Journal of Coastal Research Fort Lauderdale, Florid a
Historical Evolution and Morphological Analysis of "EI Puntal" Spit, Santander (Spain)
M.A. Losada, R. Medina, C. Vidal and A. Roldan
Departamento de Ciencias y Tecnicas del Agua y del Medio Ambiente Universidad d e Cantabria Santander 39005, Spain ABSTRACT _
LOSADA, M. A. , MEDIN A, R., VIDA L, C., and ROLDAN, A., 199 1. Hi storical Evolu tion and Mor pholo gical Analysis of"EI Puntal " Spit, Santander (Spa in). J ournal of Coastal R esearch, 7(3), ,tllllllll:.. 711- 722 . Fort Lauderdale (Florida) . ISSN 074 9-020S. •• • The hi st ori cal evolution of'EI Puntal' Spit in Sa nta nde r , Spain, is herein pr esented . Field mea sure me nts of tides, currents a nd bathymetric pr ofiles, ca rr ied out to design a new navigation t!I3Jl~ ~ ¥" cha nnel for the harbor of Santander, are used to expla in th e morphodynamics of the tidal chan nel and th e spit. Th e Empirical Orthogonal Functi on (EOF) method is applie d to analyze th e ¥ S-- long shore changes of th e spit ca us ed by storm and tid e activities . Results of th e EOF analysis show th at the spit ca n be divided into a tide dom inated sect ion and a sto rm dominated sect ion. The inte rti dal shoreface slope of th ese sect ions sho ws a distinct pattern of behavi or under storm condi tio ns: while the tidal sectio ns accreties , t he sto rm sec tio ns erode; durin g wa ve ca lm periods t he opposit e occurs . Dredgin g act iv ity in the na vi gation chan ne l (tide sect ion ) during the last fifty yea rs ha s led to an over all non-equilibrium of t he spit .
ADDITIONAL INDEX WORDS: Beaches, matrices, navigati on, tides, sedi ment tran sport.
HISTORICAL EVOLUTION OF 'EL bay, an offshore shoal emerged. This shoal was PUNTAL' SPIT called Las Quebrantas which means 'breaking zone .' Under wave action, sediment was trans The harbor of Santander is located on the ported from this shoal to the beach. Cantabrian Coast of Spain, Gulf of Biscay, The main consequence of the development of within the Bay of Santander, Figure 1. The nav the shoal was the separation of the spit dynamic igation channel which connects the open sea into two regions: Somo-Loredo Beach, which and the bay has a W-E orientation and is had a predominant east longshore transport bounded northward by the Magdalena Penin and the Puntal Beach which had a west long sula and Southward by El PuntaI Spit, a sandy shore transport. The sediment was carried to spit which protrudes well inside the bay. In this the bay and drifted into the channel where ebb section we review the morphological evolution tidal currents brought it back to the shoal. of the spit in the last two hundred years due to During the 19th and the first half of the 20th ocean dynamics, mainly wind waves and tidal Century, the city of Santander grew remarka currents, and to human action. bly, as did its harbor. The land needed for this Figure 2 shows the harbor entrance in 1730 . expansion was obtained from the bay by At that time, Santander was a small town reclaiming its western part (see Figure 3) which spread around the Cathedral. The bay r esulting in the subsequent decrease of the had a tidal prism approximately 60 % larger tidal prism. Figure 3 shows the entrance chan than the present value and the channel was nel in 1875 . Notice the difference in size of the slightly different from today. offshore shoal compared with Figure 2 and also The main channel features at that time were the curvature of the spit end. (1) a NE -SW orientation, (2) a great depth and The situation in 1960 is shown in Figure 4. (3) a steep slope at the spit side. Outside the At that time the Location Project was almost
90123 received 8 September 1990; accepted in revision 2 J anuary completed. Since then, intensive dredging 1991. activity, mainly in the offshore shoal Las Que- 712 Losada et al .
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SANTANDER ATLANTIC OCEAN BAY
1.
