or me anvmg runcuons UI due, winu,

tributary inflow, and constitutent sources.

Thp r;rd • thp W::ITt>r cii"nt>r- • ..·0'

in the positive and negative x and y directions. On land

areas, reference water depths (h) are replaced by land

altitudes (- h), and water velocities are computed only

at tImes when water levels exceea lanu anlIuaes. ume

(t) also is simulated in a stepwise manner, with computason coefficients (see equations 10 and 11), starting constituent concentration distributions, and starting watersurface altitudes. The lateral dispersion coefficient (D",)

ana starting concemrauons can oe spedlieu il:> unique

values at each cell in the model.

::~.

.(~:.:

....

+-+-+-+-+-+ I

+-+-+-+-+ + I

+-+-+-+-+-+\'+

n+3 + - + - + - + - + - + I +1 I

I f"\ I f"\ I f"\ I f"\ I f"\ I + + +

EXPLANATION

Water level and solute

concentration location

m-2 m-1 m m+1 m+2 m+3

n I T

1

0 T

1

T

1

T

1

T

1

T

1

I + I t time-step index

o 0 0 0 + I t+2 m x direction grid index

Velocity y direction location

-VefocitV x OlreCllon lOCation

I

o Water depth or land altitude I~_~":~-

hwing 1m, n) IUblcripts

II EncloHs.1I grid eIementa

n+-+-+-+-+-+ It +1+1

I ...... I ...... 1 1"'\ I 1"'\ I 1"'\ I

ITT I I I T I + I

n+2 + - + - + - + - + - + I I I I ...... , ...... I ...... I + I

n+1+_+_+_+_+_+ I + I

10101010101+11+

n - 2 + - + - + - + - + - + I t ' " y direction grid index

I 0 I 0 I 0 I 0 I 0 I + t-1

n .~ ...L. ...1.. ...L. ...L. ...L. ...L. .. .,

y

:

:

'.'.

:

"

"

:

:

:

::

"

"

'::

:

:

:

:

:

::: / ' .................................................................................................................................................................•......•..................... , x - Figure 5. Finite-difference scheme for computer SimulatIon mOdel \modltled tram Leendertse ana uTluon, I ~/ I}.

12 Tidal·Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
The second category includes information on the tion at all locations in the model at sufficiently small time

physical size and dimensions of the estuarine basin. Basin increments, usually 30 minutes, to define the time variageometry IS aetmea by specltymg a water aepth or lana tIon ot computea vanables. Computations aone between

altitude at each model cell. The resistance to water flow- the time intervals of SIMHST are lost. SIMHST is the

0"''' ""o~ fho ;~ ~. J..., ..ftl ,~o I'~~ ~".. ~,..o ,,+, ...11 .~oA ._ .l..~ DAC''T' .c> 'J -r -c> c

Manning's roughness coefficient (n) at each cell. PROCESSOR section.

The third category includes information that can be In the initial step (POSTGEN) of the POST PROentered as functions of time. Tidal fluctuations are de- CESSOR section, the SIMHST tape is read, and several

tmea at the ocean bounaary. :Speea ana auectIon ot the speclauzea alsk aata mes, each usmg Only a small part

wind is defined at the water surface. The rates of water of the total data available, are created. Each disk file is

.,,.,rl ,,+, . "~o • ~. ...f . I",..... fl. ..,., .. ..rl .,~ ;,.,......f f" .~

'rr r -r • 'r. lnnp] tions to simulate rivers sewae:e outfalls dye injections to nroduce mans and e:ranhical disnlavs of m, I rp~l1lt~

and so forth. (fig. 6). The post-processor programs are frequently

changed as new ways of viewing or applying the data are

concelvea. ~eparale programs or me ru~ I\.1n1'1 type are

Operations often needed to create special data files from SIMHST fnr ...,,..h ,.,..,,, ,.

SIMSYS2D is comnosed of several interrelated nrograms and files, as shown in figure 6. The system has four

main sections that have distinctly different functions. MODEL DEVELOPME NT AND APPLICATION

Ine INru 1 IA A r '''' {iVY} scans the

user-prepared input data file, often several thousand card Model development is a process by which a general

images in size, and checks for many potential format and estuarine simulation system is structured and adjusted to

lo~ic errors. This step detects as many errors as nossible represent a particular estuary. embayment or other

before submitting the data to the more lengthy MIXER coastal area. The objective of the process is to achieve

and simulation-computation'steps. Data listings and error as close agreement as possible and practicable between

messages are prmtea to gUlae error correction. Slmulatea ana ooservea valUes ot tlaal stage, Haal curnr,·.L • .S: Tn..... "",_, s:" • .,... ... LL • 'H" V. ~~~ , u .."'''' .....,~ ..."'., ~.'"

."''''''' , ....... v ..."'• ,..."'-

written for subsequent use. (1) The SIMULATION IN- tors. The closer the agreement, the more confident model

PUT (SIMINP) file is a restructured version of the users can be that results of subseauent numerical exoriginal input data that matches requirements of the com- periments accurately reflect real conditions.

putation section of the system (SIM2D). (2) The SIMPTl The development procedure is composed of two basic

file contains input overrides that allow minor changes to steps, calibration and verification (fig. 7). Both steps in- -' '.. -, ,J: .I _. v", ........'" .v u.'" "'puc ........, puv••v , • v' ,~ v • ....u vv,,~. y~U Ui:lLi:l. 1 He

having to rerun the IDP and MIXER sections. The most calibration step has a feedback loop that is not present

common input override chanlZ:e is settinlZ: of start, restart, in the verification step. Feedback allows adjustments to

and end times for simulation runs. (3) In the SIMCOM imprecisely known input data to improve the match befile, the size of all dimensioned variables for each model tween observed and simulated data. Verification is conapplication, as determined by IDP, is stored as common ducted for one or more data sets that were not used dur- s:. .L •• .~. J:,

• v. "'p~ .v ...'" .."'~. ,- -,. "'eo .c> , .~...."'.

The MIXER section combines SIMCOM with the are not allowed. The degree of agreement achieved beFORTRAN source code of the model. Compilation and tween observed and simulated data during the verificalinkage-editing steps produce an executable load module tion step is a measure of model accuracy and reliability.

that IS tailored to each geographic area bemg moaelea. The tollowmg sections aescribe how bottom configuraThe computation section (SIM2D) executes the load tion, boundary conditions, and initial conditions were • • .l..ft' ...ft. . • J..... IT'~~ ft_A • • • ft_A ~h" ~o~' .1+~ ,,+, • • _...I .~.

.. 'J .- - SIMINP and SIMPTl data files created by IDP. Com- tion comparisons for development of the Tampa Bay

puted water elevations, transports, constituent concen- model.

trations, and other variables are stored at user-selected

tIme mtervals on two tape meso Ine restart tape

(SIMRST) contains sufficient information to restart Bottom Configuration ...f • .. , ....n;,.,f~ ~n fh.,f ,..n~fhr .. - tions do not have to be reneated in case of nroe:ram or The area of Tamna Bav and the Gulf of • I , chn~pn

computer failures. The restart capability can be used also for application of SIMSYS2D is shown in figure 1. The

to segment long simulations into small, manageable total modeled area was 826 mF, approximately 45 perlengthS. The history tape r... II} contams mtorma- cent ot WhiCh was lana tnat naa altItuaes hIgher than

Model Development and Application 13
;;::::::::::::::::. : INPUT;' .. :::::::::;:::::::~

•••••••••••••••• u

.:;:·'oATA··;W .:::::::::::::::::::

............................... .i:····PROCES·SOR··..:r ~::::::::::::::::::::::::::::;:::

Printed .....--I-:.,Iif, 0 utnut

lOP

data

Process input

/SIMCOM~ / SIMINP "" /SIMPT ,""

.~ Common ):k Simulation )~ Ov~~:~~.~~to )

( Input \ ..i:

.\. data r'W':

------- .- .- EXPLANATION

/ Model","", :::t- M_ix_e_r__---l

( source .. Combine comoile

:::: Computer program or

, : command list

.::::::::::::::::::::

I ,;; MIXER r .:::::::::::::::::::::

Printed (' Load

~." :,,/

,

~kstorage~

:;~::mm::...:,·~

Printed

output

.1" .

.i!: (.~~.~I?~!~!!~.~L .

output

_.

I

SIM 20

...;; l.Umpuul.,."gll,

velocity. concen-

,.... tretion, a~~.~~ ~:......... ::

! :;.::::::: ::::::::::::,::::::::::::::::::::' :.::m::m;;m;;::''''

~~I Restart )- 1 Historv 1

------------------~-------------------

i

l files stage, ~::: Generate post- : velocity, transport. processor files

\:. concentration. and so on .,' :::

.: :::.

1 .::...~.~:;>.....;:

.;!:::~~~~~:~:=:/

Plot programs

for graphs

and maps

.:.':::::::::::::::::::::::::::::::::::::.

Plotted

output

::;::;:::::::;;::::...

FilllJrp (, rof filec inn, ,t ... "rl~, ,t~, ,t f~. thn '0

14 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
.'.'

,:~. DETERMINE REGION ;:: AlUn ~Dln C>'7C

.':. OF MODEL

~~;!!!mm!!!!mm!!!t!!m!!m!m!!!!::'

DETERMINE WATER

PROPERTIES AND

BASIN BATHYMETRY

.... .',

:.:-:.' ,,"VLL<o" LI,. I,. (stage, inflow, wind)

}~!!m:mm!!::mmm!!~mm:mmmmmm:'

:,. ,,"VLL<O"'~ '<O"'VY' UI"\ 11"\

:~:: (stage, velocity)

:;:1m!:mm:m!m!:m!m.!!!m,mmm::!m!!:·

• • ,'" PREPARE DATA FOR

\: INPUT TO MODEL

.'

~.~

:.:

PREPARE DATA FOR

COMPARISON

WITH COMPUTATIONS

- I

OPERATE SIMULATION ~Y~T~U /f;n iiI

.:;1(,:::::~~EI:~~~¥K)~:::::::::1!lil!:·

, .:::::::::::::::::::~t::::::::::::::::::::::::::·

·:.:1 I

:~;!m:mmmm::m::m,mmmm::m:mm:' ---------r-----------'

:,f ,~, 1 ",v~" .. ",v~" v , ~~

AND OBSERVED DATA

•

·.·or ."

::s:

ne v,;:,e IVIUUCL

INPUT AS

APPROPRIATE

~",,,,<or ~"Le

DEGREE OF

CALIBRATION?

I

BOUNDARY DATA

_ .-:!~mmm::mmm::~:~:~ _:.~;~!~:;!~~!~m:. _

, , .,:~ rn, crT

'::~ PREPARE DATA ~()R :.;, INPUT TO MODEL

~;;m::::!!!m!:!!!!!m!!i!mmmm!!!!!!!:·

:0•

•::- ..~. .. UAIA I'UH

•

••i:·:!,.:':; COMPARISON WITH COMPUTATIONS

<: OPERATE SIMULATION

:.:.; SYSTEM (fig.G)

,

.-:::::::::::::::::::::::::::::::::::::::::::::::::::::::::'

,

'::; COMPARE COMPUTED

••.• ANU UAIA

:':. TO DETERMINE

.::.: DEGREE OF

:;::' VERIFICATION

~:~~::::::::::::::::::::::::::::::::::::::::::.

Figure 7. Calibration and verification steps in model development.

Model Development and Application 15
12

The bay bottom is treated as an impermeable, immovable boundary that causes resistance to free flow of

boundary in the Gulf of Mexico, and the water surface.

the model. A related open-channel flow equation by

A description of the data used to describe conditions at

material increases. Values of the roughness coefficient,

n in Manning's equation, were assigned to each cell of

eac oun ary 0 ows.

to convert from Manning's n to Chezy's Cis:

ezy mcorpora es ano er 0 om-roug ess coe 1-

cient, C, that is actually used in model computations (see

either 1: 10 000 or 1:20 000. The densit of covera e

Manmng's n IS an empmca coe lClent t at cannot e

measured directly. By varying the coefficient, modelcomputed tidal stage and current can be adjusted to closewhere H is the water depth, in feet.

e 0

Resurveys of selected areas were made by the U.S.

Geological Survey in 1971 and 1973 by using automatic

ositionin e ui ment and a di 'tal fathometer. The objectives were (1) to determine whether any significant,

areally extensive bottom changes had occurred since the

ranged from about 100 to 1,000 depth observations per

square mile. For this study, all depths were adjusted to

surveys. Direct stereo-compilation of bottom configuration also was conducted wherever low-level aerial

photography could sufficiently penetrate the water column to define bottom relief. A description of fathometric

and photogrammetric approaches is given by Rosenshein

model computations. In a study of Jamaica Bay, N.Y.,

L n ertse 1972 . 11 used n .alues that ran ed from

0.026 to 0.034. For areas of corresponding depths in the

St. Lawrence River, Prandle and Crookshank (1974, p.

523) used a Manning's n of 0.028. April and others (1975,

changes were detected.

Depth assignments were made by using a combination

of automated and manual techniques. The automated

proce ure ( a rane an a tzer, mvo ve compilation, editing, combining, and gridding of data from . .

observations were fitted to a polynomial surface from

which a representative depth for each cell was computed.

The cell depths were then compared with bathymetric

charts an manua y revise 1 necessary. evlSlons were

sometimes needed near shorelines and channels and in

for Mobile Bay, Ala. In a study of Masonborough Inlet,

N.C. Mas h and Brandes 1975 . 230 used n values

that ranged from 0.018 to 0.035 for depths from 4 to 30

ft. Beauchamp and Spaulding (1978, p. 525) used an n

value of 0.028 for the Long Island Sound, Block Island

, , New England. Wang (1978, p. 505) used an n value of

2 r th Bisca e Ba Fla.

An initial n value of 0.025 was chosen for this study

on the basis of the most comparable conditions reported

in the literature. Other n values, as low as 0.022, were

Land altitudes for cells that were higher than mean high

water were assigned a default value of 3.0 ft. This value

limited the model to investigation of tides that reached

maximum a 1 u es 0 ess an. IS Iml a Ion was

not a constraint for this study.

of 0.0235 was chosen as providing the best fit to prototype

data. Whenever water depth in any cell became less than

1 ft, however, the model automatically reassigned an n

value of 0.040 to simulate the increased importance of

bottom friction.

Boundaries of the Tampa Bay model include the bay

bottom, the shorelines, tributary streams, a seaward

The shoreline is defined as a no-flow boundary except

where tributary streams enter the bay. A flooding and

16 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
drying feature of the model simulates landward or

seaward movement or the shorelme with changes 10 tlClal . . . . . Stage. 1 IllS IS Jess III 1 i:Ullpi:l Di:lY wm::ll

compared with other coastal plain estuaries that have ex-

~rp~c: nf titi~l flM.C:

Freshwater inflow of streams tributary to Tampa Bay

(fig. 1) was determined from data published by the U.S.

Geological Survey (1977). The freshwater inflow used in

_'-I f. •• ,",' • ••. • ...

..." ULV"'''I \.avI" oJ, I" "I" al..lU<11 .~ U ..IV'" c

from long-term records at the most downstream gaging

station on each river lV.S. Geolollical Survev. 1977). The

inflow contribution from ungaged areas was approximated by a proportionate increase based on drainage

area ratios. Inflow was entered at appropriate cells near ... .. 01. .•

..." VI ..." ULVU"I.

Once-through. cooling-water systems of power-

.e;eneratin)!; stations were handled in a similar wav.

Cooling-water intakes were simulated as negative

discharges at cells close to the locations of intake structures. Cooling-water discharges were simulated as positive .1, .11••1. • ,_~"'~ ~. ~"'.. ~.~~'" .~ ...'" .."'~. 1 ..

of the Tampa Electric Company (oral commun., 1975)

indicated that typical cooling-water discharge rates for

both the Big Bend and Gannon stations (fig. 1) were 1,960

ft 3/s. Information from a Florida Power Company

representative (oral commun., 1975) indicated typical -'. ... ~~~~.. . ~- 'a."1 la."" "'''I'' '.vvv 1L "IVI VVLlI

the • . ~nti ..• Tc:l~nti (fil1 1\

Seaward Boundarv

Fluctuations in tidal stage, the primary force causing

time-dependent water motion, were applied at the • nf th......nti..l Th...... nti..l ,

water to and from sections of the estuary by solving equations 1, 2, and 3 for each designated time and space increment. At the seaward boundary. velOCIties were com- .. pUU::U oy USIng llli:ll UIU

not require any information outside the boundary. This

proceaure proaucea less precise computations at ana near .. Lilli:: Llldll dL ULIlli::1

Because of less precise velocity computations and in-

.. ilitv of the simnlified eauations to

numerical instability, the seaward boundary had to be

established some distance from areas where model results

could be significant and where large depth changes could • .• • • T

IIlUU"'li:: VI L"" " approximately 4 mi offshore from Egmont Key accomplished these two objectives.

To generate offshore tidal conditions, a cross-spectral

analysis technique described by Leendertse and Liu (1974)

and used by Van der Ree and others (1978) was applied .• .J ". n. ..... ("0

.v .....a.-".a6'" ..u."-""..",, ........ IVI .. vn ~'" u.,,.~

(site 22. fig. 8) to the seaward boundary at location

WC-154 (site 24. fill. 8). The technique required concurrent time-series data at each location to define crossspectral relations. Once established, these relations could

then be used to generate time-series data at site 24 for • ..I ,,_ ,.1..' ..I " 1::'.... T'\~ C'~.~ ...., P"'''~~ .~. •... .. ~....."'.~ ~, .. ~. ~~ .~.

Concurrent time-series data were available for the

period January 25 to February 11,1979, when offshore

pressure recordings were obtained by Woodward-Clyde

Consultants (1979) and when the Fort De Soto gage was

in operation. A part of the concurrent data (fig. 9) shows • • . L • ~~ ....1..

~ade to the Fort De Soto record, are shown in figure

10 and compared with measured data. The standard error between measured and computed data IS about 0.1 n.

The tide conditions that existed in the Gulf of Mexico

during a period of intensive field measurements in Tampa

'R",,;n 10'7') Ul..r.. . h" lldnl1 I"rnc:c:_ • .,

relations. Computed results are shown in figure 11.

Because additional information on tidal conditions in the

Gulf of Mexico was not available, the computed tides at

sire ~4 were apPliea along me emire seawara

Table 3. Average annual discharge of streams tributary to Tampa Bay (U.S. Geological Survey, 1977)

Tamoa Bav

subarea "'''''0'

TYO n:

.. ----- ------ --- -- - - --- Alafia River _

Total of several small streams _

.... .r

"0

discharge

(cubic feet per

second)'

459

99

11"7

Middle Tampa Bay Little Manatee River _

Lower lampa nay AIVCI _ __ _ _ -____ -- -- --------

Total -------------------

1All values linearly adjusted to include effect of ungaged drainage area.

240

1,904

Model Development and Application t 7
_ (:'L'" 'U '" '" BEACH 7A

\ 1ST. PETERSBURG \:

\ ~20 ,J_ \

PASS-A-GRILLE lW~;. J \ I "... ~~~lEI 'I I I _0' , lJ 0 to I 12 ,..

EXPLANATION

TIDAL STAGE GAGE AND

~II t

SUBMERGED PRESSURE RECORDER

I~U.:> 'fU

WOODWARD-CLYDE

CONSULTANTS, 1979)

TIDAL CURRENT SITE AND SITE

"," SKYWAY!i" '"

EGMONT v·23... ------ II·-~~ SHIP CHANNEL

CHAN:EL FORT • Y'~, ""I'

'\\ // <:r)lIT" -

•

NUMBER

NATIONAL OCEAN SERVICE LONGTERM T ~II t~TE

NUMBER (FROM DINARD' 10711\

\

~NNA MARIA ~--~~ - _ :,./"~

~aV \ 0 1 2 3 4 5 MILES

Figure 8. Location of tidal stage and tidal current measuring sites and submerged pressure recorder and long-term currpnt <itoO<

In Tampa Bay.

18 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
4

........ GULF OF MEXICO (WC-154)

TAMPA BAY AT FORT DE SOTO

..J

«

Z ? &

::::'

t- r. « ."

Z N

.. ."

,

. ·i .. al

w :::!: ol ,~ - ::l ,. .. :. w Cl :0. li. V'~ A fA li N f* > ..J • # • o « 0t:*". ..' 1'.. -- t- ffi , III \ -' ,. ., . • . J J w . ." - y . fI )j JJ u.. u ,. 4

z i= • I _," . - W • , .-

W 0 .~ .. .\} 'J • w .. . - .\J - . :U . .. #

(/) • . t ..J .- . « -2

!:::'!

t-

-4 I I I I I I I I I I I I I I I I I I I I I I

0 50 100 150 200 250

TIME. IN HOURS

Figure 9. Comparison of observed tidal stage in the Gulf of Mexico and at Fort De 50to inside the mouth of Tampa Bay. Locations of sites are shown in figure 8.

for the model calibration and verification periods shown 7 and were applied to spatially averaged wind fields deterin figure 11. mined from hourly observations of wind speed and direc- .. IIUt: uunng tnt: peuuu wele llUll IUCiue Cit sues III tne I Cllllpa Day alea. llle

chiefly dirunal and had a tidal range of about 2.4 ft. The sites used for this purpose include the Tampa Internan1 ri",' Me tirl.. Ul!'!" !'! hnllt 11'\ hnllr" Th.. tinn!'!1 ' ~. Air Pnrr.. 'R!'!".. ~t - of falling tide was about 9 hours. The first verification Clearwater International Airport Sarasota-Bradenton

period also had a predominantly diurnal tide that had a Airport, and Albert Whitted Airfield (fig. 1).

range of 3.6 ft. The second verification period had mixed The wind field was computed by averaging hourly or- . . . . . . ~. llue cUIU lCll~e • J. Ht; 11Ulll lllt;llt; 11v t; IlHt;Il, HI a~-

diurnal tidal range was 3.0 ft. The three tides are repre- cordance with equations 13 and 14:

sentative of conditions in Tampa Bay.

