Monitoring harbor dredging and sedimentary changes in coastal habitats ofthe Santa Cruz Bight, California
A Thesis Presented to the Faculty of Cal State University Monterey Bay
Through
Moss Landing Marine Laboratories
In partial fulfillment of the requirements for the degree Master of Science in Marine Science
Prepared by:
Steven G. Watt December 2003 ©2003 Steven G. Watt ALL RIGHTS RESERVED Table of Contents
LIS(. 0 fF'Igures ...... 11.. List ofTables ...... iii
Abstract...... !
1. Introduction ...... 2 2. Sediment accumulation and transport in northern Monterey Bay ...... 5 3. Local geologic setting ...... 9 4. Methods ...... 14 4.1 Monitoring program ...... 14 4.2 San Lorenzo River ...... l5 4.3 Santa Cruz Harbor ...... 18 4.4 Oceanographic data ...... l8 4.5 Sediment sampling ...... 21 4.5.1 Beach sample collection ...... 21 4.5.2 Offihore sample collection ...... 24 4.5.3 Sediment sample processing and analysis ...... 25 4.6 Geophysical surveys ...... 27 5. Results ...... 31 5.1 Sediment input over the monitoring program ...... 31 5.2 San Lorenzo River ...... 31 5.3 Santa Cruz Harbor ...... 35 5.4 Oceanographic conditions and littoral drift ...... 35 5.5 Sediment sample analyses ...... 40 5.5.1 Beach sediment samples ...... 40 5.5.2 Offihore sediment samples ...... 47 5.6 Geophysical surveys ...... 58 6. Discussion ...... 69 7. Conclusions ...... 73
Acknowledgements ...... 75
Literature cited...... 75
Appendix A. Beach sediment sample database tables ...... 80
Appendix B. Offshore sediment sample database tables ...... 85
Appendix C. Greene eta!. (1999) Benthic habitat classification ...... 89
S.G. Watt, 2003 1 List of Figures
Figure 1. Study area location ...... 3 Figure 2. Littoral cell ...... 8 Figure 3. Wave direction ...... 1 0 Figure 4. Study area beaches ...... 12-13 Figure 5. Monitoring program flow chart ...... 15 Figure 6. Oceanographic buoy and river st_ations ...... 16 Figure 7. Wave model stations ...... 19 Figure 8. Sediment sample locations ...... 22 Figure 9. Geophysical survey area ...... 27 Figure 10. Sediment shifts example ...... 30 Figure 11. San Lorenzo stream flow ...... 33 Figure 12. San Lorenzo River, flood ...... 34 Figure 13. San Lorenzo River, low stream flow ...... 34 Figure 14. Buoy and array wave graphs ...... 36 Figure 15. Wave model and Santa Cruz array comparison...... 39 Figure 16. Harbor photo ...... 39 Figure 17. Lagoon flooded beaches ...... 42 Figure 18. Observations at Twin Lakes Beach ...... 43 Figure 19. Pre-Experiment beach sample mean grain sizes ...... 44 Figure 20. Experiment beach sample mean grain sizes ...... 45 Figure 21. Post-Experiment beach sample mean grain sizes ...... 46 Figure 22. Pre-Experiment offshore sample mean grain sizes ...... 50 Figure 23. Experiment offshore sample mean grain sizes ...... 51 Figure 24. Post-Experiment offshore sample mean grain sizes ...... 52 Figure 25. Pre-Experiment silt and clay percentages ...... 53 Figure 26. Experiment silt and clay percentages ...... 54 Figure 27. Post-Experiment silt and clay percentages ...... 55 Figure 28. Sediment parameter surface interpolations ...... 57 Figure 29. Pre-Experiment processed multibeam image ...... 59 Figure 30. Pre-Experiment processed backscatter image ...... 60 Figure 31. Examples of identified benthic habitat types ...... 61 Figure 32. Post-Experiment processed multibeam image ...... 63 Figure 33. Post-Experiment processed backscatter image ...... 64 Figure 34. Pleasure Point fault...... 66 Figure 35. Blacks Point outcrop and Pt. Santa Cruz channel...... 67 Figure 36. Santa Cruz Bight sedimentary environments ...... 71
Plate 1. Seafloor interpretation comparisons ...... back cover envelope
S.G. Watt, 2003 ii List of Tables
Table l. Sediment sources, sinks, and transport ...... 6 Table 2. Monitoring period timeline ...... 23 Table 3. Sediment inputs over the monitoring period ...... 32 Table 4. Littoral drift estimates ...... 37 Table 5. Beach sediment sample descriptive statistics ...... 41 Table 6. Offshore sediment sample descriptive statistics ...... 48-49 Table 7. Habitat descriptions and area analyses ...... Plate I Table 8. Sediment shift explanation ...... Plate 1 Table 9. Sediment erosion and deposition totals ...... Plate 1
S.G. Watt, 2003 iii Abstract
In March of2001 a unique case-study was conducted in Santa Cruz California that included an experimental harbor dredging event into the natural framework of a well-studied, dynamic, coastal environment. The Santa Cruz Small Craft Harbor was permitted to dredge a small amount of mixed sand and mud (silt and clay) sediment from the upper harbor into the surf-zone at Twin Lakes Beach. Tlus [me-grained dredging experiment is the first of its kind in California. A challenge to the Environmental Protection Agencies (EPA) "80/20 rule" which states that dredged (non-toxic) sediment released into the surf-zone should contain at least 80% sand. Before this experiment, it was considered too great a risk to release sediment containing more than 20% mud into the surf-zone because it might have damaging affects on the coastal environment. A monitoring program was designed and implemented to determine if sedimentary changes occurred on the beaches and in nearshore benthic habitats of the Santa Cruz Bight during the experimental dredging period. In addition to a comprehensive scientific literature review, a variety of data were collected to monitor the experimental dredging event and natural conditions in the Santa Cruz Bight. Time-series data were collected including San Lorenzo River stream flow, oceanographic swell information, and beach and offshore sediment samples. Sets of pre- and post-dredging geophysical imagery were collected and compared using a new GIS mapping technique that quantified areas of sediment erosion and deposition on the Santa Cruz Bight seafloor. The complete integration and analyses of all the data types collected during the monitoring period leads to the conclusion that the muddy upper harbor sediment released into the surf-zone during the experimental dredging event (including sediment derived from other nearby sources), did not significantly change, alter, or impact the beaches or nearshore marine benthic habitats in the study area. The monitoring program data provides new detailed small scale information about the sedimentary environments in the Santa Cruz Bight, creating a strong baseline for comparison to future dredging events and adding to the current base of coastal and shelf processes knowledge in northern Monterey Bay. The implementation of this new methodology has prompted local, state, and federal agencies to reevaluate the "80/20 rule" and consider harbor sediment as a possible source of sand for beach replenishment.
S.G. Watt, 2003 1 1. Introduction
Harbors act as gateways to marine and coastal environments in California, providing access to economic, recreational, and natural resources vital to coastal communities (Harville, !971; Heimlich-Baran, J.R. 1988; Leet eta!., 1992; Komar, 1998). While providing access to marine resources, harbors may also cause detrimental impacts to the environments in which they are built. Some harbor jetties have been shown to block the littoral flow of sand, causing beaches downcoast of harbors to erode over time (Griggs and Johnson, 1976; Komar, 1998). Another potential impact is surf-zone disposal of dredged sediment that has accumulated in harbor entrance channels, vessel slips, and waterways. The dredged sediment may contain contaminants or be composed of grain-sizes that are incompatible with local beaches and benthic habitats near the harbor community (Devinny and Volse, 1978; Oliver, 1980; Goldberg et a!, 2000). The Santa Cruz Small Craft Harbor, located in northern Monterey Bay within the Monterey Bay National Marine Sanctuary (MBNMS), is subject to sediment accumulation in two locations which require dredging, the harbor entrance channel and upper harbor slips and adjacent waterways (Figure I). While the entrance channel sediment is pennitted for surf-zone disposal because of the high percentage of sand within the sediment (>80%), high concentrations of silt and clay (or mud) in the upper harbor sediment are prevented from surf zone disposal according to Environmental Protection Agency (EPA) Region IX standards for grain-size disposal (Foss, 1999). This rule is referred to as the "80/20 rule", which states that dredged (non-toxic) sediment released into the surf-zone should contain at least 80% sand. The npper harbor sediment at the time of the study was composed of -40% sand and 60% silt and clay (Sullivan and Krcik, 1999). The concern is that the fine-grained material may be retained on the beach and in nearshore benthic habitats and change the existing natural environment and sediment transport properties. Questions raised by the Port District of Santa Cruz concerning the origin of the specific sediment percentages defmed in this rule, led to the discovery that there was no scientific basis for their implementation. This information, coupled with the need for sandy beaches (to attract tourists and for coastal protection benefits in Santa Cruz) has led to the experimental mixed sand and mud dredging event reported upon here.
S.G. Watt, 2003 2 a. Red box denotes location of the study area in northern Monterey Bay, California
- - ~ ~ ~
~ I e § § e ij §
~ ~ !Om ~ ~ Santa Cruz Bight ~ i
0 ~· ~ JOO ~~ 20m - ·= - - ~ - - - .., - b. Red box indicates the approximate boundary of the beaches and offshore regions studied within the Santa Cruz Bight. Major geographic points, rivers, beaches, lagoons, and the Santa Cruz Harbor are shown. Yellow areas indicate approximate area of beaches and green areas indicate the approximate location of kelp forests.
c. Area of upper harbor that was dredged (I )with location of dredge outfall (.-f) offshore of Twin Lakes Beach.
Figure I. Location of study site in Santa Cruz, California.
S. G. Watt, 2003 3 Having demonstrated to State and Federal Agencies that the upper harbor dredge sediment is non-toxic in two chemical and biological laboratory tests (Sullivan and Krcik, 1999), the Santa Cruz Small Craft Harbor was permitted to release approximately 3,000 yd3 3 3 3 (2,300 m ) in 500-700 yd (approximately 380-540 m ) increments of mixed sand, silt and clay sediment into the surf-zone on March 28, 29, and 30 of 200 l. The sediment was excavated near
J-Dock in the upper Santa Cruz Harbor and relea~ed approximately 70 yards (64 m) from the shore of Twin Lakes Beach near the east jetty within the Santa Cruz Bight (Figure 1). The mud-rich sediment was dispersed at night between the hours of7:00 pm and 12:00 am so as not to disturb local residents. The scientific approach was to monitor the habitats that had the greatest chance of being impacted by the experimental dredge sediment. Thus, this study focuses on the beaches and the nearshore benthic habitats bounded between Point Santa Cruz and Soquel Point (the western and eastern extents of the Santa Cruz Bight) and offshore out to -20 meters water depth (Figure 1). Of particular concern to the Monterey Bay National Marine Sanctuary (MBNMS), the Environmental Protection Agency (EPA), the California Department ofFish and Game (CDF&G), California Coastal Commission (CCC), and the U.S. Army Corps of Engineers (USACE) are the kelp forest habitats near the Santa Cruz Harbor. Kelp forests provide a unique refuge for various species of fishes, invertebrates, marine alga, and marine mammals (Rose, 1979; Breda, 1982; Thompson, 1982; Solonsky, 1983; Foster and Schiel, 1985). The regulatory agencies mentioned above fear that the fine-grained sediment would bury the bedrock substrate, a stable platform essential for kelp growth in the shallow coastal waters near the harbor. Covering of this substrate could prevent the proliferation of kelp, ultimately thinning the kelp forest over time (Burdette, 1992; Devinny and Volse, 1978; Rose, 1979). Other important habitats exist within the Santa Cruz Bight such as sandy nearshore seafloors, which are populated by a variety of flat fish, skates, sand crabs, and sand dollars (Oliver, 1980; Stan et al., 2002). Muddy seafloors offshore (>30 meters deep), outside of the Santa Cruz Bight, are inhabited by many different species of benthic invertebrates and fishes that rely on the muddy substrates for their survival (Oliver, 1980; Starr eta!., 2002). The sandy beaches are another important habitat for many species of birds, in particular the endangered
S.G. Watt, 2003 4 western snowy plover, which nests in the upper reaches of many Santa Cruz beaches (U.S. Fish & Wildlife Service, 2001 ). To determine if the fine-grained sediment delivered during the experimental dredging event were retained on the beaches or in the nearshore habitats of the Santa Cruz Bight, a monitoring program was conducted over three phases: before dredging (Pre-Experiment phase), while dredging occurred (Experiment ph~se), and following dredging (Post-Experiment phase). Data collected over the monitoring period phases included two multi beam bathymetric surveys, downloaded stream flow data and oceanographic swell information, and beach and nearshore sediment sampling. These data were analyzed over the three phases to provide a comparative timeline of sediment inputs, oceanographic conditions, grain-size distributions, and habitat changes that occurred in the Santa Cruz Bight over the monitoring period.
2. Sediment accumulation and transport in northern Monterey Bay To monitor an experimental dredging event in an open coastal system such as the Santa Cruz Bight, it is necessary to monitor the existing sediment sources, sediment sinks, and the forces that drive sediment transport. The Santa Cruz harbor resides within, and contributes sediment through dredging to the Santa Cruz Littoral Cell. The northern boundary of the cell is believed to be the Golden Gate Bridge in San Francisco and extends southward to Monterey submarine canyon (Best and Griggs, 1991 ). Recent volume estimates (m3/year) of sediment sources, sinks, and transport in the Santa Cruz Littoral Cell are shown on Table 1, modified after Eittreim eta!. (2002a). Sediment sources include rivers, streams, Santa Cruz Harbor entrance channel dredging (separate from the experimental dredging event), and coastal cliff erosion. Research by Arnal eta!. (1973), Oradiwe (1986), Best and Griggs (1991), Eittreim et a!. (2002a), and Edwards (2002) suggests that the majority of sediment enters the cell during episodic storm and flooding events, most of which (90%) occur in the winter months from November to March (Best and Griggs, 1991 ). Sediment sinks include aeolian transport of sediment to dunes and loss down the Monterey submarine canyon and the continental slope. While the absolute values for sources and sinks, and transport of sediment are not fully
S.G. Watt, 2003 5 Silt and clay Total Littoral sand s,EDIMENT SOURCES Source (mud) Pajuro River briggs und Hein (1980) 297,500 59,500 238,000 an Lorenzo River Best and Griggs (1991 )1 212,500 56,875 155,625 f'\mal et al. (1973) 37,472 pradiwc ( 1986) 92,050 28,300 63,750 Hicks and lnmun (1987) 180,000 48,000 132,000 antll Cruz Harbor 1965-2002 Harbor Dredge Logs' 124,048 114,124 9,924 roastal cliff erosion Best und Griggs (1991) ave111.•e 26,695 8,996 17,699 loructiwc ( l986)J 97,180 77,744 19,436 Gully erosion Best and Griggs (1991) average 7,830 1,169 6,661 Stream erosion Best and Griggs ( 1991) uveraoc 49,368 6,076 43,292 Erosion of submerged rock outcrops unknown unknown Ullb.'llOWO Littoral sand from the north unknown UllkTIOWO unknown
unknown unknown Lewis ct at. (2002)~ 1,100,000 0
TRANSPORT RATES LiUonll sand transport Best and Griggs (1991)1 200,000 lAma! ct al. (1973) at Capitola 159,000 Mudbelt silt and clay transport lxu et al. (2002) 220,000 1Upduted in Eittreim et al. {2002a) 1 Average of37 years of entrance dredging records obtained from Ron Duncan, Maintenance Services, Santa Cruz Harbor Sediment composition is based on nn estimated 92% sand /8% silt and clay from Sullivan and Krcik (2000) 3 Point Sruttn Cruz to La Selva Beach, based on an estimnted composition of 80% sand illld 20% silt and clay 4 Calculated over an area of 421 km 2
Table I, Volume estimates (m3 /year) of sediment sources, sinks, and transport in the Santa Cruz Littoral Cell (modified after Eittreim et al., 2002a) understood, researchers agree (Arnal et aL, 1973; Oradiwe, 1986; Best and Griggs, 1991; Eittreim et aL, 2002a) that there is a net deficit of sand in the system. Two significant sources of sediment located within the Santa Cruz Bight must be accounted for in order to estimate the total sediment input to the study area over the monitoring period. These two sediment sources are the San Lorenzo River sediment load and sediment dredged from the Santa Cruz Harbor entrance channel (Figure 1 and Table 1). The San Lorenzo River is the second largest contributor of sediment to the northern Monterey Bay, releasing -212,500 m3 of sediment per year, which is composed mostly of silt and clay, 156,000 m3 or 73% (Best & Griggs, 1991; Eittreim eta!., 2002a). Entrance channel dredging at the Santa Cruz Harbor releases -125,000 m3of sediment per year onto the shore or into the
S,G, Watt, 2003 6 surf- zone at Twin Lakes Beach, and is composed primarily of sand (only 8% silt and clay sediment). For comparison, the experimental dredging event sediment (2,300 m3 total) is composed of 1,400 m3 (or 60%) silt and clay sediment. Sediment entering the coastal ocean (from flooding rivers or harbor dredging) are sorted by the forces of waves and currents based on differences in grain-size, density, and shape (Bascom, 1951). Best and Griggs (1991) d,!)termined that sediment in the Santa Cruz Littoral Cell could be divided into two categories at a cut-off grain-size diameter of 0.18 mm (2.45 phi) based on the depositional and transport characteristics of the sediment. Sediment smaller than 0.18 mm is categorized as fine-sediment (roughly silt and clay sized sediment or smaller) and sediment larger than 0.18 mm is categorized as littoral sand (roughly fine-sand and larger sized sediment). Fine-sediment smaller than 0.18 mm in size are believed to either bypass the inner shelf (less than 20 meters water depth) in a river flood plume, or are winnowed from the seafloor shortly after deposition by wave or current processes. The fine-grained silt and clay sediment is transported to calmer, deeper water on the continental shelf between the depths of30 to 90 meters (Greene, 1977; Best and Griggs, 1991; Lewis eta!., 2002; Eittreim eta!. 2002a; Edwards, 2002). Northern Monterey Bay current meter (Xu eta!., 2002) and seismic reflection profile data (Greene, 1977) suggest that silt and clay material is transported at these depths to the northwest by the poleward flowing Davidson Current (a fall/winter seasonal component of California Current System) along a midshelf mudbelt. The mudbelt extends from the continental shelf south of Santa Cruz to north of HalfMoon Bay (Figure 2). The mudbelt is up to 30 meters thick and accumulates sediment at an average rate of 0.27 g/cm2 per year (Lewis eta!., 2002). Sediment larger than 0.18 mm are deposited on the beaches and nearshore environments of the Santa Cruz Bight (Best and Griggs, 1991 ). Transport of sediment larger than 0.18 mm is driven by littoral currents and waves produced from three main sources, the Northern Hemisphere, the Southern Hemisphere, and locally generated wind swells (Breaker and Broenkow, 1994; Xu, 1999). Northern Hemisphere swells develop in the north Pacific near Alaska and are common throughout the winter, with swell heights topping 8 meters. Southern Hemisphere swells develop off the coasts of New Zealand, and South America, traveling great
S.G. Watt, 2003 7 --
Figure 2. A conceptual model of sediment transport and accumulation for the northern Monterey Bay shelf from Point Ano Nuevo to Monterey Canyon modified after Eittreina et al. (2002a). Black lines are 50 meter bathymetry contours. Orange to brown lines represent the general outline and sediment isopachs (m) of the midshelfmudbelt. Green arrows indicate direction of silt and clay transport along the mudbelt. Blue arrows show discharge of sediment from the San Lorenzo and Pajaro Rivers. Black arrows indicate the direction of transport of littoral sediment. Arrows do not indicate transport rates or sediment discharge magnitudes. For details regarding transport rates and sediment discharge magnitudes, see Table I. This figure was reproduced using GIS data from Wong and Eittreim (2002).
