HomeMy WebLinkAboutReport entitled Artificial and Natural Influences on the Bea INcr®��
CITY OF HUN'T'INGTON BEACH
COP " ENGINEERING DEPARTMENT
ington Beach, California
®u"Ty JAN 3 1966 Lecember 28, 1965
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Deire&R o APPRON ED BY CITY COUNCIL
-J.AN 17 196j&___I9
Honorable Mayor fcs
and City Council M,.._ CITY CLERK
City of Huntington Beach
Attention Mr Doyle Miller
City Administrator
Gentlemen
Transmitted herewith is a report titled "Artificial and Natural Influences
On The Beaches At Huntington Beach" prepared by J D Frantschy and D C Inman
It became apparent during our initial meeting, two months ago, with the
staff of the State Lands Commission and the Huntington Beach Company that it
had to be reestablished that man-made influences were a significant factor
in our ever changing beach front. Although, in my opinion, this was cited
many times in the Corps of Engineers erosion control report, the staff engineer
for the Lands Commission indicated that he found nothing to support my opinion
regarding changes being caused by man-made structures A careful review of
the Corps of Engineers report mentions accretion and/or erosion more than ten
times. Especially pertinent to our position is the comment of the State Lands
Commission, which says, "The subject report has been reviewed by the staff of
this Division, who concur with the findings of the United States Corps of
Engineers that remedial action must be taken to prevent further erosion of
the shoreline. Whenever the ocean shoreline is to be effected by construction
of breakwaters or by other artificial means, this Division will survey the
shoreline to establish the position of the last natural mean high tide line.
For this reason the State Lands Division appreciates the opportunity to
review such reports of proposed construction "
I felt that it was essential to seek expert advice in order to properly
represent the City position in this matter After consulting with Dr Inman
and evaluating the need for this report I requested its preparation '1
Having this report and the Corps of Engineers report at hand makes it
even more evident to me that man-made influences have effected our beach to
such an extent that the problem of who owns any portion of the sand deserves
the careful consideration of the City officials, if the best interests of the
public are to be served
17
Honorable Mayor
and City Council
December 28, 1965
Page 2
Your attention is directed to the recommendations on pages 9 and 10
Attached is a copy of the invoice and the letter of transmittal accompany-
ing the report As in similar cases payment should be from Account 4137,
Contractual Services
r truly yours,
S�
James R Wheeler
Director of Public Works
JRW am
Attach.
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ARTIFICIAL AND NATURAL INFLUENCES ON THE BEACHES AT HUNTINGTON BEACH
Huntington Bed< h in common with many other peach communities is
properly concerned abou+ tEe continuing existence of a useful and attractive
beach While This s a regional problem rather tnan a local problem and
the major solution must be a result of Federal or State action local
action is st it entirely appropriate and, in fact, necessary Municipali -
ties preferahly working cooperat vely, can demonstrate public need for
action and can demonstrate the packing of a significant segment of the
population in such work
To appreciate the regional nature of the proolem one must first
understand the physical nature of beaches and the factors constantly
acting to modify thern A oeac", is, in fact, a river of sand in almost
continuous flow along the shore the volume and race of flow being a
function of the sand source potential and the transport potent al An
the case of the California coast there is not a continuous single "river "
of sand moving from north to south but rather a se-les of rivers with
well defined geographical limits Each of these "r vers" of sand is said
to occupy a sedimen4d+ion compartment or cell Character stically, each
of the California coastal cells begins at the upcoast end with a stretch
of rocky coast where the sand is limited In a downcoast direction
determined by prevaiiing waves the beaches gradually become wider and
the coastline straightens where the streams supply a sufficient amounT
of sand At the downcoast end of the cell the peach sand is caprured in
the head of a sunriarine canyon from whence it flows to deeR water and is
permanently los+ tc iFe ijeach This sand piracy starves the shore) ne
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downcoast from +he su urine canyon head Thus a new cell begins with
a coast devoid of beaches There are four well -defined sedimentation
cells in southern Cal rornia The cell including Huntington Beach starts
in the vicinity of Palos Verdes Hills, south of Redondo Canyon, and
extends south and east ro Newport Submarine Canyon Factors or comb na-
tions of factors which create changes in other southern California cells
do not necessarily lave any effect on the cell in which Huntington Beach
is located, but any factor acting to modify significantly a beach w thin
the cell is apt to resulT in modification of all downcoast- reaches in the
cell in t e vicinity of Huntington Beach, only two soirces of sand need
be considered One is stream-introduced sand and 'tie other is artificial