Water-Surface Boundary Wx=t LW; • sin<Pi (13)

i= 1

I ne water surlace is tl eateU all a verdl;auy , • • 1.~ ••:~~ • • . . ..- .., .-

stresses transmitted to the flow, depending on wind speed S

and direction. Wind-shear stress components at the air- -

Wy = <"IE Wi • COScPi (14)

water interface were computed by using equations 6 and i= 1

Model Development and Application 19
4

N

Ol

u..

0 ......... COMPUTED ::E

OBSERVED 0

....J

«

a:: L

f w

>

J,

w

0 • 1

t;:i ,... It Il • A c.:l

....J

« .. IJ

0

(\4 ~' f A.~ tJ . F1\ It i « o f-~ z .- l!i

, f\ \j , J J ... \/

::J \) .. V ., w

ell

a:: ,... \J •

, w

ell W « V ... U

u..

W

,;i

(J)

....J

I I I I -4 I I I I I I I I I I I I I I I I I I I I

0 50 100 150 200 250

TIME, IN HOURS

Figure 10, Comparison of observed tidal stage in the Gulf of Mexico with tidal stage computed by using cross-spectral procedure (described by Leendertse and Liu, 1974).

where 4> =spatially averaged wind direction, in degrees

Wx=x component of spatially averaged wind clockwise from north.

- speeu, in miles per nour; The computed wind field was assumed to be vanable

Wy= Y component of spatially averaged wind with time but spatially uniform over the modeled area.

s.need in miles. ner h01lr' • ...I ,I. ,

Wi =hourly wind speed, in miles per hour; and .... ....- were dmi1<lT no larae error due to s.natial averal!'inl! is

4>i =hourly wind direction, in degrees clockwise expected. Wind speeds were generally within ±2 knots,

from north, that the wind is blowing from. and directions within ± 30 degrees, of each other. ExThe results were reconstituted by using equations 15 and ceptlOns occurrea pnmanly aurmg rapla wma Shilts

16 to produce average hourly wind speed and direction associated with the passage of cold fronts. Wind speed

over the study area: and direction during calibration and verification periods

-;;;: f-.rr -;;;: ~"I\ • " ..., ::Ire s.hown in fil!'1Ire 12 rr \.. x y) '£ 071 Wind during the calibration period was initially light, - about 5 knots from the east, became calm by the end of _ <lTf't<ln W. (Hi\

u'/'

20 hours, ana plckea up trom the west aunng the last - , . .... ,. " ~' y .. UVUl;) VI • yv lUU ;)jJ....U UUIU15 .U<; 111;)•

where verification period averaged about 6 knots. The direction

w ... wind sneed in miles ner chanlled at a uniform rate in a clockwise manner starthour, and ing from the east-southeast, through north, and around

20 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
4

Q)

N •••••••• GULF OF MEXICO

0 TAMPA BAY AT FORT DE SOTO

- :5

I-«

0

...J A " « •

i= 2

1 YI ,~ a:

l\ ,., w

> _'\

u

i= l 1~14

0

J I ) I yJ :. 1 f\j 1 ••, 1\ J 0 Iw

=Ai t=l

...J I I I « 1 1 • • • ;\ z

0

L:: .J

« v

z 1 ~t !/ • "J -• , .... l .~ , " 0 • I. ...J .~ U ,\l 1-

:~ a: .. .. • 0

. - . w •

> • 0

CZl

«

tu- 2

w

'A ,IIUN FIRSt Z PERIOD IIUN v mN

u.i PERIOD PERIOD t=l

«l-

(/)

...J

«

0

i=

I I I I I I I I 4

24 25 26 27 28 29 30 31 1 2

JANUARY 1972 FEBRUARY 1972

IIIVII:, II~ UA T;:)

tlgure 11. Lomparlson OT computeo tloaJ stage in me LJUIT or Mexico wim UU31:"1 ,"",u Liu~ dL rUIL LJ~ ~ULU uurifllS II IVUI:"I carioration and verification periods.

the points of the compass to reach north a second time. starting water level at the seaward boundary. CorrespondWind during the second verification period began as ingly, all tidal currents at the start of each model run were

calm, then averaged about 7 knots from the south- zero. The bay was motionless.

southwest tor most ot the penoa. Operationally, about 12 hours of real time must be

Initial Conditions simulated before the effects of these assumed initial conomons Olsappear Hom me SOludon anu oeIOre mooel

Establishing initial conditions is necessary to define computations accurately reflect real stage and current

three time-varying parameters-tidal stage, tidal current, conditions. Circulation computations are more sensitive

and constituent concentration when startin~ model n ...rl "f ..,h""t "A ~f ~anl t;..... A

computation. The following sections describe how these -. before the effects of initial conditions disappear. Model

initial conditions are assigned and how they affect simula- comoutations durin.!!: these periods are disre.!!:arded. If a dUll n:SUllS. model run is restarted to extend a previously simulated

Tidal Stage and Tidal Current period, initial tidal stages and currents for each cell are

A level water surface was assumed throughout the bay read from a restart tape created by the prior run (see fig.

at the start of each model run at an altitude equal to the 6).

Model Development and Application 21
water can cause rap1 egeneratlon 0 compu e concenFurther description of turbidity plume simulation is give~

below in the section Calibration and Verification.

ing the seaward boundary during floodflows.

The initial concentration used for calibration of model

allows reasonable computation of concentrations to continue at the seaward boundary through all phases of the

tide. This procedure is considered to be more realistic than

model allows a gradual return of concentrations to an

initiall defined value. This rocedure is a roximate but

Calibration and Verification

dispersion was a constant, near-zero value for turbidity.

tions can be brought from outside the modeled area. This

21 Z9 30 31

TIME

24 25 26

JANUA Y 7Z

Constituent Concentration

Table 4 shows starting and ending times for the calibration and verification eriods and availabilit of field data

for comparison with model computations. Tidal current

data were not available for January 24 and 25, 1972; as

a result, calibration was based on stage data only. Stage

An initial concentration must be assigned to each cell

for each constituent included in the computation. periods.

specifying a default value; (2) the default value can be

changed at one or many cells by specifying values that

override the default value; and (3) a complete array can

be provided that defines the initial concentration at each

cell.

Tidal Stage

Tidal stage data were measured at 14 locations (sites

10-23, fig. 8) from June 1971 to December 1973 (Goodwin and Michaelis, 1976). Table 5 gives the site number,

the downstream order number, the complete station

name, and the latitude-longitude position (progressing

ments that measured water-level altitudes every 5 or 15

. . r cure

station) for tidal stage stations in Tampa Bay. Each of

the 14 stations was equipped with digital recording instruuseful when simulating the spread of dye or other constituent injected at a point. Overrides can be used to advantage 1 one or more sma su reglOns are nown to

v

s/mo. Gages were referenced to the NGVD of 1929 by . .

o t e mo e are compute rom v ues at mtenor pomts

lated region. An array is normally provided if an accurate . ..

of a model run.

Constituent concentrations at the seaward boundary

ing unassigned and uncomputed constituent concentra- vals during the last 24 hours of simulation ranged from

Table 4. Calibration and verification time periods and field data availability for tidal stage and current observations in Tampa

Bay, 1972

Period Start End Duration

Field data

availability

First verification _ 1-27-72 1205 1-28-72 2400 36 Yes Yes

econ veri ica io

22 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
Table 5. Information summary for tidal stage stations in Tampa Bay

r, ,rr-r

downstream Station identification' North West (see latitude longitude fig. 8) order no.

10 ___________ 02-3000.72 Tampa Bay at Anna Maria ______________________________________ 27°32'03" 82°43'50"

II ____________ 02-3000.85 Tampa Bay near Terra Ceia (South Skyway) _______________________ 27°35'30" 82°37'45" 12 ____________ 02-3000.88 Tampa Bay near Piney Point (Port Manatee) _______________________ 27°38'06" 82°33'32"

____________ u<.-.)V\J.).ov I~U1P~ D~Y 1~~1 AU'Aiu lAPOIlO ~eacn ____________________________ "'I-'+O·~I 0<' <.j j.) 14 ___________ 02-3017.61 McKay Bay at Tampa __________________________________________ 27°54'54" 82°25'25"

15 02 3060.32 HilIsborouszh Bav at Ballast Point at Tam"" ':)70 ~~'.,.," R.,0.,R'<17" - 'L "" ~,,£ nn r\' T. n ~. ....... ,'~ ...'~nll - '--If --- .. -, "r' --- - ~. ~J 0<' .).) j

17 ___________ 02-3075.78 Old Tampa Bay at Safety Harbor _______________________________ 27°59'17" 82°41'07"

18 ___ 02-3077.69 Old Tampa Bay near Bayview __________ --------- ------- 27°56'28" 82°43'15"

19 ___________ 02-3079.30 Old Tampa Bay at Gandy Bridge near Tampa ______________________ 27°52'46" 82°34'57" 20 ___________ 02-3080.82 Tampa Bay at St. Petersburg ____________________________________ 27°46'24" 82°37'25" <'1 ____________ U<.-.)UO' .<.V I~UlP~ D~Y ~, .:>Uu.ui"c ~lI.yway ~rioge near ~[. relersDurg <'/·.HUO lS.l-4Vl.l'

(North C;:\'"",,,,,\

22 ___________ 02-3086.00 Tampa Bay at Fort De Soto Park near Pass-a-Grille Beach ___________ 27°36'53" 82°43'33"

.,~ m-lORfi.~O P"...".Gri11~ Ch"nn,,! n.."r p"...".nrm.. R"",.h .,7°<11'1/y' ".,OA~'A""

24 ___________ - --- ---------- - Woodward-Clyde gage number 154 offshore of Egmort Key (WC-154)_ 27°36'12" 82°51'54"

'Underlined name is shown in fig. 8.

0.03 ft at South Skyway near the mouth of Tampa Bay, computed tidal stages for the first and second verificasite 11 to 0.13 ft at Safetv Harbor site 17 and B~vview tinn • ~rp I:hnum in fiollrpl: 1.<1 ~nn I.e:: . -r

site 18, in Old Tampa Bay (table 6). The average stand· Iy. Some difference between observed and comouted

ard error for calibration was 0.07 ft. Graphical compari- stages is to be expected since all model adjustments were

sons between observed and computed tidal-stage water designed to make model computations match calibration· . ~. .. ~JVJ :11.11. BVlU lil\; lUVUIU IV IU\; U\;i:lU~ periou neJU VV,""'l as ClOselY as posstore.~-

bay are shown in figure 13. From the graphs it can be justments were not made for verification periods. That

seen that about 12 hours of real time must be simulated the standard errors are about the same for all three

before the effects of assumed initial conditions disappear periods lends credibility to the model's caoabilitv to ac·

and before model computations reflect real stage and cur· curately simulate real conditions.

rent conditions. ....., L' . 'M Tidal Current .1 11'" _'" <;l1Vl lVl lIVlll

\110",' (1- (10 ft <Inn th.. r<lno,," U1<10 frnrn (I {)A .~ () 1C 'T':--1_1 ..._.- • ,,+ ~:+_~ 1 0 ,,--- - -~ ~, "'" '7

ft (table 6). Graphical comparisons between observed and 25 to 31, 1972 (fig. 8 and table 7). Instruments used were

Table 6. Standard error of tidal stage in Tampa Bay for calibration and verification periods

Site no. Standard error (feet)

(see :,rallon name First Second

fig. 8) Calibration verification verification

10 Anna Maria 004 0.09 o l() - - - - - ---- -- -- - - 11 ------------------ South Skyway _________________________ .03 .07 .08

12 ------------------ Port Manatee ------------------------- .04 .04 .04

15 ------------------ Ballast Point __________________________ .06 .07 .11

1" RnC'1<v Pnint 11 11 n"7

17 ------------------ Safety Harbor _________________________ .13 .15 .10

18 ------------------ Bayview ------------------------------ .13 .15 .11

.-17 ------------------ ~<tuuy D11U~~ _==__=_=====__==__==___== .Vll .l~ .W

'0 {)C {)J; no

21 ------------------ North Skyway _________________________ .04 .06 .07

22 ------------------ Fort De Soto __________________________ .04 .06 .07

Average - ---- ------------- .07 .09 .09

Model Development and Application 23
SAFETY HARBOR SITE 17 GANDY BRIDGE SITE 19

3 3

- ... V, 2

1 - 1\ 1 V'~

O~ V \ .I \ " oJ'

:: .\. / "I 0

~~ ::I ... I!" ., '\J .. 1 1

LL.

0 -2 -2 I3 h .. . . 3 =. II • . . . . :..,.

0 v

" .... '0 L~ oi7U IV V U 'L ... ... oi7U .. ...J

a::

w

>

r

t- ST. PETERSBURG SITE 20 BALLAST POINT SITE 15 w ., ., 8 f- w 2t- CJ t- 2

II( J1 '\ ~.J' "' z 1

V 1 .. ,/ \ 0

\ to

II( .... / 0 z .;/' o i:\ \. ./ ~/ \ / ..,,", ~rc- -1 ..\. .; "

./ o -1 ...J

== !!!

a:: 2 2

....

w -3 .. • • . -3 > 0 6 12 18 24 30 36 0 6 12 18 24 30 36 Q

II(

w

W

LL.

Z

W ANNA MARIA SITE 10 PORT MANATEE SITE 12

Cl 3 3 _

l! . ..

...J 2 2

a y - ,/ 1 • 1

V \ l/ , .. 0 J1' , 0 /' \ JT

v V ,,/ ,

-2 - -2

.. r- I •• • . ... :; I. I•• . . "'0 6 12 18 24 30 36 0 6 12 18 24 30 36

............ .-.. nME, IN HOURS

-_.... _._-

Figure 13. Observed and computed tidal stage at selected sites in Tampa Bay during calibration period.

24 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
SAFETY HARBOR SITE 17 GANDY BRIDGE SITE 19

~~ .. 2~ 2~ 1.0.

..1 \ / \ j I

"'""' , / 0 0 " / jh..J"

en o • ~/ Ie. N

~.:' \. v r:" r\ en 7

0 \:.:I

:::l -2 -2

<l:

0 . . , . . "

...J ~O . 6 12 18 24 30 36 -"'0 6 12 18 24 30 36

<l:

u

w

>

::I

ST. PETERSBURG SITE 20 ., BALLAST POINT SITE 15

w

0 E

W 2 r- 2~

1 / \ / . / \ /

Z

Vi \ / V V \ .- .I

0 ;' ,...

<l: 0 0

z r:: . t r'\ J 1

-..' r\ J

0 '-.J ...J

-2 -2

(5 . ::1 ~, I I I "

. . , 3 . . , , w 0 6 12 18 24 30 6 0 6 12 18 24 .:su 10

>

0

al

<l:

....

w

w ANNA MARIA SITE 10 PORT MANATEE SITE 12 u. 3 3

. 2

V' /

2

/ \ / <l:

....

(/) r\ 1 1

<1. \ - 'if ~~ \ r-, 0

.... 0

\ I O~ •

\ I 1= i 1 1

I::

"

-2 -2 I::

3 hi . I , I I. I I I 3 h . , I.

L4 '"

OBSERVED ............... COMPUTED

TIME. IN HOURS

Fil!ure 14. Observed and comDuted tidal stalZe at selected sites in TamDa Bav durina first verification neriod.

Model Development and Application 25
SAFETY HARBOR SITE 17 GANDY BRIDGE SITE 19

" ., v

2 .- ....... 2

4

v·····~ . ! 1 1'\ j' :.\ / v \ f N \ '0.

(J)

N 0 0

\ / \ / (J)

-

0

::> -2 -2

«

0 " I-. " -0

...J V

o 6 12 18 24 30 36 Vo 6 12 18 24 30 36 «

u

E

w

> ST. PETERSBURG SITE 20 BALLAST POINT SITE 15 u

i= 3 3 w

2 - w L

r\ 1\ L

~"\ V"\ t:l

;i 1 1 . z / \ / '-./ \ 0 \ i= 0 0 « !"V V \ " \., Z

;;: 1 1

0

...J

w -2 -2 III

- 0 3 -, 3 •

> v v ,.. L' ~v V L'+ 10

0

III

«

w ANNA MARIA SITE 10 PORT MANATEE SITE 12 wu.. 3 3

. 2 2

t:l

1 ~\ / r\ '\ .I"'" \ 1 en \ .-. .I \ '\ ......... / \

« \ "' \ ,.

0 0 0 If' - \ ..of ../ \/ V

-1 1'-' -1

-2 -2

3

0 6 12 18 24 30 36 "0 6 12 18 24 30 36

OBSERVED ............ COMPUTED

TIME, IN HOURS

Figure 15. Observed and computed tidal stage at selected sites in Tampa Bay during second verification period.

26 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
Water surface

I

/

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

"- I ... I .... .... I .... I ....

scn

sphere

Magnetized

buoyant

rigid rod

Horizontal angle,8

Midtide

depth=D

bay bottom

Site no. North West and direction of flow.

1 _

2

3

27°43'01"

27°42'54"

27°42'59"

82°36'04"

82°35'18"

82°34'25"

the average velocity in the vertical. The center of each

meter was placed at approximately four-tenths ofthe midtide water depth from the bottom of the bay (fig. 16).

5 _

6

9 _

25 Ross Island _

27°42'42"

27°42'39"

27°50'57"

27°49'54"

82°32'28"

82°31'45"

82°34'47"

82°34'12"

1 a current ata co e eye in i ardi, 1978) showed velocity profiles typical of vertically

Model Development and Application 27
Errors in the measurement of tidal currents were due Measurement error for tidal current direction ranged

rent meters and 2 the visual-manual data r n lin

procedure needed to digitize the data. Visual interpretation errors between scribed lines on sequential frames of

p otograp IC I m were approxImate y or t e mc mation angle, ¢. The error ranged from 1° to 9° for the

horizontal angle, e, based on the range of ¢, as follows:

current speed at sites 7 and 8 in Hillsborough Bay helps

explain the high standard errors for direction at these sites

(ta e 8). DIrection errors also could have resulted from

inability of the model grid size (1,500 £1) to adequately

resolve details of many channels, islands, and submerged

Range of inclination

Translation error of

horizontal angle (8),

are considered to be representative of real conditions but

less accurate than in other areas of the bay.

Di r i n

7. Errors associated with the residual currents at these

for the horizontal angle. Measured tidal current, therefore had an overall error of about 0.1 ftls at velocities

reasonably simulate the shape ofthe observed plume was

Costs of model operation precluded making a separate

run devoted exclusively to plume analysis. Therefore, the

the model.

Satellite imagery of a turbidity plume caused by

image is rectified and superimposed on the simulated

plume in figure 19B. The barbell-shaped plume is unique

to tidal waters and depends on the relative timing of tur- . .

3

1

11 to 20

21 to 90

ficient to compute a long-term residual current. Locations

of these sites 25 and 26 are iven in fi ure 8 and table

sites are not known. According to Cheng and Gartner

(1985), uncertainties exist when computing residual curof less than 0.5 ftls and greater than 1.5 £1/s. Between

these bounds, the error is about 0.03 ftls.

Tidal current data collected over a 30-day time period

ner (1985) were able, however, to demonstrate close

agreement between two independent methods for computation ofresidual currents in South San Francisco Bay.

They concluded that satisfactory residual computations

could be made from tidal current measurements.

primarily for tidal stage and tidal current verification. The

simulated tidal range at St. Petersburg, near the plume,

was 3.1 ft (fig. 14), and the actual range at St. Petersburg that produced the observed plume was approximately 1.9 ft (U.S. Department of Commerce, 1971, p. 129).

the second verification period. Tidal currents were not

measured during the calibration period. Graphical comparisons between observed and computed tidal currents

(both speed and direction) for selected sites are shown

, w

d= 25 (J. J. Leendertse, oral commun., 1980).

Tidal stage and tidal current (at the simulated dredge

site) and the period of turbidity generation that were used

to simulate the turbidity plume are shown in figure 20. . ..

range from 0.08 to 0.17 ftls, with an average of about

0.11 ftls. Standard errors for direction range from 5° to

25°, with an average of about 14°. With a fewexceptions, these comparisons are very good and provide additional assurance that the model simulates real

series of six illustrations in figure 21 follows plume

development at 1, 5, 9, 13, 17, and 23 hours after start

of turbidity generation. Figure 21A shows a nearly circular plume at high slack tide. An elongated plume is

shown during maximum ebbflow in figure 21B. Figure

Measurement error for tidal current speed ranges from

about 0.03 to 0.10 ftls for the currents encountered.

more 0 e compu e s an ar erro. e

error is attributed to local conditions that were not adeMeasurement error, therefore, may account or ha or

28 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
SITE 2 SITE 4

500 500

450 .. . . 450

...

.