S. G. Watt, 2003 8 Figure 2. A conceptual model of sediment transport and accnmulation for the northern Monterey Bay shelf from Point Ana Nuevo to Monterey Canyon modified after Eittreim et al. (2002a). Black lines are 50 meter bathymetry contours. Orange to brown lines represent the general outline and sediment isopachs (m) ofthe midshelf mudbelt. Green arrows indicate direction of silt and clay transport along the mudbelt. Blue arrows show discharge of sediment from the San Lorenzo and Pajaro Rivers. Black arrows indicate the direction of transport of littoral sediment. Arrows do not indicate transport rates or sediment discharge magnitudes. For details regarding transport rates and sediment discharge magnitudes, see Table I. This figure was reproduced using GIS data from Wong and Eittreim (2002).
S. G. Watt, 2003 8 distances to reach the shores of northern Monterey Bay. As a result, the swells are less frequent, have smaller wave heights, but very long periods (over 20 seconds). Locally generated wind swells develop in response to low-pressure system movements off the California coast. They generally last only a few days, developing and degrading quickly in the winter, spring and summer months. Waves produced by locally generated wind swells are less energetic than the average Northern Hemisphere swell due to shorter wind durations and fetch lengths. Through refraction, waves approaching the Santa Cruz Bight converge on Point Santa Cruz and Soquel Point, creating larger wave heights at these points than other places within the Bight. The south facing shoreline is subject to the full force of directly approaching Southern Hemisphere storms, but is partially protected from the powerful North Pacific winter storms. West, and to a greater degree northwest, swells lose energy as they are refracted around Point Santa Cruz (Xu, 1999) (Figure 3). However, most of the beaches, cliffs, coastal homes and roads between Point Santa Cruz and Soquel Point are protected in some way by seawalls or riprap to prevent further wave-induced damage along the shoreline (Griggs and Savoy, 1985).
3. Local geologic setting Local geologic and coastal structure has been shown to play a significant role in sediment transport and deposition in the Monterey Bay by Anima et a!. (2002) and by Storlazzi and Field (2000); providing the framework over which modern coastal processes take place and continually modify the coastal zone. The Santa Cruz Small Craft Harbor is incised into the lowest of a series of erosional marine terraces that step up from the coast into the Santa Cruz Mountains. These wave-cut terraces formed in response to glacioeustatic fluctuations in sea level and tectonic uplift caused by the oblique convergence of the Pacific Plate with the North American Plate and strike-slip/reverse movement along faults within the San Andreas transform fault system, specifically from the offshore San Gregorio and Monterey Bay fault zones and the inland San Andreas Fault (Greene, 1990). The lower terrace is eroded into marine sedimentary rocks of the Pliocene Purisima Formation, composed of moderate- to well consolidated sandstone, siltstone, and mudstone, interspersed with beds of mollusk shell hash or coquina in the Santa Cruz area. The terraces are overlain by 1.5 to 6 meters thick, poorly consolidated marine and non-marine gravels, sands and silts (Best and Griggs, 1991). The
S.G. Watt, 2003 9 Northwest swell (from 300° T) High refraction of swells into the Santa Cruz Bight.
West swell (from 270'T) Moderate refraction of swells into the Santa Cruz Bight.
I ··- -,- + + + i South swell (from 200'T) Little to no refraction of swells into the Santa Cruz Bight.
+ i
Figure 3. Illustrations of three different swell directions approaching the Santa Cruz Bight, northwest (300°T), west (270°T), and southwest (200°T). In each of the three examples, the red arrows represent the direction of swell travel, while the black lines represent wave fronts. Note that all wave fronts travel nearly perpendicular to the eastern Point Santa Cruz shoreline (creating high potential for littoral drift), and nearly parallel with the Santa Cruz Bight beaches (creating low potential for littoral drift). Bathymetric contours are at I 0-meter intervals. (Modified from Wiegel, 1964)
S. G. Watt, 2003 10 purisima Formation 1rnconformably overlies the late Miocene Santa Cruz Mudstone, a medium- to thick-bedded, highly fractured, folded, and faulted siliceous mudstone that is visible in the cliffs just north of the study area (Greene and Clark, 1979). The Purisima Formation, which forms the shoreline cliffs in the Santa Cruz Bight, has been identified in side-scan sonar imagery in the shallow waters ( < 20 m) of Santa Cruz by Anima et a!. (2002) and Eittreim et a!. (2002b). T]le offshore bedrock exposures provide a stable structure for kelp forests to grow and are bordered by flat sand channels. The channels are believed to have been carved into the Purisima bedrock by paleo-stream flow during the last glacial maximum (22 ka) and have filled with sand following the present rise in sea level (Anima et al., 2002). The offshore sand channels geographically match with the present day locations of river and lagoon drainages. Beaches have formed between Point Santa Cruz and Soquel Point (Figure 4) in response to natural physical processes. The cross-shore width of these beaches (or in some cases the presence or absence of these beaches) varies depending upon season, coastline orientation, proximity to sediment sources, coastal geology, exposure to swell and other dynamic physical processes including storm activity. Beaches occur where a protruding cliff or jetty interrupts littoral transport and has created a trap, allowing sand to accumulate over time (i.e. Seabright Beach). Some local beaches are seasonal, accumulating sand throughout the calm summer months only to completely erode back to the bases of shoreline cliffs, sea walls, or protective revetments in the winter (i.e. Cowell's Cove, the Boardwalk Beach, and 26°' A venue Beach). Other beaches have formed in low-lying areas where streams and rivers intersect the shoreline. Mixed semi-diurnal tides, with maximum ranges of2.4 to -0.8 meters, can at high-tide completely submerge some winter beaches and inundate the bases of cliffs, sea walls or protective revetments and at low-tide reveal tidal pools of exposed, flat bedrock (Best and Griggs, 1991 ). In addition to high surf and tides experienced at all beaches in the study area during winter months, heavy winter rainstorms cause rivers, streams, and creeks to flood and lakes and lagoons to overflow, accelerating the erosion of these beaches. This essentially makes these beaches prone to "attack" from both the seaward and landward sides (i.e. Twin Lakes Beach, Corcoran Beach, and Moran Beach).
S.G. Watt, 2003 11 1. Cowell's Beach 2. Boardwalk Beach
3. San Lorenzo River Beach
4. west Seabright Bench 5. east Seabright Beaeh
Figure 4a. Photos of west Saota Cruz beaches observed aod sampled during the monitoring period. Photos after Kenneth Adehnan, California Coastal Records Project, Copyright© 2002 www.califoroiacoastline.org.
S. G. Watt, 2003 12 - -
6. Santa Cruz Harbor Area 7. Twin Lakes Beach
8. Blacks Point Beach 9. Corcoran Beach
10. 26th Avenue Beach 11. Moran Beach
Figure 4b. Photos of east Saota Cruz beaches observed aod sampled during the monitoring period. Photos after Kenneth Adehnao, California Coastal Records Project, Copyright© 2002 www.califomiacoastline.org.
S. G. Watt, 2003 13 4. Methods 4.1 Monitoring program The monitoring program design was based on information gathered in a review of scientific literature, a pilot field research project conducted prior to the experimental dredging event, and a marine biological assessment of the l~abitats at risk due to the experimental dredging specific to this study reported upon by Goldberg et al. (2000). The monitoring program consisted of three phases, Pre-Experiment, Experiment and Post-Experiment (Figure 5). The purpose of the Pre-Experiment phase was to establish a baseline of existing natural sedimentary conditions in the Santa Cruz Bight prior to experimental dredging. The Experiment phase is designed to monitor any immediate impacts that may occur while dredging is taking place. The Post-Experiment phase monitors the return to 'natural conditions' after experimental dredging has ceased. The comparison of the three phases provides a timeline of sediment inputs, oceanographic conditions (which drive sediment transport), grain-size distributions, and changes to habitats in the Santa Cruz Bight over the monitoring period. San Lorenzo River stream flow data were used to estimate sediment discharge. Oceanographic swell information was downloaded to monitor wave conditions and to calculate littoral drift estimates. Over 300 sediment samples were collected and analyzed to produce descriptive grain size statistics. Two separate ~ 7 km2 geophysical surveys were also executed to describe and quantifY benthic habitats and sedimentary changes that occurred during the monitoring period.
S.G. Watt, 2003 14 PreMExpcrimcnt phase (2-18 to 3-27) Daily river and swell data Geophysical survey 4 beach sedimenl sampling events 4 offshore sediment sampling events ~
Experiment phase (3M28 to 3-30) Monitoring Program . Daily river and swell data 3 Phases 3 beach sediment sampling events February, 18 2001 to April, 14 2001 3 offshore sediment sampling events
Post-Experiment phase (4M 1 to 4-14) Daily river and swell data Geophysical survey 4 beach sediment sampling events 4 offshore sediment sampling events
Figure 5, Timeline and data types collected during the three phase monitoring period,
4.2 San Lorenzo River In order to monitor the total sediment input to the Santa Cruz Bight, sediment discharge estimates were calculated for the San Lorenzo River for the duration of the monitoring period. Figure 6 shows the locations of USGS river gauges which measure the real-time average daily stream flow in meters3 at the Big Trees station (#11160500) and at the Santa Cruz station (#11161000). The Big Trees station has recorded 64 years of non-consecutive historical stream flow data while the Santa Cruz station has recorded 48 years of non-consecutive data. Daily stream flow (m3/second) values for the Santa Cruz station were downloaded over the duration of the monitoring period from the USGS Real-Time Water Data website http://waterdata.usgs.gov/ca/nwis/rt. Stream flow records were not available for the Big Trees station during the monitoring period,
S.G, Watt, 2003 15 .. ~ ... ~-0 ~-0
! Oceanographic buoys <> Monterey Bay #46042 • SantaCruzHarbor#00601
I USGS stream flow gauging stations *Big Trees § i:l SnntnCruz ! 5 """"'=
i. '§ ! 8
i ! '8
1 I 8
§. ' 8 ' <> w•o s.a"ooo wooo !TllOilO '!11000 ~"'"" ~-· Figure 6. Locations of real-time USGS stream flow gauging stations and oceanographic buoys used in tbe monitoring program. Bathymetric contours are at I 00 meter intervals.
Stream flow data and suspended sediment measurements at the Big Trees station have been used by Oradiwe (1986) and Best and Griggs (1991) to produce sediment-transport curves to estimate sediment discharge from the San Lorenzo River. Sediment discharge estimates are based on the following relationship.
where Qs =total sediment discharge (m3/day) Q =mean daily water discharge (m3/second) m & k = empirical constants that are solved as the slope and intercept of the least square linear fit to the plot oflog (Q, Qs) (Oradiwe, 1986). The log of the equation gives:
logQs = m logQ + logk
S.G. Watt, 2003 16 A total sediment discharge estimate was calculated for the monitoring period by summing the results from two sediment-rating curves presented in Best and Griggs (1991 ). For total suspended sediment load:
2 22 Qs = 0.335Q · (where k = 0.335 and m = 2.22)
And for bed load:
Qs = 3.64QI.23 (where k = 3.64 and m = 1.23)
The total sediment discharge estimate (suspended load plus bed load) for the monitoring period was broken into separate littoral sand, and silt and clay volumes by applying percentages oflittoral sand (27%) and silt and clay (73%) calculated from the annual sediment discharge volumes reported for the San Lorenzo River in Eittreim eta!. (2002a) (see Table 1). Sediment discharge estimates from the San Lorenzo River were computed for each experimental phase and for the entire monitoring period. Short-term sediment discharge estimates may be subject to errors of an order of magnitude or more. During the monitoring period, sediment discharge estimates for the river were calculated using Best and Griggs (1991) sediment transport curves, which were based on sediment concentrations and stream flow data from the Big Trees station. Because stream flow data were not available for the Big Trees station during the monitoring period, stream flow data from the Santa Cruz station were applied to the Big Trees station sediment transport curves. It is unknown whether this method causes sediment discharges to be over or under estimated. Other potential factors that lead to errors in sediment discharge estimates include either the build up or removal of sand prior to extreme floods or drought along the river channel. The velocity and duration of the stream flow through the entire river cham1el (not only at gauging stations) plays a crucial role in determining sediment discharge (Brown, 1973). In addition, San Lorenzo River stream flow and sediment discharge is extremely episodic. While years of drought may not produce significant amounts of sediment, a winter fueled by the El Nino/Southern Oscillation phenomena or even a particularly large winter storm may deliver
S.G. Watt, 2003 17 many years of "annual" sediment discharge in one winter or over the course of a few days (Best and Griggs, 1991; Hicks and Inman, 1986).
4.3 Santa Cruz Harbor The entrance channel dredging records for the past 3 7 years and records for sediment that was dredged during the monitoring period were obtained from the Santa Cruz Harbor and used for two purposes. First, as an estimate of another source of sediment being returned to littoral drift in the study area from a temporary sediment sink (the protected waters of the harbor), and second, as an estimate oflongshore sediment transport rates to compare with estimates produced using oceanographic swell data and a spectral wave refraction model. The annual entrance channel sediment accumulation and the sediment which had accumulated over the monitoring period were each divided into littoral sand, and silt and clay (mud) categories based on sediment grain-size analyses performed by RRM Inc. (Sullivan and Krcik, 2000) who found that the entrance channel sediments were composed of approximately 92% sand and 8% silt and clay (Table 1).
4.4 Oceanographic data Nearshore sediment transport in the northern Monterey Bay is driven by waves and wave induced currents (Best and Griggs, 1991; Breaker and Broenkow, 1994; Xu, 1999; Xu et a!. 2002). To monitor wave conditions in the Santa Cruz Bight over the monitoring period, significant swell height (meters), period (seconds), and dominant swell direction (degrees tme north) were obtained from the Coastal Data Information Page (CDIP) at http://seaboard.ndbc.noaa.gov/station_history.phtml?station=46042 for buoy #46042 (a permanent ocean surface buoy) outside of Monterey Bay and for array #00601 at http://cdip.ucsd.edu/trnp/stream _frame 14659 .htrnl (a configuration of pressure sensors mounted on the seafloor) offshore of the Santa Cruz Harbor (Figure 7). Swell direction was not
S.G. Watt, 2003 18 + + Soouel Point Wave Model Station Locutions lOrn 0 Outfall fliD Array 0 • Ill Offshore 20m
Figure 7. Locations of wave model stations used to calculate littoral drift estimates over the monitoring period. Twin Lakes Beach faces -200°T southward, an important consideration when calculating littoral drift estimates.
available for the Santa Cruz Harbor array. Data from both locations were averaged into daily values to monitor the oceanographic conditions present over the course of the monitoring period. Wave data from the Point Reyes buoy (#02901) were downloaded into a spectral wave re.fraction model (O'Reilly and Guza, 1993) to estimate littoral drift rates at the Santa Cruz Bight over the monitoring period. The model incorporated multibeam bathymetric data collected during the Pre-Experiment phase of the monitoring period (gridded to 30 meters resolution). For chosen points within a study area (Figure 7), the spectral wave refraction model produces values of significant wave height (meters), peal( wave period (seconds), mean wave direction (degrees true north), radiation stress (Sxy), and an associated Sxy direction (degrees true north). S,yis the longshore-directed (y-component) of radiation stress that is
S.G. Watt, 2003 19 moving toward the shoreline (in the x-direction) and is defined by the following equation (Komar, 1998):
Sxy = En sin a cos a,
Where E is the wave-energy density, n is the ratio of the wave group and phase velocities, and a is the angle the wave crests make with a shoreljne. Twin Lakes Beach shoreline (which faces 200° T) was used as the shoreline to compare with approaching ocean waves. The value a is calculated by subtracting a given shoreline (200°T) from an approaching wave angle (for example 220°T), a= 220- 200 = 20°. The smaller the angle between the shoreline and the approaching swell, the less energy there is available for producing a longshore current. When the angle between approaching wave crests and the shoreline equals zero (or become parallel), there is no driving force for longshore currents. Sxy radiation stress daily mean values were converted to P(l), which is referred to as the "longshore component of wave power" and is described by the following equation (Komar, 1998):
P(l) = (ECn) sin a cos a which is reported in Newtons/second or equally Watts/meter. P(l) is then used to calculate Q(l), the volume transport rate (m3/day) according to the following equation (Komar, 1998):
Q(l) = 2.6P(l)
Using the spectral refraction wave model (O'Reilly and Guza, 1993) and the above two equations from Komar (1998), littoral drift rates were calculated for three different study area locations. The first is the Outfall Station (6 meters deep) near where the experimental dredge outfall was located. The second is the Array Location (13 meters deep) where the Santa Cruz Harbor Array #00601 is located. The third is the Offshore Station (17 meters deep) at the outer edges of the study area (Figure 7). Littoral drift transport volumes were calculated at each station for all three experimental phases and over the monitoring period.
S.G. Watt, 2003 20 4.5 Sediment sampling The influx of mixed sand and mud sediment into the smf-zone could alter sediment transport and the composition of beaches and nearshore benthic habitats within the Santa Cruz Bight. Ifthere were a lasting sedimentary change due to the addition of fine-grained sediment following the experimental dredging event, grain size analyses would indicate increases in sediment sample silt and clay percentages and decreases in mean grain size. To ascertain if this is the case, sample analyses in the Pre-Experiment phase were compared to Experiment and Post-Experiment sediment sample analyses. The sediment data is useful in explaining coastal processes and sedimentary environments within the Santa Cruz Bight. Combinations of changing or recurring sediment parameters on the seafloor provide clues about the environment in which they are deposited. Factors such as exposure to wave or current energy, dispersal of sediment from local sources, and coastal or bathymetric features (that may impede, alter or enhance sediment transport) dictate the range of possible grain size parameters that may be deposited in a particular area. For example, non-cohesive, small diameter particles (such as silt and clay) are more easily transported by wave or current energy than larger sand-sized particles (Folk, 1974). Therefore, high percentages of silt and clay would not be expected in beach or near surf-zone sediment samples, and would raise suspicion if percentages increased in these areas over the monitoring period. Furthermore, identifYing the locations of recurring, relatively high silt and clay percentages could indicate a sedimentary environment less exposed to wave or current energy.
4.5.1 Beach sample collection Comprehensive sets of sediment samples were collected throughout all three phases of the monitoring period (Figures 5, 8, and Table 2). Three sets of 20 beach sediment samples were collected in Pre-Experiment san1pling events 1, 2, and 3 and one set of 13 beach samples in Pre-Experiment sampling event 4. Samples collected during Pre-Experiment 4 were originally planned to be collected on the first day of experimental dredging, however the experimental dredging event was postponed for a day due to permitting issues, which is why the Pre-Experiment 4 sampling event has the same sample design and nUlllber of samples as those collected in the Experin1ent phase. Therefore, Pre-Experiment 4 samples were collected
S.G. Watt, 2003 21 " " IIJ ® " "17 " " + + ~ .. I! " "16 "15 " " "
a. Locations and lD numbers of Pre- and Post-Experiment phase sediment samples. The onshore sample !D's are black with green dots, and offshore are red with blue dots.
~ "14
10m + + + \ I 2" 16" "15 - '"' - '"" M'"" b. Locations and ID numbers of Experiment phase sediment samples. The onshore sample !D's are black with green dots, and offshore are red with blue dots.