beach building by dredging or pumping operat;ons Because of man' s
intervention wit-i natural processes the only sigrificarn` sand source for
maintaining oeaches of the area is now artificial
The transportation of beach materials is largely a result of wave
action The back-and-forth motion of waves in shallow water produces
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stresses on the bottom that place sand in motion The interaction of
the wave stresses with the bottom also induces a net boundary current
flowing in the direction of wave travel The most rapidly moving layer
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of water is near the bed and for waves traveling over a horizontal bed,
the interaction of wa\,e stresses and the boundary current produces a net
transport of sand in the direction of wave travel Thus the wave- nduced
transport of sand acts to contain sand along the shore
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The water transported onto the beach by breaking wa,,es produces a
r complex system of water currents nearshore This nearshore circulation
' of water consists of an onshore transport by the breaking waves, a lateral
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transport inside the oreaker zone by longshore currents and a seaward
return of the flow Through rre surf zone by rip currents
Since the waves supply yre energy to set the sand in motion, any
net current will produce a transport of sand in the direction of the cur-
rent In effect wave stresses "de-weight" the sediment load, placing
it in a condition where any current no matter how weak is competent
to move the load in the direction of the current Tnerefore, the trans-
port of sand should be proportional to the product of the amount of wave
energy dissipated and the veloct'y of the current In the case of long-
shore transport of sand in the surf zone, the break na wave supplies the
power for placing sand in motion, as well as the longshore current that
carries the sand toad The volume of longshore sediment transport along
oceanic coasts is otten estimated from ooserved rates of eros on or
accretion, most commonly in the vicinity of coastal engineeriig structures
such as groins and jetties A second method of transport estimation is
based on computaTion using the budget of wave energy in the area In the
vicinity of Huntington Beach the longshore transport rate s estimated
by the first method a+ about 300,000 cubic yards of sand per year moving
in a southerly direction The wave energy computation is in good agree-
ment predicting a flow of 282,500 cubic yards per year moving in the
same direction
Along the California coast the principal sources of beach and near-
shore sediments have been the rivers which brought large quantities of
sand directly to tie ocean Secondary sources are sea cliffs eroded by
waves and sea-floor material Generally, sea cl ffs (-ontribute only I to
30 per cent of the sand found on beaches in the Huntington Beach area
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the cliff contribution is near the lower portion of this range Although
sand is probably Transported onshore from the flat shelf offshore, it is
unlikely that this supply s of consequence when considered in terms of
the large longshore +ran port rate of 300,000 cubic yards per year
Occas onal heavy floods transport large volumes of sand For example
during the flood of 1938 the Los Angeles River is estimated to have
deposited about 6,600 000 cuuic yards of sediment in outer Los Angeles
Harbor
Littoral sand is transported along the coast until it reaches a
"sink" of some kind In the case of sand on the beach at Hunlington
Beach, the principal "sink" is Newport Submarine Canyon
From the foregoing, it will be seen that the dimensions and character
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of a beach reflect
I The kind and amount of sediment introduced
2 The action of waves and wave-induced currents
Both factors have been extensively modified by man during the past
century, and there is little reason to suspect that his actions will 5e
less important to the beach regime in the future
Prior to the activities of civilized man in the Los Angeles area,
the rivers descending from the northern and western mountains flowed in
channels which migrated over the flat terrain of the Los Angeles Basin
The channels retained little permanence of location except as controlled
by an enfilade of low hills along the coastline The low areas between
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these hills were referred to, in a clockwise sequence from Point Fermin
as the Wilmington Gap, the Alamitos Gap, the Sunset Gap the Bolsa Gap,
and the Santa Ana Gap In the historic past, the Los Angeles River has
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alternated its course from as far north as Ballona Gap in Santa Monica
Bay to the Wilmington Gab in San Pedro Bay The San Gabriel River has
alternated between the Wilmington and Alamitos Gaps while the Santa Ana
has alternated between +' e Sunset Bolsa, and Santa Ana Gaps
The mouths of these streams have now been artifir ally stabilized so
that they are no longer free to migrate In addition, large dams and
check dams have been constructed inland to control floods and stream run-
off The Hansen and SeUulveda dams have been constructed on the Los
Angeles River the Santa Fe and Whittier Narrows dams on the San Gabriel