; ...- ";"'" " - ..... '1UU .. ., 1--" 14UU

IV "l t"--",. IV ., .... 350 350

300 300

L

\:.. J LtlU L 12!:lU

: ,..... 200

.~. .:."' 200

. . 150 .. 150

ti\ 100 h 100

50 A " "

- 1<on

1 &

0 1 \ ·f'l.

~~ / \ ;:.~ .\ 0

'r-. p. N r\ . :"'.' :"

\1 \ I ... ,

\ t \. ..1 .. '. .. .-', .- 'l " \. J o r .' "Y :\V:

0 0 10 20 30 40 0 10 20 30 40

U.J

a :J

z cr:

(j SITE 5 SITE 7

500 500 (f)

(f) .' }~,:.,. 450 : . - .- - 450 U.J

cr: ..•.-. -", ..' .,. .• ......'. "",r .

~~i::;' cr:

U.J IJ 400 ~,. 400 '-' ct. 350 ....\ 350

f- 300 "- 300 U.J Z U.J 2 250 2 250 - u. .... ~-- z· ;-" -,. ".-'.

Z .. 200 200 . "" ,- 0 - 150 150 F; 6

U.J "'" f:--" 'uu U.J U.J :,.-.: ...•..... .. 50 50 cr: 0- f\.. (f) .' 0 1 0 1 0 .\. f- /.\ '" fZ "".~ t\ I f \ (7. :~ \ AI Z

U.J

a:: " ,. V II W····· ~.~.:.:'\ ._.;:.... a:: \ :J :J , u ./ - - ,_,·.k .... - ~_. u . . . --' 0 0 --'

;§ 'u LV 'V LV .>V '1U 0

i= i=

co,..... <> ~.~~

500 v ... '"

500

~,../~ -' . .,..;/".

.. ' 450 450 .-.;-

400 Ann

350 1"'\ ., 1';;;::::-"•. 350 I ~.~ 4-.--'

,jUU :-.-: .,' ----. 300

2 250 2 . 250

~. - I~ ':1.. .{ 200 .... , 200

:""i.~ ~',.. ..;,-' " ...

,~u . r"" IbU

100 ~.

A 100

50 .. ,r..;.... ., 50

u

r '\.. I J \ ( '-'- '.

~-A -0

I'·, f .', f

\ '.

\. - .. '. • • to._' ....,~; .. ., 1/\ .... -~ -_.... ... ".- I ... ..

0 .' . 0 - ~. I"

0 10 20 30 40 0 10 20 30 40

TIME,IN HOURS

COMPUTED ---------_ .... OBSERVED

Figure 17. Observed and computed tidal current speed and direction at selected sites in Tampa Bay during first verification period,

Model Development and Application 29
SITE 2 SITE 3 500 500 .. A ..: 450 450

~.: .

n [l;'..., K1<T

- n I'WU350 \ 350

300 300

L

\ IL... £

~N \ I£:>U

'~ 200 ' . .,~. 200 '. .......... . . _ ... "'\o~ ..

150 150 , " - 100 .'- ." L~ 100 ':'X .j~ 50 ,;-.., ~- 50 " ' '

1 0 1 , 0

~, \ t (\/ "1 t' \r \ '\ f

r " '-. ...... j..: " ' :"1 -, ... "

" , U "j 1\ ' , \j I 1'- \/ ;: " :~ I ¥' ',' 1 'l IV f

00 0

10 20 30 40 0 10 20 30 40

0 w

::l

Uw ~IT 7 <n . 500 a: kc - 450 w w iC", ,:. a: a.. I":' 400 c:l . 350 0 w

w

u. 300 Z

2 250 - Z t.:" " Z· - . . " - . ~. ........ -" 200 0 ci : H"'\

ttl 100 (,) . w a.. a: (/) . 50 Ci 1

Z .. !1:! A ~, -, " a: ,.1' \r' N ~:"" a: ::l - '~ a: (,) ::l , , (,)

-' .

Ci 0 10 20 30 40 <

i= 0

i=

SITE 8 SITE 9 500 500 'i : .'

.~.-

.. 450 450 ........

h 'tVV I., 4UU

350 . ',~ :.... 350

300 300

2

~. ~:,:-, 250 2 250

,. Ir-: 200 200

,." ./...,..,:; -. 150 ---- , . .; . -' ,. 150 "

K . '

100 , .,,> 100

50 ,:~:

'''' ......... 50

1 0 1 ,'. '" 0 " / '''-. f \ f ; J ' ."'\

~l , \i~/ ~:V: ,.A'A~" r T' ',.' ~": 'r.. A ~.I,.. ;~ :

o .' J v ~: -'" ,v J~, ',1 :, , . ',\ 0 . 0 10 20 30 40 0 10 20 30 40

TIME, IN HOURS

COMPUTED •• ---- -- - ---.- OBSERVED

Figure 18. Observed and computed tidal current speed and direction at selected sites in Tampa Bay during second verification

period,

30 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
Table 8. Standard error of tidal current speed and direction in Tampa Bay for verification periods

First Second First Second

verification verification verification verification

O.Og 17

.09 0.12 5 8

.09 .12 g 10

.08 8

.12 9

.15 .16 16 16

.10 .10 17 17

.10 .08 25 22

.13 .17 14 13 -- -- - -

.10 .12 13 14

Site no.

(see

fig. 8)

1 _

2

3

4

5

6

7

8

9

Average _

Tidal current speed,

standard error

(feet per second)

Tidal current direction,

standard error

(degreesl

B

DREOGE

,

,

,

,

,

.'

\ ., ,0 EXPLANATION ,

O

\..--SHIP CHANNEL

SATELLITE , 2,1 A~

IMAGE PLUME \

':,':", SIMULATED SHELL \ ',1/1',;, PLUME

(I) vertically averaged tidal currents used in the simulation and (2) faster near-surface currents in the bay that

carry suspended-sediment particles constituting the observed turbidity plume.

Simulated and observed plume lengths can be compared by adjusting results shown in figure 19B for the

effects of different tidal ranges and different current

speeds. The length of the simulated plume (measured

from the shell dredge to the centroid of the southern end

were not available for suspended-solids concentrations

within the observed plume. In spite of these drawbacks,

the model did reproduce plume characteristics. The area

bounded by the 75-mglL line of equal suspended solids

concentration in figure 21C is reproduced as the simulated

plume in figure 19B.

The observed and simulated plumes in figure 19B show

nearly identical shape and orientation. The southern end

of each plume has a large bulbous shape. The northern

ends show less bulge because of limited dispersion time.

A narrow section that follows the ship channel connects

the northern and southern ends of each plume. The only

significant difference between the observed and simulated

plumes is their lengths. One factor causing the length difference is the inequality of tidal ranges (p. 28). Another

factor affecting plume lengths is the difference between

A

Figure 19. A. Satellite image of turbidity plume in Tampa Bay.

B. Comparison of satellite image and simulated turbidity plume.

Model Development and Application 31
'" 2.5 2.5 N 0

'" Z

~:: 2.0 r\ 2.08 ...J 0 • __• TIDAL STAGE W

:::~ / ! lJ) a::::J 1.5 TICAL CURRENT 1.5 ffi

~~ /' \ SPEED • CL.

~5 1.0 / '.0~ ·-..1 ,... ...·..\(._.1 .~..

--

HlU~ 0.5 If' \'.:,' ,,;"\ Ii'"\.//3g o.sS

~.~ 0 j' \ \.r ..,...; 0

~~-o.5 \ .!i w 0.5~ TURBK>'TY '\"' U

~~ -1,0 GENERATION \ ..... :; 1.0

« PERIOD _ i=

z -1.5L.._.......__......_--:':-_.......__......_~1.5 -

o 6 12 18 2. 30 36

TIME. IN HOURS

Figure 20. ndal stage and tidal current used during turbidity

plume simulation.

dredging (1972), and postdredging (1985) levels of development. The following sections defme the bottom configurations, boundary conditions, and initial conditions

used in each application.

Bottom Configurations

The bay shorelines and areas of bottom changes for

1880, 1972, and 1985 are shown in figures 3 and 4. In

1880, the bottom configuration was characterized by

gradually varying depths in most parts of the bay.

Notable exceptions occur at the northern end of Egmont

Key and at the mouth of Old Tampa Bay. Several islands

existed near the mouth of Tampa Bay and at other locations around the bay periphery. The 1972 bottom configuration was characterized by broad areas of slowly

changing depths interrupted by extensive manmade linear

features, charmels and islands, aligned perpendicular and

parallel to the major axis of the bay. In 1985, the bottom will have additional physical changes that will include

large disposal islands in Hillsborough Bay and more extensive submerged mounds along a deepened and widened ship channel.

This compares very well with the length of the observed

plume, 4.0 mi, as measured from figure 19B. The general

agreement between observed and simulated turbidity

plumes indicates that the dispersive features of the model

adequately simulate actual conditions.

of the barbell) can be adjusted for tidal range differences

by assuming a linear relation between plume length and

tidal range. The simulated plume can be further adjusted

by a proportionality factor relating vertically averaged

tidal current speed to near-surface tidal current speed.

The factor lI6ed was determined from velocity data presented by Dinardi (1978, p. 33) at two sites very close to

the plume location. Surface waters in this area apparently

move about 23 percent faster than the average speed in

the water column. The following computation gives the

adjusted simulated plume length:

Actual tidal range Speed

x Simulated range x cofrrection

actor

Simulated

length (from

fig. 19B)

5.2 mi 1.9

x-x

3.1

Adjusted

= simulated (17)

length

1.23 =3.9 mi

Boundary Conditions

Of the three types of tides that occur in Tampa Baydiurnal, semidiurnal, and mixed (fig. 2) - the most prevalent is the mixed tide that has two unequal high tides and

two unequal low tides during each cycle. Therefore, a

mixed tide was chosen as the open-water boundary condition for model application. A mixed tide similar to that

measured during the second verification period (fig. II)

was used as the repeating tide (fig. 22). To simplify

analysis of results, the tidal period was adjusted to 24

hours (an even multiple of the time step), and small

irregularities in the second verification tide were eliminated by assuring smooth first and second differences in

tidal stage (table 9).

Because it was considered least likely to mask tidal

flow, circulation. and flushing changes, a zerO wind condition was used for all model applications. Changes in

flow, circulation, and flushing due to wind were beyond

the scope of this investigation.

Freshwater river inflow was held constant for each

model application at the average annual discharges listed

in table 3. Cooling water used by power-generating stations was treated as described under model development

for 1972 and 1985 levels of development (p. 17). There

were no power-generating stations on Tampa Bay in 1880.

Application to 1880, 1972, and 1985

Levels of Development

The model, after calibration and verification, was applied to determine flow, circulation, and flushing characteristics of Tampa Bay for historical (1880), preInitial Conditions

Tidal currents throughout the modeled area were

assumed to be zero at the start of each model application. Tidal stage throughout the modeled area was initially constant at the National Geodetic Vertical Datum of

1929.

32 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
(0;;}"" ',) '-"'---.. • i,'"' ~- - - .- - .?' ~~r\ ' I

. ',II ....t.\.,\---- -.?' "~S , ~'I' / fJ

~S I c"".. " WI"

I _...lJ.,q (I.... '" '" I ~ll .... "

/

,

r Ci /

f \ , I /

\ /

, , , /

--------' '--------'

\

\ \~ /3SO

A ,

{ j ( I I

I ~.oo ): 60 •

, '00 ,

<:JV I

V 'Jy so-(@) ;/ f

!

N N f

I

f

./ "\./? \ ./

~O , , , . . < " • , , 2 3 • 5 ,

rV

r V MILES MILES

A. 1 hour after start. D. 13 hours after start.

'J~\. ',':' v_ . I ,/' 7~L ',!. -v--. , I I C V~ 'I ........ ,'a-o:.. v~ I I co(!." // I _ ell," ..#/(1 ~"\E:

~¥ I

'" , ,

If Y I //

/

if \ , / I . , , , /

, /

--- -----", '-------~ 250

k I

r A '~ ,oor ,

I

~26O !J

hi };!

'1\J ~' ~~ q~ 50~ ""-

,'Loo (J/ N

P/ N

l f \.

.~ {/) \ LJ" ./

I l(~ \ ,, " -rv 0

, 2 3 • • ,,

rv? , 2 3 . , • MILES MILES

8. 5 hours after start. E. 17 hours after start.

~O '",{~ '-"'---.. ft

1i>t.\.,\---- ''i.e mo ",t v_ . #""1<..,.. /' Q e>_ ..lJt,/ 1i>t.\.,"-----;-tC (1 ..

o~ c:,': .... .... '

If nlt I ~+\'........ /

!? I I

/ , ,

. , /

• ~' 150 -------_/I '-------« ~c:...

I I

I

I J 1 /r-.~'?Z,oo J

k r

300 it 5O-lg( .~~ ~I ~c.-... q'<{) I

, ~t.--..

.ood; fr N I

fJr f N

\.. f \..

.J J:J::t f</ \ ./

f

f

K_

5~1S!J ;V9

, 2 3 • 5 " ;Va , , 2 3 • • I 75 MllES MILES

C. 9 hours after sta . F. 23 hours after start.

EXPLANATION

-TOO-Contours show lines of equal computed concentration of suspended solids, in milligrams per liter,

with a simulated injection rate of 15 cubic feet of suspcndable material per second (Gren, 1976). . -~ .~" .. . .u 'U' ." ..., 'a, '" ,~, , .",

r' - M . . +:~ ~r r+~r+ ~. ..

"6"''''''' . JII"tJ'" VI lUI VIUI.y f-JIUI <;; '0 <>

Model Development and Application 33
Table 9. Stage, first difference, and second difference of repeating, 24-hour tide in Tampa Bay used as boundary condition for .... "'rl~1 ..

r"'~~a ,,~I .._••_I~,:.,a .~ . . .P '~~M

'T

First Second First S;sond <:hno ,.1:«0._ ..J:u~._ c.- ._ ..J:U~

lime lime ·0

(feet) ence ence (feet) ence ence

(feet) (feet) (feet) (feet)

0000 -------- 0.00 0.23 -0.02 1200 -------- 1.67 0.13 -0.03 ~~~~

vV.JV -------- ..... - ..... .V.:l I':'.:lV _ --- L .IV .UJ

0100 -------- .39 .18 - .03 1300 -------- 1.84 .07 - .03

0130 -------- .54 .15 - .03 1330 -------- 1.88 .04 - .05

0200 -------- .66 .12 - .04 1400 -------- 1.87 - .01 - .08

0230 -------- .74 .08 - .05 1430 -------- 1.78 - .09 - .08

0300 -------- .77 .03 - .08 1500 -------- 1.61 - .17 - .08

0330 -------- .72 - .U:5 - .05 1530 -------- 1.36 .25 .05

0400 ------- .62 - .10 - .03 1600 -------- 1.06 - .30 - .03

04":\0 .49 .13 00 It;10 71 .":\":\ 11'7 --

U'UU ________ .JO .1J .UJ l/UU ________ .Jll .J' .oz

0530 -------- .26 - .10 .03 1730 -------- .01 - .37 .00

0600 --- -- - .19 - .07 .03 1800 ---- - - .36 - .37 .03

0630 -------- .15 - .04 .04 1830 -------- - .70 - .34 .06

0700 -------- .15 .00 .05 1900 -------- - .98 - .28 .07

0730 - ---- .20 .05 .04 1930 -- ---- -1.19 - .21 .07

0800 -------- .29 .09 .04 2000 -------- -1.33 - .14 .08

0830 -------- .42 .13 .03 2030 -------- -1.39 - .06 .09 nonn (Q 1,;; n~ ",nn , ~£ n~

---- --- .'"'"

0930 - ----- .77 .19 .02 2130 -- - -- -1.23 .13 .08

1000 -------- .98 .21 0 2200 -------- -1.02 .21 .06

1030 l.1Q 21 fI'7 '7'71f1 7( '77 nn - --- - 1100 -------- 1.38 .19 - .03 2300 -------- - .48 .27 - .02

1130 -------- 1.54 .16 - .03 2330 -------- - .23 .25 - .02

2 •

/\ • -. i\ • •i\ -. ...J

«

Z

0

.:::: / \ / \ / \ N

/ \ \ / 1 ~~ 1

g~ - - \ al~ (\ / (\ (\ / , a::::>

o~

>0 V 'J

;::., II V II V , al « v

\ , «u

..... 1= wa:: w J J J ~> I I \/. z~ \ \ - ..... w·w

t!:l 0 -1 «0 •

r.nt!:l

;J. V V V

0

.....

-2 • • • 2400 1200. 2400 1200 2400 1200 2400

TIMF IN I-InllR~

Figure 22. Repeating, 24-hour tide used as boundary condition for model application.

34 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
To help determine changes in the flushing rate of Note that - B is the same magnitude but of opposite

Tampa Bay between 1880, 1972, and 1985, a representa- direction to B.

tlve constItuent dIstnbutIOn, measuroocrunng JUlY 1'J " Water and constituent transportounng Hood and ebb

and reported by Goetz and Goodwin (1980), was used. conditions at each cell in the model are computed as the 'T'1..~ • . {r.~ "'~\' .1... ., " . ,. "1..~... :~

".~. .~ . -0 v. ".... '''''''.v,,, ... un",. _u, _. u,

source of phosphorus existed along the eastern shore of figure 25A. Averaging avoided overemphasis of possiHillsborough Bay in the vicinity of the Alafia River. Con- ble short-term, local oscillations. The direction of the

centrations ranged from 1.5 to 2.5 mg/L in Hillsborough summation vector defines the direction of the average vectlay, were nearly constant at U.l:S mg/L m Uld umpa tlay, tor. The magnitude of the average vector IS one-sIxth the

and decreased to less than 0.2 mg/L at the entrance to summation vector. ...., R"" T">'- • U'~.~P 0 ~~,l .. "rp -. -. -0.

Tamna Bav were 10 to 100 times I1:reater than that of rp<;:idual-transnort vectors at each

hypothesized as needed to maintain primary productivi- cell. The computation is shown schematically in figure

ty (photosynthesis) in this area of Florida (U.S. Depart- 25B. For a repeating, 24-hour tide, such as given in figure

ment 01 the Intenor, I~'I, p. 24). At these elevatea con- 22, the summation of 288 5-mmute transport vectors IS

centrations, phosphorus is a conservative (nonreactive) actually computed at each grid location. Twenty-four ~,,' "nrl ;~ 11~pfll1 ,,~ " tr",",pr 11.~"p ,L '-1..~p~+,~p~l~p:.... Thp

lllC'k of'

-r

thp <;:tllrtinl1 noint of vector 1 and

the ending point of vector 24 indicates a net or residual

MODEL RESULTS AND ANALYSIS transport equal to the summation vector at that location.

Magmtudes 01 resIdual-transport vectors are generauy

The results of model computations presented in this one to two orders of magnitude less than those of typical

section are largely dependent on using vector maps that flood- or ebb-transport vectors at any location.

visually represent water and constituent movement computed at each cell of the model. Vector transport sym- Transport-Change Maps bois (representing the directional flux of material, either

water or constituent passing mrouglreacITmuucll,;CU) i:1IC , 1 - '0 111<1p:> '0 .v ...." ~. •.. " •. -l +'~_ 0 ~~,l • ~+' • rp~, Ilt~ fnllnm;na o • tn Hnw mllC'h llnt! what Darts of - - ... The flux of water, in cubic feet per second, is described Tampa Bay have undergone significant transport changes

in this report by the specific terms ebb, flood, and residual between 1880 and 1972? and (2) How do these changes

water transport. The flux of constituent, in pounds per compare with those expected between 1972 and 19l:S5'! The

second or pounds per day, is described in this report by symbol plotted at each cell location on a transport-change

the specific terms ebb, flood, and residual constituent map represents a difference range (in percent) between

• fnr hun levels of 'r --.

Analysis of methods to discern differences in tidal flow, development.

circulation, and flushin~ among the 1880, 1972, and 1985 Percentage differences at each cell are computed as 100

levels of development is dependent on some concepts of times the magnitude of the difference vector (A - tl) m

vector anthmetIc. The methoas usee are aescnoea m o 0 0 n

llgure ;l4L:, OIVIaea oy-me- UI Ult; Vt;\';~UI

some detail in the following section. associated with the earlier level of development (B), or

IA H I X 100 = percent change in transport (18)

O. • I B I

This technique recognizes that changes in transport direcVector Computations tion are often as important as changes m transport

magnitude. Directionality is inherently incorporated in-

,-. - • npp£1 nnt f\.ooition anu SUDtraction 01 Vt;I,;~UI:> \ng. U'tJ <11t; U<l:>~\'; ~u Lilo; "V u.~ r "",'

computations used to present and analyze flow, circula- be associated with a positive or negative concept of

tion, and flushing patterns. Figure 24A shows two directionality.

directional-line se~ments, A and 13, that represent the

magnitude (proportional to the line length) and direction Longitudinal Summary of two vector quantities, such as water or constituent ... '~ - _. . A .. \11"~ • -' to lri:1US£,Ort. VCl,;lUI \ug. ~D} lCSUHS u, .....u ..... ",,,,- '. IA D\ nO • 1..•• 1:~~ +,p~_ .I.~ • nn;nt nf thp effect of chanl1:es indicated by the ~'V~ 'J _ . A transport-change maps and to answer the following ques- to the ending point of B. Vector subtraction (fig. 24e)

also results in a third vector (A - B) defined by a line tions: (1) Has dredge-and-fill construction (channels,

from the starting point of A to the ending point of - B . islands, causeways, and so forth) causea sIgmncam

Model Results and Analysis 35
N

40' 35' 30'

+ Sampling site

per liter

- - - - Ship channel

--- Line of equal concentration

5

, MILES

36 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
A

Item 4 is computed by summing all residual, constituentVA"'"'' h".h _ <Inri

ll11lfward-flowinl1 normal to a cross section. Item 5 is self- V

y Vector explanatory.