Figure 8. Locations for beach and offshore sediment samples.
S.G.Watt, 2003 22 3 Phase Monitoring Date in Sampling Event I Number of Program 2001 Survey Sediment Samples
Prc~Expcrimcnt phase 2118 Pre l Beach 20 2/21 Geophysical Survey nlu
2/28 Pre f Offshore 21
311 Pre 2 Beach 20 313 Pre 2 Offshore 21
317 Pre 3 Offshore 21 3/10 Geophysical Survey n/u
3/13 Pre 3 Beach 20 3127 Pre 4 Beach"' 13 3127 Pre 4 Offshore"' 10 Experiment phuse 3/28 Experiment I Bench 13 3/28 Experiment 1 OITshorc 10 3/29 Experiment 2 Beach 13 3129 Experiment 2 Offshore 10
3/30 Experiment 3 Beach 13
3/30 Exneriment 3 Offshore 10
Post-Experiment phnse 4/1 Post 1 Beach 20 412 Post l Offshore 21 4/5 Post 2 Offshore 21
4/8 Post2 Beach 20 4/10 Geophysical Survey nlu
4/11 Geophysical Survey nlu 4112 Post 3 Offshore 21 4/14 Post3 Beach 20
Totals 56 duvs 24 Events 338 sanmlcs
Table 2. Timeline of the three phase monitoring program, sampling events, geophysical surveys, and number of sediment samples collected over the monitoring period. • Denotes sediment sample events collected for Pre Experiment 4 on 3/27/01, which were collected the day before experimental dredging took place (beginning on March 28, 2001) and are of the same sample design as Experiment sampling events.
S.G. Watt, 2003 23 24 hours prior to the initiation of the experimental dredging event, providing an excellent comparison to Experiment and Post-Experiment phase samples. In the Experiment phase, three sets of 13 beach samples were collected. In the Post-Experiment phase, three sets of20 samples were collected in the same manner as those collected in Pre-Experiment sampling events 1, 2, and 3. Beach sediment samples were taken along, or slightly above, the high tide berms of beaches from Cowell's Cove to Moran J-ake because the high tide berm is the most likely location to deposit sediment during the monitoring period (Bascom, 1951 ). Sample sites were relocated to the position of the high tide berm for each individual day of sampling, which shifted over time because of high surf, flooding, and seasonal summer beach rebuilding throughout the monitoring period. Twin Lakes Beach received the greatest focus for sediment sampling, including four back beach samples, based on the beaches proximity to the experimental dredge outfall.
4. 5. 2 0./fthore sample collection Three sets of21 offshore samples were collected in Pre-Experiment phase sampling events 1, 2, and 3 and one set of I 0 samples in Pre-Experiment sampling event 4 for reasons described in the previous section (Figures 5, 8, and Table 2). Three sets of 10 offshore samples were collected in the Experiment phase. In the Post-Experiment phase, three sets of21 offshore samples were collected in the same manner as those collected in Pre-Experiment phase sampling events 1, 2, and 3. GPS was used to locate pre-detetmined offshore sample locations utilizing the Port District's Harbor Patrol vessels HPl or HP2. A petite ponar grab sampler (borrowed from the U.S. Geological Survey) was deployed to obtain surface sediment samples. High-energy winter wave conditions experienced during the monitoring period made it difficult to collect sediment samples from all intended targets offshore. In order to compensate for the impossibility of resampling an exact location on the seafloor, designated sample locations were occupied and position coordinates were recorded as soon as possible after the sediment grab sampler reached the seafloor. Samples obtained using this method were mapped using GIS. Positional error was measured to be no greater than seventy-five meters from the intended targets. Other sample locations were moved intentionally at the time of survey because of large brealcing waves, a thick kelp canopy, or the close proximity of otters or harbor
S.G. Watt, 2003 24 seals. The largest displacement of these intentional relocations was approximately 275 meters to the southeast at offshore sample location 7, due to large breaking waves at Point Santa Cruz.
4.5.3 Sediment sample processing and analysis Sediment samples were processed at Moss Landing Marine Laboratories using dry sieve analysis described in Folk (1974). Percentages of each sieve weight for each sample were calculated and graphed on probability paper to obtain phi values needed to calculate mean grain size diameter (phi and mm) and sorting (phi) for each individual sample. The percentage of silt and clay for each sediment sample was also calculated. The following formulas from Folk (1974) were used in the calculations:
Graphic mean:
mo~ (016 + 050 + 084)/3
The graphic mean is an estimation of the mean grain diameter for an individual sediment sample, which is the most common way of displaying sediment information. The mean can be categorized into a Wentworth size class for a common verbal description of sediment size such as, "medium-sand". In a dynamic coastal environment, mean grain size can provide clues about sedimentary environments. For example, locations that consistently have large sediment particles can indicate a location of relatively higher wave or current energy because larger particles are more difficult to transport than smaller sediment particles.
Inclusive graphic standard deviation (sorting): cro= (084- 016)/4 + (095- 05)/6.6
Inclusive graphic standard deviation (sorting) is a measure of how closely grouped around tl1e graphic mean the remaining grain-size fractions are. A sample that is poorly sorted indicates that tl1ere are significant percentages of other grain sizes in the sample, other than the graphic mean. The units from the equation are reported in phi values, which can be described verbally according to the sorting scale. The best sorting of sediment occurs when waves or
S.G. Watt, 2003 25 currents are of intermediate and constant strength. Sand-sized sediment found in nature is usually better sorted than coarser sediment found in nature (Folk, 1974). Silt and clay percentages were computed by adding the weights of the silt and clay fractions of a sediment sample together and dividing them by the total sample weight. Silt and clay percentages are a primary concern to this study, providing direct evidence of whether or not the experimental dredge (or other sources) o( silt and clay are being retained on the beaches or nearshore habitats within the Santa Cruz Bight. To understand the sedimentary environments within the Santa Cruz Bight over the monitoring period as a whole, all beach and offshore sediment samples (338 samples total) were analyzed as a group. Interpolated geospatial surface averages were calculated for three different grain size parameters (mean grain size, silt and clay percentage, and sorting) using Arc View 3.3® Spatial Analyst. The Inverse Distance Weighting (IDW) interpolation method was used to calculate the three gridded surfaces. IDW estimates (interpolates) new grid cell values by averaging the values of known sample points in the vicinity of each cell (or nearest neighbors). The closer a known point is to the center of a cell being estimated, the more influence, or weight, it has in the averaging process. The significance of known sample points on interpolated points can be controlled by defining a power. By defining a high power, more emphasis is placed on the nearest points, creating a more detailed surface interpolation. A lower power will give more influence to data points spatially further away, creating a smoother, less detailed surface interpolation. The best representation of mean grain size, silt and clay percentage, and sorting for sediment samples collected during the monitoring period were computed using the IDW method, gridded to 75 meter cell-size, using 12 nearest neighbors, to a power of 6. Data tables (Appendices A and B) were produced for each sampling event in the monitoring period. Table fields contain sample identification information, location in UTM Zone 10, date of collection, mean grain size (phi and mm), Wentworth size class, sorting (phi), and percentages of gravel and larger sediment, sand, silt and clay. The sample tables were imported to ArcView3.3® in order to display them geographically for comparison to other samples over time, to compute geospatial surface interpolations, and to overlay on seafloor images produced from two separate geophysical surveys.
S. G. Watt, 2003 26 4.6 Geophysical surveys Two separate geophysical surveys were conducted in the Santa Cruz Bight area (Figure 9) using California State University Monterey Bay (CSUMB) Seafloor Mapping Lab's 32-foot RfV MacGinitie. The vessel is equipped with a pole mounted Reson 8101 SeaBat shallow water (1-300 meter depth range) multibearn sonar system. The 240KHz SeaBat 8101 multi beam measures discrete depths (accurate to 1.25 em in ideal flat water conditions), enabling complex underwater features to be mapped with precision. Dense seafloor coverage is achieved utilizing up to 3,000 soundings per second. In addition to bathymetry, the SeaBat provides backscatter data that can be mosaiced into separate seafloor images. Differential GPS (DGPS) vessel positioning for multibearn surveys were obtained using a Trimble 4700 GPS with differential corrections provided by a Trimble ProBeacon receiver. Heave, pitch, heading,
--e------+ + + + + '" 1000 MeleG
Figure 9. Planned track lines of the -7km2 geophysical surveys conducted in the Pre- and Post-Experiment phases. Swath widths ranged from 75 meters offshore to 30 meters inshore.
S.G. Watt, 2003 27 and roll data were provided by a TSS HDMS heading and motion sensor (±0.02 degree accuracy). Coastal Oceanographics HyPack® software was used for survey design and execution. All raw data were logged using Triton-Elics International Isis Sonar® data acquisition system. Water column sound velocity profiles were collected using an AML SV+ sow1d velocity profiler. The two surveys covered the same -7 km~ from Point Santa Cruz to Soquel Point and took two full days per survey to complete. The bathymetric multibeam data were edited line by-line using CarisHIPS® to produce WGS 84, UTM Zone 10 geo-referenced artificial sun shaded images and ASCII text files with northings, eastings, and depth values in meters for each sounding. The ASCII text files were gridded using nearest neighbor statistics to 1-meter pixel size using Fleidem1ouse®. The 1-meter grids were imported into Arc View 3.3® to create bathymetric contours, sun-shaded images, and to produce maps for visual interpretation and presentation. Backscatter survey lines were processed into separate geo-referenced gray-scale images at 0.20-meter pixel size using Triton-Elics International Isis Sonar®. The separate backscatter lines were imported into TNTmips 6.7® for line editing and to create mosaiced images of the seafloor. The final geo-referenced seafloor mosaic (WGS 84, UTM Zone 10) was then exported to ArcView 3.3® to produce maps for visual interpretation and presentation. Artificially sun-shaded multibeam bathymetric imagery, mosaiced backscatter imagery, and physical quantitative sediment sample data were used to visually classifY the seafloor into benthic habitats according to Greene, et al. (1999) habitat classification scheme (Appendix C). Hand-drawn habitat interpretations were made on clear mylar sheets overlain on hard-copy artificially sun-shaded multibeam bathymetry and backscatter maps at a scale of 1: 2,500. The hard-copy interpretations were scanned into digital images after which they were geo referenced and vectorized using TNTmips 6.7®. The visual interpretations were then edited and improved at a scale of 1:750 by displaying the geo-referenced vector interpretation directly over multibeam and backscatter imagery. Sediment san1ples were also displayed over the seafloor images to "groundtruth" or provide physical quantitative evidence of seafloor substrate where it was collected geographically. The edited vectors (one for each survey) were
S.G. Watt, 2003 28 exported to ArcView3.3® to attribute polygon shapefiles into their respective benthic habitat 2 2 types. Once attributed, an area analysis (in km and m ) was performed for each habitat type. Habitat interpretations of Pre- and Post-Experiment geophysical surveys were compared to evaluate shifts in sediment distribution (erosion, deposition, or no habitat change) that occurred between the times of two surveys using the Spatial Analyst extension in ArcView3.3® (Figure 10). The two habitat interpretation shapefiles were intersected to create a single shapefile containing the attributed polygons from both surveys and creating new polygons where habitats crossed into one another. Where a habitat polygon from the Pre Experiment survey intersects with the same habitat type polygon in the Post-Experiment survey, it produces a polygon where the habitats have not changed over the course of the monitoring period. Conversely, if a habitat polygon from the Pre-Experiment survey crosses into a different habitat type polygon in the Post-Experiment survey, it produces a polygon where change has occurred over the course of the monitoring period. Depending on the shift in habitat types, erosion or deposition may be inferred. For example, if a rocky habitat in the Pre Experiment survey shifted to a sandy habitat in the Post-Experiment survey, it is assumed that sand was deposited over the exposed bedrock during the time between the two surveys. In this 2 manner, a sediment shift map was produced and an area analysis (in m ) was executed to quantify the amount of erosion and deposition of sediment that occurred between the two geophysical surveys. When comparing two different interpretations of seafloor imagery it is extremely important to know as much as possible about the geophysical data: how it was collected, what type of system was used, under what oceanographic conditions, how it was processed, how it was gridded and to what resolution, direction of artificial sun illumination, map scale of interpretation, and the extent of any vertical or horizontal error associated with the data. Preferably, all of these parameters would be identical between the two different surveys to provide the best possible accuracy for a sediment shift estimate. The seafloor imagery interpreted in this study meets those criteria with the added bonus of having the same interpreter for both sets of data. However, even under the most desirable circumstances, a reasonable amount of error must be assumed when visually interpreting seafloor imagery. After careful review of the sediment shift results, any polygon in the sediment shift map that had an
S.G. Watt, 2003 29 Benthic Habitat Classification Ssf b/u D (Oatsand) Sh(b)/e_f D (exposed rock outcrop) ·--·- Pre-Experiment Post-Experiment a. Boxes represent patches of Pre- and Post-Experiment habitat interpretations from the same geographic location. Both areas have been classified as exposed rock outcrops bordered by flat sand, although subtle changes in bedrock exposure are apparent.
b. This box displays the geographic intersection of the two habitat interpretation patches before any sediment shifts have been identified and attributed.
-·--·-
Sediment Shifts Legend .. Erosion D Deposition No habitat change D (rock outcrop) No habitat change D (flat sand) ·---·- c. This box highlights the sedimentary shifts that have occurred at this patch between the Pre- and Post Experiment surveys. Polygons have been attributed based on the comparison between Pre- and Post-Experiment habitat types. Areas that were identified as exposed rock outcrops in the Pre-Experiment phase and then identified as flat sandy areas in the Post-Experiment phase indicates deposition of sediment. Patches that were identified as flat sand in the Pre-Experiment and then identified as exposed rock outcrops in the Post-Experiment phase indicates erosion of sediment. For more details about other types of sediment shifts, see Plate I.
Figure 10. Creating a sediment shift map by comparing two geographically similar habitat interpretations modified after Greene eta!. 's (1999) habitat classification scheme (see Appendix C.)
S.G. Watt, 2003 30 area of 10 m2 or less, was not counted as a sediment shift and was included in the "no habitat change" category.
5. Results 5.1 Sediment input over the monitoring period A combined total of39,000 m3 ofsedimept was released into the Santa Cruz Bight over the monitoring period from the San Lorenzo River, Santa Cruz Harbor entrance channel 3 dredging and the experimental dredging event. Of the combined total, 78% (-30,000 m ) is 3 estimated to be sand and 22% (-9,000 m ) is estimated to be silt and clay (Table 3). Sixty percent of the total silt and clay was delivered during the Pre-Experiment phase, primarily by 3 the San Lorenzo River (4, 746 m ) and to a lesser extent by Santa Cruz Harbor entrance channel dredging (489 m\ The experimental dredging event accounts for -6% of the total sediment input to the study area and -16% of the total silt and clay delivered over the monitoring period.
5.2 San Lorenzo River Stream flow in meters3/second measured at the Santa Cruz station from February 18 to April14, 2001 is compared to the 48-year average for tlris station and the 64-year average for the Big Trees station in Figure 11 (see Figure 6). The stream flow during the monitoring period was below both stations' historical averages with the exception of two stream flow spikes, which occurred on February 18-26 and March 3-7, prior to the experimental dredging event. These two occasions mark the times of the heaviest rainfall, contributing -84% of the total San Lorenzo River sediment discharge load during the monitoring period (Figure 11 and 12). The river released 56% of the overall total silt and clay to the study area, most of which (97%) occurred during the Pre-Experiment phase. Sediment discharge dropped substantially after early March (Figures 11 and 13). Only 184 m3 of sediment was released by the San Lorenzo River to the study area over the Experiment and Post-Experiment phases.
S.G. Watt, 2003 31 Pre-Experiment phase (38 days) Littoral Sand Silt and Clay Total %of phase % of overall total San Lorenzo River 1,755 4,746 6,501 52 16.7 Harbor Entrance Channel 5,627 489 6,116 48 15.7 Experimental Dredge 0 0 0 0 0 phase Sediment Total 7,382 5,235 12,618 100 32.4 % of phase Sediment Total 59 41
Experiment phase (3 days) Littoral Sand Silt and Clay Total %of phase % of overall total San Lorenzo River 10 26 36 0.1 Harbor Entrance Channel 4,403 383 4,786 67 12.3 Experimental Dredge 917 1,376 2,294 32 5.9 phase Sediment Total 5,330 1,785 7,116 100 18.3 % of phase Sediment Total 75 25
Post-Experiment phase (15 days) Littoral Sand Silt and Clav Total % ofnhasc %of overall total Sun Lorenzo River 40 lOB 148 0.4 Harbor Entrance Channel 17,613 1,532 19,144 99 49.1 Experimental Dredge 0 0 0 0 0.0 phase Sediment Total 17,653 1,639 19,292 100 49.5 %of phase Sediment Total 92 8
Monitoring Period Total (56 days) Littoral Sand Silt and Clay Total %of total Sun Lorenzo Rive 1,805 4,880 6,685 17 Harbor Entrance Channel 27,643 2,404 30,047 77 Experimental Dredge 917 1.376 2,294 6 Sediment Total 30,366 8,660 39,025 % of Sediment Total 78 22
3 Table 3. Summary of sediment inputs (m ) during each experimental phase and for the entire monitoring period.
S.G. Watt, 2003 32 r 45 ~ ------~------;;,·'.'.•. .,,,•.·.·.····. pf/J $ 40 ~ 0 '"0 w 35
E Post-Experiment 30 ~ Pre-Experiment X High-Energy p e 25 ~ r :0 c m 20 8 e .!!!"' n t 1;: 15 ~ 0 o;:: Low-Energy ~ 10 ~ ~ 5
See Figure 13. 0 ' ' 1>2 ~ .. ... ~ ~ ...... ~ ~ ~ ~ ~ ~ ;;;"' ;;;'"' ;;;:'"' ill i$'"' '"' '"' ~ ~ ~'"' ;;;'"' ;;;'"' 15 ;;;'"' ;;;'"' w'"' w (;;.. 'OJ ii5 :0: 0> 0 0> 0 0> 0 0> 0 ::: --J .. "' .. "' - .. "' "' ... "' '"'- "'- "' "' Date in 2001
Figure II. Plot of stream flow in meters'/second measured at the Santa Cruz Station throughout the -Santa Cruz Station (throughout the monitoring program) monitoring period (red) in relation to the 48-year average at the Santa Cruz Station (green) and the 64- year average at the Big Trees Station (blue). The light green vertical band represents the time frame when ··-·-· Santa Cruz Station 48-year average the experimental dredging event took place. In general, the flow for the San Lorenzo River during the Experiment from February 18 to April 14, 2001 was below both station's historical averages with the -Big Trees Station 64 year-average exception of two stream flow spikes, which happened prior to the experimental dredging event from February 18-26 and March 3-8. See Figures 12 and 13 for photographic evidence of San Lorenzo stream w w flow. Figure 12. Photo of the mouth of the San Lorenzo River taken February 20, 2001 looking westward towards the Beach and Boardwalk. This flood represents one of the largest stream flow and storm surge wave events observed during the Pre- Experiment phase and the entire monitoring period, and is considered a high-energy winter storm. See Figure II for recorded stream flow measurements.
Figure 13. Photo of the San Lorenzo River mouth, looking southward toward the ocean, in the Post-Experiment phase on AprilS, 2001. Water flow at this particular time alternated between landward tidal flow and weak seaward river flow, and represents a low-energy spring/summer conditions. See Figure II for recorded stream flow measurements.