CIT Y
* TIDAL SURVEY o= iOOO M. 00 GEOPHYSI CAL stJRVEY kdr~J INTERTIDAL AREAS R. Figure 1. Study ar ea. brantas and in the spit end, has been carried the following points can be noted: (1) A loss of out in order to maintain a navigable channel sand of about 2 x 106 m" along the spit between (see Figure 2). its end and Las Quebrantas; (2) a retreat of the Comparing the figures from 1960 and 1875, low tide bathymetric of roughly 100 m; (3) an Journal of Coas ta l Research , Vol. 7, No.3, 1991 Evolution of El PuntaI Spit, Santander,Spain 713 ATLANTIC OCEAN l. V MOURO I . B. HARBOUR ENTRANCE IN 1730 Figure 2. Harbor entrance in 1730. ATLANTIC OCEAN SANTA MA RINA l. Q MOURO I. o ;:.. LOREDO BEACH 1000. M. I HARBOUR ENTRANCE IN 1875 Figure 3. Harbor entrance in 1875. increase in the steepness of the channel slopes; As can be observed, all the alterations (4) the increased depth of the channel, achiev described above continue to happen and some of ing in some points 15 meters under low tide them more noticeably. In particular, the Que level; (5) a slight variation in the channel ori brantas shoal has almost disappeared, the entation towards the east; and (6) the discharge Loredo region has retreated about 200 meters point of the Cubas River was moved to inside and some rocks in the submerged as well as in the Bay. the aerial beach profile are now visible. An Finally, Figure 5 shows the situation in 1985. evaluation of the sand lost in the system during Journal of Coastal Research, Vol. 7, No.3, 1991 714 Losad a et al. 1000M t= 1 .:;." . ,) : .:':.: HARBOUR ENTRACE IN 1960 Figure 4. Ha rbor ent ra nce in 1960. ATLANTIC OCE AN SANTAMARINA r I. 10 EL PUN TAL 50 MO r" 70 - - -BATH YM ETRIC SURVEY -- - - CURRENT S SURV EY HARBOU R ENTRANCE IN 1985 Figu re 5. Harbor entrance in 1985. Journal of Coas ta l Research, Vol. 7, No. 3, 1991 Evolution of El Puntal Spit, Santander, Spain 715 the last 25 years might be as large as 6 x 106 Field measurements of water level around m". the bay, currents, bathymetric beach profiles of Now, after more than 25 years of intensive the spit and geophysical profiles along the nav dredging and strong alterations of the equilib igation channel were recorded during one year. rium conditions of the spit-navigation channel Figures 1 and 5 show the areas of monitoring. system, the navigation conditions at the In order to avoid human influence upon the field entrance are far from satisfactory. Further data, dredging activity was suspended during more, present conditions are not compatible the period of measurement. with today's harbor traffic and its future devel Water level was recorded at three locations opment. Consequently, the Harbor Authority within the bay (Figure 1) using pressure decided to study the morphodynamic conditions gauges. Currents were recorded in four channel of the navigation system in order to seek a solu sections (Figure 5) ten times per tidal cycle . An tion which satisfies the navigation require ACDP (Acoustic Doppler Current Profiler) ments, minimizes the dredging costs and takes mounted on a boat was used. Bathymetric pro into account the role of EI Puntal Spit as a files were surveyed eleven times from December branch that is used as a recreation area. 1987 to January 1989, at the locations shown in Figure 5. The exposed beach was measured PHYSICAL ENVIRONMENT AND FIELD using standard surveying techniques and the MEASUREMENT offshore portion was measured using sounding and triangulation. The north coast of Spain consists of a series of pocket beaches and small inlets separated by pronounced rocky headlands. Santander Bay