B Water Transoort

/ Water transport is computed at water-depth locations

of the finite-difference scheme (fig. 5) by using the cell

8 B dimension (l,500 ft), the depth value, and the four velocil.y anu lour Water-lt:Vt:l Vl:llues on Lne siut:s i:lIlU

of the surrounding square. Transport, rather than velocitv W"'i: rhn"..n "" th.. nnit tn f1nw and cir~nl,,-

tion results in this study to avoid potentially misleading

Vector addition (A + Bl

visual portrayals. The length of a transport vector is

directly related to the quantity of water being moved,

c

wnereas large velUdlY vt:cwrs can oe W llIl llLue

-13 water transport.

4 / nuuu dnu I:DD .......el

. . .... A· tlV A 1 YPl\;i:ll Wi:llt:l- .C • ""u"'5 'Vl

1880, 1972, and 1985 levels of development are shown

in filmres 27 28 and 29 resnectivelv. The transoortVector S4JbtrKtion (A B) vector maps show many similarities, including flow concentrations at the mouth of Tampa Bay and Old Tampa

Fh~ure 24. Computationsfor vector addition and subtraction. Bay. Each map also confirms that regions of high transA and B represent the magnitude and direction of two vector .. . ". pUlL all;; <lUl ........}-I, .a".- -'"

quantities, such as water or constituent transport. areas of the bay and that low transport regions are coincitipnt"l with "h"llnw areas. For areas of similar denth

changes to the overall circulation and flushing character- transport magnitudes generally decrease with distance

istics of the bay? and (2) How large are the changes in from the Gulf of Mexico.

various parts of the bay? The magnitudes and directions of flood-transport vecThe tecnmque summanzes computea transport Hong __ • • ••• "" T •

lUI S i:ll 1t.:J I>U<;I> al <; 11l>ll;;U 111 .av..... v.

a series of cross sections within the bay. Each cross sec- of the sites are shown in figure 27, and reference dots

tion extends from bank to bank and is approximately are given in figures 28 and 29. From 1880 to 1985 levels

•.. the nredominant direction of tidal flow. of development, vector magnitudes were computed to deThe series of cross sections extends from the model boun- crease from about 105,000 ft 3/s to 97,000 ft 3/s at the

dary in the Gulf of Mexico to the head of Hillsborough mouth of Tampa Bay (site 1), from 37,000 ft3Is to 29,000

and Old Tampa Hays along the 10ngltUamal summary ~. . .. - . ~,~ -~,"~, """ U-I S111 1111U-l i:llllpi:l va, \I>U<; 7), 11 Ull1 ,vvv.. "'V ,vvv

• .~. _, • L" d. r.3/. ;,.. Al,.1 - n<l" {.;... "'" ",,..,.1 r..,,~ , MfI ft3 I .. IlIlt:S I>I1V..-lllll i1~UII;; Jt.U. ll11UI UVU1--.rro;;- -, ,.

model for each level of development for each cross sec- to 1,000 ft 3/s in Hillsborough Bay (site 18).

tion includes: At some sites, significant computed increases in trans1. water and constituent transport during a typical port magnitude or changes in direction among 1880, 1972,

floodtide, and 1985 levels of development are evident, such as at

2. water ana constituent transpon aunng a typical eoo- • ~, ,. _~ -' "',.. .... .L I>lL<;1> -', U, lU, 17, ...v, au.......... Inv". "lL"", , »uv .. 1;..1.. ;~ _;..1.. •• " ..., nf f1nnrl_ UUt:, .~

3. landward-flowing residual water transport (defined as transport vectors.

tide-induced circulation for nurooses ofthis reoort) Typical water-transport patterns during ebbflow for

4. net residual constituent transport (defined as total con- 1880, 1972, and 1985 levels of development are shown

stituent flushing due to tide and streamflow effects), in figures 30,31, and 32, respectively. Overall ebb-transand port patterns, although opposite in direction, are similar , " .." ._-'- tn f1nnrl_ "hnwn in fi<Yl1rp.'i: '.7 'It "nti J ••Ulal Ula"" v. .a..... a..... v.......... ·c

cross section. 29. Flow concentrations occur in the same general areas,

Hems 1 lInd 2 are comnuted bv summing the ao- and transport magnitudes are greatest near the mouth and

propriate vector components normal to a cross section. least near the head of the bay.

Item 3 is computed by summing all landward-flowing, une aurerence oelWt:t:Il BUUU anu eoo . II> l11al

residual, water-transport vector components normal to maximum ebb transport is substantially greater than max-

,- .- . imnm f1nncl . t the bav. This difference a \;IUI>I> "......LlVU. '-'w.. , .....- .'" .'"

Model Results and Analysis 37
5min 10min 15min 20min 25min 30min

V ,,/ / ./ ---'" - - i=l i=2 i=3 i=4 1=5 i=6

5-minute transport vectors I vii

.// P:/ " " " "

l/""

6 11

Summation of vi :( Ivi) Average-transport vector: I ~_I vi I

1=1 i=l

A. Computation for average transport vector for flood or ebb conditions.

'",

2/ 1\ Il ,

,

,

'X/ '\ / !s,mm'''O"Of24hO,'', transport vectorsWj I,

each the summation

of 12 5-minute vectors

//~:/" \ VII Vi~~V' / /'"

/

, "', \ r--/ j=1

.r Residual vector , II /

", \

\,//

Residual vector= 2; Vi

------ "" / :/

1-1

-----------.

B. Computation for 24-hour residual-transport vector.

Figure 25. Computations for average flood- or ebb-transport vector and for residual-transport vector.

38 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
"" \

.( 'V'A ZONE 7 ~vru:: Q \

I~" /'X jHi/lsborough -

1\

\

A

-

\ T ZONE 4 \" r

TAM P A : 8 A ;"

I

" Boco I~f' Ciego 5

'\]., I l/

'- ~~ ! _, L ) ZONE 3/" j::?'./J LONGITUDINAL SUMMARY LINt:::>

""""\~ • .1, , AND DISTANCE, IN MILES

./t'A .•.

------

--

5MILES

I

\

o 1 2 3 4

I I I I I

CIRCULATION ZONE BOUNDARIES

AND TYPICAL CROSS SECTIONS

-

o 1r'4, / ~[V

---- Figure 26. Longitudinal summary lines and circulation zones of Tampa Bay.

Model Results and Analysis 39
............ '" . ..",.. , . ... , ........ '\ " , .. .. ",.. ,.,Il, .... ",,,,, '\ . &"",1."" II- ... "\,,\\.. ,,,. a","""4' • ... "\\'\,'\,'\\,,.

.. """"", .. , ....",\ '\ '\ '\ '\ \ \ .. " -" ...""""" -.. """",,\, .. -...

listed in tables 10 11 13 15 16 and 18.

EXPLANATION

LOCATION OF MODEL COMPUTATION

SITE (NODEI

OF NODES TO AID VISUAL CLARITY

'- TRANSPORT VECTOR WITH NODE

LOCATION SYMBOL

LENGTH OF LINE

o 10' u...J...J...J..

CUBIC FEET PER SECOND

VECTOR DIRECTION DEFINED FROM NODE

LOCATION SYMBOL TO END OF LINE

LOCATION SYMBOL

• LOCATIONS OF TRANSPORT SITES LISTED

IN TABLE 10

40 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
INED

CUBIC FEET PER SECOND

VECTOR DIRECTION DEFINED

FROM NODE LOCATION

SYMBOL TO END OF LINE

o 10'

NUMBERS)

, TRANSPORT VECTOR WITHOUT

NODE LOCATION SYMBOL

• LOCATIOIII OF MODEL

COMPUTATION SITE (NODEI

SYMBOLS ARE SHOWN FOR

AID VISUAL CLARITY

\. TRANSPORT VECTOR WITH

o 4 5 MILES

Figure 28. Water-transport pattern during typical floodtide in

Model Results and Analysis 41
.. ,.,.. ,. , ... .. , "''' ", , , , ., . .. . . ... '" \ "\ ,"", " " . """Il,",,""'.

... """,,,,,, . .. """",,,,.~. ... """",\" . .. ,"""'"'.' .... ... "",\\\'\\, .. - .. "\,,,\.,.,.~ , ... ,'\'""" .... , .

-""------,~,////'., .... ~,"'~---r'~'~/~J.'•.•.•. ' ... ""------"",,,., ..... .......... ~,.-.-r'~~~'~' •.•.•.•.•.• -" ..... ------",-~~", •......... ·".'.. ~.-r-r'~'w~.'•••.•.•.•.•. ... , -----",,-~-_., . ·1 -.·.~.~.·.· · .

42 Tidal·Flow, Circulation, and Flushing Changes in Tampa Bay, Florida

EXPLANATION

LOCATION OF MODEL COMPUTATION

SITE (NODE)

L ARE SHOWN FOR 25 PERCENT

OF NODES TO AID VISUAL CLARITY

TRANSPORT VECTOR WITH NODE

LOCATION SYMBOL

LENGTH OF LINE

o 10'

lli.llJ

CUBIC FEET PER SECOND

VECTOR DIRECTION DEFINED FROM NODE

LOCATION SYMBOL TO END OF LINE

LOCATION SYMBOL

• LOCATIONS OF TRANSPORT SITES LISTED IN

TABLE 10 (SEE FIG. 27 FOR SITE NUMBERS)
LOCATION SYMBOL

TRANSPORT VECTOR WITH NODE

LOCATION SYMBOL

eve opment.

SYMBOLS ARE SHOWN F R

F NODES TO AID VISUAL CLARITY

LENGTH OF LINE

o 10'

L....w...,j

CUBIC FEET PER SECOND

VECTOR DIRECTION DEFINED FROM NODE

LOCATION SYMBOL TO END OF LINE

LOCATION OF MODEL COMPUTATION

SITE (NODE)

• LOCATIONS OF TRANSPORT SITES LISTED

IN TABLE l' (SEE FIG. 21 FOR SITE NUMBERSI

Figure 30. Water-transport pattern during typical ebbtide in Tampa Bay for 1880 level 0

Model Results and Analysis 43
44 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida

EXPLANATION

LOCATION OF MODEL COMPUTATION

SITE (NODEI

SYMBOLS ARE SHOWN FOR 25 PERCENT

l. TRANSPORT VECTOR WITH NODE

LOCATION SYMBOL

VECTOR MAGNITUDE DEFINED BY

LENGTH OF LINE

o 10'

CUBIC FEET PER SECOND

VECTOR DIRECTION DEFINED FROM NODE

LOCATION SYMBOL TO END OF LINE

ay or 1972 level of development.
• LOCATIONS OF TRANSPORT

,

EXPLANATION

LOCATION OF MODEL

COMPUTATION SITE (NODE)

TRANSPORT VECTOR WITH

NODE LOCATION SYMBOL

VECTOR MAGNITUDE DEFINED

o 10' ...............

VECTOR DIRECTION DEFINED

FROM NODE LOCATION

SYMBOL TO END OF LINE

T

NODE LOCATION SYMBOL

(SEE FIG. 27 FOR SITE

Model Results and Analysis 45
Table 10. Water transport and direction during typical floodtide at selected sites in Tampa Bay for 1880, 1972, and 1985 levels

of development

Site no. (thousands of cubic feet per second) (degrees, clockwise from north) (see fig. 27) 1880 1972 1985 1880 1972 1985

1 --------------------------- 105 101 97 114 114 115

2 --------------------------- 71 68 67 69 69 70

3 --------------------------- 36 33 33 65 65 65 , -- -- -- ---- -- --- ---- -- ... "'0 "'0 .." ..0 '+/

5 --------------------------- 58 63 65 51 48 48

6 --------------------------- 14 11 12 45 85 85 - ,~

-- ---- - ----- --- - --- ..... "' ...... .... "J 4.l

8 --------------------------- 25 24 25 31 32 31

9 - --- - ---- -- --- -- 37 35 29 28 28 32

10 --------------------------- 22 21 22 29 30 31

11 '1 ')Il ,)Il '20 '211 "0 -- 12 - -- -- -- --- --- - - 15 14 13 16 14 15

13 --------------------------- 20 21 23 19 17 15

14 --------------------------- 6 5 5 59 59 59 1.0: 1.0: .'" . "'., ~~ ~~

---- -- ------- -- -- -'-'

16 --------------------------- 10 17 16 24 39 54

17 --------------------------- 6 6 4 6 31 355 , 0 "l . "".. " "

-.- --- --- -- ---- -- -- . JJ J"V

".." 19 --------------------------- 4 1 2 348 348 31

20 --------------------------- 26 31 30 359 356 356

~. n , , -,~ ... - -- - - --- -- -- - v V V ""0

"" "'~/

22 --------------------------- 14 19 19 313 316 316

23 --- ----- -- ------ 7 10 10 298 285 285

24 --------------------------- 2 4 4 251 280 280

25 --------------------------- 7 4 4 305 348 348

is caused by the faster rate of water-level change for faH- in most other areas, particularly where natural or man- : __ ..:..:1_ ..1.__ ~~. _:~:_ ..:..:1 ..:I • ..:_ ..1 • •. U'! -_..:I _L .1 "CO "0 ._- - ..."'0 ...- \He;. ........._ " ..v ..." v __.....

", Th,. f!:ld,.r r!:lt,. i,," h" !:I .•; ..... '" n~ ",1..1.._

flow duration. Ebb-transport magnitudes and directions Flood and Ebb Water-Transport Differences

for 25 selected sites are given in table 11. From 1880 to For 1880, 1972, and 1985

19~5 levels of development, ebb-transport magnitudes Figure 33 shows computed flood water-transport difwere computed to decrease from 239,000 ft 3/s to about ferences for Tampa Bay between 1880 and 1972. Com- ""'2 ,

f\IV\ ..3 /~ n" ..I..", .. .... n

-,

.w.

\"

,_,........,, ........... , ,~-~ . -- }JU.~'" 17' ... CUI". J "0.1 i:tn::: snuwn HI

from 51 000 ft 3/s to 40000 ft 3/s in mid-T!:Imn!:l R!:IV (<:it,. ~:~...'" '2/1 - .<'1, ..:I _ .L

-." ....... " ..v ...

9). Ebb-transport magnitudes increased from 8,000 ft 3 /s in both figures, with more and larger changes indicated

to 13,000 ft 3/s in Old Tampa Bay (site 23) and remained between 1880 and 1972 than between 1972 and 1985. The

constant at 3,UUU 1t"/s m HIllSborough Hay (SIte 18). largest changes are the result of (1) shoreline changes in

The most visible differences between flood- and ebb- Boca Ciega and Hillsborough Bays (fig. 1), (2) constructransport patterns occur in localized areas that are alter- tion of causeways for four major roadways, (3) ship- n!:lt,.h tn !:Inti th,.n •• • frnm .;..1.,1 . .,nrl IA\ .;..~-

due to the presence of islands, causeways, shoals, or islands and submerged disposal areas. Channel and island

points of land. A good example is near the eastern shore construction between 1972 and 1985 has and will cause

of Egmont Key, at the mouth of Tampa Bay (fig. 1), additional changes in Hillsborough Bay and along the - . wnere 'IUW -c i ~see smp cnannel rrom mIQ-l ampa J::Say to tne Gull of MeXIco.

fig. 29) and ebbflows produce high transport magnitudes Areas totaling about 218 mP sustained flood-transport

{",.,. fia ':I." Thp . • pffl"rt i" rn .t'h rnnr.. .,11ht1.. . nf th!:ln 1fl 1 QQIl n_rl .... .... c

46 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
.Kj( ':::::::::::::::::::~~: ...... .......................... It ... .. "'I •••••••••••••

.. , :... ~~ .. ) •••••••••• 1I ••• 1IC1IC

.. :.: =-=--It :::: : : : : : : : : : : : : : I .. ::::::::I:::;: , .... ............ x. I 1' ••••0_

,-..~~··:::...................

...liC········ ~:::::::·l· .. leJelt.;; ....... .. .. .. .. :I .. lit ..

.. .. .... .. .. .. 1(. It Ie

.... .. :~~~~~~. :..

1\

-- ..:::::.:""",

~~::::: .~ :. . . .. '..I X······Z

,- .. ::::~:: ::: ::::::::::: .. .. .. .. .. .. .. .... ::::::::::::::;':fj -....:. ::'. I.. . JI.I

J ,,~::. .::: :::::::::.::.. .... ... :'. :::::::::: .... :: .... :::.:.:. r ) :::::'. ~:: ::: r

-~¥'" ~.: ... +il: l'

::~~::~~~~~~:It\_ .. --~-~"..... .......... ···e ....................... ~.A!a..

:::: ;;~;:: :.;;~~

.::::::••• "r", " "." ~::::;:..~~

.:::: :~::::~~~V"r J

SYMBOLS

•

x

o

•

EXPLANATION

PERCENTAGE CHANGE

0-10

11-50

51-100

101 200

>200

::::: :::S\::~1~ .. • : : : : ; : .. 0 1 2 3 4 5 MILES ..... I I

\

rlgure .u. Lnanges in warer uansporl i dllllJd DdY lUI l yt_" '-0I

Model Results and Analysis 47
\.\),

~'l."'3

•

0-10

1-00

51-100

101 200

PERCENTAGE CHANGE

EXPLANATION

\

x

.

u

SYMBOLS

.ffJ

/

_.~ f

··

.. • • • •

..

····~iJ··.

I ~:;;. •• "

..

.. ;; ·.. .." , ,

.. ........... ~~

, ~.

•••• ~~!!~. , ···~Da ••

r::: .... .."...::~\~~:: : \I ... _a_.~tr • •• • ••••·_CD .. . .•••• e -

\ ~'Jj""­ :::.~ •••• , • ••

.....• c:J~ :II

••• II ••~~•••• "

• , • • • • , , , ". :II .••

...

..

... .:r .:~~~:: !/

::::::. . ~~

J

•

... /

:::: . .:::: ~!

.. . •• t' ... ...

\¥.... . .. . " . .... .. .. .. .... .. .

. J ....... A ~.

If . """,,J

-=:....... 'ld. . .

48 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
Table 11. Water transport and direction during typical ebbtide at selected sites in Tampa Bay for 1880, 1972, and 1985 levels

or oevelopmem

Site no.

Transport Direction

(see fig. 27)

(thousands of cubic feet per second) (degrees, clockwise from north)

n, --- .nn~ ,n..,~ n,,~

'uuv "'"..

1 --------------------------- 239 232 223 290 290 290

2 --------------------------- 116 112 113 243 243 244 ':I '7 ,~ ,'" ,,,n 250 250 - ---- - ---- -- 4 --------------------------- 40 45 45 224 224 224

5 --------------------------- 89 90 104 231 230 232

It. .,n "1 ,., .,.,0 ,"'''' ,~~ - -- ------ -- 7 --------------------------- 66 60 39 225 224 224

8 --------------------------- 40 38 40 206 206 206

- - --- ~1 4~ ,+v ,,:,vo ..:.V .<.,!

10 --------------------------- 29 29 31 213 216 216

11 --------------------------- 31 28 27 216 215 215

12 -- ---- - --- -- - 2U 19 HS LUj LU4 ..:.v,+

13 --------------------------- 24 26 27 207 205 203

14 10 9 9 246 246 246

15 --------------------------- 20 26 24 234 228 226

16 --------------------------- 14 18 6 201 215 245

17 R Q 6 187 214 198

18 --------------------------- 3 3 3 166 167 170

19 --------------------------- 5 2 2 172 169 182

LU ,_n -".. - -- - - -- ":'1 --yr JU ! 'J ! " • J

21 --------------------------- 8 6 6 164 143 143

22 --------------------------- 12 17 17 137 143 143

L3 -- - ---- - --- - II !'t {J T.<..<. !VV !VV

24 --------------------------- 2 5 5 88 135 135

25 --------------------------- 7 5 5 129 150 150

1972. Areas totaling about 53 mil will sustain similar ways, and shoreline fills. Areas totaling about 188 mP

changes between 1972 and 1985. The following table gives sustaIned ebb-transport cnanges or greater man 1U pera breal«fown ot percentage cnanges ana size or arreCLe{[ __ ,n__ • " "

I,;Cl1l ~ClUU J"7/~. ~CCl;) -0 avvuc .v ....

areas. The computation of percentage change at each cell will sustain similar changes between 1972 and 1985.