River and the Prado dam on the Santa Ana River The dams and concrete
lined river cnannels liave effectively cut off all natural stream sand
supply to the beach area between Point Fermin and Newport
Wave action while not as totally artificially controlled as streams,
has also been significanTly modified in the last century The first
coastal construction competent to modify the shoreline in this respect
was the Wilmington Breakwater, begun in 1871 The breakwater caused a
reorientation of the shoreline that favored an increase in the downcoas+
transport of sediments by increasing the angle between the incidert waves
and the shoreline
Following the construction of the Wilmington Breakwater a series of
coastal structures have influenced the wave-current regime of the area,
and in turn the beaches The most important of these have been the
outer San Pedro Breakwater begun in 1889 and its extension to a porn+
11 ,000 feet south of Point Fermin by 1910, completion of the Los Angeles
County Flood Control Channel diverting and confining the Los Angeles and
Rio Hondo Rivers to their present direct connection into San Pedro Bay in
1922, completion of the original Long Beach Breakwater in 1927 construc-
tion of the middle breakwater of the outer harbor between 1932 and 1942,
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construction of The Anaheim Bay jetties in 1944, and extension of the
outer harbor breakwaters to a point opposite the Anaheim Bay jetties in
1948
The p-Psent width or the beacn at Huntington Beach can be attributed
in large measure -o artificial feeding upcoast W`)en the source of sand
for a littoral cell is depleted erosion of the beach usually begins
along the upcoast segmenTS of the cell and progresses downcoast Historic-
ally, the serious erosion pro5lems have been norttiwest of Huntington Beach
in the vicinity of Surfside and Sunset Beach These have been temporarily
remedied uy artificially placing sand on the beach and correcting the
deficit in sand before serious erosion has progressed as far downcoast
as Huntington Reach For example 202 000 cubic yards of sand was
deposited on the beach at Surfside in 1945 to act as a feeder beach to
protect Surfs, de and the downcoast areas from erosion Again, in 1947,
1 ,222,000 cubic yards was deposited at Surfside, and 874 000 cubic yards
was deposited t-)ere in 1956 Despite the deposition of 2 3 mill on cubic
yards in this area comparison of the 1939 and 1958 surveys of the Corps
of Engineers shows a net loss of 4 9 million cub c yards or a total loss
of 7 2 million cubic yards in 19 years
Again in the winter of 1963-64 portions of Anaheim Bay were dredged
and about 4 million cubic yards of sand was placed on the beach One
million cubic yards of this was to riepair beach erosion damage, and the
remainder was intended to nourish downcoast beaches from Bolsa Beach to
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Newport Beach Much of this volume of sand is on the norTh nalf of the
beach section which stretches from the south entrance jetty of Anaheim Bay
to Warner Avenue Under the wave exposure conditions now existing the
sand can be expected to temporarily widen Huntington Beacn and progress
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south This desirable movement could be hampered by creation of offshore
structures north of Hunrington Beach capable of producing a wave shadow
on the beach T-�erefore emplacement of such s+ructures should be
permitted only f satisfactory provision is made for pumping sand through
the shadow zone or around and other barriers created
It will be seen rrom the discussion above that at Hun--- ngton Beach
and elsewhere n the same sedimentation cell , beaches satisfactory for
recreational purposes and effective in preventing erosion of the upland
coastal areas can exist only by engineering intervention executed in
the interest of the public by public entities
CHARACTERISTICS OF A IINE DEFINED BY TIDAL DATUM
It is common practice to define the seaward limit of a parcel of
property in terms of the line of intersection of a horizontal datum plane
such as the mean high tide with the land This, under most circumstances
is a line which exists only at one point in time, and wnicii except under
unusual circumstances is never again reproduced in detail for reasons to
be considered in the ensuing discussion
Properly speaking a mean tidal datum is the mean tidal datum for a
specific location for a specific period of time during which water surface
level fluctuations have been observed relative to a reference point or
points ashore The period of observation resulting in determination of
the "mean" may or may not be sufficiently long to observe the effects of
annual tides (several centimeters) or of unusual periods of considerably
elevated or depressed regional water temperatures which can create
anomalous sea surface elevations or depressions Similarly, onshore or
offshore winds can elevate or depress normal sea surfaces, as do baromeir c
pressure fluctuations Even the shore reference system can be subject to
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uncertainty in that everywhere except at amphidromal points whose
existence is not ✓e Pxperiientally confirmed, the solid surface of the
earth rises and falls e✓eral inches or so in response to tidal forces