is TOPOGRAPHIC AND BATHYMETRIC one of the largest inlets on the Cantabrian VARIATION ANALYSIS Coast and is located about 200 km west of the French border. The bay provides a natural shel The data set for this study, therefore, consists ter from the waves of the Gulf of Biscay which of one year of monthly onshore-offshore profile arrive from NNW and have an annual average surveys. These profiles include not only beach significant height of 1 m with winter storm profiles (P5, P6, P7) but channel profiles as well waves of 4 m. Wave propagation to the average (PI, P2 , P3 , P4) . Alongshore spacing of the pro is modified by the Magdelena Peninsula which files was approximately 100 m for channel pro produces wave diffraction and reflexion. Most of files and 500 m for beach profiles. Each profile this wave energy is finally dissipated along the was surveyed from mean high water (MHW) on spit. Inside the bay waves are predominantly from the SW and, because of their local gener the intertidal beach seaward to a depth of ation, they are short and small waves. approximately 15 m. The landward part of each The mean tidal range in Santander Bay is 3 profile was surveyed to a depth of approxi meters; the spring tidal range is 5 meters and mately 1 m from a series of bench marks estab the tides are semidiurnal. The actual tidal lished in the dune areas. In this way, the sea prism is about 87 x 106 m" and the maximum ward part of the land profile overlapped with discharge around 5500 m3/sc . the shoreward part of the offshore profile. Four rivers discharge into the Bay: Cubas, Channel profiles crossed the entrance from side Boo, Tijero and Solfa, Their average discharge to side. does not reach 15 m3 /sc, although under flood These data were arranged in the form of a conditions the discharge may be as large as 400 matrix htx.y.t), where x = 46 (number of on m3/sc mainly from the Cubas River. offshore points), y = 9 (number of transects) The mean grain size is D = 0.3 mm , however and t = 11 (number of surveys). The transect a very significant longshore grain distribution spacing and location was designed to allow for exists, so that at the end of the spit the mean the space variability of waves and tidal cur grain size is D = 0.45 mm and at Loredo Beach rents. Transects PI-I, P2, P3 are in a current is D = 0.25 mm. The source of this sand is dominated area, transects P5, P6, P7 are in a mainly fluvial (60%) but the biological source wave-dominated area, whereas P4-1, P4 are in (35%) is also noticeable. a transition area. Journal of Coastal Research , Vol. 7, No.3, 1991 716 Losad a et al. Cross-Shore Variations area and their different time scales, give differ ent profile morphologies and time delays along Beach profiles P5 , P6 , P7 showed typical sea the spit. This can be easily observed applying sonal changes during the survey, (see Figure 6.) the EOF method to any longshore characteris These variations occurred mainly within the tic , for instance the intertidal slope or a long tidal range in transects P5 and P6 . Further shore profile. The longshore variation of the more, the development of one or more storm intertidal mean slope can be represented by bars (between 0, -5) can be observed. No signif X ty.t), where y = number of transects, t = icant variation below the - 10 m depth contour number of surveys and X(y,t) = horizontal dis was detected. Transect P7 showed a 'perched tance between high water level (+ 5.0) and low beach' profile which leant a ga in st the rocks water level ( + 0.0). The smaller the value of X, which have emerged in the last decade. These the steeper