:~ . ~. _ ••1." nf 10 Pl"rcenta~e chan~es and size of areas involved are given

in the following table:

Water transport, floodtide

Percentage Area of change, in square miles Water transport, eootloe

change 1880 to 1972 1972 to 1985 Percentage Area ot Change, In square miles

0-10 ------ 244 393 change 1880 to 1972 1972 to 1985

.- .,n <1\ ..... ! !'-JV ______ .vv V-IV _____ .. <""

51-100 ----- 51 8 11-50 ______ 130 38

101-200 ----- 6 1 51-100 53 7 ----- >200 --- I 0 101-200 5 1 - - ":'lJ\J " - -

Figure 35 shows computed ebb water-transport differ- 1 00" n~,.l 1 n.." £"" . h",. Fil!ure 37 shows tvnical floodflow and ebbflow deter-

"'""'''',, v",c ._.. _ •

tUlPpn 107' l:md 1QR'i lIre shown in figure 36. Areas of mined for each cross section along longitudinal summary

ebb-transport change are substantial and similar to those lines (see fig. 26) for 1880, 1972, and 1985 levels ot

computed for flood transport (see figs. 33 and 34). The development. Progressive flow reduction throughout the

largest changes are closest to channels, ISlanas, cause- ,. UClY UVCl UIUC 1;) Cl V! u'J - ....---"'"

Model Results and Analysis 49
I: -1:.".' .~ ....,L l.. J

1.'00 j:::::::::::::D ~_~ "'llll1 • •••••••••••••Q DDD~

... .. a ~tj·u·~·~·Li·o;·~·~lC~iIQ~~c--------~,A-!-~ll-~~f1f------------------------1--

~~

.;:~::u gg::::~::::::::.~::. .: ~=: l-

•...•........... •••••a.·······....... • .,..•..,~

. , ,..... .~.

r; III III...... .. .. .. .. .. •••••••• ••••• '. ". "••••••••••• ",,"••• .. • III .

.. .. .. , _CCa" , , , .. .. .. .... .. .. .. .. .. .. " .. .. ." ..

~···...I.;i:."" .. • .. ···.. ·i#··;;iOiO "" .. 111 .. .. .. ::·:·:::::·11\ .. ":::::::t::::: J .. .••••••..•.• ;: .. :~~

f----------IL---~-_t--"'" - - ~........... ...• I .:::".•:::::Uq '" -w -1 r,. III =.. •.. .. .. .. .. .. .. .. .. .. .. if

. . ,,, :::::::::::~.::. •• ~:::::•• ~:., •••• ,.:J "

""'--lJij] ...:::::::::: .... , .....l l::::::;::::;;n:)7 . , . .... ... " .. ,., . , .. ." , .

I" ..

·.. . , . ·. . . • ::::::y: ....

.. .;=.:.:•...::.LiJ ............. .. . .. , ""IlIIIl~. . .. . . . . . .." , .'-"- \

\

\

\

EXPLANATION

SYMBOLS PERCENTAGE CHANGE

0-10

51-100

101-200

>200

11-50

x

•

o

•

.........

::::~::~ ....... .......

::::::::=.......=:r11 /' J V

............ 1.J-~~? d ::::::::::::i'~ __.- ........ ,.~~ r '.'-

, :::::.~--~~

c---.- .. -

....

, ...

:::::~·~o 3 4 5 MILES

\

rlgure ,);,. Lnanges In water transport in Tampa Bay for typical ebbtide between 1880 and 1972 levels of development.

50 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
A,fa: '.~. .:·l," )J,,_

J~ ; V1~~~ / . . :..:l::.~

.. / tll~ '"J ·::::t:t;: :::~::..:. :~*' ... : , 11.

, 'V );I( 7" ::::::a..," ·C ~-,\----------+------j

f(

'"

....

""~I~~:> . ••• •••x· .... . .. ..... .. ..

'1

51-100

0--10

.~' ---

11-50

101-200

>200

PERCENTAGE CHANGE

~~,~. ,IIUN

•

x

o

•

SYMBOLS

'" .• !-- ......... • :: ':::.=:~~ ... . .. ...

.~~. ....... ..::::::. :---r:::.o '. ... ..,."...,

.. .. .... .. .... ~~:::::::::. ....... ~.? .. .....

~l /J V

~~'--'------------+-----1 ~~ ..::~ 'V.. \ 0 1 2 3 4 5 MILES

\

Figure 36. Changes in water transport in Tampa Bay for typical ebbtide between 1972 and 1985 levels of development.

Model Results and Analysis 51
1.4

t"\.

~,"" IU.;jU

III..

1.3

'~>~ , ' 1880 ~BI~'~, 0.'Z5

1.2 "',~'~ ------- 1972

'~~~, ,', ~:!lo. ~~l'iI ""', ---- 1985

'~~+. 0.20

'''-.'

0 1.1

...'", FLOOD '~~~ 0

0 '~~ 0.15 U

w " '~ U \, (J)

, w 1.0 " (J)

II: '\.~<:'\.EBB , 0.10 ffi

"'-

~\~ '\ w

w 0.9 ~,, w

''':, UJ LL 0.05 LL

U

,,:~ u iii 0.8

...."....

iii :::)

---

:::) U .. ,~, U LL -_::::~"- ''''0-. 0 5 10 LL 0 ~- -'-::,---- DI~TAN~1t ItROU 01 n TAU"A .,AV 0 (J) -:-- ~'~ ENTRANCE, IN MILES (J) Z -....::::~, FLOOD ' , Z 0

"~""'":..."'''' "' ...

0 ::::i , , ::::i v ...

""-~~~ .;jU .....

--, "\:, Z :~ ~,

~~...... "~... 0.5 .~, "4 \ • 0.25~· II: "~... :-r

lr ~'~ ~EBB 0 ~, Q.. (J)

.~- (J) Z 0.4 " < 0.20 '::.... ,

~\~~ II:

to-

-

~~~ II: UJ 0.3 • 0.15

\.~, "'\" < 1: 1:

0.2 ' ": 0.10 ~" \' ...

FLOOD '~, "~" ",

0.1 ~\~~ "":,,> ... In no::

~~~ ~-

n . - 0 5 10 15 20 25 30 35 40

-ursTANCF~MODEL BOUNDARY IN GULF OF MEXICO, IN MILES

Figure 37. Water transport along longitudinal summary lines (see fig. 26) during typical floodtide and ebbtide in TamDa Bav

tor HmU, 1YlL, and 1Yl:l~ Tevefs of development.

and tidal prISm (see table 2). Water-transport and per- cause minor flow reductions into and out of Old Tampa

.~ ~OI are given "Hay.

in table 12 for the seaward end of each major bay subarea

(see fig 4). A of t<lhlp , <Inri t<lhlp l' "how.;: Residual Water Transport

that the greatest changes in water transport occur between Figures 38,39, and 40, show computed residual waterthe times and in the areas that have the greatest change transport (circulation) patterns for 1880,1972, and 1985

in surface area and tidal prism. levels of development, respectively. Each vector map .. . Shows a senes ot :w or more CirCUlatory t"eatures or gyres JUli111 -r III Wi:Ut;r ~li:lUlt;

12) for Old Tampa Bay between 1972 and 1985 were that range in diameter from about 1 to 6 mi. These . no wPrP .. . - r1ohno .:-1~" • ""t..... . ~~. _:"0-1

in that part of Tampa Bay. Apparentlv. a change in the tide in the absence of density s .-. <Inri winrl

distribution of tidal flow between Hillsborough and Old effects.

Tampa Bays, as a result of channel construction between Residual transport-vector magnitudes are several times .~-~ .~,.,~ ... . - --.... - 171~i1UU 170-', WU1",uO' &J Ii:lVUI -0 Di:lY ClUU greater near me emrance LO 1 ampa ooy man at most IOca52 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
Table 12. Flood and ebb water transport and percentage changes in Tampa Bay for 1880, 1972, and 1985 levels of development

u _l

Area (cubic feet per second) 1880 1972 1880

1880 1972 1985 to to to

I~/L I~O:> ':10:>

During typical floodtide, computed at the seaward end

Lower Tampa Bay _____________ 7.46 x 105 7.09x 105 7.00x 105 -5.0 -1.3 - 6.2

""''''.n T. n .... II\< ,~ .", "" ,", .. .. 0 ._......- -'J - ---- --- ... .~ • T. .~ •• J . ... .~

Old Tampa Bay ______________ 2.43 x 105 2.32 X 105 2.30x 105 -4.5 - .9 - 5.3

Hillsborough Bay ______________ 0.91 x WS 0.83 X 105 0.77 x 105 -8.8 -7.2 -15.4

During typical ebbtide, computed at the seaward end

Lower Tampa Bay _____________ 11.94 x 105 11.55 x 105 11.35 x 105 -3.3 -1.7 - 4.9

Middle Tampa Bay ____________ 7.94 x 105 7.66X 105 7.53 x 105 -3.5 -1.7 - 5.2

Old Tampa Bay _______________ 2.78 x 105 2.62 X105 2.60 X105 -5.8 - .8 - 6.5

Hillsborough Bay ______________ 1.28 x 105 1.18 X 105 1.10 x 105 -7.8 -6.8 -14.1

tions within the bay. At the scale of figures 38-40, cir- other and to partially or wholly cancel residual transport

culation patterns near the entrance are not easily dis- where the pairs join.

cernea. J:mtrance ClfcUlatlOn patterns ror HSlSU, I':J /L., ana ill spire 01 me large lOcal variaoiIitY in compULeU

1985 levels of development are very similar because few residual water transport, the overall pattern of circulaphysical changes have been made in that area; figure 41 tion for each of the three levels of development is similar.

shows a reoresentative residual oattern at an enlarged Maior gvres that existed in 1880 can be identified in the

scale. 1972 and 1985 maps. Detectable changes include deflecComputed residual water-transport magnitudes and tion or skewing of gyres, strengthening or weakening of

OlreCtlOns are given In table Ij tor L., selectea sites {see resiauaHransporr vecTors, alKf aaarnon 01 new gyres £'.' .... £'.' • ...... • L' • • . . ••.:.1.. . ...I. ...~A

ue..... .v. ••'" '''''e''' uv,,, , ,

19,300 ft 3/s in 1880 to 18,100 ft 3/s in 1985 at the entrance channels.

to Tamoa Bav (site n. from 1 200 ft 3 /s in 1972 to 700 Sufficient tidal current data have been collected by the

ft 3 Is in 1985 at site 9 in mid-Tampa Bay, from 400 ft 3 Is NOS at two sites in Tampa Bay, Ross Island and Egmont

in 1880 to 1,200 ft 3 /s in 1972 at site 23 in Old Tampa Channel (sites 25 and 26, fig. 8 and table 7), to deterBay, and from 400 ft 3 /s in 1880 to 500 ft 3/s in 1985 at mine long-term residual currents for comparison with n' TT' . . ." .J .1 _1. ....,. •••• •• L'. 11 •

~H" ." 'I! . .L>ay.oy ~au..." • v, ", •nvu",•• "'~u..~. ...,...,...~...... and 13, the degree of residual-vector variability among table:

levels of develooment can be seen to be much greater than

the corresponding variability in either flood or ebb vec- Residual current

tors for many sites. The sensitivity of residual transport Location Measurements Model

to physical changes in the bay is greater than the sensitivi- Ross .r L'1 _1..L .1- . .J v, uvv" v. "'vv .v ...'" ~u.n", IslanCl __V.JL. I1IS lL.. K. MUir- V.u::>' 1l/~ en

Circulation at the entrance to Tampa Bay is dominated head, written commun., 306° clockwise

bv (l) large gulfward-flowing vectors in the deeD chan- 1983) in flood direction from north.

nel north of Egmont Key (site 1, fig. 41 and table 13), (358°) (from Dmardl, ;"..n .. "

(2) small bayward-flowing vectors at other locations at • 'v,}o.

the entrance (sites 2 and 3, fig. 41 and table 13), (3) in- Egmont .11 ... " • r. __ 'I:l Channel _0.29 fUs in ebb direc- 0.27 fUs at w .. ... , cJ .... ~p'V ..... ~~J ,~ .. uv.. · ~c tion (289°) (from 284° clockwise

mont Key, and (4) significant south-to-north residual Dinardi, 1978, p. 30). from north.

transport about 1-2 rni bayward of the entrance.

Gyres and residual-transport features near the entrance

to Tampa Bay adJOIn other less Intense gyres Within the At Egmont Channel, the comparison IS very gooa.Ine

bay (see figs. 38-41). Each gyre or residual-transport residual current speeds determined by both measurements .. • 1- " .J .1 .J.1 • ..:.1:_ 1(\ ~-...I·,I 1'''''. v ....... ... p' -0" "........".V u ..u ...... ...v...... u. '" ....., ,

th" h"",rI (\f TT' "'nrl ()lrI .... R",,,~ ~nTt1" ,."nt .... .mhh;n "1 0 At th" Rn~" Island site . gyres mesh like a pair of interlocking gears and enhance the comparison is not as good as at Egmont Channel but

residual-transport magnitudes where they join. Other is sufficient to indicate a fair level of agreement between

pairs of gyres seem to rotate m drrectlOns opposite to each measurements and model values, partIcularlY In a regIOn

Model Results and Analysis 53
I

,I

I,

{'

I' \/'...'

".

"

I'

a 3 4

EXPLANATION

LOCATION OF MODEL

COMPUTATION SITE (NODEI

SYMBOLS ARE SHOWN F R

25 PERCENT OF NODES TO

AID VISUAL CLARITY

NODE LOCATION SYMBOL

VECTOR MAGNITUDE DEFINED

BY LENGTH OF LINE

CUBIC FEET PER SECOND

VECTOR DIRECTION DEFINED

FROM NODE LOCATION

, TRANSPORT VECTOR WITHOUT

NODE LOCATION SYMBOL

• LOCATIONS OF TRANSPORT

ISEE FIG 27 FOR SITE

NUMBERSI

5 MILES

Figure 38. Residual water-transport pattern in Tampa Bay for 1880 level of development.

54 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
o 3 4 5 MILES

Fi ure 39. Residual water-transport pattern in Tampa Bay for 1972 level of development.

Model Results and Analysis 55
o 3 4

EXPLANATION

LOCATION OF MODEL

COMPUTATION SITE (NODEI

SYMBOLS ARE SHOWN FOR

25 PERCENT OF NODES TO

AID VIS AL

NODE LOCATION SYMBOL

VECTOR MAGNITUDE DEFINED

BY LENGTH OF LINE

o 5000

CUBIC FEET PER SECOND

VECTOR DIRECTION DEFINED

FROM NODE LOCATION

SYMBOL TO END OF LINE

" TRANSPORT VECTOR WITHOUT

NODE LOCATION SYMBOL

• LOCATIONS OF TRANSPORT

SITES LISTED IN TABLE 13

{SEE FIG 27 FOR SITE

5 MILES

Figure 40. Residual water-transport pattern in Tampa Bay for 1985 level of development.

56 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
~.~.:~iJ~·~· .: r· :. . . - ... . - . .. ~<-

,

\

EXPLANAnON

• LOCATION OF MODEL COMPUTATION

SITE INODE)

SYMBOLS ARE SHOWN FOR 25 PERCENT

OF NODES TO AID VISUAL CLARITY

'- TRANSPORT VECTOR WITH NODE

SYMBOL LOCATION

,,,:('Tn,, UAr-lU'T"n<: ""<:'.... <:n BY

LENGTH OF LINE

o 20000

::::::::::~~... ~-- :, , , - .. , .. , .. , . I~ ,. . .. \ ..

: : = : = : : : : :, \ l\~ i ''t :. . • .\. " ....... , ...... ", \

CUBIC FEET PER SECOND

VECTOR UIHt:C IIUN DEFINED ~HUM NUUt:

LOCATION SYMBOL TO END OF LINE

"TRANSPORT VECTOR WITHOUT NODE

LlJ(;A' IVN SYMBOL

• LOCATIONS OF TRANSPORT SITES LISTED

IN TABLE 13

"\ ... . ...

, , ... .. .. \ , I

I

" " ' , , \ \ \ \' '1_ t\... V· - , . - ". 4' • ~\I\"'~\\\"~ ""1 .•. 1', •.•.• _ ...... ,.

\ , ' , , \ \ \ \ \ , I , ' -f . . , / , I 1 / - \

, " .. , .. , , , ... , r ' • .~ . • \1 \. •~. .,' / f ' .. :5

... " " " " " " " , " , " " " \ I \ /..--__\: --. ... / - • 1 ,-

- "' " \ \ \ " " " " " "\ 1\ \ \ \~~--, II', . I I I ' - .. " , I , , , , ,l '\' 'f IlI'I '. , / I ,

I, ( .:: " " ...Key - _ ... 1 " \ 1/1 I I

"\\\\,_ .... ,,, ....... II'

""""'1 r'"'~''' '111 / "1/1/- ,\, II

't ---- ." ,'-, .... • • • I , I

, / , 1

, I 1 1

. .

.. -

, 1

, I

I I

,/

/ /

,/

I I I I , ....

, , . - --- ... --r'/r--...--'"'..... -_- ... - ..

o

1

MILES

2

I

Figure 41. Representative residual water-transport pattern at the entrance to Tampa Bay for 1972 level of development.

Model Results and Analysis 57
Table 13. Residual water transport and direction at selected sites in Tampa Bay for 1880, 1972, and 1985 levels of development

c:.~ _~ Transport Direction \"'uUJa"UJ u, ~uu,~ ,~~, t"'~, J~~U"UI 'U~o'~~J, 'U' ,un",

(see fig. 27) 1880 1972 1985 1880 1972 1985

1 --------------------------- lY.j HI.J JO.J '"'OJ '"'0'+ 2.02.

2 --------------------------- 4.2 4.2 3.6 119 118 130

3 --------------------------- 5.1 5.0 4.7 59 59 59

4 --------------------------- 1.3 1.0 1.0 207 195 193

5 --------------------------- .Il 1.4 2.4 j,j JUY 291

(\ - .3 1.6 1.6 319 267 267

7 --------------------------- 1.3 1.4 1.6 224 260 227

8 --------------------------- 2.1 2.0 1.9 17b 174 174

9 --------------------------- 1.1 1.2 .7 67 59 212

10 _'i LO .9 310 290 211Q

11 --------------------------- 1.5 1.5 1.4 199 208 206 , ,~,

I .. - -------- ------- - .U .U .-' v·v ...·.v ",JU

1'2 1 1 1 r. 1 r. 14'\ 1'\r. Ll - 14 --------------------------- .8 .8 .8 263 260 259

15 --------------------------- 1.2 1.2 1.3 148 166 167

16 --------------------------- .3 3.5 7.1 76 58 58

17 --------------------------- .1 .3 1.0 12 222 283

18 --------------------------- .4 .4 .5 187 171 175

lY --------------------------- . J .j .0 ,",YU JJL; IY

20 --------------------------- .9 1.5 1.4 67 192 193

21 --------------------------- .5 .9 .9 37 30 30

22 --------------------------- 1.1 2.j 2.3 292 283 283

23 --------------------------- .4 1.2 1.1 178 79 79

'4 1 1'. 1'. 210 I11Q lSlQ

25 --------------------------- .4 .8 .8 278 87 87

of very complex, computed residual transport (see ng. more rellaOle man me reSlQUal transport values them39). selves.

- .l' .. -, ~+ +"'~~~ ..... ~:.~~ :~ -r . "",t t", ;l1t'1ap thp TTlnt'lpl'" j:lhilitv tn Residual Water-Transport Differences

simulate residual currents throughout the modeled area. For 1880, 1972, and 1985

Results of the comparisons, although encouraging, may Areas of change in residual water transport between

be SPUrIOUS for several reasons: 1880 and 1972 levels of development are shown in figure

1. The accuracy of residual currents computed from 42. Areas of change between 1972 and 1985 levels of :" _~+ Ir_~..._ .. .'-' l': 1"1 - • _& - ~&&~ ,&& &&& -"". . -.- , 2. Residual currents comnuted throu~hout the bav are frnTTl 1SlJ~() tn 1Q7' j:lrp . ",,,,,,,r' thp .~

on the same order as reported standard errors be- bay, and extend into the nearshore region of the Gulf of

tween observed and computed tidal currents (table Mexico. The largest changes are associated with causeway

H); thiS simllanty InCllcates the prooaolllty or mgn construction in Old Tampa Bay; ship-channel and portpercentage errors associated with residual currents facility construction at the mouth of Old Tampa Bay;

at the Egmont Channel and Ross Island sites. residential, commercial, port-facility, and ship-channel

Twn ~ite~ do not adeauatelv renresent the ran~e of in lind ::It thf' mouth of Rj:lv'

conditions within the modeled area. causeway, port-facility, and ship-channel construction in

Although these shortcomings are recognized, residual lower Tampa Bay; and residential and causeway construccomputatIOns are conslaerea useIUI ana InstructIve, par- tion In Boca Clega Bay. . . . " ., ... ., ftU n::siuucu- •v, _~ 1 .....«.. " • ....« .."....... v~ & " l,;Ul:tllgCS HVlll J Y 12. ro J YO;' are

modification to Tampa Bay. Computed changes in due to ship.-channel construction and associated

residual water and constituent transoorts orobablv are . and . . ~itf'~

58 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
PERCENTAGE CHANGE

EXPLANATION

0-10

• 11-

X 51-100

0 101-200

• >200

11"3\)'

5 MILES

SYMBOLS

o 4

.... ......

...... ....... ........ ........

........

.. • 1' , ••

.....

.... ..

Figure 42. Changes in residual water transport in Tampa Bay between 1880 and 1972 levels of development.

Model Results and Analysis 59
>200

0-10

11-50

51-100

PERCENTAGE CHANGE

EXPLANATION

•

5 MILES

SYMBOLS

4

in Tampa Bay between 1972 and 1985 levels of development.

. . .. ... ... ... .. .

.. .. .. ..

...

...