S. G. Watt, 2003 34 5.3 Santa Cruz Harbor The Santa Cruz Harbor entrance channel was dredged eleven times during the monitoring period, returning -30,000 m3 of temporarily trapped sand sediment back to the Twin Lakes Beach surf-zone. The majority of the entrance sediment was released in the Post Experiment phase (19,145 m\ The three-day upper harbor experimental dredging event took place during the evenings of March 28th, 29th, and 30tl', releasing approximately 2,300 m3 of sand, silt and clay sediment. The event was stopped on the third evening due to mechanical problems with the dredging equipment. The experimental dredging event released about the 3 same amount of silt and clay (1,376 m ) as the Post-Experiment phase harbor entrance channel 3 dredging (1,532 m ) between April 1 and 4, 2001. This equals three days of upper harbor dredging with a one-day break followed by four days of entrance channel dredging. A total of 21,438 m3 sediment, -2,900 m3 [or 14%] silt and clay, was delivered to the study area over this period. This eight-day period marks the greatest sediment influx to the study area over the entire monitoring period (-55% of the monitoring program total), coming at a time of relatively low wave-energy. A few other sources that may have contributed sediment to the study area over the monitoring period have not been considered or accounted for in this study. These consist of the transport of sediment in longshore drift from the north or south, erosion of submerged bedrock outcrops, and cliff erosion (not observed within the study area beaches during this investigation). Previously deposited deeper water shelf sediment returning to the nearshore could also have contributed sediment to the system.
5. 4 Oceanographic conditions and littoral drift Figure 14 is a plot of wave height (m), period (seconds), and wave energy (wave height 2 in meters ) for buoy #46042 offshore of Monterey Bay and the Santa Cruz Harbor Array #0060 1 just south of the Santa Cruz Harbor (see Figure 6) displayed with categorized directional wave data (in degrees true north) obtained from buoy #46042. Swell directions were grouped into three categories, northwest (290-325°T), west (245-290°T), and southwest (190-245°T). Directional data for the Santa Cruz Harbor Array #00601 were not available.
S.G. Watt, 2003 35 Significant wnve height {meters) for buoy #46042 nnd nrray #00601
··················•···•········•·················•···········•··••·•·•·•·•··••••···•••••••
N ~fill-12 Wa.-.:: Diro:tion ("n I .., ••2 1 w ' I " s
I.J
O.l
Ontt:iD1001
Dominant wave period fur buoys ff.l6042 and nrroy #00601
o~tcin21lOI
Wave energy (H2 1n meters) for buoy #.:16042 11nd army f/00601
N 46U-12Wa~·~Oire:cu0ll(- '""' 'I
W E ' " s
'"
Date ill1001
Figure 14. Wave height (meters), period (seconds), and wave energy (wave height in meters') from Monterey Bay buoy #46042 (black line) and Santa Cruz Harbor Array #0060 I (blue line) are shown separately with categorized swell direction obtained from buoy #46042. Directional wave data (in degrees true north) were grouped into three colored categories, swell approaching from the northwest is red (290-325° T),lrom the west is blue (245-290°T), and from the soutl1west is yellow (190-245° T) as indicated by the wave direction compass. The swell direction was primarily northwest (73% of the time), while west ( 20%) and southwest swells (7%) were much less frequent. Directional swell data were only available for buoy #46042.
S.G. Watt, 2003 36 Waves during the Pre-Experiment phase were primarily from the northwest with a few significant storms from the south and west. The Experiment and Post-Experiment phases were subject to primarily short period wind swells from the northwest. Figure 14 highlights the decreases seen in wave height and wave energy in the offshore Monterey Bay buoy (#46042) and the nearshore Santa Cruz Harbor array (#00601). Note that southwest swells directly approach the Twin Lakes Beach shoreline (whicl;t faces 200°T to the south) and decrease less in wave height than northwest and west swells, which are refracted around Point Santa Cruz (see Figures 3 and 7). Littoral drift estimates from the three spectral refraction wave model locations and entrance channel dredging records are shown in Table 4. The model estimates suggest that longshore currents are very weak in the middle section of the Santa Cruz Bight between the depth range of 6 to 18 meters because approaching waves are refracted to become nearly parallel to the coastline. The model predicts a small component of energy that is directed to the southeast (207° -219°T). As a group of waves from the same direction approaches the shoreline, tl1ey become increasingly more parallel to the shoreline the closer they are to it. Tlus means tl1e component of wave-energy directed in the longshore direction, S(xy), becomes decreasingly closer to zero as the waves approach the shoreline. This may be why littoral drift estimates predicted by the spectral wave refraction model are higher at the deeper water Array (13 m water depth) and Offshore stations (18 m water depth) than the inshore Outfall station (6 m water depth). This does not imply that there is not enough energy to resuspend and transport
Harbor Outfall Array Station Offshore entrance Experimental Phase Station Q(l} Direction Q(l) Direction Station Q(l) Direction channel Direction Pre-Experiment total 1.90 2.99 4.35 6,116 Assumed 38 day average 0.05 207 0.08 215 0.11 219 161 southeast Experiment total 0.06 0.09 0.16 4,786 Assumed 3 day average 0.02 214 0.03 223 0.05 229 1,595 southeast Post-Experiment total 0.23 0.31 0.69 19,144 Assumed 15 day average 0.02 214 0.02 223 0.05 231 1,276 southeast Monitoring Period total 2.19 3.39 5.20 30,047 Assumed 56 day average 0.04 209 0.06 217 0.09 223 537 southeast Table 4. Comparison of entrance channel dredging events and littoral drift estimates (total m3/phase and average m3/day for each phase) and directions (degrees true north). See Figure 7 for station locations.
S.G. Watt, 2003 37 --- sand-sized sediment, just that as modeled, it is not directed in a overwhelming southeast littoral current direction at the model locations. Wave heights recorded at the Santa Cruz Harbor array #00601 agree reasonably well with the predicted wave heights calculated independently by the numerical spectral wave refraction model at the same location (Array station), building confidence in the numerical models Sxy calculations (Figure 15). Estimates oflongshore transport at the t!u;ee model stations do not agree with the Santa Cruz Harbor entrance channel dredging records. Model results indicate that there has been very little transport of sediment downcoast during the monitoring period at the model locations. In addition to the results of the spectral wave refraction model, McLaren's (2000) sediment trend analysis of sediment samples collected in the late summer of 1999, also indicate that there is little downcoast littoral drift occurring in the harbor region. The observation that the west jetty at the Santa Cruz Harbor has accumulated more sediment than the east jetty over time (Figure 16), producing a wide beach at Seabright, and the fact that tl1e harbor entrance was dredged eleven times over the course of the monitoring period, indicates that there may be significant transport of sediment to the southeast in littoral drift. One explanation for the differences between model results and the entrance dredging records may be that the spectral wave refraction model locations were located in waters too deep to accurately predict littoral drift. Littoral drift is at its peak near the breaker zone (Komar, 1998), which was inshore of the shallowest model station (Outfall station, 6 meters water depth) for most of the monitoring period. It is possible that increased littoral drift is occurring inshore of the model stations, but it is unlikely due to the nearly parallel approach of waves to the shoreline noted at the wave model Outfall station. Another possible explanation is that littoral drift rates at Point Santa Cruz or at Soquel Point, east of the harbor are likely to be significantly higher than near the harbor due to the increased difference between angles of approaching waves and the shoreline. Waves at Point Santa Cruz break nearly perpendicular to its eastern shoreline. Perhaps this angle produces a littoral drift momentum that the spectral wave refraction model has not accounted for. It is also possible that sand-size sediment near the harbor entrance is simply resuspended during large winter storms and forced into the entrance with storm surge or the rising tide. Once in the protected harbor waters, the sand settles, eventually clogging the harbor entrance.
S.G. Watt, 2003 38 Corrparison of Santa Cruz Harbor Array #00601 and fv'lodel Array Station wave heights (m)
2.00 +--»--···----.;:---·------··---- :E t 1.50 1--"'1-+·H-1:1 " ~
y y ~ !
Figure 15. Comparison of wave heights recorded at Santa Cruz Harbor Array (red) and those predicted independently by the spectral refraction wave model (Array Station location, blue). See Figures 6 and 7 for locations.
Figure 16. Photo shows the wide beach near the west jetty at Seabright Beach in comparison to the east jetty at Twin Lakes Beach and the approximate direction of littoral drift. Photo after Kenneth Adelman, California Coastal Records Project, Copyright© 2002,www.californiacoastline.org.
S. G. Watt, 2003 39 5.5 Sediment sample analyses 5.5.1 Beach sediment samples
Averages and ranges of mean grain diameter and sorting for each beach sediment sampling event are displayed on Table 5, providing a comparison of grain-size parameters over time. Beach samples collected from Cowell's Cove to Moran Lake range from fme- to coarse sand and very-well- to poorly-sorted. Beach samples analyzed during the monitoring period contained virtually no silt or clay, having percentages of99.5% sand class size or larger in all sampling events. Beaches at the start of the Pre-Experiment phase were in "winter profile", meaning there were no well-developed berms or extensive back beaches at most locations. There was evidence that most beaches had at some point been completely submerged to their landward extent, leaving narrow, compacted, flat winter beach profiles. Beaches backed by lagoons or lakes (Figure 17) had been severely eroded by flood waters, creating sea level trenches to the ocean that were increasingly excavated by high tides and large surf. Sand at Twin Lakes Beach was eroded deep enough to reveal wooden pilings protruding out of the low tide beach (Figure 18). Seabright beach just west of the harbor was the exception, maintaining the majority of its width throughout the monitoring period. Wentworth classification of mean grain diameters from analyses of beach samples collected during the monitoring period are graphically displayed in Figures 19, 20, and 21. The experimental dredging event took place in calm wave conditions and during mild weather. Beach sediment samples were collected at night while dredging was taking place to observe any immediate abnom1al beach deposit or odor. Neither were observed. Beaches during the Experiment phase were observed to be in the early stages of rebuilding. At Seabright beach, large cusps were cut into the soft rebuilding beach by high tides. During the high tide at Twin Lakes Beach, the ocean would breach the high tide berm in the evening causing a pool to form on the back beach, recharging the exchange of water between Schwan Lagoon and the ocean.
S.G. Watt, 2003 40 Prc~Experiment I Average Average c ass Range Range c asses mean diameter (mm) 029 medium-sand 0.20 to 0.53 fine to course-sand mean phi size 1.77 medium-sand 2.32 to 0.92 fine to coarse-sand sorting (phi) 0.46 well 0.39to 0.64 well to moderatelv-we\1 Pre-Experiment 2 mean diameter (mm) 0.29 medium-sand 0.17to0.70 fine to course-sand mean phi size 1.77 medium-sand"' 2.56 to 0.52 fine to coarse-sand sorting (phi) 0.53 moderately-well 0.34to 1.37 very-well to poorly Pre~ Experiment 3 mean diameter (mm) 0.27 medium-sand 0.16 to 0.55 fine to coarse-sand mean phi size 1.89 medium-sand 3.11to 0.86 fine to coarse-sand sorting (phi) 0.50 well 0.34 to 0.82 v~_fY-wel\ to moderately Pre-Experiment 4 mean diameter (mm) 0.31 medium-sand 0.19to 0.63 fine to coarse-sand mean phi size 1.69 medium-sand 2.39 to 0.67 fine to coarse-sand sorting (phi) 0.52 moderately-well 0.39to 0.97 well to modenllelv Experiment 1 mean diameter (mm) 0.29 medium-sand 0.19to 0.56 fine to course-sand mean phi size 1.77 medium-sand 2.39to 0.84 fine to course-sand sorting (phi) 0.59 moderately-well 0.41 to 1.62 well to very-poorly Experiment 2 mean diameter (mm} 0.29 medium-sand 0.19to 0.50 fine to coarse-sand mean phi size 1.77 medium-sand 2.39 to 1.00 fine to coarse-sand sorting (phi) 0.51 moderntelv-well 0.37 to 0.64 well to moderately Experiment 3 mean diameter (mm) 0.32 medium-sand 0.20 to 0.53 fine to course-sand mean phi size 1.65 medium-sand 2.32 to 0.92 fine to coarse-sand sorting {phi) 0.56 moderately-well 0.40 to 0.83 well to moderately Post-Experiment I mean diameter (mm) 0.35 medium-sand 0.21to 0.83 fine to course-sand mean phi size 1.52 medium-sand 2.25 to 0.27 fine to coarse-sand sorting (phi) 0.65 moderately-well 0.39 to 1.49 well to poorly Post-Experiment 2 mean diameter (mm) 0.33 medium-sand 0.20 to 0.55 fine to coarse-sand mean phi size 1.60 medium-sand 2.18to0.86 fine to coarse-sand sorting (phi) 0.52 moderately-well 0.40 to 0.72 well to moderately Post-Experiment 3 mean diameter (mm) 0.27 medium-sand 0.19to 0.42 tine to medium-sand mean phi size 1.89 medium-sand 2.39to 1.25 fine to medium-sand sorting {phi) 0.56 moderately-well 0.37 to 0.91 well to moderately
Table 5. Comparison of averages and ranges of grain size descriptive statistics for beach sediment sampling events throughout the monitoring period. Samples are at or above the Best and Griggs (1991) cut-off diameter (0.18 mm) for littoral sediment.
S.G. Watt, 2003 41 a. Erosion at Twin Lakes Beach after a Schwan lagoon flood. Photo taken on February 18,2001 during low-tide looking southeastward from East Cliff Drive. Note house for scale.
b. Erosion of Corcoran beach after a Corcoran lagoon flood. Photo was taken on March 1, 2001 during low-tide looking south (seaward) from East Cliff Drive. Note people for scale.
c. Photo of a trench cut through Moran Beach after a Moran Lake flood, taken on March 13,2001 during low-tide, looking northeastward from the shoreline towards East Cliff Drive. Note person in trench for scale.
Figure 17 a, b, and c. Results of flooding lagoons or lakes (caused by rainstorms) on study area pocket beaches in the Pre-Experiment phase.
S. G. Watt, 2003 42 •• b.
Pre-Experiment phase conditions at Twin Lakes Beach. Sand has been eroded approximately 0.5 meters below the depth of remnant pilings. Photos a and b were taken on March 3, 2001. Photo a was taken looking southeastward and photo b was taken looking westward towards the harbor. Note the house (a) and person in the foreground (b) for scale. Both photos taken during low-tide.
c. d.
Post-Experiment phase conditions at Twin Lakes Beach. Beaches were observed to be in a rebuilding phase ftom winter to summer conditions, exposed pilings have been completely covered. Photo c was shot looking eastward towards Blacks Point and Photo d was shot looking westward towards the harbor. Both photos c and d were shot on Aprill4, 2001. Note people for scale. Both photos taken during low-tide.
Figure 18. Changes in beach sediment accumulation at Twin Lakes Beach, evidence of transition ftom winter profile beaches to rebuilding of summer beaches.