the slope is . rocks were located 800 m away from the shore The first eigenfunction, corresponding to the and in 6 to 10 m water depth. largest eigenvalue, represents a mean slope Channel profiles PI, P2 , P3 showed not onl y along the spit, Figure 8. This ei genfunction seasonal changes but an annual trend, see Fig accounts for about 99.9% of the variance, that ure 7. Transect P1-1 (see Figure 5) showed that is the mean square value of the data. Notice the the Spit lengthened Westward more than 30 m longshore variation of the mean intertidal in one year . Transect P4, located in the tran slope, that reaches 1140 in the wave dominated sition area, recovered its initial situation as a section and 1110 in the current dominated sec beach profile. tion. The second largest eigenfunction accounts for Eigenfunction Analysis the 0.07 % of the variance, or about 70% of the variance with the mean slope function removed. Previous studies of beach changes and other The second temporal eigenfunction, Figure 9, phenomena have been conducted using the identifies seasonal variations through the sur Empirical Orthogonal Function (E OF) method veyed data. The second spatial eigenfunction, (LORENTZ, 1959 WINANT et al ., 1975; DAVIS, Figure 10, identifies the location and the mag 1976; AUBREY , 1978; DICK and DALRYMPLE, nitude of these seasonal changes. Notice the dif 1984; ZARILLO and Lnr, 1988; MEDINA et al ., ferent sign of the spa ti al eigenfunction of the 1990). The method is an efficient way to profiles PI, P2, P3, P4 and the profiles P5, P6 , describe beach profile changes, both spatial and P7 stating that when the slope increases in the temporal. This method can be used to expand wave dominated area , it decreases in the cur the data in the form: rent dominated area. This result can be further explained if we look h(x,yo,t ) = htx.t) = I anen(x) cn(t) (l) for the evolution of the longshore profiles + 5.0, + 2.5 and + 0.0. The first eigenfunction, Figure 11, represents a mean situation of the profiles where htx.t) are the beach profile data, cn(t) rep during the survey. The longshore variation of resent the temporal eigenfunctions, en(x) rep the intertidal slope can be observed as pre resent the spatial eigenfunctions and an repre sented above. The second temporal eigenfunc sent the normalizing factors , see AUBREY tion, Figure 12, shows the same trend in all the (1978). profiles but a delay between each of them. The Obviously, the method can be applied not second spatial eigenfunction, Figure 13, shows only to cross-shore profiles h (x,yo,t) but to long that the different behavior between wave/cur hore profiles h(xo,y,t), to bathymetric maps rent sections occurs only in PI for profile + 5, h(x,y,to) and to any multi-dimensional set of PI, P2, P3 for profile + 2.5, and in PI, P2 , P3, data. P4 for profile + 0.0. Longshore variations Temporal Longshore Variation: The different dynamics that govern the wave (Figure 12) dominated area and the current-dominated The shape of the curves for the three contour Journal of Coastal Rese arch, Vol. 7, No. 3, 1991 Evolution of El Pu ntal Spit, Sa nt a nder, Spain 717 12 8 4 P- 5 - 18/ 12/ 87 ~ 0 ---- 05 /11 / 88 -, I - 4 -, ~ , Q. w 0 - 8 - 12 - 16 -20 0 500 1000 1500 OFFSHORE DI STA NCE (M) 12 ------ 8 4 P-6 - 18/1 2/ 87 ~ 0 --- - 05/ 11/ 0B I ~ - 4 Q. w 0 - 8 - 12 - 16 - 20 0 500 1000 1500 OFFS HO RE OISTAN CE (M) 12 8 4 P- 7 - 18/ 12/ 87 , - --- 05 /11 / 68 ~ 0 -, I ~ - 4 Q. w 0 -8 - 12 - 16 - 20 0 500 1000 '1500 OF FSHOR E DIS TA NCE (M) Figure 6. Cha nne l pr ofiles. lines is worthy of comm ent. The y are slightl y tour. Notice that the 0.0 contour r each es its phase la gged . This lag indica tes the r ecovery maximum deviation a bout 2 month s earlier time delay of the 0, + 2.5 and + 5 beach con- than the + 5.0 contour. It is al so worth noting J ournal of Coastal Research, Vol. 7, No. 3, 199 1 718 Losa da et al . 