.......... .. .. .. .. ...

... .. ...

......

.. .. .. .. ..

..... t.. . .. ." ....

60 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
along the longitudinal swnmary lines (see fig. 26) for each

eve 0 v .

entrance.

Com uted residual transport changed little in Old

of Mexico to zero at the heads of Hillsborough and Old

Tampa Bays for all three levels of development. Except

Tampa Bay from 1972 to 1985. Although no physical

changes were made in Old Tampa Bay during that period,

a small difference in the distribution oftidal flow between

in Hillsborough Bay, tide-induced circulation is consistently greater than the average inflow from streams.

On the basis of figure 44, Tampa Bay was divided ina small change in residual transport.

Areas totalin about 306 mi 2 sustained computed

residual water-transport changes greater than 10 percent

between 1880 and 1972. Areas tota mg a out ml sustained similar changes between 1972 and 1985. The

,

circulation characteristics. The zones are shown in figure

26 and listed in table 14. The computed average tideinduced circulation in each zone for each level of development so IS giVen m ta e ,Wit t e percen age mcrease

or decrease between 1880 and 1972, between 1972 and

and affected areas. The progression from the Gulf of Mexico to the head

of Hillsborough and Old Tampa Bays consists of three

sequences of high-circulation, transition, and lowPercentage

change 1880 to 1972 1972 to 1985

ClrCU atlon zones. e 1rst sequence zones , ,an

defines circulation characteristics within the lower half

action between tidal water motion and bottom configuramotion in a bay. Areal changes, however, are static in

nature and do not rovide information on how the

change in circulation characteristics in Tampa Bay.

G es are tide-induced features that are caused b inter-

, in the zone. Circulation throughout zone 1 was greatest

for 1880 conditions. Circulation was reduced by about

has low circulation, about an order of magnitude less than

zone 1. Zone 2 serves as a transition between zones 1 and

3.

125

30

21

139

71

59

11-50 _

51-100 _

101-200 _

>

tion. Without the tide, there could be no mcommg

residual-transport vectors. All vectors would be outgoing,

dynamics of water motion are impacted, particularly the

dynamics of circulatory features such as gyres. Standard

methods for comparing gyre intensity do not exist. Therewould be equal to the total inflow from streams. A

feature of tide-induced water trans ort is that some areas

of the bay show residual incoming flows. To satisfy continuity, these areas are b ance y outgomg ow m ot er

areas. Both conceptually and by computation, the sum

a particular cross section also equals the total freshwater

stream inflow landward of the cross section.

Tide-induced circulation, as defined in the section on

t e ong1tu na summary me 0 see p. , IS use

as a measure of circulatory intensity. The units of tide- . .,

1,600 ft 3/s for 1972 conditions and by another 2,800 ft 3/s

for 1985 conditions. These reductions indicate that

cumu a 1ve p YSlca c anges re

entrance of Tampa Bay by about 10 percent.

Circulation reduction in zone 1 is not considered a

significant factor influencing overall flushing and constituent interchange rates of Tampa Bay. Circulation

magnitudes are so high at the bay mouth, in comparison . . .

have a limiting effect. High circulation and mixing in zone

1 are the likel causes for low radients of specific conductance reported by Goetz and Goodwin (1980, p. 23).

Zone 2 had an average C1rcu atlon 0 a out s

for 1880 level of development. Zone 2 is characterized . .

Model Results and Analysis 61
70

I I I 14

I

Q'" - kf('7\ 1 I I i ~"r ........ , , 50 .

.\~\~ ! I I 12

" I I I

,I I

40 I I II

" I \~ \·\1 I I I 30 I 10 I' I .,~ I I , ' . z 20 1 ' I I I : , 0 , I

I , ft I ,

I , ::; I J ::>0 18 I U z I I , a:,n .' 1972 AND 1985 r I I

UU , I uuu I I:l

~w .. I "I III 1\ (\! : a: VI I I:l '. :/': - -- 1 l:I ( <!

J 'j'V' I 1

I :: I Oa: ! ....., \1 ,'., I . " 1985 I

<4 Q.w , I i',: ............

r rnQ. ., : , \I , \

z~ 14 I .. il ,: I I V !\( \ ' . I, . <W

CIRCULATION I \./ . a:w if I: I \ t: . ~u. I : : I •.to:.'. I ---- ZONE • 2 I ~\

iii::::: I ' ,: I I~ :

~111 1 2 ' . l'A, I 7 : 8,\" .' Ii: •

<0 II~I: 1: 1

I r !: I I;

l~ 0

0 u. • I ~: r I 5 10 ;;'0 I r. .~ TIDE-INDUCEDI II I

1n , ::>rn I

~\ / CIRCULATlON!l~ .'0

"".. . o:-.v .... VL.LI I'\M'I'\ DI'\ , 00 '. ENTRANCE, IN MILES I 1\ :. -z : : rn< I. " I I\; : . w ,: .: , I: , .. rn I

V .; :: , 1 \.'''1' ' : a:::> I 8

I I::. i,,: I f }.I f I 00 I u~ , , i..;', ! " I

I H": : ,,:': i"~ 1 \ .•; I I I I POSITION OF ::>z ~: :' : i f I: . : ' f .' I I . ALAFIA RIVER MOUTH IN: 0_ 6 ::' I \ ;! j \ ;:\ : , Z , : , ~\,'.AI "f(~''f/' , ;"~.. w I \('.: I .--1880

- I I

-0/ V·' IVi~ i/ :' I -1972 AND 1985 4 \. I I ;, : I I ,:...... ~\ :1 I . I I. I : " i', I :'

1 I 2 , 3 ! 4 I 5 ~!rl;~:\ 4 6 , 2 I

I '. h I ....... t'1v\ I " AvdRAGE

I I . 1 I: !\ ", , \

I TRIBUTARY STRE"rFLOW , i'I;';'~""\ \ 1 , r I I I J1 "Y '"-'

0 5 10 15 20 25 30 35 40

DISTANCE FROM MODEL BOUNDARY IN GULF. OF MEXICO, IN MILES

Figure 44. Average tributary streamflow and tide-induced circulation in Tampa Bay along longitudinal summary lines (see fig, ... r nn" ~u, IVI 'VVV, 1071.<0, <1IIU I O7O~ It:Vt:I:> VI ''''...

laOle .'t. f"\verage tlae-maucea CircUlation and percentage changes tor each circulation zone in Tampa Bay for 1880, 1972, and 1985 levels of development

Distance along

urCUIalion longitudinal .~.u,,~

~'~~".u,,~ '""0"5"

zone (see summary line (cubic feet per second) 1880 1972 1880 fig. 26) (miles) 1880 1972 1985 to to to \,t:t: "5' -<UI 1':J7L 1985 1985

1 ----------- oto 6.5 45,500 43,900 41,100 - 3.5 - 6.4 - 9.7

2 ----------- 6.5 to 11.5 10,400 11,800 13,400 + 13.5 + 13.6 + 28.8

3 --- - -- 11.5 to 21.5 4,900 5200 6300 + 6.1 +21 , ... 'R (,

4 ----------- 21.5 to 25.5 8,600 7,900 7,800 - 8.1 - 1.3 - 9.3

5 ----------- 25.5 to 31.5 2,700 3,600 3,700 + 33.3 + 2.8 + 37.0 {;, ':11 C .~ ':10 l\ ''''' .,"" .~ ~~

- ----- ',JUU ... ,,,,,,,, -""oJ .'oJ . T~I:J

71 oto 7.0 4800 <;.<;00 'i'iM 1<1. (, (\ 1 A t;. - -- 81

---------- 7.0 to 14.0 1,400 2,500 2,500 + 78.6 0 + 78.6

,ro. .... ~.- ._•••J-- -J'

62 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
Zone 5, leading into Hillsborough Bay, was characteriz i

volume of water in the zone. Average circulation

o t zone 2 was least for 1880 level of develo -

ment, with an increase of about 1,400 ft 3/s for 1972 conditions and another increase of 1,600 ft 3/s for 1985 conditions. Physical changes in and near zone 2 caused an

culation from 1880 to 1985.

Zone 3 is a 10-mi-Io re ion of low circulation between regions of high circulation. In 1880, zone 3 had

an average circulation of about 4,900 ft 3Is, about a

of the average circulation in adjacent zones 2 and 4 (table

6. The increase in circulation (see mi 30, fig. 44) in 1972

and 1985 was caused by the combination of powerplant

cooling-water flow, dredging of channels, and construction of spoil islands at the mouth of Hillsborough Bay.

Average circulation in 1880 was computed to be about 3 9 3 _c ..._> __

tidally interchanged each day, or about 1 percent of the

total water volume in zone 5. Largely as a result of the

powerplant cooling-water discharge and channe constructlOn, e average clrcu a Ion in

3,600 ft3/s in 1972 and about 3,700 ft 3/s in 1985, a

cooling-water discharge (see mi 36, fig. 44) and extensive dredging and filling throughout the zone caused an

increase in average circulation of about 900 ft 3 Is by 1972

o tel s oroug Iver,

change each day was about 0.035 x 109 ft 3 , or only 0.4

I nt

Zone 6 at the head of Hillsborough Bay has the least

circulation of any zone in Tampa Bay. Circulation in 1880

averaged about 400 ft 3/s, less than the average ISC arge

zone 3 was very low, only about 3,000 ft3 Is (see mi 14.2,

fi . 44 about double the tributar streamflow at that

water was tidally interchanged in zone 3 eac ay, or

about 1 percent of the volume of water in the zone.

constriction to the interchange of water and constituents

between adjacent zones. Limited circulation is the likely

cause of the steep specific-conductance gradients reported

point. In 1880, an average of about 0.42 x 109 ft 3 of

conditions. The circulation increase at mi 3 (fig. 44) is

attributed to cooling-water discharge from a powerplant.

Ion zone e ween ig r

average circulation. Because physical changes are not expected in Old Tampa Bay between 1972 and 1985, one

line is used in fi ure 44 to re resent both 1972 and 1985

circulation of any zone in Tampa Bay.

Zone 7, the lower half of Old Tampa Bay, is a transihowever zone 6 has and will continue to have the poorest

an anot er s Increase y .

cumulative circulation increase of 275 percent, the largest

urred

creased circulation by about 30 percent. Long-term resu ts

of increased circulation in this area could be (1) more

rapid flushing of waterborne constituents that have their

r -

in zone 3 by Goetz and Goodwin (1980, p. 23).

Physical changes in zone 3 between 1880 and 1972 re- o " •

between 1972 and 1985. Cumulative physical changes in

zone 3 have reduced its natural constrictive effect and insion into the bay of constituents that have their source

south of zone 3.

Zone 4 is a 4-mi-Iong region 0 greater average clrcu aIon an in a j

culation increase of about 700 ft 3Is, or about 15 percent.

In 1880, circulation in zone 8 was about 1,400 ft 3/s.

volume, was tidally interchanged each day. Physical

chan es between 1880 and 1972 caused an average circulation in 1880 was computed to be about 8,600 ft3 Is.

9 3 interchan ed

in zone 4 each day, or about 5 percent of the water

volume in the zone. Zone 4 functions for Hillsborough

and a d Tampa ays In t e same way t a zone uncions a e r

strict water and constituent interchange, as zone 3 does,

. This mixing contributes to rapid removal of constituents that have

their source in the north and to rapid intrusion of constituents that have their source in the south.

changes in zone 8 between 1880 and 1972 caused an

avera e circulation increase of about 1,100 WIs, or about

79 percent. The increase in circulation at mi 9.5 (fig. 44)

is due to effects of the Courtney Campbell Causeway (fig.

1). The circulation increase at mi 13 (fig. 44) is attributed

caused a reduction in average circulation of about 700

3 An d itional reduction of about 100

ftJ/s occurred between 1972 and 1985. The cumulative

circulation reduction of 9 percent in zone 4, accompanied

by a 30-percent cumulative circulation increase in zone

, arge y er se

1880 to 1985.

in circulation in zones 7 and 8 between 1972 and 1985

are com uted to be minor because no physical changes

are expected.

Constituent Transport

transport are developed in the model and presented in

Model Results and Analysis 63
this report in a manner analogous to that used for water same as those chosen for water transport (see fig. 27). A .. :~ •• ~~,.l ..l.~.. 1. ., . .. initial concentration distribntinn l'1m:plv

-_ ...-.... ' .......v. v • ll;C:l~U J ,Jw-n ceu were near- • . th"t I., "t ~,,~.... l\ t::. 1" /~ ~.. -. . - ... •... ~""'p"

measured for phosphorus in July 1975 (fig. 23). Constitu- Bay (site 1) for each level of development, varied from

ent transport and flushing results presented in this report about 1.0 Ibis in 1880 to 0.8 Ibis in 1985 in mid-Tampa

are appllCaOJe lor tms OIStrIOutIon only. Companson of Bay (site 9), varied from about 0.5 Ibis in 1880 to 0.7

results for 1880, 1972, and 1985 levels of development, Ibis in 1985 in Old Tampa Bay (site 23), and were nearly however, provides a means for assessing constituent- constant at 0.2 Ibis in Hillsborough Bay (site 18).

transnort chanl!:es due to nhvsical chanl!'e!: in Tamna 'R~v ,. , ;~

or direction at some sites for 1880, 1972, and 1985 levels

Flood anti Fhh - of development are evident. Sites 6, 7, 16, 19, 24, and

25, for example, show changes due to construction of

- - uuring r10m ow lor causeways, ISlanas, Channels, or submerged dIsposal - 1880, 1972, and 1985 levels of development are shown areas.

in fijl;ures 45 46 and 47 resnectivelv Thellp. man!: ~hm" r, ,.l••_:_ , c. - - -0 _...- many similarities, including low constituent transport 1880, 1972, and 1985 levels of development are shown

near the bay mouth, where concentrations are low, and in figures 48, 49, and 50, respectively. Ebb patterns,

HIgn constituent transport In the upper parts 01 the Day, although opposite in direction, are similar to the flo(])d . ,.~, . . ._---- in ngures 4)'-4/. High constituent ...... "'6'" lUI; , dUU un I;~- }.I"L'~' no> /Snown

tions of constituent-transport vectors at 25 selected sites transport occurs in the upper parts of the bay, and low

during floodtide are listed in table 15. The sites arp thp . n('('nr~ np~r th....... "'..th.

Table 15. Constituent transport and direction during typical floodtide at selected sites in Tampa Bay for 1880, 1972, and 1985

levels of development

Transport Direction Site no. (pounds per second) (degrees, clockwise from north) (see fig. 27) 10nr, ,~-~ .~ 'L OJVJ 100U .:J/L J'It!:.

1 --------------------------- 0.626 0.611 0.598 115 115 116

2 .406 ~S17 ~7" 1::0 ,en ..n ---- ---- -- - -------- 3 --------------------------- .152 .143 .143 65 64 64

4 --------------------------- .298 .346 .355 49 48 48

5 --------------------------- .576 .631 .692 51 48 48

6 --------------------------- .205 .161 .163 45 85 85

7 --------------------------- .688 .595 .377 44 41 42 0

---- --- ----- ---- - .:11 31 31 .JJ'" ..:"'.:> .:>-'0

9 07') n')o '111:.'1 "0 ~~ --- ---- ~v "'0 "'... 10 --------------------------- .688 .650 .679 29 30 31

39 38 38 .. - - -- -- - ---- ----- .,,,, ./S.:I4 ./SI/S

12 --------------------------- .708 .670 .648 16 14 14

13 -- - - ----- -- -- -- 1.10 1.17 1.24 IQ 17

14 '" --------------------------- .439 .395 .373 59 59 59 'J --------------------------- l.ol/S 1.47 1.36 62 55 55

16 -- -- - --- - ------ -- 1.08 1.71 1.63 .,.:1 '10 ,A

17 --------------------------- .842 .761 .542 6 31 355

18 --------------------------- .238 .161 .170 336 345 348 19 --------------------------- .582 .163 .320 348 346 30

20 1.81 21l 20Q ~"o '1,11:. --- - - ---- - --- '1 ell:. --

21 --------------------------- .723 .571 .562 347 337 337 ')') ,

316 316 -- -- --- - - --- --- •.• v !. 1'+ L I! .:IU

23 .:1QIl 1::111 1::7f\ "no "n~ "n, --- -- "UJ "uv 24 --------------------------- .139 .207 .203 251 280 280

25 --------------------------- .688 .368 .364 304 348 348

64 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
ical floodtide in Tam a Sa for 1880 level of development.

" TRANSPORT VECTOR WITHOUT NODE

EXPLANATION

LOCATION OF MODEL COMPUTATION

4

I

2

I

a

I

VECTOR MAGNITUDE DEFINED BY

LENGTH OF LINE

VECTOR DIRECTION DEFINED FROM NODE

LOCATION SYMBOL TO END OF LINE

• LOCATIONS OF TRANSPORT SITES LISTED

IN TABLE 151SEE FIG. 27 FOR SITE NUMBERSt

o 4 5 MILES

............ ", , --........................... . .. ............... - ,.,"' - - . .... ,,,,,"', .

· . · ..

·....

Model Results and Analysis 65
5 MILES

SYMBOLS ARE SHOWN FOR 25 PERCENT

4

I

2

I

o

I

VECTOR MAGNITUDE DEFINED BY

LENGTH OF LINE

VECTOR DIRECTION DEFINED FROM NODE

LOCATION SYMBOL TO END OF LINE

TRANSPORT VECTOR WITHOUT NODE

L

LOCATION OF MODEL COMPUTATION

SITE (NODEI

TRANSPORT VECTOR WITH NODE

LOCATION SYMBOL

... ...... o 4

...........

figure 46. Constituent-transport pattern during typical floodtide in Tampa Ba for 1972 level of develo ment.

66 Tidal·Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
.. A ~.

,.:~

\ ,

\

I-':~:X ."\h +' f.H 7,'./.:~"r::'" :.: :~~.. tXI"'LANAllUN l"""\l~ '".;' ~X' liZ Z~///,·· ...

~:~~ "'" I ,.,:r~ +: r~ ~7~~:':' • LOCATION OF MODEL COMPUTATION

I-t-;-~~Ml~-_.r---=.-..~----rl"l'lil"j.-;::;tI1ti~ltHrttm,,~,~ ':::u "'T<: IlIJnn<:1

110~: : : ~~: ., ~~ : ,.. "I: .: Z'l ,~, "':1 SYMB?~L;; A!,E ~~OWN FOR 25~PERCENT ~"''O ...---....... .. \...~~ ... ~&"-'-" .. ...-"--'--'11: .. ~c-=------------t-'1.,----0+. I ~p'H-'-'H:1,1,~ J,I',:jif"- ~' ,~~~~ ~,~ ,~~~~ ~~r

:::::: :: ~"':' .. :::: ~, A'; : i+ t~7;:'J/i! !:: : ... '- TRANSPORT VECTOR WITH NODE .. . .. .. .. .. ',................ '.. ., II ,1/ 'I ~lj~:lr. I I, • LOCATION SYMBOL • . • • • • • • • . • • '111 I"" ....... .•.•.•.• I • I 4 I IJ 11~1,6, I••

... .. '.)('11'" ///'////////Ilill "~~:~:Y' ~~... L.U ""UN ., r1VH'UL.

•.•.•.•.•.•.•

.. - ....•••••••

,•.•.

, • • •

•

"////,;"//JI//"

' .. .,W'''./.../~/~/~J~/ r III I I..

I

··-····'1 ; ie.,;;., . . . q. • LOCATIONS OF TRANSPORT SITES LISTED IN •.•.•.•.•.•.•.••• , .'o'/r/o'/rf/"/"/"""'."~.A J.. : : .•. :. .•••••• "_....//-;/'~' // // / /I I , , , I , , •• : . : :-........:~ .-Iii TABLE 15 (SEE FIG. 27 FOR SITE NUMBERS)

Fi~ure 47. Constituent-transport pattern during typical floodtide in Tampa Bay for 1985 level of development.

Model Results and Analysis 67
· '

·- . · . ,. .. ... ' . o 3 4

1.

VECTOR MAGNITUDE DEFINED BY

LENGTH OF LINE

VECTOR DIRECTION DEFINED FROM NODE

LOCATION SYMBOL TO END OF LINE

LOCATION SYMBOL

• LOCATIONS OF TRANSPORT SITES LISTED IN

TABLE 16 (SEE FIG 27 FOR SITE NUMBERSI

5 MILES

Figure 48. Constituent-transport pattern during typical ebbtide in Tampa Bay for 1880 level of development.

68 Tidal·Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
in Tam a Sa for 1972 level of develo ment.

-~--- --- /........~, .. 41-..4-- " •••.• '

....._--------", "'" .. ",., .... .~.............. ·, ...........-_..&-...- 'A ....... ;.o' ••

. :.:~: ~; ~:~:~:~ .. j;';Z=~:~:~:~:~:~:~;;:;:~ .• o.:·· ......... ---....:: ~/..,.,.-- -- --- ----- - .

• • .. .. I , • • • • • • • •

• i ••••••

........ , I' ••• •

· , . · . ·.. - .