S. G. Watt, 2003 43 r
p"' Wentworth size class ~ J"' @Fine sand N 0 8 (3-2 0!!.!: 0.125-0.25 mm) Q Medium sand (2-1 0!!.!: 0.25-0.50 mm) • Coarse sand (1-0 0!!.!: 0.50-1.00 mm)
Figure 19. Locations and Wentworth size class of beach sediment samples collected during Pre-Experiment phase sampling events I, 2, and 3 from February 18 to March 13, 2001. Each section of the pie chart represents a sampling time (progressing clockwise from high noon) during the Pre- -1'- Experiment phase with a corresponding color code for the Wentworth size class . .p. 'OC!II···.-1}:~,;~ pen .~ Wentworth size class Finesand "'0 @ 8 (3-2 0!!!: 0.125-0.25 mm) Medium sand (2-1 0 or 0.25-0.50 mm)
• Coarse sand (1-0 0 or 0.50-1.00 mm)
Blacks Point
0 !Om llXl 0 l!Xl /;l Figure 20. Locations and Wentworth size class of beach sediment samples collected during Pre-Experiment phase sample event 4 (collected on March 27, 2001, the day before the experimental dredging event) and Experiment phase sampling events from March 28 to March 30, 2001. Each section of the pie chart represents a sampling time (progressing clockwise from high noon) during Pre-Experiment 4 and the lll""" Experimental phase with a corresponding color code for the Wentworth size class. ''iAI~ "<~~L\:5; .. ffi7000 Ol7,000 """"' "'-""' !'!!1000 [/l p Wentworth size class j @ Finesand § -~ (3-2 0 or 0.125-0.25 mm) 0 0"' w Q Medium sand (2-1 0 ill 0.25-0.50 mm) i 4J Coarse sand i (1-0 0 or 0.50-1.00 mm) 0 lOrn ~ Sllil Sllll M.otors ffi7000 """"' """"' 5llll500 '"""" """"' """"' """"' $1000 Figure 21. Locations and Wentworth size class of beach sediment samples collected during Post-Experiment phase sampling events I, 2, and 3 .,. from April I to April 14, 200 I. Each section of the pie chart represents a sampling time (progressing clockwise from high noon) during the 0'> Post-Experiment phase with a corresponding color code for the Wentworth size class. Beach sediment sample descriptive statistics remained consistent over the course of the monitoring period from February 18,2001 to April14, 2001. No sample had a silt and clay percentage of over 0.5%. Redeposition of sand to the beaches in the seasonal rebuilding process did not extensively change the descriptive statistical parameters recorded over time. This suggests that the exchange of sediment between beaches and offshore was of sediment having common relative statistical parameters. It.is important to note that the mean and ranges of beach sediment samples on Table 5 are close to, or above, Best and Griggs (1991) cut-off diameter (0.18 mm) for littoral transported sediment. 5.5.2 Offshore sediment samples A comparison of the averages and ranges of silt and clay percentages, mean grain size diameters, and sorting for offshore sampling events during the monitoring period are showu in Table 6. In general, offshore sediment samples range from very-fme- to very-coarse-sand with some samples containing broken rock, shell fragments, pebbles and attempts where no sample could be recovered after multiple attempts near Point Santa Cruz, Soquel Point and Blacks Point in the nearshore. Offshore sediment samples have a greater variety of mean grain sizes, silt and clay percentages, and sorting values than beach sediment samples. Diverse descriptive statistical ranges are found at many sample locations over time, which can be explained by positional shifts in offshore sample collection (see Methods section above) and the deposition or erosion of sediment that is common in an active high-energy environment such as the Santa Cruz Bight. Figures 22, 23, and 24 graphically depict the locations and the color-coded Wentworth classification of mean grain-size diameters for samples collected in each of the experimental phases over the monitoring period. Samples composed of greater than sand-sized material such as shell hash, pebbles, or those which indicated exposed rock outcrop, and samples in areas where sediment could not be recovered after repeated attempts, were grouped into one category expressed by a red circle. Percentages of silt and clay obtained from grain-size analyses of samples collected during the monitoring period are illustrated in Figures 25, 26, and 27. Percentages of silt and S.G. Watt, 2003 47 Pre-Experiment I Average Average class Range Range classes %silt & clay 3.63 n/a 0 to 14.4 n/u mean diameter (rum) 0.21 fine-sand 0.08 to 0.35 very-fine to medium-sand mean phi size 225 fine-sand 3.64 to 1.51 very-fine to medium-sand sorting (phi) 0.84 moderately . 0.49 to 1.36 well to poorly Pre-Experiment 2 %silt& clay 6.35 n/a 0 to 18.7 n/a mean diameter (rum) 0.27 medium-sand 0.09 to 1.09 very-fine to verv-coarse-sand mean phi size 1.89 medium-sand 3.48 to -0.12 very-fine to verv-coarse-sand sorting {phi) 0.93 moderately 0.57 to 1.42 moderately-well to verv-noorlv Pre-Experiment 3 %silt& clay 3.74 n/a 0 to 25.7 n/a mean diameter (mm) 0.09 verv-fine-sand 0.08 to 1.08 very-fine to very-coarse-sand mean phi size 3.48 verv-fine-snnd 3.64 to -0.11 very-fine to very-coarse-sand sorting (phi) 0.43 well 0.52 to 1.24 modcratclv-well to very-poorly Pre-Experiment 4 %silt & clay 7.72 n/a 0 to23.2 n/u mean diameter (mm) 0.14 fine-sand 0.08 to 0.23 very-fine to fine-sand mean phi size 2.84 fine-sand 3.64 to 2.12 very-fine to fine-sand sorting 0.75 moderatelv-well 0.62 to 1.21 modcratclv-well to poorly Experiment I %silt& clay 7.35 n/a 0 to 24.9 n/a mean diameter (mm) 0.16 fine-sand 0.07 to 0.26 very-fine to medium-sand mean phi size 2.64 fine-sand 3.84 to 1.94 very-fine to medium-sand sorting (phi) 0.76 moderately 0.38 to 1.14 well to poorly Experiment 2 %silt& clay 8.04 n/a 1.72 to 19.5 n/a mean diameter (mm) 0.13 fine-sand 0.09 to 0.22 verv-fine to medium-sand mean phi size 2.94 fine-sand 3.48 to 2.18 very-fine to medium-sand sorting (phi) 0.76 moderately 0.57 to 1.20 moderately-well to poorly Experiment 3 %silt& clay 7.69 n/a 0 to 14.1 n/a mean diameter (mm) 0.13 fine-sand 0.10 to 0.24 very-fine-sand to medium-sand mean phi size 2.94 fine-sand 3.32 to 2.06 verv-fine-sand to medium-sand sorting (phi) 0.85 moderately 0.61 to 1.10 moderately-well to poorly Table 6. Averages and ranges of offshore sediment sample grain size descriptive statistics for sampling events throughout the monitoring period. Continued on next page. S.G. Watt, 2003 48 PostRExperiment I AveraPe Average class Ran•e Ran!!e classes %silt & clay 7.14 n/a 0 to 26.3 n/u mean diameter (mm) 0.21 line-sand 0.09 to 0.54 very-fine to coarseRsand mean phi size 2.26 fineRsand 3.48 to 0.89 very-fine to coarse-sand sorting (phi) 0.88 modemtelv 0.51 to 1.38 moderatelv-wcll to ooorlv PostRExperiment 2 %silt& clay 6.14 nla 0 to 22.5 n/a mean diameter (mm) 0.19 fine-sand 0.09 to 0.54 vcrv-finc to coarse-sand mean phi size 2.39 fine-sand 3.48 to 0.89 very-fine to coarse-sand sorting (phi) 0.85 modemtelv 0.55 to 1.18 moderately-well to poorly Post-Experiment 3 %silt& clay 8.60 nla 0 to 25.5 nla mean diameter (mm) 0.15 fine-sand 0.07 to 0.33 verv-fine to medium-sand mean phi size 2.74 nne-sand 3.84 to 1.60 verv-fine to medium-sand sorting (phi) 0.81 moderatclv 0.36 to 1.40 well to noorlv Table 6. Continued from previous page. clay are broken into six classes from 0 to 25% and greater. Sediment samples that were composed of shell fragments, pebbles, or rock chunks, or where a sample could not be recovered after multiple attempts, received a value of 0% silt and clay and are displayed as gray circles in the figures. The greatest percentage of silt and clay found within any sample over the monitoring period was 26.3% at sample location 7 collected during Post-Experin1ent I on April4, 2001. The highest percentage of silt and clay in samples collected in the Pre-Experiment phase was 25.7% for sample location 14 obtained during Pre-Experiment 3 on March 7, 2001. The highest percent silt and clay found in the Experiment phase was sample location 16 (24.9%) collected during the Experiment 1 sampling event on March 28, 2001 (see Figures 8, 25, 26, and 27). Offshore sediment samples containing over 20% silt and clay in the study area were rare, representing only six of 166 total offshore sediment samples collected (<4%). Sample location 16 (see Figure 8) had the highest number of samples collected with a silt and clay percentage over 20%, sampled three times (March 28th, April 5th, and April 12th) over the course of the monitoring period. S.G. Watt, 2003 49 '!!''~~-"' Wentworth size class @!) Very fine sand (4-3 0 or 0.0625-0.125 mm) @ Finesand (3-2 0 or 0.125-0.25 mm) Q Medium sand (2-1 0 or 0.25-0.50 mm) 41 Coarse sand lOrn (1-0 0 or 0.50-1.00 mm) Q;) ~Q...:.Y e Very coarse sand C3 (0- -1 0 or 1.00-2.00 mm) • 20m 4l Rock. pebbles, shell fragments, >OO 500 M< Figure 22. Locations and Wentworth size class of offshore sediment samples collected during Pre-Experiment phase sampling events I, 2, and 3 from February 28 to March 7, 200 I. Each section of the pie chart represents a sampling time (progressing clockwise from high noon) during the Pre Experiment phase with a corresponding color code for the Wentworth size class. v. 0 wa"'"Jilt\, Cllp :E J; (Exp-3 Pre-4 "'0 0 (3-30) (3-27) "' Exp-2 Exp-1 (3-29) (3-28) Wentworth size class @ Very fine sand (4-3 0 or 0.0625-0.125 mm) @Fine sand (3-2 0 or 0.125-0.25 mm) Q Medium sand (2-1 0 or 0.25-0.50 mm) I'J Coarse sand (1-0 0 or 0.50-1.00 mm) - Verv coarse sand (0- -1 0 or 1.00-2.00 mm) 8 Rock, pebbles, shell fragments, :;so 191 ~L-t Figure 23. Locations and Wentworth size class of offshore sediment samples collected during Pre-Experiment phase sampling event 4 (collected on March 27,2001, the day before the experimental dredging event) and Experiment phase sampling events from March 28 to March 30,2001. Each section of the pie chart represents a sampling time (progressing clockwise from high noon) during Pre-Experiment 4 and the Experiment phase with a corresponding color code for the Wentworth size class. -V> '« 11, 9"' ~ Ji N 0 Post-1 8 (4-2) Post-2 (4-5) Wentworth size class @ Very fine sand (4-3 0 .ru: 0.0625-0.125 mm) @Fine sand (3-2 0 .ru: 0.125- 0.25 mm) Q Medium sand (2-1 0 or 0.25-0.50 mm) • Coarse sand lOrn (1-0 0 .ru: 0.50-1.00 mm) fl) Very coarse sand ~ (0- -1 0 .ru: 1.00-2.00 mm) • • Roc(<, pebbles, shell fragments, ~) 51)(1 M Figure 24. Locations and Wentworlb size class of offshore sediment samples collected during the Post-Experiment phase sampling events from April2 to 12, 200 I. Each section of the pie chart represents a sampling time (progressing clockwise from high noon) during the Post-Experiment phase with a corresponding color code for the Wentworth size class. u, N :;~··'".·.· '">, pC/l .~ N 0 0 w Pre-3 Pre (3-7) (2-28) (T\ Ill\. ., ~(1\ % Silt & clay per sample ~'1'.- \C) 0 Oto5% i"T') 5to10% I/"} ((:) (~ Q '-./ ~- -~- ~ 0 lOto 15% O 15 to20% ((:) ():J O 20to25% ~J:j ~ ~ ·~ ~o ~ • >25% 20m lm SIX! M:lcn Figure 25. Locations and percentages silt and clay in offshore sediment samples collected during Pre-Experiment phase sampling events I, 2, and 3 from February 28 to March 7, 2001. Each section of the pie chart represents a sampling time (progressing clockwise from high noon) during the Pre Experiment phase with a corresponding color code to the percentage of silt and clay per sample. Samples that were composed of shells, pebbles, rock outcrop, or where sediment could not be recovered after multiple attempts were given a value of 0% silt and clay and are colored gray. U> '-' "-'__ , ___?,- __ _ ~'<'!;"' 0"' .~ N 0 0 w Exp-3 l're-4 ~ (3-30) (3-27) § Exp-2 Exp-1 (3-29) (3-28) :/ • § ~ ~- § Q7~ % Silt & clay ner samnle Blacks Point C[~) \ I 0 Oto5% !Om o EB • 5to10% ~ ,L\ ~ ~ 10 to 15% .., f:'; ~ 0 15to20% 0 20to25% CD ' - 1__ -·_-;_-_·•;-1 • >25% ~ \~ ~ 2ln 2511 Mct,-, """"' """" 5l9lJO fi!3!ll() """" """" Figure 26. Locations and percentages of silt and clay in offshore sediment samples collected during Pre-Experiment phase sampling event 4 (collected on March 27, 2001, the day before the experimental dredging event) and the Experiment phase sampling events from March 28 to March 30, 2001. Each section of the pie chart represents a sampling time (progressing clockwise from high noon) during Pre-Experiment 4 and the Experiment phase with a corresponding color code to the percentage of silt and clay per sample. Samples that were composed of shells, pebbles, rock outcrop, or where sediment could not be recovered after multiple attempts were given a value of 0% silt and clay and are colored gray. u, -!'- ,, "'p !iHJlJ -~ N 0 8 ~ Post-1 (4-2) ~ QJ % Silt & clay per sample 0 QJ .(1:) . ) /"'o.v!l;;;::--_ '<:' 'As... ··:_...!Til-..''"•· >t:) ~r~A"" \ . 0 Oto5% 5to10% ~~~ CJ) ~ 0 ~~· w ·~ ~ Q tOto 15% lOrn 0 15to20% (I::J (~ (1) 20to25% ~· ~· 0 Q;'b A·~ • >25% ~ J 20m ~[ll ~lo±J. / ~ ~ ~ '" " !iHJlJ 5l7llXJ !iHJlJ 5BlJO """" """" Figure 27. Locations and percentages of silt and clay in offshore sediment samples collected during the Post-Experiment phase sampling events from April2 to Aprill2, 2001. Each section of the pie chart represents a sampling time (progressing clockwise from high noon) during the Post-Experiment phase with a corresponding color code to the percentage of silt and clay per sample. Samples that were composed of shells, pebbles, rock, or where sediment could not be recovered after multiple attempts were given a value ofO% silt and clay and are colored gray. v. v. In addition to the analysis of sediment samples to determine grain size changes over time, geospatial surface interpolations were computed using Arc View 3.3® Spatial Analyst's IDW surface interpolation method at 75-meter cell-size, using 12 nearest neighbors, to a power of 6. All beach and offShore sediment samples collected over the monitoring period (338 total) were used in the interpolations. Confidence in interpolation results increases with the number of samples used in a particular area. Sediment Sai.)lples that indicated bedrock outcrop, or where sediment could not be recovered after multiple attempts, could not be used in the mean grain size or sorting surface interpolation processes because they do not have numeric values for these parameters (27 samples). Sediment samples collected near Soquel Point indicated rock outcrop 11 out of 12 times, resulting in low confidence in mean grain size and sorting interpolations near Soquel Point, which is considered as a rock outcrop in the interpolations. These samples were used in the silt and clay percentage surface interpolation, using a value 0% silt and clay. Geospatial surface interpolations of mean grain size, sorting, and silt and clay percentage are presented in Figure 28. The interpolation of mean grain size data indicates that beaches are primarily composed of medium-sand, with the exceptions of eastern Seabright Beach (coarse-sand) and Twin Lakes Beach (fine-sand at eastern and western extents). Fine sand grades to very-fme-sand in the middle inshore seafloor of the Santa Cruz Bight. Very coarse-sand offshore of Point Santa Cruz grades to fine-sand along the Point's eastern flank and into Cowell's Cove. The southern offshore region of the Santa Cruz Bight is composed of medium-sand. The sediment sorting interpolation illustrates that beaches are well-sorted, with exception of Seabright Beach (moderately-well-sorted in the west and moderately-sorted in the east) and Moran Lake Beach (moderately-well-sorted). Sediment sorting grades from moderately-well to poorly-sorted eastward and offshore of Point Santa Cruz, at localized patches offshore of the harbor and Blacks Point, and on the southeastern seafloor of the Santa Cruz Bight. According to the results of the silt and clay percentage interpolation, sediment with relatively high silt and clay percentages are deposited in the middle part of the Santa Cruz Bight: near the mouth of the San Lorenzo River, east of Point Santa Cruz, and near Blacks S.G. Watt, 2003 56 r;;::;:1 Very fine sand (11 Coarse sand Lill {4·3 {)!!I 0.062.5 -0.125 mm) (1·0 0 or 0.50- 1.00 mm) Fine sand 8 Ill Very coarse sand Lill {3·20mO.l:!5-0.:!5mm) (0··1 Ogrl.OO-:!.OOmm) Medium sand []Bench 0 {:!·I {) Qf 0.25- 0.50 mm) f0l Low interpolation confidence· W..d Rock outcrop Mean grain size diameters are larger on beaches, offshore • near Point Santa Cruz, and the middle southern section of the Santa Cruz Bight. Sediment grades to very-fine-sand in the middle inshore section of the Bight. rt'lean grain size surface interpolation C2l Well Poorlv tflJ {0.35 to 0.50) • {l.Oto2-0) Moderately well []Bench 0 {0.50 to 0.71) Moderatelv ~ Low interpolation confidence ,,-.. Rock outcrop D {0.71\o 1.0) Sorting is best on the beaches and in the nearshore environments and becomes more poorly sorted in the southwestern and southeastern sections ofthe Santa Cruz Bight. 0 0 to 5% [ill 20 to25% (ll5 to 10% Ill >25% IJ}J I 0 to 15% II] Beach 015 to20% Relatively high sediment silt and clay percentages are deposited in the middle section of the Santa Cruz Bight, away from the shoreline and wave activity. Silt and clay percentage surface interpolation Figure 28. Sediment parameter geospatial surface interpolations were computed using the lOW method gridded to 75-meter cell-size using Arc View 3.3 ®Spatial Analyst. The surface interpolations are average geospatial representations of mean grain size, sorting, and sediment silt and clay percentages from sediment samples (338 total) collected in the Santa Cruz Bight over the monitoring period. The red striped polygon near Soquel Point denotes an area where confidence in the interpolation results are low, and are considered to be rock outcrop. S.G. Watt, 2003 57 Point, away from the shoreline and wave activity. Sediment with silt and clay percentages less than 5% are deposited on beaches and on the seafloor near Point Santa Cruz and Soquel Point. 