12 8 P- l 4h' - l B/ 12/ 87 ~ o t. ---- 05/11/8B :r: >- - 4 Q. w 0 - 8 - 12 I \;£ -1 5 - 20 0 150 300 450 500 750 900 1050 OFFSHORE DISTANCE (M) I:J 4 P-2 - 18/ 12/87 ~ 0 ---- 05 /11 /88 :r: >- - 4 Q. f~ w 0 -8 - 12 - 16 - 20 o 150 300 450 500 750 900 1050 OF FSHORE DISTANCE (M) 12 8 P- 3 :~, - 18 / 12/ 87 ~ - - -- 05/ 11/88 :r: >- -4 Q. w 0 - 8 I \ /' - 12 -16 - 20 . 0 150 300 450 600 750 900 1050 OFF SH ORE DISTANCE (M) Figure 7. Beach pr ofiles. J ournal of Coastal Research, Vol. 7, No. 3, 199 1 Evolution of El Puntal Spit, Santander, Spain 719 250 .,------ I 150 in .:!:. ~ 100 c ru -oJ Ul o 50 a -l------,----r--,----.---~-c-----.--j o P 1 P2 P3 P4 [J ~ i fl6 P7 P8 Pr of i l e Figure 8. First spa t ia l eige nfunc tion for lon gshore intertidal slope. 1.00 -,------, a 0 J F M A M JJ A S O N 0 J Tim e (Mont hs) Figure 9. Second t emporal eigenfunct ion for long sh or e intertidal slope. that the shape of curve is asymmetric, in the Figure 10, when the longshore evolution of the sense that it takes longer for the beach to beach slope is drawn. recover (about 8 months) than to erode (about 2 months). MORPHODYNAMICS OF THE SPIT: DISCUSSION Spatial Longshore Variation: (Figure 13) The morphology of the inlet shown in Figure The variation of the 2.5 and 5.0 contour lines is 2 are similar as those described by BRUUN much smaller in absolute value than the 0.0 (1978); a lateral sedimentary structure and a contour. Further, the opposed behavior of the large offshore shoal. Under wave action, sand wave dominated area (P6 and P5) and the cur moves from the shoal to the beach and from rent dominated area (PI to P4 ) is important. there drifts alongshore to the east and to the When P5 and P6 recover, PI, P2 , P3 and P4 west. Once sand reaches the spit end it falls retreat, and vice versa. As will be seen later, down into the channel. There the sand moves this morphological pattern reflects the overall upstream and downstream under current action sediment transport along the spit (beach and as a rolling carpet. Finally, most of the material channel). This behavior may also be observed in returns to the shoal where the cycle starts Journal of Coastal Res earch, Vol. 7, No. 3, 1991 720 Losada et al . 1 .00 1 ,,- OJ '0 I "- :0 ..., I "- ~ I a. E I < 0 .00 .,< '0 -, / OJ -, N / <, / ~ m E L 0 z -1.00 0 P 1 P2 P3 P4 P5 P6 P7 P8 Pr of i l e Figure 10. Second spatial eigenfunction for longshore intertidal slop e. 5 0 3 woo 1 2 5 ur o 0 U Z (f) 0 500 J '-1.; • C!: -;- <, t-r- ii) u, -, u,'" a 0 6 500 1000 1500 2000 2500 3000 3500 LD ~ GS ~D R E DIS TANCE 1M) P 1P2 :-: ~ p.: Ph P7 Figure 11. First spat ia l eigenfunction for longshore profiles. again. However the cycle is not a continuous dredging of the spit end became necessary. Fig se di me nt trans port process, because of the time ures 4 and 5 show the evolution of the spit lag between the sediment transport capability under this dredgin g. of waves and ti des. The main feature is the cancellation of the Figure 3 shows the entrance after one inten spit curvature which means that the longshore sive la nd recla ma tion project wh ich reduce d the sediment transport goes farther inside the bay. tidal prism by roughly 40 % (CENDRERO et ai ., The spit growth displaces the River Cubas dis 1981 ). Consequently the onshore and longshore charge poin t