Fi ure 49. Constituent-trans

o 4

EXPLANATION

OF MODEL COMPUTATION

SYMBOLS ARE SHOWN FOR 25 PERCENT

OF NODES TO AID VISUAL CLARITY

). TRANSPORT VECTOR WIThi NODE

LOCATION SYMBOL

VECTOR MAGNITUDE DEFINED BY

LENGTH OF LINE

o 2 4

I I I

POUNDS PER SECOND

VECTOR DIRECTION DEFINED FROM NODE

LOCATION SYMBOL TO END OF LINE

" TRANSPORT VECTOR WITHOUT NODE

• LOCATIONS OF TRANSPORT SITES LISTED IN

TABLE 1 SEE IG. 27 R SITE NUMBERS

5 MILES

Model Results and Analysis 69
SYMBOLS ARE SHOWN FOR 25 PERCENT

5 MILES

VECTOR MAGNITUDE DEFINED BY

LENGTH OF liNE

4

I

2

I

o

I

EXPLANATION

LOCATION OF MODEL COMPUTATION

SITE (NODEI

• LOCATIONS OF TRANSPORT SITES liSTED

IN TABLE 16 (SEE FIG 27 FOR SITE NUMBERS)

VECTOR DIRECTION DEFINED FROM NODE

LOCATION SYMBOL TO END OF liNE

" TRANSPORT VECTOR WITHOUT NODE

..... TRANSPORT VECTOR WITH NODE

LOCATION SYMBOL

o 4

................~/ ........-.-..- ..- -.~ . : : : : : : ~: - /-"--::-;:-:-:-:-: .. : : - : .

·' '

· . · .

· . ·. .... .... ....... ...

----......, .. .

--

~-----~~ _/.,,1// I ••

.- "./ .. ,. .

Figure 50. Constituent-transport pattern during typical ebbtide in Tampa Bay for 1985 level of development.

70 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
As with water transport, maximum constituent trans- tween 1972 and 1985 are shown in figure 52. Comparison

port dunng ebbtlde IS substantially greater than that dur- of fIgures 51 and 52 wIth hgures 33 and 34, respeCtIVelY, • • P 0 0 .. • . . - . HI!:> lUI; llUI; VI W,UI;I-II;VI;I II> snows IOClL sunuar r ~~H<1H!:>~ W<1C,,1

faster than the rate of water-level rise (fig. 22 and table and constituent transport during floodtide. This similarity

9). The malZnitudes and directions of constituent-trans- is exnected because constituent transnort is the product

port vectors at 25 selected sites during ebbtide are listed of concentration times water transport and because the

in table 16. Vector magnitudes through each 1,500-ft cell initial constituent concentrations used for each simulawere nearly constant at about 1.8 Ibis at the entrance to tion were the same. The following table summarizes the .. o 0 o '" . -' . - I <1UI}J<1 U<1,. \I>U.. IJ IVI I;C1~H I"VI;I VI .~ , '<1111;'" LOLal an:a auu r IVI uaUi)-

from about 1.5 Ibis in 1880 to 1.2 Ibis in 1985 in mid- port during floodtide between 1880 and 1972 and between

Tamna Bav (site 9) varied from 0.6 Ibis in 1880 to 0.9 1972 and 1985. The data confirm the lZeneral similarity

Ibis in 1985 in Old Tampa Bay (site 23), and remained to water transport during floodtide (see p. 49 ).

nearly constant at OAlb/s in Hillsborough Bay (site 18). Constituent transport, floodtide

I:I~ .... .... 1:.... Area of change, in square miles

For 1880, 1972, and 1985 change 1880 to 1972 1972 to 1985

'nf" tiII1'_ 0-10 260 397 - - . . 11-50 144 41 inlZ floodtide conditions for 1880 1972. and 1985 are ------

shown in figures 45, 46, and 47, respectively. Changes ' I-IOU _____ :>L, 0

in constituent transport for a typical floodtide between 101-200 ----- 7 1

>200 1 0 IOOV anu 1-' I '" are SnOwn in Iigure .} I, anu --- uc;:-

Table 16. Constituent transport and direction during typical ebbtide at selected sites in Tampa Bay for 1880, 1972, and 1985

IC"C'~ v.

Transport Direction C' " L

.. IfJUUIIU' fJC 'CLUIIUI ,

(see fig. 27) '00" ,n." 'o,,~ ,,,,,n 1Q7"J 19B5

1 --------------------------- 1.86 1.82 1.76 290 290 290 -.- ... L. --------------------------- • I L,O ./IL, • I"" -- 3 --------------------------- .152 .148 .150 250 250 250

4 --------------------------- .635 .728 .724 224 224 223

5 --------------------------- 1.12 1.26 1.32 231 230 231

6 --------------------------- .353 .397 .395 229 266 266

7 ---- -- --- - - - 1.29 1.19 .800 225 225 224 --- 8 .977 .948 .959 206 206 206 --------------------------- 9 --------------------------- 1.'3 1.'2 1.L.4 --zm> -zu7 ... 11

10 --------------------------- .997 1.01 1.04 214 217 216

11 1.31 1.22 1.19 216 215 215 --------------------------- 12 --------------------------- 1.05 .979 .955 203 204 204 ,~ ALe , "" .., , £. ..,n"T "'I\~ 1m - - ---- -- - .. 1.:1 - .796 .754 .721 246 247 247

15 1.92 2.55 2.42 234 227 226 --------------------------- ~~ o ~~ Eo'" ...", .., .., "AI; 10 -- ---- - ------ - 1 • .,7 '.7"- .HoJ

17 --------------------------- 1.16 1.29 .809 187 214 199

18 --------------------------- .414 .379 .401 166 167 170

19 --------------------------- .754 .291 .311 172 168 183 .- ,~, ,..,,, • "TO

L,U ---------------------- - 1. '0 ......" .... I 'J

21 --------------------------- .732 .509 .500 164 143 143

22 --------------------------- 1.05 1.45 1.42 137 143

-~ .~~ In" ~~ L,j --------------------------- .;:l"" .0" • 00' I ...... . 24 --------------------------- .130 .276 .271 89 134 135

25 -- ------- - -- .662 .428 .421 129 150 150

Model Results and Analysis 71
,I."'-....::.-:c".~ xx .... l~OL-'" l '11.... -.....

:::::::::::;aBta-Braaa -:v "'- .........••CD~....... a x

,:::::::: ::~::~.::\

......, ... .••..•I ••••"...::1&•... .....~~l- I , II " .. J •••••••••••••••• .•.••••••t:...•a • •• ••••••• ···lII!ft ViI

«

..::'\:i II. • " • II .. x • t IIM • )f II" ••

t l1li X ••

• :II I •

.. """-wi ••••••••••••• ••••••:) .." ~.. . / ,

1~

·;;;;_.~Dax •••••••. ,••xaaa~

xClDx. ..•••••....... x ••ao.···· .....•••• ,......:X!a.. 1~

•••

.x.e.·········· • • .. • • • • • • • • • ••.....••••••• • • • II II II II ••

a II .

)& ca••••X JI····························· t ..

.. .. .. .. ..

". -~XIx... ..:::.. :::: . .l .... . . .....". . ... \

................ ::: ::~::::[ti? . ....••..•..•• • .

••••• 111 •••• •• • .. . .• :::::~:WM • • •••• ".~••••III. .... ...•....•.. ••• •••••••••••

.... '1J .. ..... , ..;~

· .. .....··········l ....................... .. . . .. .. .. .. .. .

1\

}

~::: ::::.:. .., ~~-,\.' ···t··· :J...IolIIl~~~~ ...A·· :::.::

V "'... • •••••

~.- ~""""I' -. tilt· .......

: ~ .. .

·.·.

·

·

• -IX ..............."T ············ly·· ...................

. .. .. . . .. . . ..........

,y' 1--'l.1~ill~~:.i~~~ ••-.~tJ.f-__---~~rtl~I------.-.-~tU--.-----T\--------11 ...... ...... xx~ , J .:.: .~. :::.~ .. ... ,yIf . r ",. _ -- "'-11-II' ..

EXPLANATION

>200

0-10

51 100

11-50

101-200

PERCENTAGE CHANGE

\

x

•

o

•

5 MILES

SYMBOLS

4

. . . . . . .............

. :\. ............. ~~

::::::::~ I /:1 y

...... . .•.••• .•••••• x"",.,.....h.~ r.,.. " .. ::::;:..~~~

:::::~:::::::.V'"" ._7

:: ~::::~~~::::::: . I • ~~ •••••••a~I.iiJ .... ···.xx ."....

.. .' .:.: . ... .. . . . ..···OC .. ···•· ... .. :::.1: :::: •.. .;:::: ::. ::~~

• • • • ."';~~""" .. .. • • .. • • •••

.x;~~~~lIC ... ••

...... e ···IIt . ... ..,. ~'i:' :11 •••••• .... ··11 ~... .. .. ..... ..•....... ...

..

..

..

..

.....

• lII· •••

x ••

.... :c ••••••

..

..

Figure 51. Changes in constituent transport in Tampa Bay for typical floodtide between 1880 and 1972 levels of development.

72 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
.>J\~ ~'O~ \ ~, ~- '01':,0,- r'\~ I:' """' ~-

C~ ~'O' ) ..-,. 7.-.

;;; -q

~~ .' ~1.. _ ... :::: ....:·:d -0, r • •• • •• • _ex.

::: :;~:.

../ ~~ "},.

r::.. "f\ili" •

·,..

•••

....

...~~~~~R!: • .... ••

••

aw

:I'M'

• )1(_ J ". f •••••~,.~ -, ... ··:~l .. ... .. ~~ '\ "'~DD".;) • ••• • ....II' •

·.... . ...... • ••• II ..:r" .. • • ••• a:r ••• ..............

aQ...\~ • ..., .......... \ • .. f '11:; .::'11

'¥) II•• .. .. ~f) .. .. ... 'J

'Ott;S' a 1'"::) .... .. {/} 11't;'J

~,lJj j ..

'l~ ..

IhA\ ...

.....

... If{ l ...

..

..

.. I~~ ..

~. .....

.

...

f'"

.. ,r ~.~~~~ 11 , ...,. l(...., ........

..... , J ...... rv ............ EXPLANATION ...... ( )'~4T .....

..

.

0\ ..

~I ·IVJDVL.~ ~, ..... ~, ..... u~

~.~ .. ...

.. ) . 0-10 ...

... , .... " .."" ... ...

t\~ ...

... c~ X 51-100 . r-. \ , ... ... - \ . .. -~ U lUl--,WU

~..•••••••••

•• 1 •••••

t ••

. -~:;q

.. ........

.......... ~J ........ t:I:? r;:t, . . .... .... . .. 11°:,0'--- . .. ...... ~I /--1 ., ...

I.' • ,

C'--..

..

. ~--~

,~~0 1 2 3 4 5 MILES (>,)0:,0'

__1

1°:,0' \ '\~ -V \

Figure 52. Changes in constituent transport in Tampa Bay for typical floodtide between 1972 and 1985 levels of development.

Model Results and Analysis 73
Transport patterns of a representative constituent dur- Progressive constituent-transport reductions throughin fi ures 48, 49 and 50, res eetivel . Fi ure 53 shows

changes in constituent transport between 1880 and 1972,

and figure 54 shows changes between 1972 and 1985. As

reductions in water trans ort fi. 37 . Constituenttransport values and percentage changes among levels of

development are given in table 17 for the seaward end

WI 00 1 e con Ions, e e con 1 Ions pro uce

patterns of constituent-transport change that are similar

to patterns of water-transport change (see figs. 35 and

36 . The followin table summarizes the total area and

o eac ay su area. ompanson 0 percentage-c ange

figures between water and constituent transport, tables

12 and 17, respectively, shows a substantial difference

onl at the seaward end of H' r h

percentage changes for constituent transport during ebbtide. The values are generally comparable to those for

1880 and 1972. This difference indicates that constituent

concentrations in Hillsborough Bay during the simulaIon peno 0 ours were re uc more or an

transport patterns for 1880, 1972, and 1985 levels of

were not sufficiently long, however, to determine

e uilibrium concentrations for each level of develo ment. Percentage

0-10 ------ 276 399

51-100 ----- 53 7

101-200 ----- 6 1

>200 ------ 0 0

Figure 55 shows flood and ebb constituent transport

for each cross section along longitudinal summary lines

(see fig. 26) for 1880, 1972, and 1985 levels of developseries of circulatory features or gyres found for residual

water transport (see figs. 38-40). Vector magnitudes

defining constituent-transport gyre intensity are different

1 • g W spo gyre in ensi y ecause

low at the Gulf of Mexico but increases to a maximum of the influence of the concentration distribution. The

Residual constituent-transport vector magnitudes and

directions are given in table 18 for 25 selected sites (see

. i w c

per parts of Tam a Ba in areas of hi h concentrations.

is divided between zones 5 and 7. Constituent transport

decreases to zero at the head of zones 6 and 8. Typical

at the upper end of zone 4, where subsequent transport

(site 9), to range from 0.03 Ibis in 1880 to 0.07 Ibis in

1985 in Old Tampa Bay (site 23), and to range from 0.06

. s oroug ay si e

puted to be about 0.17 Ibis at the entrance to Tampa Bay

(site 1) for all three levels of development, to range from

0.04 Ibis in 1880 to 0.03 Ibis in 1985 in mid-Tam a Ba

distribution that is very similar to but of lesser magnitude

than that for ebb conditions. Maximum values reach

about 24 Ibis for 1880 and 22 Ibis for 1985. The change

in transport at mi 37 in figure 55 for 1972 and 1985 conditions corresponds to the location where tide-induced

Table 17. Flood and ebb constituent trans for 1880, 1972, and 1985 levels of develo ment

Percentage change

1880 1972 1985 to to to

1972 1985 1

During typical floodtide, computed at the seaward end

Lower Tampa Bay _____________ 5.22 4.93 4.89 - 5.6 -0.8 - 6.3

Middle Tampa Bay ____________ 13.7 13.1 13.0 - 4.4 - .8 - 5.1

Old Tampa Bay _______________ 13.9 13.3 13.2 - 4.3 - .8 - 5.0

Hillsborough Bay ______________ 9.46 8.29 7.71 -12.4 -7.0 -18.5

During typical ebbtide, computed at the seaward end

------------- Middle Tam a Ba 21.5 20.9 20.5 - 2.8 -1.9 - 4.7 ----------- Old Tampa Bay _______________ 15.6 14.8 14.6 - 5.1 -1.4 - 6.4

Hillsborough Tampa Bay _______ 14.5 13.1 12.3 - 9.7 -6.1 -15.2

74 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
-I...I~·: :::::'::::::::~t(.:' ,'::::::::::::::::>' ••........ .........••••• ...... .. .. , .. , .. .. , N.

... .. .. .. .. .. .. .. .. , .,. .. .. .. .. .. . , , .......... , ,

J ..•.' ,I " ••• t,' :~ ~. ,~ "." """ " .. ,, .. ,...,

'- " " -... "

_...-.... r.' ...••.. 7..'.r-- __~_: . ~L..\. ... •.. '" .:::::~w:ft .. : :.~:: .. " " .....:11;••••• ~~~JII .. :::::::: •.•• :::::::::::~

\ ..'

'Oz.-

\

... "'-!: ..

_....-::~::::::: :" .. .,.... . .. .. .. .. .. .. , .. .. ., ..

G:. .. :::

1

~.

.. , . ...................~~

.. . .. ..

.~~~~;t

·.::r .. :..... ::~~ . :.. "::::::: .. . .. .. ....... "::'::

--

.. r·~........... ...--:.:!, ~§ .

..

."~ .::::: J'II ~~•••\:;:• ....... :::

I ••••••••••

., ~:~.CI. :::::

.. :::, iL..:~::::;~::. .:: :c.~~~·: :;;;::~::: •••••• •••• r...• ••••• , •••••

.. ::::: :4~:::::::::·

..

.

.::.../

::::: :::6: , ..... ......

......

...... ...... ...........;:\. ..............

••,~V'..

•

x

L.J

....

EXPLANATION

0-10

11 50

51-100

/LUU

:........ -.., ./J v •••••••• ~I F "

•••••

::::i!::::~·D 1..;It ........~.,~

:::: :~::::::~ . ..y......',.._.,.-

.. .... ~_ v-~~

- . """ - ""../'

\

.~, ....

...

...

2 3 4 5 MILES

\

FiR;ure 53. Changes in constituent transport in Tampa Bay for typical ebbtide between 1880 and 1972 levels of development.

Model Results and Analysis 75
PERCENTAGE CHANGE

EXPLANATION

0-10

• 11-50

X 51-100

0 101-200

• >200

7.1"30'

5 MILES

SYMBOLS

o 3 4

... .. ...... ........ .........

.... .... .. .. ... .. .. ... .. ..... .. ... .....

Igure 54. C anges in constituent transport in Tampa Bay for typical ebbtide between 1972 and 1985 levels of development.

76 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
3'tr--~---------------------' I

I~

Ii

z

I~

Z

o

IL

\ 1

I

I

I 2 7

II' -~ "I 0 14"'--'" ~,\. (J

10

F~-r--~~~I I 2 FLOOD "'~t

-

1880

1// // ~\~ v 0

I If~' :\: .--_IN_M_IL_ES -----,

/,~'I I /

I

I

I BOUNDARYA,1 I 1'/

I ~~(

I

I

I

I

I

I

I

~I // 1 I \"-__ \\\

II)

ffi 22 l:L.

28

II)

0 20 Z

::)

l:L.

II)

Z

14 a:

lI26

o

z

" ::)

lF .-

Ii': ,.. ..,:

:s 16

2V' 1 I 2 I 3 I 4! 5 i 6

I I I 1 ........ I

o 5 10 15 ZO ,;) ~a

DISTANCE FROM MODEL BOUNDARY IN GULF OF ME)(ICO. IN MILES

Figure 55. Constituent transport along longitudinal summary lines (see fig. 26) during typical floodtide and ebbtide in Tampa

Bay for 1880, 1972, and 1985 levels of development.

'lll .. . ~...- ........_ ...u ...vaa

firm the general similarity with areas of change computed

fnr rf"l:idual water transDort (D. 61 ).

-I'ClII".... ' L

For 1880, 1972, and 1985

~c ~"7 __... ~o _,-_.. nl'" • ,..",n_ • aeo_a ...u -,v, -' ,

stituent transport for 1880, 1972, and 1985 levels of

development, respectively. Areas of change in residual

constituent transport between 1880 and 1972 are shown

in figure 59, and changes between Pin and l~lS' are

shown in figure 60. As with previously discussed differ- ,. "71 __... "7 ... - \ • '.-

........... \}'... " .,nri •• • _ are similar.

Comparison of figures 59 and 60 with figures 42 and 43,

respectively, shows the similarity of patterns. The following table summan~s the total area ana percentage

Percentalle

change

0-10 _

11-50 __

51-100 _

101-200 _

>200 _

Residual constituent transport

Area of change, in square miles

1880 to 1972 1972 to 1985

98 241

166 144

IS'; ;'6.

72 24

45 6

Model Results and Analysis 77
1\ ,

1J

\

".'~ '1""#;~I"'to'_'#_"''''''''''I ... ;,:~:.... ~~~ .:~: ~~ :~:'d:~:~:~;~:~:~:,~~:~:·:· • LOCATION OF MODEL COMPUTATION •. . •• • - II> \:. I , •••••••• -r-.._._ •• • 11 SITE (NODEI · . . . . . '-.I: It'....... " • I , - -, " ,,,, ... I

1 ' ~: ~: ~'-~: ~: .--..•'-. 'j .: \ ~: .. :,:. ~:.r -.,. :~J ~BOLS ARE SHOWN FOR 25 PERCENT lb''''' :.~: .=-).".: : : ~: ~: : \ .. : ~: ~: ~~~:'" ~~:: :"'.A OF NODES TO AID VISUAL rI ARITY

.. I,!' .. . " • ......I.I., · •... - .•••••• , .,. , , .•••••• • ••• ' • • . . VECTOR DIRECTION DEFINED FROM NODE •.•.•.• , .,.,•• ........ I •.•.•.•.•''', • .o ...... _ • I •• , ," " .... ••.

.·.·.·.I.I~f"·"IIIr..:.· · , "," •.•.•.• [,',~""" ", '"''•.•' ••_ , • , .• , , , • • •• . .. .

:.' LOCATION SYMBOL TO END OF LINE

: : : : ' .. • .. : :\.1 : .. "'1' , - '- v ".'- 'vc .v ''OVUI:

• LOCATIONS OF TRANSPORT SITES LISTED IN

TABLE 18 ISH FIG 27 FOR SITE NUMBERS)

...·m1';:-~/.'· , ~:~

;.., ~-,. .~ I.· ~;:~:~:~:~:~:~:~:<~:.~::. I................... 'r' ..~7 :~:\ .. d

":, '.,~;::.::;:~: ~: ..,i~~;:~:~:~:;:~:~:~:;:~:;:· ,~:~:. .';.:: ....... :~ ., l\'---...... ~· •• ~",..................... ..~... :r'r-r-

........... ........... :_:, .. ...... .....

:.:.:~. ...... ~:.:~.j~ . .. .. . . : : : : : : : : : : : : : : . ~.:, : : .. ...... .... .. .- -. ..... .. .. .. . . '" .. " 01I 23,4I MILES .-.. •.•.•. •.•.•.•.•.•. •.•. •.•.• - I I I

rlgure "b. Kesldual constituent-transport pattern in Tampa Bay for 1880 level of development.