5.6 Geophysical surveys The experimental dredging event was planned for the winter months to insure that the fine-grained sediment released to the surf-zone would have the best chance of being quickly dispersed by high-energy winter waves. While good for dispersing sediment, high-energy waves are not conducive to the collection of geophysical survey data. The Pre-Experiment survey began in rough weather on February 21, 2001, and had to be terminated a third of the way through due to deteriorating sea conditions. The survey was rescheduled and completed in better weather conditions on March 10, 2001. As a result, there is a certain degree of vertical error in depth measurements (±60 em) associated with the collection of data during times of rough seas. In addition, in the Pre-Experiment survey data, a latency shift error in the acquisition software Isis Sonar® caused a significant roll error to appear in the sonar data. Triton-Elics International greatly improved the quality oftl1e data by supplying a software patch that was applied to the data after the survey. Seafloor features such as rock outcrops, boulders, sandy substrate and sediment waves are easily distinguished in the sonar images. Figures 29 and 30 display the processed multibeam bathymetry and backscatter imagery used in conjunction witl1 the Pre-Experiment phase sediment sample data to create seafloor habitat interpretations. The survey spans from -4 to 18 meters water depth and is roughly 6 km2 in area. Four different benthic habitat types were identified and classified according to the Greene eta!. (1999) classification system (Appendix C). Figure 31 displays multi beam bathymetry and backscatter imagery examples of the four benthic habitat types identified in the images, written descriptions of tl1e benthic habitats, and the attribute codes used in GIS mapping. Features such as scour depressions filled with coarse sediment waves had been previously identified in side-scan sonar records by Anima et al. (2002) and Eittreim eta!. (2002b). The Pre-Experiment phase habitat interpretations descriptions and the survey 2 2 area analysis (in km and m ) are described in Table 7 on Plate 1. S.G. Watt, 2003 58 p"' -~ N 0 0 "' -1- -1- -1- -1- -1- 500 0 500 1000 Meters Figure 29. Pre-Experiment processed multibeam bathymetric image used in conjunction with sediment sample data to produce seafloor habitat interpretations. Black boxes correspond to four different habitat types described in Figure 31. This survey was conducted on '-0"' February 21,2001 and March 10,2001. r •TYf······''x';:~t~-,,..··•··. 0"' ~ N 0 8 500 0 500 1000 Meters Figure 30. Pre-Experiment processed backscatter mosaic used in conjunction with sediment sample data to produce seafloor habitat o-, interpretations. Black boxes correspond to four different habitat types identified and highlighted in Figure 31. This survey was 0 conducted on February 21, 2001 and March 10,2001. Multibeam Image Example Backscatter Image Example Code Description Flat, unconsolidated, well~ to moderately-sorted very~ fine- to medium-sand. with occasional coarse Ssf_b/u sand, pebbles and shell !Tagments on the inner continental shelf. Shallow(< l.5 m) bedrock scours or fractures filled with unconsolidated, poorly-sorted very-fine to very coarse-sand, pebbles and shell fragments on the Smw_b/f/s inner continental shelf. Some scours contain sediment waves, having an approximate wave length of 2 meters und are oriented nearly parallel to Twin Lakes Beach. Patchy rock subcrops dmped in most area'> by an estimated 0-15 em thickness of unconsolidated, Sm_ b/u poorly-sorted, very-fine to very-coarse-sand, pebbles, and shell fragments on the inner continental shelf 29c 30c Flat to low-relief(< 2.0 m) e.\.-posed rock outcrops and occa<;ional boulders on the inner continental Sh(b)/c_f shelf Some have ffactures, ledges, folds, and faults. Patchy kelp forests are associated with most outcrops. 29d 30d Figure 31. The four benthic habitats identified within the study area using multibeam and backscatter imagery in conjunction with sediment sample "groundtruth". Each image is 250 x 250 meters. See Figures 29 and 30 for location of these features within the Santa Cruz Bight. S.G. Watt, 2003 61 Based on sediment sample data and geophysical imagery, the seafloor surface is interpreted to be composed of approximately 50% sand in the very-fme to medium-sand range (shown as Ssf_b/u) that are deposited on flat expanses on the inner shelf and fill what may be ancient, eroded, river channels formed during times of lower sea level (Anima et a!., 2002). Mixed sediment has filled in many current or wave induced scour depressions and fractures (shown as Smw_b/f/s) on the inner shelf and com.Prise about 5% of the study area seafloor. Patchy, mixed sediment covered rock subcrops (shown as Sm_ b/u) on the inner shelf account for -25% of the survey area. Exposed, eroded and locally fractured rock outcrops of low relief (shown as Sh(b)/e_t) on the inner shelf account for the remaining 17% of the study area's seafloor surface. There was no bathymetric or textural evidence in the Pre-Experiment phase geophysical imagery of a dredge deposit or river fan deposit on the seafloor near the San Lorenzo River like the one mapped by Hicks and Inman (1987) after intense flooding of the San Lorenzo River during the 1982-83 El Nino. Post-Experiment phase processed multibeam bathymetry and backscatter images are displayed in Figures 32 and 33. The Post-Experiment phase survey was conducted on April10 and 11, 2001 almost a month after the Pre-Experiment phase survey was completed. The Post 2 Experiment phase survey covered more area (-7 km ) than the Pre-Experiment phase survey 2 area (-6 km ). The Post-Experiment phase survey was executed in calmer sea conditions, which allowed the vessel to map closer to the shoreline, resulting in more seafloor coverage. Like the Pre-Experiment phase geophysical images, there was no bathymetric or textural evidence of a fan deposit near the San Lorenzo River nor a dredge deposit near the experimental dredge outfall in the Post-Experiment phase geophysical images. It is possible that sedimentary mounds may have been produced by the San Lorenzo River and the experimental dredging event that were under the vertical geophysical detection limits (i.e. ±60 em) or that were modified by wave activity between the two surveys. The seafloor conditions imaged during the Post-Experiment phase are very similar to the conditions imaged during the Pre-Experiment phase. Areas of rock outcrop, sediment covered rock subcrop, sand flats and channels, and scour depressions or bedrock fractures filled with mixed sediment were identified in the same general locations and with similar spatial distributions as those identified in the Pre-Experiment phase image interpretations. S.G. Watt, 2003 62 .. "".'·o/···.··f;t~,, CZlp "~ N 0 8 Figure 32. Post-Experiment processed multibeam bathymetric image used in conjunction with sediment sample data to produce seafloor habitat interpretations. The survey was conducted on April!O and II, 2001. The three boxes indicate the locations of three prominent bathymetric features that may affect sediment transport in the Santa Cruz Bight shown in Figures 34 and 35. "'w '"'"l'f'~.,...•... ·•••• Cllp -~ N 0 0 w Figure 33. Post Experiment processed backscatter image used in conjunction with sediment sample data to produce seafloor habitat interpretations. The survey was conducted on April l 0 and ll, 200 l. The three boxes indicate the locations of three prominent ~ bathymetric features that may affect sediment transport in the Santa Cruz Bight shown in Figures 35 and 35. The Post-Experiment phase seafloor habitat interpretation, including an area analysis is presented in Plate 1. Several features imaged on the Santa Cruz Bight seafloor may play significant roles in trapping, diverting, or enhancing sediment transport Increased seafloor coverage of the Post Experiment phase survey, revealed an area of rugged bottom topography in the southeastern margin of the survey. A fracture or fault is image!f (referred to from here forward as the Pleasure Point fault), which trends offshore of Soquel Point and along the coastal cliff to Capitola, approximately 4 km in length (Figure 34). The Pleasure Point fault trends NE-SW (nearly perpendicular to the NW-SE trending, right lateral, strike/slip San Andreas and the roughly N-S trending San Gregorio fault zones that dominate the structure in this region) and may signify a cross-setting fault that accommodates shear stress between the two active major faults (Peacock et al., 1998). Fractures intersect the Pleasure Point fault following the dominant NW-SE trend of the San Andreas fault. Aiello et al. (2001) observed similar NE-SW trending fractures, faults, and carbonate structures in shoreline cliffs and wave eroded platforms located in western Santa Cruz. The exposed, fractured, and eroded bedrock in the sonar imagery is the Pliocene Purisima Formation. The fractures control erosion in the bedrock creating ledges and low-lying troughs where sediment has accumulated, and which may partially obstruct sediment transport downcoast around Soquel Point. Observations made during beach and offshore sediment sampling events indicate that Soquel Point, and the abrupt change in bathymetry created by the Pleasure Point fault offshore, magnify local wave heights. Another interesting bathymetric feature in the seafloor imagery is an irregularly shaped rock outcrop shelf extending southwestward offshore of Blacks Point (Figure 35). This bathymetric feature may also be the result of shear stress accommodation between the San Andreas and San Gregorio fault zones in the form of cross-setting faults. The ledge rises -2- meters above the surrounding flat sandy seafloor and may act as an obstruction to littoral drift downdrift from Twin Lakes Beach or may alter nearshore currents, diverting sediment transport offshore. The downcoast (or eastern) side of the ledge may provide a low lying, wave protected area for fine-sediment accumulation on the seafloor, resulting in the relatively high sediment silt and clay percentage interpolation illustrated in Figure 28. S.G. Watt, 2003 65 Post-Experiment multibeam A possible fault or fracture (dashed red line) in the Pliocene Purisima Formation revealed in the Post-Experiment multibeam image follows the trend of the coastline from offshore of Soquel Point to Capitola, almost 4 Ian. The black box locates the offshore imagery of the fault pictured above right and in the 3D-perspective image below. The Pleasure Point fault trends NE-SW (nearly perpendicular to the NW-SE trending, right lateral, strike/slip San Andreas and roughly N-S trending San Gregorio fault zones that dominate the structure in this region) and may signily a cross-setting fault which accommodates shear stress between the two major faults. NE-SW trending fractures intersect the Pleasure Point fault and are marked by dashed black lines. 3D-perspective image. Vertical exaggeration= 5 times Fractures intersecting the Pleasure Point fault (dashed black lines) and the faults fracture axis (dashed red line) have produced ledges and low-lying areas (- 2 meters in vertical relief) which have trapped sediment and which may impede sediment transport downcoast. Observations made during sediment sampling events indicate that Soquel Point and the abrupt change in bathymetry created by the Pleasure Point fault magnify local wave heights Figure 34. Possible fault revealed in the Post-Experiment multibeam and backscatter imagery offshore of Soquel Point. S.G. Watt, 2003 66 Post-Experiment multibeam image 3D-perspective image. Vertical exaggeration= 5 times. a. A flat rock-shelf extends offshore of Blacks Point that may impede, alter or enhance littoral sediment transport. The shelfs edges are steep, dropping 2-meters into flat, sandy channels. Dashed red lines in the images mark features which may indicate additional NE-SW cross-setting faults. The blue oval indicates the location of a fine sediment pocket described in Figure 28. Point Santa Cruz Post-Experiment multibeam image b. A channel, or depression on the seafloor off Point Santa Cruz (which may have formed as a result oftectonics, ancient river flow, or both) is up to 18 meters deep. Observations indicate that the relatively deep and steeply sloping channel magnifies wave-energy in this location and possibly increases littoral sediment transport. Figure 35. Post-Experiment multibeam and 3D-perspective imagery (vertically exaggerated 5 times) highlights features on the seafloor that may have a significant impact on sediment transport in the Santa Cruz Bight. Top figures (a) highlight a rock outcrop extending offshore from Blacks Point, and bottom figure (b), a deep channel (or depression) just offshore of Point Santa Cruz. See Figure 32 and 33 for locations of these features in the Santa Cruz Bight S.G. Watt, 2003 67 A relatively deep channel (or seafloor depression) is imaged on the seafloor offshore of the eastern flank of Point Santa Cruz in the Post-Experiment multibeam imagery (Figure 35). The seafloor feature may have been eroded by San Lorenzo River flow in times oflower sea level (Anima et. a!., 2002), may be the result of fault activity, or a combination of both. This feature is the deepest location (18 meters water depth) mapped in the Santa Cruz Bight. Observations made during offshore sediment sampling events indicate that Point Santa Cruz and the abrupt change in bathymetry near the channel magnify wave heights at this location. Using the Spatial Analyst extension in ArcView3.3®, the seafloor habitat interpretations of the two surveys were geographically intersected and analyzed (see Figure 10) to produce the sediment shift map shown on Plate 1. The sediment shift map highlights locations in the Santa Cruz Bight where habitat types changed over the monitoring period, which indicate sediment erosion, deposition, or no habitat changes. The explanation table (Table 8) in Plate 1 describes the type of shifts that were identified and quantifies the areas (in 2 meters ) and percentages for each shift type in the Santa Cruz Bight. The GIS sediment shift area analysis, calculated by comparing the Pre-Experiment and 2 Post-Experiment habitat interpretations, indicates that approximately -86% (-5 km ) of the 2 seafloor habitats had not changed,- 8% (-476,000 m ) had undergone sediment deposition, 2 and -6% (-317,000 m ) had been eroded of sediment in the time between the two surveys. Therefore, a net total of -160,000 m2 of sediment was deposited between the two surveys. The majority of sediment deposition occurred in deeper waters (-12 m water depth and deeper) in the southern middle region of the Santa Cruz Bight, which consisted of primarily sand-sized sediment based on grain-size analysis results. The greatest amount of sediment erosion occurred in shallow depths (<10m water depth) in the northeastern region of the study area. The sediment shift map cannot indicate sediment transport directions or magnitude, or sediment sources. It is not possible to account for the shifts in sediment that are undoubtedly taking place on many of the areas categorized as "no habitat change". The methods used cannot resolve vertical changes on the seafloor under ±60 em due to the vertical roll error problem previously described in the Pre-Experiment geophysical survey data explanation. S.G. Watt, 2003 68 6. Discussion The data collected in the Santa Cruz Bight suggests that the monitoring period occurred during a seasonal transition from high-energy winter conditions to mild spring/summer conditions. Time-series data analyzed from the San Lorenzo River illustrates a decline in stream flow (and sediment discharge) over the monitoring period (Table 3 and Figure 11). Oceanographic data analyzed over the monitoring period shows a distinct change in wave climate from long period northwest swells to short period, locally derived wind swells (Figure 14). Photographs at Twin Lakes Beach indicate that sand returned to local beaches over the monitoring period (Figure 18). Recorded sediment inputs into the Santa Cruz Bight over the monitoring period were dominated by harbor entrance charmel dredging, followed by input from the San Lorenzo River, and lastly the experimental dredging event. Beach sediment sample grain size parameters did not show any sign of silt and clay retention throughout the monitoring period with sediment samples having 99.5% sand compositions or greater. Offshore sediment sample grain size parameters had a broader range than beach sediment samples, and in some locations, relatively high silt and clay concentrations (up to 26.3%) were sampled. The mud present in samples may be the result of experimental dredging sediment input, sediment from another source, is a natural sediment size for the Santa Cruz Bight, or a combination of all three. Other investigators (Wolf, 1970; Arnal et al., 1973; Best and Griggs, 1991; Edwards, 2002) did not find evidence of high silt and clay percentages in sediment samples collected in the Santa Cruz Bight. In addition, McLaren (2000) found similar grain size distributions in samples collected in late summer of 1999 (prior to experimental dredging), including areas that he described as "muddy sand" near locations in this study where over 20% concentrations of silt and clay were found (sample location 16 in Figure 8). Nearly 25% silt and clay composition samples (although rare) were collected throughout all phases of the monitoring period, suggesting that sediment containing 25% mud are normal for the Santa Cruz Bight. New mapping techniques, data integration, synthesis and comparison in a GIS framework provides small-scale details about sediment deposition and transport in the Santa Cruz Bight, adding new information to the current base of large-scale coastal and shelf processes knowledge in the northern Monterey Bay (previously illustrated in Figure 2). Diverse S.G. Watt, 2003 69 coastline orientations, unique bathymetric features, and wide ranging sediment parameters interacting with waves of varying intensities traveling from an array of different angles creates a complex range of possibilities for sediment transport and deposition in the Santa Cruz Bight. The synthesis of the data collected in this study suggests that the Santa Cruz Bight can be divided into three distinct sedimentary environments that were controlled by the interaction of wave-energy, coastline orientation and bathymetric features over the monitoring period. These sedimentary environments are defined as High-Energy Points, Beaches and Inshore, and Mixed Sediment Flats, and are illustrated in Figure 36. 1. High-Energy Points This sedimentary environment is defined as the shorelines and surrounding seafloors adjacent to Point Santa Cruz and Soquel Point, the western and eastern extents of the Santa Cruz Bight. Observations, numerical wave model results (Table 4), and the presence of sediment waves oriented parallel to the Twin Lakes Beach shoreline (Figure 31 ), leads to the conclusion that waves approach the Santa Cruz Bight inner shoreline at a nearly parallel angle. Waves approaching parallel to the inner Santa Cruz Bight shoreline run perpendicular to the eastern flanks of Point Santa Cruz and Soquel Point (Figure 3 ). This creates a climate of greater sediment transport rates at the two points than in other environments within the Santa Cruz Bight. Wave-energy converges on Point Santa Cruz and Soquel Points, producing higher wave heights at these locations than the inner beaches or middle section of the Santa Cruz Bight. Abrupt changes from relatively deep to shallow bathymetry occur at the charmel imaged near Point Santa Cruz (Figure 35) and the Pleasure Point fault offshore of Soquel Point (Figure 34), further magnizying wave heights. High wave-energy at these locations has exposed and may erode rock outcrops on the seafloor, and transport fine-sand and smaller grain-size sediments to calmer environments. More difficult to transport poorly-sorted coarse-grained sediment has been trapped in the charmel and in other low-lying depressions and fractures over the monitoring period (Figure 28). S.G. Watt, 2003 70 - - Wave climate Habitats, bathymetry and littoral drift Grnin~size and sediment shifts Synopsis Waves transport fine-sand Highest wave~energy Poorly-sorted very- Seafloor composed of rock outcrop, and smaller grain size locations. Wave-energy is coarse-sand offshore sediment covered subcrop, and sediment to calmer focused on Point Santa Cruz Point Santa Cruz to mixed sediment filled scours. A environments, leaving and Soquel Point and modcrutely-well-sortcd fault or fracture ncar Soquel Point High poorly-sorted course-grnined refracted to break fine-sand in Cowell's und a deep water channel (or sediment and exposing rock Energy perpendicular to both points Cove. Offshore Soquel depression) near Point Santa Cruz outcrop. An erosional Points eastern flanks, creating the Point is generally rock magnifY local wave heights (Figure environment for fine~sand greatest potential for littoral outcrop and subcrop. 