inwards. An increase ratio of 10 m/ current s in duced by the wave action predomi year is the average va lue estimated for the last nate over the tide current action, the shoal 80 years. Note that during these 80 years over advances to t he beach and the spit end turns 6 x 10 6 m" of sand was dredged. However, du r towards the insid e of the channel. ing the study no dredging was done and the spit Due to the incr easing size of ships in the last grew 30 meters in the year. few decad es, a situation was reached in which The present situation is as follows: Journal of Coas t al Research , Vol. 7, No.3, 1991 Evolution of El PuntaI Spit, Santander, Spain 721 1. 00 -+ 5 .0 - - + 2 .5 OJ -- - + 0 .0 "0 .....::J ~ a. E ... 0 .00 "0 OJ N ';;; E L z0 - 1 .0 0 0 0 J F M A M J J A S 0 Ti me (Mon t h s ) Figure 12. Second temporal eige nfu nction for longshore profiles. 150 00 -,------ - + 5 0 z -- + 2 .5 o - - _. + 0 .0 >- ~ ~ o .oo .- , ~ - - IT -cr ~ ,_ > ..------'---==- W .-r -- cr: - " " o , iJj - 50 00 u, u, o <, z o J - 150 00 I" "" " , I ' , ,, , , ,, , Ii' , , r e o , , I ,,, , i , , , , I ' , ,, o 50 0 1000 1500 2000 2500 L9NGSHORE flT;; TANCE (1-1) P1 P2 P3 PL1 P6 Figure 13. Second spatial eigenfunction for longshore profiles. (1) The beach pr ofile survey shows that rock ever , during a certain period of ti me, usually appears in profile P7. around 8 months, the deviati on of the spit from (2) Dunes have bee n cut by successive sto rms, its mean posit ion reduces the navigation chan thinni ng their aeria l structure . nellocally. To avoid these situations it was rec (3) The time lag between lon gshore transport ommended to t he Harbor Author ity that they and ebb current sa nd trans port provokes te m dredge small amounts of sand from the spit end poral sedimentation of sa nd in the navigation and discharge it close to the beach in the large cha nnel. area called Quebrantas, helping to spee d up the (4) The Ha rbor Authority needs to dr ed ge natural process of current action . around the spit end. Th e metho dology followed in t h is study ACKNOWLEDGEMENTS serves to discover the mean equilibrium condi tion of the entrance to Sa ntander Harbor and This study was fu nded by the M.O .P.U., its deviations. The mean spit shape is compat Junta del Puer t o de Santande r, and by t he ible with t he navigation requirements. How - CICYT under contract n° PB87-0800. Journal of Coastal Research, Vol. 7, No. 3, 1991 722 Losad a , Medi na and Rold an LITERATURE CITED nat ion al Confe re nce on Coastal En gin eer ing (Amer ican Society Civi l Engin eers), pp. 1650-1667 . AUBREY, D.G., 1978. S tatistical and Dynamical Pre LORENTZ, E .N ., 1959 . Empirical Orthogonal Func d ict ion of Changes in Natural Sand and Beach es . tion s and Statisti ca l Wea ther Pred ict ion. R eport No. San Diego : Uni ve rs ity of California . 1, St a t ist ical For eca stin g Project , Dep artmen t to BRUUN, P., 197 8. Stability of Tidal Inlet. Th eory a nd Meteor ology, Massachusett s In stitute of Tec h no1 Engin eering. Lasal ar: El sevi er, pp . 506 . (Devel op ogy , 49p . men t s in Geot echnical Engineering, 23 ). MEDINA, R.; LOSADA, M.A . a nd DALRYMP LE, R.A. , CENDRERO, A., DiAZ DE TERAN, J .R ., a nd SALINAS, 1990. An al iais de Perfiles de Playa por medi o de J .M., 1981. Env ironmental economic eva luat ion of Funciones Or to gonales Emp iric as , Metodo FOE. the filling and reclamati on process in the Ba y of R evi sta de Obra s Publicus, (in press). Santander (Spa in). Environmental Geology, 3, 325 WINANT, C.D.; INMAN, D.L ., a nd NORDSTROM ,C.E., 336. 