Diastrophic effects sucr as the recent Alaskan earthquake can elevate
depress or tilt major locks of the earth hundreds of square miles in
extent wiTh vertical movements of many feet
These are all real ractors which create change w th lime in the line
of sea surface inteisection witi the shore However, they are generally
less pertinent to considering definiTion of shorelines particularly on
a sandy coast than the changes brought about by changes in peach front
geometry in response to cnanging sand supply or wave exposure
In soutnern California it is common for beaches to build up to
higher elevation and to widen during the summer montns in response to
the action of low, long period swell from the southern hemisphere
During the winter months and exposure to short, steep waves of local and
northern storm generation, the beach sand is carried offshore often
reducing the beach width by hundreds of feet and the beach elevation by
eight or more feet Thus, with no change in sea level the line of the
mean high tide can migrate seasonally by hundreds of feet
Similar situations exist when by reason of floods or dredging
operations, the source of sand feed ng the beach is greatly augmented for
a time and the beach grows wider than usual Depletion of the sand source
by drought, the denudation of upcoast beaches, or sand interception up-
coast by coastal structures can result in the narrowing or loss of a beach
and a shoreward movement of the line of the mean high tide
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SELECTED REFERENCES
Inman, D L and J D Frautschy ( in press) "Littoral processes and the
development o` sforelines", Trans Amer Soc Civil Enqrs ( a
manuscript copy is enclosed)
Herron W J and R L Harris ( 1962) "New methods of conserving beach
sand" Shore and Beacn, vol 30, no I , pp 34-37
Shepard F P ( 1963) Submarine Geology, Harper and Row, 557 pp (see
especially Cnapters III , V, and VII )
Troxell , H C ( 1942), "Floods of March 1938 in southern California",
U S Geol Survey Water Supply Paper 844
U S Corps of Engineers ( 1962), "San Gabriel River to Newport Bay,
Orange Co , Calif Appen V, Phase II , Beach Erosion Control
Report" House Document No 602, 87th Congress 2nd Session, U S
Gov't PrinTing Office, 167 pp
RECOMMENDATIONS
I Create public recogn Lion of the beach as a community economic
and cultural asset in terms of recreation aesthetics and
erosion control
2 Provide for Faison and cooperation witn other coastal communi -
ties, particularly along the coast from Long Beach to Newport
Beach in matters concerning beach management for the purpose
of improving effectiveness in relations with State and Federal
agencies
3 Maintain close liaison with the Corps of Engineers requesting
competent evaluation of the probable effects on beaches of pro-
posed coastal engineering structures and installations, and
requesting compensating and corrective work as a part of any
project which would adversely affect beaches
4 Encourage cognizant State and Federal agencies to plan for a
continuing program of sand replenishment sufficient to provide
assurance of continuing beach maintenance
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5 Regula+e p- i ✓ate construction and property use near the beach
to the extent `)at such construction and use would be compatible
With tie publicl , maintained beach
6 Clarif / rr)a5ral property lines and where poss ble acquire in the
public domain 5each areas suitable for public use Useful
beacie- n the area can in the future exist only at public
expense and as a result of public action
Report Prepared By
J D Frautschy and D L Inman
20 December 1965
,4 `= I i en-own Road
, a Jolia California
l, )e( err er 1965
�1 James < ee I Fr
D i-e< tot of r'uu I i k s
C i ty of Taunt i nq I ca
hJr- -,S „ r3ea(- , a I 1 1 n a
Dear M- Plee e
In accordan,-e w t /ou- leiier of 2z Novemhe and conversai ons Nith
Mr Hi I I Hdr i ge and 'Ar "eo-ge Sri ale of -re ni 7 y of I unt i ngton Reach,
we submit t e encloses' el minary repo-T on "Arii - ic al aia na-1-ural
influences T,. e -eazl es a i '-iunt i ngT-n seas' "
It was oir uncersla J ng 1ra1 you wis ed us ru make a study aia
report summer zing -r"e natural I +1 *o-al processes ope-aT ve alora the
shore aT Hun+ na'c^ il-eac aoa TIe eftecj u, the numerous coasial engineer-
ing struc+dreg- )n e - Iati l ty of t1,e heac, and on tFP PCs T,on of the
mean or o-d ia y y" ride I ne It is nfenaed * a r e study De used
as �)ackgrcund maTer d , -r- _e considered n tre City 's tuture zoning
prob I erns
We hope t^aT 11iis report w II aid n clarify ng * e ra+"er compl [cdted
Iitrn al proses-e operative along your heacres A manusc, pt copy oT a
paper by Mr Frau-,,i y and me, treating some aspecTs of your pronlem in
greater detail , is al .,) enclosed
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Sincerely,
�Q)iuglas L Inman
Consul ant in Oceanograp ,
DLI If
Enclosures
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a
-604 Ellentown Road
t La Jolla, California
21 December 1965
Mr James R 4"ie,�I er
Director of Public works
City of HLntingloi Beach
Hunt i ngron Beac`i California
} Re Reporl "Artificial and natural inTluences on the beaches at Hun ington
Beach" as per your letter of 22 November 1965
Consultan+ (one and one-half days) $240 00
Typing and duplicalion 22 70
Total $262 70
h
Douglas L Inman
p Consultant in Oceanography
�r
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