34 and 35). Erosion of sand and smaller sediment sizes drift in the Santa Cruz Bight Sediment silt and clay occurred most often where sediment and depositional for coarse (Figure 3). percentages are < 5%. shifts could be identified in Plate I. sediment. Sand has been well~sorted by Waves approach parallel to Downcoast littoral sand transport consistent low to moderate the inner Santa Cruz Bight Wcll~sorted medium~ may be blocked or diverted by the wave-energy and winnowed shoreline, producing low sand on beaches grades west harbor jetty and Blacks PoinL of silt and clay. Sand moves Beaches potential for littoral drift to moderately-well- Offshore, sand channels are from beaches to offshore and during low to moderate wave sorted fine-sand interspersed with rock outcrops and sand bars with seasonal conditions (see Figure 3 and otl5hore. Sediment silt Inshore subcrops. Deposition was observed transitions. An erosional or Table 4). Extreme stonn and clay percentages on local beaches while erosion depositional environment events episodically erode range from 0% to 5%. occurred mostly offshore (Plate I). depending on season and D beaches completely. wave intensity. Calmest wave-energy Seafloor is a flat to gently sloping location. Waves approach expanse of mixed-sediments, Patchy mixed-sediment A matrix of mixed sediments parallel to the inner Santa subcrop, sparse outcrop, and mixed- from moderately-well are episodically transported Cruz Bight (Figure 3). The sediment filled scours. A rock shelf sorted very-fine-sand and deposited over time as a Mixed seafloor is generally too extends offshore from Blacks Point to poorly-sorted function of varying wave Sediment deep to be modified by low (Figure 35) that may affect sediment medium-sand. intensity, water depth, and wave-energy, is modified transport. Erosion occurred Flats Sediment silt and clay grain-size. Erosion and periodically by moderate southeast of the Blacks Point rock percentages range from deposition may occur wave-energy, and is shelf, while the southern offshore 0 to26.3%. simultaneously. D modified episodically by region was dominated by deposition extreme stonn events. (Plate 1). Figure 36. Illustrations and descriptions of Santa Cruz Bight sedimentary environments that existed over the monitoring period; a wave dominated depositional system. S.G. Watt, 2003 71 2. Beaches and Inshore This sedimentary environment includes the Santa Cruz Bight beaches from Cowell's Cove to Moran Lake and extends offshore to- 7 meters water depth (Figure 36). Terrestrial coastal features such as the west Santa Cruz Harbor jetty and Blacks Point may impede or divert downdrift (southeast) littoral sediment transport. Offshore sand channels are interspersed with flat rock outcrops and sediment draped subcr?ps (Plate 1). Refraction to parallel wave approach into the Santa Cmz Bight causes a decrease in wave-energy and low littoral drift rates at the Santa Cruz Bight beaches (Figure 3). Consistent, low to moderate wave-energy has produced a sedimentary environment primarily of well sorted medium-sand containing little to no silt and clay sediment (Figure 28). Sand moves from beaches to offshore sand bars and returns with seasonal transitions. Over the monitoring period, deposition of sand was observed on local beaches, while the sediment shift map in Plate 1 indicates that erosion of sand occurred in the Santa Cruz Bight nearshore. 3. Mixed Sediment Flats This sedimentary environment is offshore from the High-Energy Points environment and inner Santa Cruz Bight shoreline extending offshore from -7 meters water depth. The seafloor is a flat to gently sloping expanse of sporadic, very-fine to coarse-grained poorly sorted sediment, subcrop, sparse outcrop, and mixed-sediment filled scours. A rock ledge extending from Blacks Point may divert sand offshore and provide a wave protected depositional area for fine-sediment on the eastern side of the 2-meter high ledge (Figures 28 and 34). With wave-energy focused on and refracted by Point Santa Cruz and Soquel Point at the eastern and western extents of the Santa Cruz Bight, the Mixed Sediment Flats sedimentary environment is the lowest wave-energy environment in the Santa Cmz Bight. The seafloor is generally too deep to be modified by locally derived wind wave-energy, is modified periodically by moderate wave-energy, and is modified episodically by extreme storm events. This produces an environment where sediment deposition and erosion may occur simultaneously. Sediment erosion occurred southeast ofthe Blacks Point rock shelf during the monitoring period, while the southern offshore region was dominated by deposition. Over all, S.G. Watt, 2003 72 this sedimentary environment experienced a net deposition of sediment over the monitoring period (Plate 1 ). The sedimentary environments identified over the monitoring period establish a strong comparative baseline for future dredging events or other sedimentological studies. To better understand the full extent of weather patterns and how they affect the sedimentary environments in the Santa Cruz Bight, it would b$! necessary to monitor the environment at least over the course of a year so that the changes between the intense dynamic winter season and the calmer summer season could be completely observed. A good comparison to this winter/spring study would be a similar study conducted in late summer, when the river and streams have stopped flowing, when wave action is less intense, when the harbor entrance does not need to be dredged, and after the beaches have completely rebuilt. A more complete picture of the study area could be described following an El Nino/Southern Oscillation event when weather conditions are most extreme and capable of causing dramatic coastal change. 7. Conclusions The integration and analysis of the data collected during the Santa Cruz Small Craft Harbor experimental dredge monitoring period from February 18,2001 to April14, 2001lead to several conclusions: I. The Experimental dredging event monitoring period occurred during a seasonal transition from late winter to spring conditions. 2. Sand, silt, and clay sediment released during the experimental dredging event (or input from other sediment sources) were traceable using a methodology of GIS integrated grain-size and geophysical imagery and did not substantially change the beaches or alter the sedimentary characteristics of offshore benthic habitats. 3. Different sedimentary environments existed over the monitoring period in the Santa Cruz Bight that are controlled by the interaction of wave-energy, coastline orientation, and bathymetric features. S.G. Watt, 2003 73 4. New quantitative GIS-based mapping techniques and methodologies have established a strong baseline for comparison to future dredging events or other sedimentological studies in the Santa Cruz Bight. The monitoring program methodology used in this study could be improved with the use of new emerging technologies. The data gap J:>etween the beaches and offshore environment could be bridged using airborne bathymetric light detecting and ranging (LIDAR) technology, such as the SHOALS 1000 system, to provide a seamless digital grid between land elevation and seafloor bathymetry. Accuracy corrections made with Real-Time Kinematic (RTK) GPS data collection could greatly in1prove the vertical resolution ofmultibeam data to centimeter to tens of centimeters scale. This would allow two gridded data sets to be spatially 3 "subtracted" in GIS to calculate volumes (m ) of sediment that had eroded or deposited over time, including areas described in this study as "no habitat change" where sediment shifts could not be resolved, in place of comparing and intersecting subjective habitat interpretations 2 in two dimensions (m ). The San Lorenzo River, just a kilometer west of the harbor, has released an estimated 212,500 m3 of multi-grain sized sediment on an annual basis to the Santa Cruz shelf and has done so over periods of decades and possibly centuries. Even with this amount of multi-grained sized sediment discharge, a high percentage of silt or clay has not been sampled within the Santa Cruz Bight. The episodic high-energy nature of this coastline (especially in the winter months, from November to April) is of sufficient magnitude to suspend the majority of silt and clay sediment delivered to the study area by any source, including harbor dredging. The silt and clay is most likely transported to deeper waters offshore, outside of the study area (30m and greater water-depths) and deposited on the midshelfmudbelt. Past and present research has identified the midshelf mudbelt to be the largest sink of silt and clay sediment in northern Monterey Bay and that deposition of mud sediment continues in that location (Greene, 1977; Edwards, 2002; Lewis et al. 2002; Eittreim eta!. 2002). S.G. Watt, 2003 74 Acknowledgments This research was made possible by funding from the California Department of Boating and Waterways and the Santa Cruz Port District. Special thanks to my major advisor Dr. H. Gary Greene and committee members Dr. Ivana Aiello, and Dr. Mike Graham. I would like to thank the Santa Cruz Port District and the Harbor Patrol for their help and patience with this project, specifically Port Director Brian Foss, Op~rations Manager Kimbra Eldridge, Ron Duncan (Maintenance Services), and Harbormaster Larry White. Thanks to Nisse Goldberg for her ecological assessment and research dives with the help of John Heine and Heather Spaulding near the harbor to keep this project going. Thanks to Dr. Rikk Kvitek and Pat Iampietro of CSUMB SFML. I would also like to thank Kevin O'Toole of the USGS for the use of a grab sampler on such short notice, John Haskins for the use of his Niskin bottle and nephelometer, and Dr. William O'Reilly for generously running his wave model. Thanks to Kenneth Adelman of the California Coastal Records Project for the use of his Santa Cruz aerial photos. Conversations, suggestions and comments regarding this study by Dr. Tracy Vallier greatly improved the quality of this work. 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Marine Biology.48: 343-348 Folk, R.L., 1974, Petrology of Sedimentary Rocks, Hemphill Pnb. Co., Austin Texas, 182pp. Foss, B, 1999, Impact of Santa Cruz Harbor Dredging Disposal Sediment on Kelp Forest at Twin Lakes Beach, Santa Cruz Port District Report to CDF&G, MBNMS, U.S. Army Corp of Engineers, CARWQCB, and California Coastal Commission. Foster, M.S. and Schiel, D.R. 1985. The ecology of giant kelp forests in California: A community profile. United States Fish and Wildlife Service Biological Report 85, 152 pp. Edwards, B.D. (2002). Variations in sediment texture on the northern Monterey Bay National Marine Sanctuary continental shelf. Mar. Geol. vol. 181, pp. 83-100. Eittreim, S.L., Xu, J.P., Noble, M., Edwards, B.D., (2002a). Towards a sediment budget for the northern Monterey Bay continental shelf. Mar. Geol. vol.181, pp. 235-248. Eittreim, S.L., Anima, R.J., Stevenson, A.J.,(2002b). Seafloor geology of the Monterey Bay area continental shelf. Mar. Geol. Vol. 181, pp. 3-34. Goldberg, N., Foster, M. and Watt, S.G., (2000). Expected dredge material transport and habitats at risk within the vicinity of The Santa Cruz Small Craft Harbor. Prepared for S.G. Watt, 2003 76 Mr. Brian Foss, Port Director of the Santa Cruz Small Craft: In response to the California Coastal Commission request. Greene, H.G., 1977. Geology of the Monterey Bay region. US Geological Survey Open-File Report OF 77-718,347 pp. Greene, H. G., 1990. Regional tectonics and structural evolution of the Monterey Bay region, Central California. In: Garrison, R.E., Greene, H.G., Hicks, K.R., Weber, G.E., Wright, T.L., (Eds.), Geology and Tectonics of the Central California Coastal Region, San Francisco to Monterey. Pacific Section of the American Association of Petroleum Geologists Guidebook vol. 67, pp. 31-56. Greene, H. G. and Clark, J.C., 1979. Neogene Paleogeography of the Monterey Bay Area, California. lN: Cole, M.R., Ter-Best, H., Armentrout, J. (Eds.), Cenozoic Paleogeography of the Western United States. Pacific Section SEPM, Pacific Coast Paleogeography Symposiwn vol. 3, pp. 277-296. Greene, H.G., M.M. Yoklavich, R.M. Starr, V.M. O'Conoell, W.W. Wakefield, D.E. Sullivan, J.E. McRea Jr., and G.M. Cailliet, 1999. A classification scheme for deep seafloor habitats. Oceanologica Acta. vol 22: 6. pp. 663-678 Griggs, G.B., 1987, Littoral cells and harbor dredging along the California coast, Environmental Geology and Water Sciences, v. 10, n. 1, p. 7-20. Griggs, G.B., Hein, J.R., 1980, Sources, dispersal, and clay mineral composition of fine grained sediment off central and Northern California, Journal of Geology, vol. 88 p. 541-566. Griggs, G.B., Johnson, R.E., 1976, Effects of Santa Cruz Harbor on coastal processes of northern Monterey Bay, Califomia, Environmental Geology and Water Sciences v. 1 n. 5, p. 299-312. Griggs, G. and Savoy, L., 1985, Living with the California Coast, Duke University Press, Durham, North Carolina, 394 pp. Harville, J.P. ( ed. ). 1971. Environmental Studies of Monterey Bay and the Central California Coastal Zone. Moss Landing Marine Lab. Anoual Report, 113pp. Heimlich-Boran, J.R. 1988. Marine Resources and Human Activities in the Monterey Bay Area Center for Environmental Education, April 1988. Hicks, D.M., Inman, D.L., 1987, Sand dispersion from an ephemeral river delta on the central California coast, Marine Geology, v. 77, p. 305-318. S.G. Watt, 2003 77 Komar, P.D., 1998, Beach Processes and Sedimentation, Second Edition: Prentice Hall Inc. Simon & Schuster/ A Viacom Company, Upper Saddle River, New Jersey, 544pg. Leet, W., C. Dewees and C. Haugen (eds). 1992. Califronia's living marine resources and their utilization. California Sea Grant Extension Program. 257 pp. Lewis, R.C., Coale, K.H., Edwards, B.D., Marot, M., Douglas, J.N., Burton, E.J., 2002. Accumulation rate and mixing of shelf sediments in the Monterey Bay National Marine Sanctuary. Mar Geol. vol. 181, pp. 157-169. McLaren, P. 2000. A Sediment Trend Analysis (STA®) of Santa Cruz Harbor and its Vicinity: Implications to Dredge Disposal Operations. Prepared for the Santa Cruz Harbor and The California Department of Boating and Waterway by GeoSea Consulting (Canada) Ltd. 789 Saunders Lane, Brentwood Bay, B.C. V8M IC5, Canada Mullins, H.T., Nagel, D.K., Dominguez, L.L., 1985. Tectonic and eustatic controls oflate Quaternary shelf sedimentation along the central California (Santa Cruz) continental margin: high-resolution seismic stratigraphic evidence. Sed. Geol. 44, 327-347. Oliver, J.S. 1980. Processes affecting the organization of marine soft-bottom communities in Monterey Bay, California and McMurdo Sound, Antarctica. PhD Thesis, Univ. Calif., San Diego. Oradiwe, E.N., 1986, Sediment Budget for Monterey Bay. M.S. thesis, U.S. Naval Post Graduate School, Monterey California, 10 I pp. O'Reilly, W.C. and Guza, R. (1993). A Comparison of two spectral wave models in the Southern California Bight, Coastal Engineering, vol. 19, p263-282. Peacock, D.C.P., Anderson, M.W., Motris, A., Randall, D.E., (1998) Evidence for the importance of 'small' faults on block rotation. Tectonophysics, vol. 299; 1-13. Rose, D.K. 1979. The understory algal associations in six central California kelp forests. California State University, Hayward. Masters' thesis. 117 pp Solonsky, A. C. 1983. Fish colonization and the effect of fishing activities on two artificial reefs in Monterey Bay, Califomia. California State University, San Francisco. Masters' thesis. 55 pp. Storlazzi, C.D., Field, M.E., 2000, Sediment Distribution and transport along a rocky, embayed coast: Monterey Peninsula and Carmel Bay, California. Mar. Geol. vol. 170, pp. 289- 316. S.G. Watt, 2003 78 Sullivan, M., Krcik, S.E., 1999, Sediment Sampling and Analysis Report for North Harbor Sediments, RRM Engineering and Contracting Firm, prepared for the Santa Cruz Port District. Sullivan, M., Krcik, S.E., 2000, Sediment Sampling and Analysis Report for Entrance Sediments, RRM Engineering and Contracting Firm, prepared for the Santa Cruz Port District. Starr, R.M., Cope, J.M., Kerr, L.A., 2002. Trends in Fisheries and Fishery Resources Associated with the Monterey Bay National Marine Sanctuary from 1981-2000 Published by the California Sea Grant College Program University of California, San Diego, La Jolla, California 92093. Thompson, J.P. 1982. Benthic illumination within aMacrocystis bed at Pt. Soquel, Santa Cruz, California, and its influence upon Macrocystis population structure and the abundance of benthic red algae. University of California, Santa Cruz. Masters' thesis. 110 pp. U.S. Fish & Wildlife Service, 2001. Western Snowy Plover (Charadrius alexandrinus nivosus) Pacific Coast Population Draft Recovery Plan. Portland, Oregon. xix + 630 pp. Weigel, R.L., 1964. Oceanographic engineering: New York. Prentice Hall. 532 p. Wolf, S.C.l970, Coastal currents and mass transport of surface sedin1ents over the shelf regions of the Monterey Bay, California, Marine Geology, v. 8, n. 5, p.321-336. Wong, F.L. and Eittreim, S.L., (2002) Continental shelf GIS for the Monterey Bay National Marine Sanctuary. Mar. Geol. vol. 181, pp. 317-321. Xu, J.P. 1999. Local wave climate and long-term bed shear stress characteristics in Monterey Bay, CA. Mar. Geol. vol. 159, pp. 341-343. Xu, J.P., Noble, M., Eittreim, S.L., (2002). Suspended sediment transport on the continental shelf near Davenport, California. Mar. Geol. vol. 181, pp. 171-193. S.G. Watt, 2003 79 Appendix A. Beach sediment sample database tables S.G. Watt, 2003 80 r.