197 5. Descr ipti on of seasonal bea ch changes using DAVIS, R.E ., 1976. Pre dictabili ty of sea surfa ce tem empirical eigenfu nc t ions . J ournal of Geophysical perature and sea level pr es sure a no ma lies over the Research , 80 (15 ), 1979-1 986. North Pacific Ocean. J ournal Ph ysics Ocean , 6, 249 ZARI LLO ,G.A. a nd LIU, J .T., 1988. Resolvin g bathy 266. metric com po ne n ts of the upper shorefa ce on a DICK, J .E. a n d DALRYMPLE, R.A ., 19 84 . Coa stal wave-dom in ated coast. Mar ine Geology, 82 , 169 changes a t Bethany Bea ch , Del aw are. 19th Inter- 186 . o RESUME 0 Presen t e l'evolu tion hi stor ique de la flech e EI PuntaI a Santa nder (Espagne). Pour l'el aboration d'un nouvea u che na l de naviga t ion au port de Sa nta nder, on a exec ute des mesures in sit u des marees, des courants et des pr ofils bath ymet riqu es. li s ont permis d'expliquer la morphody nami que du chena l de maree et de la fleche. Une fonction orthogo nale em pirique a se rvi a analyse r les modific ation s causees pa r les te mpetes et I'act ion de la maree Ie lon g de la fleche. Les resul tats de cette methode montren t qu e la fleche peut etre divisee en deux sec t ions, l'une domi nae pa r la maree, l'autre par les tempet es. Les petnes de l'estran oceanique de ces sect ions se comportent differern ment en conditions de temp ete : les sections dom inoes par la maree son t en acc retion , celles qui Ie son t par la ternpet e s'e rode nt, Au cou rs des periodes de ca lmes , c'est l'i nverse qui se pr odui t. Les dr agages du chena l de navigation (sect ion domine e par la m a ree) effec tues da ns lcs 5 de rn ieres a n nee s on t con d uit a u n deseq uil ib re g lobal de la flech e. Catherine Bousq uet -Bressolie r, Geomorphologie EPHE , Mont rouge , Fra nce. o ZUSA MMENFASSUNG 0 In di eser Ar beit wird die histori sche Entwickl u ng des Hakens "El Puntal " in Santander (Spa nie n) vorg es tellt. Feldmessu ngen der Gezeiten,Stro rnungen und Ti efenprofile, die wahrend der Anlage ei nes Zufah rt sk an al s fur den Hafen von Sa nta nder gewo nn en wu rd en , werden zu r Erklarung der Morph odyn amik des Gezeitenkanals und des Hak ens her an gezogen. Die Meth ode empirischer Orthogonal funktion en (EOF) wurde angewen det, urn di e Ver a nderungen des Ha kens durch Sturm und Gezeiten in sei ner Lan g sabtragung festzu stell en . Die Ergebnisse der EO F-Analyse zeigen, dalJ der Ha ken in cine geze itendomin iert e und eine st urmdom ini erte Abteilung getrenn t we rden kann.Der St ra nd im Gezeiten bere ich in diesen beide n An schn itten weis t gan z spezifische Verhalten unter Stu rmbedi ngu ngen a uf: wa hrend die Geze it ensekt ion Akku mu la tione n zeigt, wird die St u rmse k t ion erod ie rt . In Phasen m it ruhigem Wellen re gime tr itt gena u das Gegenteil auf. Baggera ktivitaten im Gezeite na bsc hnitt des Naviga tionska na ls ha ben dazu gefuhrt , da lJ in den let zt en 50 J ahren am gesamten Haken ke in e Glcic hgewic htsv erha ltnisse meh r auftreten.-Dieter Kell eta t, E ssen , F.R. G. o RESUMEN 0 En este trab ajo se presen t a la evo lucio n hi stori ca de la flecha de "E l Punt al, " en Santa nder (Es pa na) . Para explica r la morfodi namica del ca na l de marea y de la flech a se ha utilizad o las medi das de ca mpo de mareas, cor riente s y perfiles bat.im etricos real iza dos para el di sen o de un nu evo canal de navegacion para el Pu erto de Santander. Se ha a plicado el metodo de las Fun ciones Ortogon al es Empiri cas (EOF) para analizar los ca mbios lon gi tudinal es del Punta l debidos al efecto combi na do de los tempor ales J ournal of Coa stal Research , Vol. 7, No. 3, 199 1