78 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
o 4

LOCATION OF MODEL COMPUTATION

SITE (NODE)

SYMBOLS ARE SHOWN FOR 25 PERCENT

N DES TO AID VISUAL CLARITY

VECTOR MAGNITUDE DEFINED BY

LENGTH OF LINE

o 0.2 0.4 I I I

POUNDS PER SECOND

VECTOR DIRECTION DEFINED FROM NODE

LOCATION SYMBOL TO END OF LINE

TRANSPORT VECTOR

LOCATION SYMBOL

LOCATIONS OF TRANSPORT SITES LISTED

IN TABLE 18 (SEE FIG. 27 FOR SITE NUMBERS)

5 MILES

Figure 57. Residual constituent-transport pattern in Tampa Bay for 1972 level of development.

Model Results and Analysis 79
I I I

POUNDS PER SECOND

VECTOR DIRECTION DEFINED

FROM NODE LOCATION

VECTOR MAGNITUDE DEFINED

BY LENGTH OF LINE

25 PERCENT OF NODES TO

AID VISUAL CLARITY

T R WITH

NODE LOCATION SYMBOL

(SEE FIG. 27 FOR SITE

NUMBERSI

EXPLANATION

• LOCATION OF MODEL

COMPUTATION SITE (NODEI

• LOCATIONS OF TRANSPORT

SITES LISTED IN TABLE 18

" TRANSPORT VECTOR WITHOUT

NODE LOCATION SYMBOL

o 4 5 MILES

In Tampa Bay for 1985 level of development.

.-... " : : : : : : : : : : : '21°30' _ .. , • I .

,"',' .

. .

· " . • .•.•.•.••• I .••••..•• "1

• •••••••••• I .••.•.•.• , II

. . ' . • • I I I • I • ...... , I , , •••••••••••••••••••••••••

~:~:~,.".:.,.,.,.,.,.,w".,•.• ,.,.,.,.,.,.,.,

. ..,. ............ .. ......... ", ......... "11'

............

•••••••• II"

· ,

............, ~:~: . ••• , ••••••• f' to •••••••• fl •••••• , .

~: ~: ~: ~: ~: ~: ~: : ~: ~: • ....... •••• ' ••••••• :'0:, ,-_....... · , .

· . ·.. ..

80 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
.. , .. .. .. .. .. ..

Fi ure 59. Chan es in

.. . .. , . ...

>200

51-100

11-50

101-200

PERCENTAGE CHANGE

x

•

5 MILES

SYMBOLS

a 2 3 4

Tam a Bay between 1880 and 1972 levels of development.

..... '" '" ......

, .. ....

lot f"

.,

...

·.·.

·.

.. .. .. .. .. .. ......................

.. .. .. .. .. ... .. .. .. .. .. ... .. .. .. .. .. .. .. .. .. .... .. .. .. .. .... .. .. ... .. .. .. ..... .. .. .. .. .... ..

..

..

Model Results and Analysis 81
0-10

>200

11-50

51-100

PERCENTAGE CHANGE

EXPLANATION

•

5 MILES

SYMBOLS

o 4

It •••••••••

. .

....ca•• xx' I .

.... • , .xwCOx . ..... ... . .

• •If. • • • • • • • • • • • • • • • • •• . . ••••••••••••• • It

.. ••• xx·· ••DDDO.····.··· ••••• X••WDOD.····· D.·······c•• ······ .x.···· -ac . . "ax' ..•••.•...

..... • wOx •••

. ga""" . .... . . II ••••• • ••0 ••••• ••••••••••0 •• x •••••••• • ~DD ••••••• xa Dx .

. .,, ..... • • • • • X Ie" •••

........ . •• •• -ax .. ' . •••• Xlii' ••

.... " ... tt ••••••

•••••••• f

.........

.. ... .....

• • • • • • • • .. • • II ••

.... It ••••••••••

.... . • t •••••••••••

... f •••

.... • t •

•• ft.

•• f" ... ....

........ t.' II ••••

Figure 60. Changes in residual constituent transport in Tampa Bay between 1972 and 1985 levels of development.

82 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
Table 18. Residual constituent transport and direction at selected sites in Tampa Bay for 1880, 1972, and 1985 levels of development

Site no. "" "I-'V' ,

(pounds per second) (degrees, clockwise from north)

(see fig. 27) 1880 1972 1985 1880 1972 1985

1 --------------------------- 0.177 0.168 0.167 288 287 285

2 --------------------------- .032 .031 .028 119 118 130

3 --------------------------- .025 .024 .023 60 60 60

.. - -- ------- - ----------- .vn' .VH\ .Vll ~V 1" 1"0

5 --------------------------- .015 .023 .040 334 309 290

6 --------------------------- .006 .034 .032 291 265 264

I --------------------------- .Vj.. .Vj~ .V~I ~~o ~::JI ~~

8 --------------------------- .056 .054 .050 179 177 177

9 --------------------------- .038 .040 .029 n 63 220

10 --------------------------- .022 .043 .038 310 286 289

11 n..,L n..,o n..,c ..,nc "'1.., 'In - ------ - - - - ---- 12 .040 .037 .033 192 228 219

13 --------------------------- .057 .071 .on 344 357 9

14 --------------------------- .on .on .068 261 259 257 IC I ... '''\c I.,n ,c., ,.... 1..,';; . -- ------ ---- - --- ---

16 --------------------------- .032 .380 .774 83 59 59

17 --------------------------- .020 .043 .145 3 229 280 In ,,,. A~n A .... .nn ,...., , ...L .u - ---- - • vV' .V..u

'. .uu 'oJ

19 --------------------------- .025 .032 .088 284 149 74

20 --------------------------- .070 .111 .108 58 194 195

~-- -- -- ~,

~1 .V· .VIO .V ;)~ ~v ..v

22 --------------------------- .093 .203 .201 290 282 283

23 --------------------------- .028 .071 .070 179 78 78

24 --------------------------- .019 .066 .064 210 189 189

25 --------------------------- .043 .on .071 278 86 86

Tide-induced flushing, for purposes of this report, can 1972, and 1985 are given in table 19 (see fig. 26 for locah", .,.. ,,~ tnt,,! . (~"'''' T ••• .:~~ ~f' ~~~O,.\

Summarv section n. 37) minus the constituent trans- Averal!:e tide-induced flushinQ: chanQ:es in zones 1 2

port caused by tributary streamflow. Figure 61 shows and 3 are generally consistent with tide-induced circulaboth computed tide-induced and streamflow flushing for tion changes shown in table 14. An overall tide-induced

HSISU, 1'111., ana I'JIS' levelS 01 aevelopment. KeSUltS are Ilusning or less man 1 .Ul ZUlU;

not given for Old Tampa Bay because tide-induced 1; an increase of about 41 percent occurred in zone 2,

·ic: ,.,. •. 7prn r1I1P tn t'nn_ ~mrl !'In . nf !'I hnl1t 1Ii. in 70ne

stituent distribution (see fig. 23). For the constituent used For the examole constituent distribution, a flushing

in this study, concentrations are highest near the head minimum occurred in zone 2 in the lower part of Tampa

of Hillsborough Bay (see fig. 23) and decrease toward Bay (fig. 61 and table 19), whereas a circulation minimum

me \JUn Or NleXlCO. ;,ucn a aismoudon proauces larger . .

1Il zum: j \llg. '+'+ ana laOle l'+}.

flushing by streamflow in Hillsborough Bay than in lower A computed 14-percent increase (table 19) in tideTampa Bay (fig. 61). induced flushing between 1880 and 1972 in zone 4 is difFor the examole constituent tide-induced flushing is ficult to understand because computed tide-induced cirgenerally low, between 2,000 and 6,000 Ibid in zones 1, culation decreased by about 8 percent in the zone during

2, and 3 for all three levels of development (table 19). the same period (table 14). The cause for this condition ,. . . . . LUUC 't i~ <111 i:11Ci:1 Ul Ui~l1liuc- , 1~ llU1\.CUlU 111 . 111 ,,"vu\,o ... ,

C .~A L .f' • 1_ .- .,...:A_ ~~A --~- .., 1001\ __ A 10.,,, T:rl.. ..- ~.~ ~.~~~ ... . . ,

induced flushing for 1972 and 1985 conditions is generally induced flushing is determined both by circulation and

greater than for 1880 conditions. Average flushing for the distribution of constituent carried by the circulating

each zone in the bay and percentage changes among 1880, water. Therefore, the amounts of constituent material

Model Results and Analysis 83
30 I I I I -... ..

- ., ..

-

1"-'

.-: > 25 ,'......J z~ 1/ .... I I ltR5U ,

If: ,

I=t -------- 1172

II) 20 ..................-.. 1986 /.:

z· I.: l 8~ - r-'Dr-III .fl.TlnAl f l POSITION OF ALAFIA

w;::) I I ZONE .f . 1\ HIVt:H MOUTH IN: I

it 2 16 BOUNDARY !' J I , \ :, I ~~ /\.,.,....1972 AND 1986

" I

~;:: l \ ":~ ; i h' V 1880

~!i .iI ~, , rjl.... /~ I I ••.•\

Cl 10 t'r '~V !\ \ .~

I'. \. , Ii 7;::) ... \. , .

~~ ~a .....;;;;;;.............~/ ~~ i I.. \ I \. UCIEO

,---:::w \, 1 ~.

~z " ' ...._... -"".... f:LUSh'a . I.. I

... .........~;~ .......... .. _Y-,:...R'{ S"t1'eJ''''''~ '"'-..... I I:' ..' '.~ \

-.:/'" '- --- - E"AGE "''''0\,1 ~.--- \ \ I--fLUSHING 8'{ A" '~ __I \

~.

0 ,- I I I i '\ I I I I , ..... i.

.. IU 10 I.U oLD "u "0

DISTANCE FROM MODEL I!IOUNDA"V IN GULF OF MEXICO, IN MilES

Figure 61. Tide-induced and streamflow flushing of example constituent along longitudinal summary line (see fig. 26) from lower

T;tmn;t R;tv tn . R;tv fnr 1AAI'l 1Q7? :lnrl 1QAt; f"""ic nf

flushed into zone 4 from zones 5 and 7 orobablv caused tween 1880 and 1985. Streamflow however remained the

significantly different constituent distributions in 1972 dominant flushing mechanism in zone 6.

ano HSlSU.rne computeol'lIl. CllstrlbutlOn was apparently This analysis shows that changes to Tampa Bay since

sufficient to more than offset the reduced 1972 circula- 1880 have generally increased tide-induced flushing of a +~_~ A A :~ 'oJ . ~, - . .. .- v ... u<,: V1U5 <': - curred in zone 4 between 1972 and 1985. tion similar to that shown in figure 23. Most increases

In zone 5, streamflow and tide-induced circulation pro- were caused by physical changes in the bay between 1880

duce about equal rates of flushing for the example con- and 1972. Assuming that streamflow and upland constistltuent. ComputatIons mdlcate that poweq,fant c06Iing- tuent inflow remain constant, this greater rate of flushing

water circulation and other physical changes will produce will cause lower concentration levels throughout the bay. _~ _ ..d¥_11 • . :~ . ., .1- .,.., ... ,. . . . . _.. v ...vv.. oJ ..."v ,... .......,,'" .. II:>'" lU , <':llUU

nercent bv 19~'i t.." ..l~ nf th"t h"".. '

In 1880, the primary flushing mechanism in zone 6 was

tributary streamflow. Powerplant cooling-water circula- (;.IIUU"RY

tlon at ID1 j() {see 1Ig. ()l), ShIp-channel constructlOn, and

shoreline filling expected through 1985 contribute to tide- Changes in two-dimensional tidal flow, circulation, and . . .... , . "f ....." ..... ,1. _~ .,CI\ 1._ • ._ .n_...I 1.. -I¥. ,-I. ....1 ":11 .. .. - ' J •• --0- ..-.. • .. £ "''''p''

Table 19. Tide-induced flushing and percentage changes in Tampa Bay for 1880, 1972, and 1985 levels of development

Circulation Average tide-induced flushing Percentage change

zone (see (pounds per day) 1880 1972 1880

fig. 26) 1880 1972 1985 to to to

1972 1985 1985

1 5,930 5,830 5,890 - 1.7 + 1.0 - 0.7 ---------------------------- 2 ---------------------------- 2,560 3,320 3,740 + 25.3 + 12.6 +41.1 1 n '" " ,on " .,.,n C C ,n , J " " - -- ------ ----- - ---- - , . J, .. .v.~

4 11'\100 HL'iI'\O 17.900 + 13.9 1 1'\ -I- Qll - --- - ----- - 5 ---------------------------- 7,070 9,830 9,650 + 39.0 - 1.8 + 36.5

6 ---------------------------- 1,150 3,950 4,100 +243 + 3.8 +257

84 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida
3. circulation computed for adjacent bayward and seaward

areas. Circulation in an area seaward of the entrances to

eac Ig an ow Clrcu a Ion zone.

Tide-induced circulation increased throughout most of

tion either at or seaward of their respective bay entrances.

Each also has a zone of low circulation at some distance

bayward oftheir entrances. A zone oftransition separates

decreased to zero at the heads of Hillsborough and Old

Tampa Bays.

tree-zone sequences ave a so been IdentIfIed and . .

Bay system. Tampa Bay, Hillsborough Bay, and Old

Computed circulation between middle and lower Tampa

Bays, an area of apparent circulation constriction, ranged

from 4,900 ft 3 /s (1880) to 6,300 ft 3 /s (1985), lower than

Eight zones have been identified on the basis of tideinduced circulation characteristics in Tampa Bay. Three

or tidal prism, caused b fillin of the ba . Hillsborou h

u e ana u

7 percent from 1972 to 1985. Hillsborough Bay also had

the largest percentage reduction in tidal prism.

Dredged and filled areas have changed the magnitude

Bay are determined in this study by using finite~ifference

P ysica changes to the bay;

2. conditions in 1972 after construction of numerous

causeways, islands, shoreline fills, and a series of

men were c osen or companson:

1. conditions in 1880 prior to any significant manmade

computer simulation techniques. Three levels of developand direction of tidal flood flows and ebbflows in large

parts of the bay. Areas near islands, causeways, chanBay has had the largest changes in tidal flows. Flow

reductions into and out of Hillsborough Bay were compercent over about 58 mP of the bay from 1880 to 1972.

Similar changes from 1972 to 1985 occurred over only

8 mP.

Residual water-transport maps for each level of development show a sequence of about 20 circulatory

curred in the upper part of Hillsborough Bay from 1880

to 1972. A 15-percent increase was computed for that area

for 1972 to 1985. In the zone of circulation constriction,

between middle and lower Tampa Bay, increases of 6 and

22 percent occurred from 1880 to 1972 and from 1972

have a large influence on the long-term interchange of

water and constituents between sections of Tampa Bay

and between the bay and the Gulf of Mexico. The overall

tion were caused by pumping for powerplant coolingwater systems. A reduction of about 4 percent in tideinduced circulation occurred near the mouth of Tampa

clrcu atlOn patterns m , an are VIsua y

similar, with some areas of obvious differences, mostly

ay rom 1 to 1972. A reduction of about 6 percent

occurred from 1972 to 1985.

was investigated in this study. The constituent distribution used in the model a roximated that of hos horus

measured in July 1975. Highest concentrations, 1.5-2.5

mg/L, were in Hillsborough Bay. Concentrations were

nearly constant at 0.8 mg/L in Old Tampa Bay and dereas 0 reSl ua water- ranspo c ange are severa

times larger than those computed for tidal flood- and ebbborough and Old Tampa Bays due to dredge and fill activity. Another area of large residual change from 1880

shape can be distorted by these physical changes.

be reduced or increased, gyre location can be shifted, new

gyres can be created, old gyres can be destroyed, and gyre

resi en i ,causeway, an s IP-C anne cons ruc IOn.

From 1972 to 1985, Hillsborough and lower Tampa Bays

to 1972 was lower Tampa Bay; the increase was due to

cent occurred in about 167 mP from 1880 to 1972. About

57 mP were changed by the same amount from 1972 to

1985. Between 1880 and 1972, large residual waterand island construction. tidal fills.

Summary 85
Residual constituent-transport maps show gyre features

,..

sImIlar to mose compurea ror reslaual water transport.

. Vl;l,;lUI i111; .... v ...v. IdI~l;a, ,

for those gyres in regions of high constituent concentration :md Iv smaller in rellions of low concentration. Areas of computed change in flood, ebb, and

residual constituent transport are in all respects very

similar to the corresponding changes computed for flood, . . . I;UU, CUIU ""4L\;1

In most areas of Tampa Bay, constituent flushing of

the examnle constituent induced bv the tide is ereater than

that induced by streamflow. In most of Hillsborough

Bay, particularly the upper part, flushing by streamflow

is larger than tide-induced flushing for all three levels of .. , • J.IU\;-

throughout most of the bay in response to physical

chanees that have been made since 1880. The 2reatest

tide-induced flushing increase, 243 percent, occurred in

Hillsborough Bay from 1880 to 1972. A 4-percent increase

occurred in Hillsborough Bay from 1972 to 1985. In a I." ....... , .1."

LV..... V' O' 0 ...V ...," ......V ..... L .......11.......... v,

lower Tampa Bay, tide-induced flushing increased 25 percent from 1880 to 1972 and 13 percent from 1972 to 1985.

Large local increases in flushing were caused by pumping for powerplant cooling-water systems.

As a result of increases in tide-induced circulation and ..1.

o

borne constituents that have landward sources to the Gulf

of Mexico. Conversely, the bay can also more rapidly

transfer constituents that have their source in the Gulf

into the upper parts of the bay.

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, ITI Ull

American Society of Civil Engineers Conference, San Francisco, Calif., September 3-5, 1975, Proceedings, p.

764-782.

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~11""!>, n.. .., ..l1U U"1 L11"I, J. ., 170"',

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-,

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.7 '"" ''''''I 'l.U"I11y Ul 1"1111-''' "'''y, CIVHU". ,,,,-

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e ,

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Proceedings, p. 220-239.

Prandle, David, and Crookshank, N. L., 1974, Numerical

specifically, the tidally averaged rate of inward-flowing

water defined at any cross section within a tidal water body,

expressed in volume per unit time. Due to continuity, this

is also e ual to the tidall aver ed rate of outward-flowin

body multiplied by the tidal range between high tide and

low tide.

erm wa er mo Ion a occurs ecause 0 e exis ence 0

alternating flood and ebb (inward and outward) movement

of the tide over an irre lar! sha ed bottom. More

Mean lower low water. A tidal datum computed as the average

of the lowest low water altitude of each tidal day observed

epoch.

a uantit of constituent material dissolved in water. expressed in weight per unit time.

Dissolved constituent. Any material that is in true solution as

Gyre. An area of rotational water flow that is characterized by

little or no motion near its center and generally circular

or eliptical motion elsewhere.

Tide-induced circulation. In general, the tidally averaged, longTidal prism. The volume of water that enters or leaves a tidal

water body between high slack water and low slack water.

water minus the average tributary streamflow.

Water transport. The rate and direction of movement of a

artsa a epor p.

adjacent waters, August 1961 through December 1962: U.S.

Fish and Wildlife Service, Bureau of Commercial Fisheries

Mexico: St. Petersburg, Fla., Florida Institute of

oss, B. ., 1 3, e ydrologyand ushing of the bays,

estuaries, and nearshore areas of the eastern Gulf of Mexico in A summar of knowled e of the eastern Gulf of

ceanography, p. IID-I-IID-45.

Ross, B. E., and Anderson, M. W., 1972 Courtney-Campbell

Department ofTransportation, Tampa Bay Regional Planning Council, St. Petersburg, Fla., 16 p.

Saloman, C. H., Finucane, J. H., and Kelly, J. A., Jr., 1964,

Glossary of selected Terms 87
Abbreviations and Conversion Factors

" , • ,0' n ". ' .n"

......'V.. <v' -g '~ u ..... u ..................pv .v , ..].......-v~~IQ

Multiply inch-pound unit By To obtain Sl unit

inch (in.) 25.4 millimeter (rom)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km) ",.. <or.......;1.. (..... '2\ ., "'Of) o".. <>r.. (1r..... 2'

cubic foot (ft3) 0.02832 cubic meter (m3)

cubic yard (yd3) 0.7646 cubic meter (m3)

1001 per secona tHIS) U.jU<+lS meter per secona tm/s) , L f.' fL' • £fV\ • _ L __ f1 ,/L'

...... t' w. ..~". v ..., ,., t' <OJ

pound per second (Ibis) 0.4536 kilogram per second (kg/s)

pound per day (Ibid) 0.4536 kilogram per day (kgld)

square loot per secona Vt'/S) U.lH.l~ square meter per secona tm'/s)

cubic foot per second (ft 3/s) 0.02832 cubic meter per second (m3/s)

foot ner sauare second (ftIS2) 0.3048 meter ner sauare second lm/s2)

pound per square foot (lb/ft2) 4.882 kilogram per square meter (kg/m2)

pound-square secona per toot" (lb-S"/tt") 515.2 kilogram per cubiC meter (kg/m')

micromho per centimeter at 25°C <ltmho/cm) 1.000 microseimens per centimeter at 25°C <ltS/cm)

National Geodetic Vertical Datum of 1929 (NGVD of 1929). -A geodetic datum derived from a general adjustment of the

first-order level nets of both the United States and' Canada, formerly called mean sea level.

88 Tidal-Flow, Circulation, and Flushing Changes in Tampa Bay, Florida '* us GOVERNMENT PRINTING OFPIC'K 1987 - 181-407 - 226}40110