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California Coastal Storm History Part One – Santa Cruz County
Darryl Hatheway, CFM, Sr. Coastal Scientist, BakerAECOM
Coastal Storm History in Santa Cruz County (1960 to 2009)

There are numerous reports of severe Pacific winter storms causing coastal storm damages throughout the 20th Century, including beach/bluff erosion, seawall damages, and flooding from wave overtopping.  These events are well-documented in reports by Ott Water Engineers (1984), National Research Council (1984), Gary Griggs (et al. 2005), and others.  This coastal storm history is often forgotten and provides a reminder that extreme coastal flood events have frequently occurred along the central California coast.  This article discusses storm damages during the 1982-83 and 1997-98 El Niño winters in Santa Cruz County, and provides a reminder of the high damage risk that the oceanfront built environment experiences in any given year.

Historically, coastal storms that occur during El Niño years are particularly severe as stillwater levels are typically elevated by 0.5 to 1.0 feet above normal tide levels throughout the winter and waves approach Santa Cruz County from more southerly directions (Storlazzi and Griggs 1998; Griggs et al. 2005).  The most severe storms typically occur when coastal water levels are elevated due to the coincidence of high tide and extreme waves, which impact areas not typically exposed to extreme conditions.  Damage was more severe during the 1982-1983 El Niño winter compared to the 1997-1998 El Niño winter, because there were more coincident high wave and high tide events and overall coastal exposure to storm waves was greater (Griggs and Brown 1998). 

In addition, coastal infrastructure  repaired following the 1982-83 El Niño winter was better engineered, more resilient, and offered better protection against subsequent  storm events  (like 1997-98 El Niño).  These two distinct and historic storm periods are discussed below regarding their impacts in Santa Cruz County.

1982 – 1983: El Niño Event

There were several large storm events that affected Santa Cruz County during the 1982-83 El Niño, inflicting approximately $8.2 million in damage (Griggs et al. 2005).  Early winter storms initiated erosion and left the beaches eroded and vulnerable to subsequent storms in January-February 1983.  Eight storms had offshore significant wave heights that exceeded 13 feet. Maximum offshore significant wave heights approached 23 feet and several times wind gusts exceeded 60 mph in Santa Cruz County (Ott Water Engineers 1984).
 
Storm waves eroded Highway 1 at Waddell Bluffs, just north of Waddell Creek in the northern county.  An additional 2,000 feet of rip-rap was placed to protect the road (Griggs et al. 2005).  Farther south in Santa Cruz, approximately $9 million of rip-rap was placed along two miles of West Cliff Drive to protect the bluffs from erosion (Griggs and Brown 1998).  The Santa Cruz Municipal Wharf was partially damaged and oceanfront restaurants in Capitola were inundated as well (Griggs and Brown 1998).  The pier, stairs, and bike trail at Capitola were damaged with an estimated replacement cost of $320,000 (NRC 1984).
 
Oceanfront properties and public facilities along Las Olas Drive, Seacliff State Beach, Beach Drive, and Via Gaviota were damaged by waves and erosion (see photo from Rio Del Mar Beach).  Several homes along Beach Drive collapsed onto the beach when the bulkhead failed and house pilings were undermined.  A new 3,500 feet long timber seawall, a restroom, and 11 recreational vehicle sites were destroyed at Seacliff State Beach and a protective revetment at Via Gaviota was overtopped and undermined.  All of the destroyed homes in these areas were rebuilt and protective revetments were constructed.  The revetments were embedded deeper to prevent scour and undermining, and built taller to prevent overtopping. 
 
At the southern end of the study area, the foredunes at Pajaro Dunes were eroded as much as 40 feet and oceanfront homes were threatened.  Roughly one mile of armoring was added after the winter season costing approximately $5 million (Griggs and Brown 1998).
 
1997 – 1998: El Niño Event
 
During the 1997-98 El Niño winter, another series of extreme wave events occurred in conjunction with elevated water levels, causing extensive coastal damages along the Santa Cruz County coast.  Structures and homes were damaged and in some cases, not previously impacted during the 1982-83 El Niño.  Coastal storms during this El Niño period caused wave overtopping of the rip-rap along the base of the West Cliff Drive bluffs in Santa Cruz.  The bluffs were eroded and the bike path, sidewalk, and parking areas partially collapsed and were closed.  Large waves destroyed a dozen pilings supporting the Santa Cruz Municipal Wharf.  South of the harbor, the beach eroded approximately 10-13 feet and exposed 6 feet of the former Santa Cruz streetcar trestle pilings.  Sand deposition in the entrance channel closed the Santa Cruz Small Craft Harbor in January and February 1983 (Griggs and Brown 1998).
 
Beaches were scoured along Cowell, Main, and Seabright beaches and large logs discharged from the San Lorenzo River were deposited along the beach.  Wave action created destructive debris impacts due to these logs being driven into the timber seawalls and oceanfront properties.  The loss of beach sand decreased protection and waves deposited sand along East Cliff Drive and forced road closures.  Private decks, porches, and a public stairway were damaged as rip-rap along East Cliff Drive settled and afforded less than adequate protection.  Bluffs between Capitola and New Brighton State Beach slumped in several areas.  Residents applied for permits to construct seawalls at the base of the bluffs immediately following the winter season (Griggs and Brown 1998).  Overall, the coastal damages were substantial but not nearly as destructive as the 1982-83 El Niño.
 
Too often, with the passage of time, we forget our vulnerability to coastal flood hazards and our past experiences with coastal storm damage, especially due to infrequently occurring El Niño winter storms. Reminding property owners of historical flooding will help them to refocus on mitigation efforts and promote the development of flood resilient communities.
 
References
Griggs, G. and K. Brown 1998. Erosion and shoreline damage along the central California coast: a comparison between the 1997-98 and 1982-83 winters. Shore and Beach, 66, 18-23.
 
Griggs, G., K. Patsch, and L. Savoy 2005. Living with the Changing California Coast. University of California Press, 540 pp.
 
NRC 1984. California Coastal Erosion and Storm Damage During the Winter of 1982 – 1983. National Academy Press, 74 pp.
 
Ott Water Engineers 1984. Northern California Coastal Flood Studies. 115 pp.
 
Storlazzi, C. and G. Griggs 1998. The 1997 – 1998 El Niño and erosion processes along the central coast of California. Shore and Beach, 67, 12 –17.

 


 
Santa Cruz pic 1.jpg
In this photo, Coastal erosion and storm damages to beachfront home and revetment from winter of 1982-1983 at Rio Del Mar Beach in Santa Cruz County (photo source: National Research Council, 1984 report no. CETS-CND-023)
 
 
The photo below shows tidal inundation and wave runup in Capitola January 2008 (photo source: Patrick Barnard, USGS Santa Cruz)
 
 

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