·..' Pre-Experiment Sediment Samples MEAN 10 DATE EASTING NORTHING %:>SAND %SAND %MUD MODE(S) MEAN (mm) SORTING DESCRIPTION prtb 21 2/tB/2001 586841.9769 4090957 233 0.00 100.00 0.00 ~10 1.85 0.28 well medium sand prtb21r 211812001 566841.9769 4090957.233 0.00 100.00 0.00 2.10 1.85 0.28 well medium sand prtb 22 2/1612001 587240.3094 4091183.218 0.00 100.00 0.00 2.10 1.87 0.27 WEll medium sand pr1b 23 2/tB/2001 587684.6224 4091265.464 0.00 100.00 0.00 ~20 1.95 0.26 wall medium sand pr1b up riv 2/1612001 587860.0239 4091522.462 0.00 99.88 0.12 ~90 2.20 0.22 wall fine sand pr1b 24 2/1612001 588041.0575 4091235.872 0.00 100.00 0.00 2.00 1.58 0.33 wall medium sand moderately pr1b 25 2/1812001 588397.611 4091195.201 0.00 100.00 0.00 2.00 1.27 0.41 well medium sand moderately prtb 26 211812001 588710.4087 4091076.423 0.00 100.00 0.00 1.20 0.92 0.53 well coarse sand pr1b27 211812001 588959.6539 4091067.94 0.00 100.00 0.00 2.60 2.11 0.23 well fine sand prtb 28 2/18/2001 589138.1364 4091047.621 0.00 100.00 0.00 220 1.94 0.26 well medium sand pr1b2Br 2/18/2001 589138.1364 4091047.621 0.00 100.00 0.00 2.20 1.94 0.26 well medium sand prtb 29 2/18/2001 589290.1795 4090982.651 0.00 100.00 0.00 2.10 1.79 0.29 well medium sand pr1b 30 2/1812001 589405.3806 4090939.495 0.00 100.00 0.00 2.10 1.79 0.29 well medium sand pr1b 31 2/1812001 589514.0315 4090862.966 0.00 100.00 0.00 210 1.74 0.30 well medium sand pr1b32 2/1812001 589603.5271 4090819.531 0.00 100.00 0.00 2.90 2.09 0.23 well fine sand pr1b 33 211812001 590315.983 4090804.896 0.00 100.00 0.00 2.10 1.61 0.33 well medium send prtb 34 2/1812001 590584.8432 4090541.338 0.00 100.00 0.00 210 1.46 0.36 well medium sand pr1b 35 2/18/2001 590943.1018 4090445.461 0.00 100.00 0.00 2.10 1.44 0.37 well medium sand moderately pr1b 36 2/16/2001 589003.7842 4091123.875 0.08 99.92 0.00 2.80 2.11 0.23 well fine sand pr1b 37 2/16/2001 589199.5206 4091137.026 0.00 100.00 0.00 2.90 2.13 0.23 well fine sand pr1b 38 2/1612001 589307.167 4091060.494 0.00 100.00 0.00 2.80 2.10 0.23 well fine sand pr1b 39 2/18/2001 589602.7069 4090897.187 0.00 100.00 0.00 2.90 2.29 0.20 well fine sand pr2b 21 3!1/2001 566841.9769 4090957.233 0.00 100.00 0.00 2.30 1.96 0.26 well medium sand pr2b 22 3/1/2001 587240.3094 4091183.218 0.00 100.00 0.00 2.90 2.13 0.23 well fine sand pr2b22r 3/112001 587240.3094 4091183.218 0.00 100.00 0.00 2.90 2.11 0.23 well fine sand pr2b 23 3/112001 587684.6224 4091265.464 0.00 100.00 0.00 3.00 2.54 0.17 well fine sand pr2b up riv 3/112001 587860.0239 4091522.462 0.00 99.93 0.07 2.90 2.17 0.22 well fine sand pr2b 24 3/1/2001 588041.0575 4091235.872 0.00 100.00 0.00 2.00 1.65 0.32 very well medium sand pr2b 25 3/1/2001 588397.611 4091195.201 0.00 100.00 0.00 2.00 1.62 0.32 well medium sand pr2b26 311/2001 588710.4687 4091076.423 0.00 100.00 0.00 2.00 1.46 0.36 well medium sand pr2b 27 3/1/2001 588959.8539 4091067.94 0.00 100.00 0.00 2.00 1.79 0.29 well medium sand moderately pr2b28 311f2001 589138.1364 4091047.621 0.00 100.00 0.00 2.10 1.92 0.26 well medium sand moderately pr2b 29 3!112001 589290.1795 4090982.651 0.00 100.00 0.00 2.10 1.81 0.26 well medium sand moderately pr2b 30 3/112001 589405.3806 4090939.495 0.00 100.00 0.00 2.10 1.79 0.29 well medium sand pr2b 31 31112001 589514.0315 4090862.966 0.00 100.00 0.00 2.20 1.96 0.2£ well medium sand pr2b 32 3/112001 589603.5271 4090819.531 0.00 100.00 0.00 2.40 1.87 0.27 well medium sand pr2b 33 311/2001 590315.983 4090804.896 0.00 100.00 0.00 2.00 1.59 0.33 well medium sand pr2b 34 3/112001 590584.8432 4090641.338 0,00 100.00 0.00 2.00 "1.23 0.43 well medium sand pr2b 35 3/1/2001 590943.1018 4090445.461 16.59 83.41 0.00 ·1, 1.9 0.51 0.70 poorly coarse sand pr2b 36 3/1/2001 589003.7842 4091123.875 1.18 9a51 0.31 250 1.91 0.27 moderately medium sand pr2b 37 311/2001 589199.5206 4091137.026 0.00 99.90 0.10 3.00 2.30 0.20 wall fine sand pr2b 38 3/1/2001 589307.167 4091060.494 0.00 100.00 a_oo 2.20 1.97 0.26 well medium sand moderately pr2b 39 31112001 589602.7069 4090897.187 0.00 100.00 0.00 3.00 2.36 0.19 well fine sand pr3b 21 311312001 586841.9769 4090957.233 0.00 100.00 0.00 2.28 0.21 well fine sand pr3b 22 3/1312001 587240.3094 4091183.216 0.00 100.00 0.00 2.16 0.22 well fine sand pr3b 23 3113/2001 587684.6224 4091265.464 0.00 100.00 0.00 2.16 0.22 well fine sand pr3b up riv 3/1312001 587660.0239 4091522.462 0.00 100.00 0.00 228 0.21 well fine sand pr3b 24 3/1312001 588041.0575 4091235.872 0.00 100.00 0.00 1.93 0.26 well medium sand mOOerately pr3b 25 3/13/2001 568397.611 4091195.201 0.00 100.00 0.00 2.00 1.48 0.36 well medium sand pr3b 26 3/1312001 588710.4687 4091076.423 0.21 99.79 0.00 2.10 1.55 0.34 moderately medium sand pr3b 27 3/1312001 586959.8539 4091067.94 0.00 99.55 0.45 3.00 2.61 0.16 well fine sand pr3b28 3/1312001 589138.1364 4091047.621 0.00 100.00 0.00 300 2.43 0.19 wall fine sand moderately pr3b 29 3/1312001 589290."1795 4090982.651 0.00 100.00 0.00 2.60 2.12 0.23 well fine sand pr3b 30 3/1312001 589406.3806 4090939.495 0.00 100.00 0.00 2.50 1.96 0.26 well medium sand pr3b 31 3/13/2001 589514.0315 4090862.966 0.00 100.00 0.00 3.00 2.39 0.19 very well fine sand pr3b 32 3/1312001 589503.5271 4090819.531 0.00 100.00 0.00 2.60 2.08 0.24 well fine sand pr3b 33 3/13/2001 590315.983 4090804.896 0.00 100.00 0.00 2.00 1.36 0.39 well medium sand pr3b 33r 3/1312001 590315.983 4090604.896 0.00 100.00 0.00 2.00 1.37 0.39 woll medium sand pr3b 34 3/1312001 590584.8432 4090641.338 0.07 99.93 0.00 2.00 1.61 0.33 well medium sand pr3b 35 3/1312001 590943.1018 4090445.461 5.07 94.93 0.00 1.70 0.66 0.55 moderately coarse sand moderately pr3b 36 3/13/2001 589003.7842 4091123.875 0.00 100.00 0.00 3.00 2.26 0.21 wall fine sand pr3b 37 3/1312001 589199.5206 4091137.026 0.00 100.00 0.00 3.00 2.14 0.23 well fine sand S.G. Watt, 2003 81 pr3b 38 311312001 589307.167 4091060.494 0.00 100.00 0.00 2.50 2.04 0.24 well fine sand pr3b 39 311312001 589602.7069 4090697.187 0.00 100.00 0.00 3.00 2.36 0.19 well fine sand moderately pr4b 24 3127/2001 588041.0575 4091235.872 0.00 100.00 0.00 2.00 1.62 0.33 wall medium sam:! moderately pr4b 25 312712001 588397.611 4091195.201 0.64 99.36 0.00 1.60 0.98 0.51 well coarse send pr4b 26 3127/2001 588710.4687 4091076.423 1.73 98.27 0.00 0.2, 1.7 066 0.53 moderately coarse sand pr4b 27 312712001 588959.6539 4091067.94 0.00 100.00 0.00 3.00 2.43 0.19 well fine sand pt4b 28 3127l2001 589138.1364 4091047.621 0.00 100.00 0.00 2.10 1.81 0.29 well medium sand moderately pr4b 29 312712001 589290.1795 4090982.651 0.00 100.00 0.00 2.10 1.68 0.31 wall medium sand pr4b 30 3/27/2001 589406.3806 4090939.495 0.00 100.00 0.00 2.20 2.00 0.25 well medium sand pr4b 30r 3127/2001 589406.3806 4090939.495 0.00 100.00 0.00 2.10 2.00 0.25 well medium sand moderately pr4b31 3127/2001 589514.0315 4090862.966 0.00 100.00 0.00 3.00 2.30 0.20 well fine sand pr4b 32 312712001 589603.5271 4090819.531 0.00 100:00 0.00 2.60 2.00 0.25 well medium send pr4b 36 312712001 589003.7642 4091123.875 0.00 100.00 0.00 2.70 206 024 well fine sand pr4b 37 312712001 589199.5206 4091137.026 0.00 100.00 0.00 1.90 1.31 0.40 well medium sand pr4b 38 312712001 589307.167 4091060.494 0.00 100.00 0.00 2.50 2.00 0.25 well medium sand pr4b 39 312712001 589602.7069 4090897.187 0.00 100.00 0,00 3.00 2.22 0.22 well sorted fine send Experiment Sediment Samples moderately d1b24 312812001 588041.0575 4091235.872 0.25 99.75 0.00 2.10 1.67 0.31 well medium sand moderately d1b25 312812001 568397.611 4091195.201 0.16 99.84 0.00 2.00 1.40 0.38 well medium sand d1b 26 312812001 588710.4687 4091076.423 16.28 83.72 0.00 ·1, 2.1 0.84 0.56 poorly coarse sand d1b27 312812001 588959.8539 4091067.94 0.00 100.00 0.00 3.00 226 0.21 well fine sand moderately d1b28 312812001 589138.1364 4091047.621 0.00 100.00 0.00 2.10 1.67 0.31 well medium sand moderately d1b29 3/2812001 589290.1795 4090982.651 0.00 100.00 0.00 2.00 1.60 0.33 well medium send moderately dtb29r 312812001 589290.1795 4090982.651 0.00 100.00 0.00 2.00 1.51 0.35 well medium sand d1b 30 3/28/2001 589406.3806 4090939.495 0.00 100.00 0.00 230 1.97 0.26 wall medium sand d1b"31 3128/2001 589514.0315 4090862.966 0.00 100.00 0.00 3.00 2.21 0.22 wen fine sand d1b32 312812001 589603.5271 4090819.531 0.00 100.00 0.00 2.90 2.10 0.23 well fine sand d1b36 3128/2001 589003.7842 4091123.875 0.00 99.73 0.27 2.90 2.13 0.23 well fine sand d1b37 312812001 589199.5206 4091137.026 0.00 100.00 0.00 3.00 2.35 0.20 well medium sand d1b38 3/2812001 589307.167 4091060.494 0.00 100.00 0.00 2.20 1.98 0.25 well medium sand d1b39 3128/2001 589602.7069 4090897.187 0.00 100.00 0.00 3.00 2.42 0.19 well fine sand d2b24 312912001 588041.0575 4091235.872 0.00 100.00 0.00 2.00 1.68 0.31 well medium sand moderately d2b24r 3129/2001 588041.0575 4091235.872 0.00 100.00 0.00 2.00 1.68 0.31 well medium sand moderately d2b25 3129/2001 588397.611 4091195.201 0.00 100.00 0.00 200 1.53 0.35 well medium sand moderately d2b26 312912001 586710.4687 4091076.423 0.34 99.66 0.00 1.50 1.00 0.50 well coarse sand moderately d2b27 312912001 588959.8539 4091067.94 0.00 100.00 0.00 3.00 2.39 0.19 well fine sand d2b28 3129/2001 589138.1364 4091047.621 0.00 100.00 0.00 2.00 1.42 0.37 well medium sand moderately d2b29 3129/2001 589290.1795 4090982.651 0.00 100.00 0.00 2.00 1.44 0.37 well medium sand moderately d2b30 312912001 589406.3806 4090939.495 0.00 100.00 0.00 220 1.8S 0.28 well medium sand d2b31 312912001 589514.0315 4090862.966 0.00 100.00 0.00 2.10 1.90 0.27 well medium send d2b32 312912001 589603.5271 4090819.531 0.00 100.00 0.00 2.90 2.11 0.23 well fine sand moderately d2b 36 3129/2001 589003.7842 4091123.875 0.00 100.00 0.00 2.90 2.13 0.23 well fine sand d2b37 312912001 589199.5206 4091137.026 0.00 100.00 0.00 3.00 2.18 0.22 well fine sand d2b38 3/29{2001 589307.167 4091060.494 0.00 100.00 0.00 2.20 1.9!! 0.25 well medium sand d2b 39 312912001 589602.7069 4090897.1 87 0.00 100.00 0.00 3.00 2.36 0.19 wall fine sand moderately d3b24 3130/2001 588041.0575 4091235.872 0.00 100.00 0.00 2.00 1.59 0.33 well medium sand moderalely d3b25 3130/2001 588397.611 4091195201 0.72 99.28 0.00 1.60 0.91 0.53 woll coarse sand moderately d3b25r 313012001 588397.611 4091195.201 0.69 99.31 0.00 1.60 0.99 0.50 well coarse sand moderately d3b26 313012001 588710.4687 4091076.423 0.18 99.82 0.00 1.90 1.21 0.43 well medium send d3b 27 313012001 588959.8539 4091067.94 0.00 100.00 0.00 2.90 2.10 0.23 well fine sand moderately d3b28 3/3012001 589138.1364 4091047.621 0.00 100.00 0.00 2.00 1.72 0.30 well medium sand d3b29 313012001 589290.1795 4090982.651 0.00 100.00 0.00 2.00 1.75 0.30 well medium sand moderately d3b 30 3130/2001 589406.3806 4090939.495 0.00 100.00 0.00 290 2.21 0.22 well fine sand d3b 36 3/30/2{)01 589003.7842 4091123.875 0.00 100.00 0.00 2.90 2.17 0.22 well fine sand d3b37 313012001 589199.5206 4091137.026 0.00 99.93 0.07 2.90 2.19 0.22 well fine sand d3b 38 3/30/2001 589307.167 4091060.494 0.00 100.00 0.00 2.3 2 0.25 woll medium send S.G. Watt, 2003 82 Post·Experiment Sediment Samples moderately pt1b21 41112001 586841.9769 4090957.233 o_oo 100.00 0.00 2.00 1.66 0.32 woll medium sand moderately pl1b 21r 41112001 586841.9769 4090957.233 0.15 99.85 0.00 2.00 1.69 0.31 well medium sand pt1b22 41112001 587240.3094 4091183.218 0.00 100.00 0.00 2.90 2.09 0.24 well fine sand pt1b23 41112001 587684.6224 4091265.464 0.00 100.00 0.00 2.00 1.85 0.28 well medium sand pt1b up riv 411/2001 587860.0239 4091522.462 0.00 100.00 0.00 2.90 2.19 0.22 well fine sand pt1b 24 4(112001 588041.0575 4091235.872 0.00 100.00 0.00 2.10 1.79 0.29 well medium sand pt1b 25 411/2001 588397.611 4091195.201 20.58 79.42 0.00 0, 1.9 0.27 0.83 poorly coarse sand moderately pt1b26 41112001 588710.4687 4091076.423 0.57 99~43 0.00 1.80 1.03 0.49 well medium sand pt1b27 41112001 588959.8539 4091067.94 0.00 100.00 0.00 2.20 1.91 0.27 well medium sand pl1b 28 411/2001 589138.1364 4091047.621 0.00 100.00 0.00 2.00 1.51 0.35 welt medium sand pt1b29 411/2001 589290.1795 4090982.651 0.00 100.00 0.00 2.10 1.64 0.32 well medium sand pt1b30 41112001 589406.3806 4090939.495 0.00 100.00 0.00 2.10 1.62 0.33 well medium sand pl1b31 411/2001 589514.0315 4090862.966 0.00 100.00 0.00 2.00 1.67 0.31 well medium sand pt1b 31r 41112001 589514.0315 4090862.966 0.00 100.00 0.00 2.00 1.67 0.31 well medium sand pt1b 32 411/2001 589603.5271 4090819.531 0.00 100.00 0.00 2.10 1.67 0.31 well medium sand pt1b 33 4/1/2001 590315.983 4090804.696 0.00 100.00 0.00 2.00 1.54 0.34 well medium sand pt1b34 411/2001 590584.8432 4090641.338 11.69 68.31 0.00 -1, 2.1 0.82 0.57 poorly coarse sand pl1b35 41112001 590943.1018 4090445.461 17.14 82.86 0.00 -1, 2 0.54 0.69 poorly coarse sand pt1b36 411/2001 589003.7642 4091123.875 0.00 100.00 0.00 2.20 1.94 0.26 well medium sand pt1b37 411/2001 589199.5206 4091137.026 0.00 100.00 0.00 2.90 2.24 0.21 well fine sand pt1b 38 411/2001 589307.167 4091060.494 0.00 100.00 0.00 2.20 2.00 0.25 well medium sand pt1b 39 411/2001 589602.7069 4090897.187 0.00 100.00 0.00 2.00 2.14 0.23 well fine sand moderalely pl2b 21 4/812001 586841.9769 4090957233 0.52 99.48 0.00 2.10 1.67 0.31 well medium sand moderately pl2b 22 41812001 587240.3094 4091183.218 0.05 99.95 0.00 2.10 1.79 0.29 well medium sand pl2b 23 4fB12001 587654.6224 4091265.464 0.00 100.00 0.00 2.00 1.78 0.29 well medium sand pl2b up riv 41812001 587860.0239 4091522.462 0.06 99.94 0.00 2.00 1.23 0.43 well medium sand pl2b 24 4/8/2001 588041.0575 4091235.872 0.00 100.00 0.00 2.00 1.82 0.28 well medium sand pt2b 25 4/812001 588397.611 4091195.201 0.74 99.26 0.00 1.70 1.04 0.49 moderately medium sand moderately pl2b26 4/812001 588710.4687 4091076.423 0.29 99.71 0.00 1.10 0.91 0.53 we!l coarse sand moderately pt2b 26r 4/8/2001 588710.4687 4091076.423 0.21 99.79 0.00 1.10 0.87 0.55 well coarse sand moderately pl2b 27 4/812001 588959.8539 4091067.94 0.00 100.00 0.00 2.60 1.97 0.26 well medium sand moderately pl2b 28 418/2001 589138.1364 4091047.621 0.00 100.00 0.00 2.10 1.97 0.26 well medium sand pt2b 29 4/812001 589290.1795 4090982.651 0.00 100.00 0.00 2.00 1.57 0.34 we!l medium sand moderately pl2b 30 41B/2001 589406.3806 4090939.495 0.00 100.00 0.00 2.00 1.52 0.35 well medium sand pl2b 31 4/812001 589514.0315 4090862.966 0.00 100.00 0.00 2.00 1.57 0.34 well medium sand pt2b 32 418/2001 589603.5271 4090819.531 0.00 100.00 0.00 2.00 1.52 0.35 well medium sand pl2b 33 4/612001 590315.983 4090804.896 0.00 100.00 0.00 2.00 1.60 0.33 well medium sand pl2b 34 41812001 590584.8432 4090641.338 0.06 99.94 0.00 2.00 1.47 0.36 well medium sand p\2b 35 41812001 590943.1018 4090445.461 0.00 100.00 0.00 2.00 1.58 0.33 well medium sand pt2b 36 41812001 589003.7842 4091123.875 0.03 99.88 0.09 2.80 1.93 0.26 we!l medium sand pt2b 37 41812001 589199.5206 4091137.026 0.00 99.98 0.02 3.00 2.31 0.20 we!l fine sand pl2b 38 41812001 589307.167 4091060.494 0.00 99.99 0.01 220 1.9£ 0.26 well medium sand pl2b 39 4/8/2001 589602.7069 4090897.187 0.00 100.00 0.00 3.00 2.10 0.23 well fine sand moderately pl3b21 4/14/2001 586841.9769 4090957.233 0.05 99.95 0.00 2.90 2.02 0.25 well fine sand moderately pt3b 22 4/14/2001 587240.3094 4091183.218 0,00 100.00 0.00 2.00 2.13 0.23 well fme sand pt3b 23 411412001 587684.6224 4091265.464 0.58 99.42 0.00 2.10 1.86 0.27 well medium sand pt3bupriv 4114/2001 587860.0239 4091522462 0.00 99.97 0.03 aoo 240 0.19 wen fine sand moderately pt3b 24 4/1412001 588041.0575 4091235.872 0.00 100.00 0.00 2.40 1.84 0.28 well medium sand pl3b 25 4114/2001 588397.611 4091195.201 0.20 99.60 0.00 2.60 1.<18 0.36 moderately medium sand pl3b 26 4114/2001 588710.4687 4091076.423 239 97.61 0.00 2.00 1.26 0.42 moderately medium sand pt3b 27 4/14/2001 588959.8539 4091067.94 0.00 100.00 0.00 200 210 0.23 well fine sand pt3b28 4114/2001 589138.1364 4091047.821 0.00 100.00 0.00 2.80 2.05 0.24 well fine sand modera!ely p\3b 29 4/14/2001 58929(11795 4090982.651 0.00 100.00 0.00 2.40 1.87 0.27 well medium sand moderately p\3b 30 4114/2001 589406.3806 4090939.495 0.00 100.00 0.00 2.50 1.89 0.27 well medium sand moderotely pt3b31 4114/2001 589514.0315 4090862.966 0.00 100.00 0.00 2.40 1.85 0.28 well medium sand moderately pt3b 32 4/14/2001 589603.5271 4090819.531 0.00 100.00 0.00 2.00 1.65 0.32 well medium sand moderately pt3b 32r 411412001 589503.5271 4090819.531 0.00 100.00 0.00 2.10 1.84 0.28 well medium sand pt3b 33 4114/2001 590315.983 4090804.896 0,00 toaoo 0.00 2.10 1.71 0.31 moderately medium sand S.G. Watt, 2003 83 well pl3b 34 4/14/2001 590584.8432 4090641.338 0.00 100.00 0.00 2.00 1.70 0.31 well medium sand moderately pt3b 35 4/14/2001 590943.1018 4090445.461 0.54 99.46 0.00 2.00 1.67 0.31 well medium sand pt3b 36 4/14/2001 589003.7842 4091123.875 0.00 99.95 0.05 2.10 1.91 0.27 well medium sand pt3b 37 4/14/2001 589199.5206 4091137.026 0.00 99.97 0.03 3.00 231 0.20 well fine sand pt3b 38 4/14/2001 589307.167 4091060.494 0.00 100.00 0.00 2.10 1.97 0.25 well medium sand pt3b 39 4/14/2001 589602.7069 4090897.187 0.00 100.00 0.00 3.00 2.32 0.20 moderately fine sand S.G. Watt, 2003 84 Appendix B. Offshore sediment sample database tables S.G. Watt, 2003 85 Pre-Experiment Sediment Samples JD DATE EASTING NORTHING %>SAND %SAND %MUD MOOE(S) MEAN SORTING DESCRIPTION well to moderately prloff 1 212812001 588311.82179 4090863.64918 0.0 95.55 4.45 3.90 3.25 well very fme sand prtoff2 212812001 588410.44324 4089963.79870 11.37 88.59 0.05 1.10 0.33 moderately to poorly coarse sand prtoff3 2/2812001 587871.51554 4090413.09092 0.10 86.46 13.44 3 3.16 moderately very fine sand prtoff 4 212812001 587156.64352 4090660.89873 0.00 99.79 0.21 3 2.53 well sorted fine sand prtoff 5 212812001 587252.97361 4089951.81743 o/s of a of a of a of a ola rodty pr1off6 2128/2001 586637.06272 4089224.34242 0.16 96.95 2.89 3.9 3.07 moderately well very fine sand pr1off7 2/281:2001 58n94.65005 40B9236.23788 0.58 91.26 8.16 3 2.68 poorly fine sand pr1off7r 2/2812001 587794.65005 4089236.23788 1.83 90.77 7.40 3.1 2.65 poorly fine sand prloffB 2/28/2001 589041.2£245 4089249.22497 0.39 98.71 0.91 2 1.53 moderately well medium sand prtoff9 212812001 590287.87633 4089262.39523 o/a of a of a o/a of a no return prtoff 10 2128/2001 591534.49173 4089275.74864 of a of a of a of a ola "''of a noretum prtoff 11 2/28/2001 591526.71402 4089996.84099 of a of a of a of a of a ola rocky prloff 12 2/28/2001 590725.36635 4089988.23506 of a of a of a of a o/a o/a rocky pr1off13 212812001 590186.33332 4090437.38250 0.05 99.51 0.44 2.30 2.12 moderately well fine sand pr1off 14 2128/2001 589741.17566 4090432.66197 0.14 98.49 1.38 2.1, 3.9 2.52 moderately fine sand prtoff 14r 212812001 589741.17556 409043266197 0.12 98.52 1.38 2.1, 3.8 2.51 moderately fme sand pr1off 14<2 212812001 589741.17566 4090432.66197 0.19 98.40 1.41 2.2, 3.6 2.50 moderately fine sand prtoff 15 212812001 589656.95043 4089978.87824 0.05 94.72 5.23 3.80 3.00 moderately very fme sand prtoff 16 212612001 589211.76912 408997218595 0.02 95.10 4.88 2.2, 3.8 2.43 moderately fine sand pr1ort 16r 212812001 589211.76912 4089972.18595 0.04 95.92 4.04 2.2, 3.5 2.45 moderately fine sand prloff 16<2 212812001 589211.76912 4069972.18595 0.05 95.07 4.88 2.2, 3.7 2.61 moderately fine sand pr1off 17 212812001 588939.89234 4090424.22391 ols o/a of a o/a ols of a =ky pr1off 18 212812001 589296.01818 4090427.96482 0.00 85.58 14.42 4.00 3.58 moderately well very fine sand pr1off 19 2128/2001 589561.47300 4090586.09241 0.00 98.73 1.27 3.80 2.94 moderately well very fine sand pr1off20 2128/2001 589292.51507 4090760.77643 ola of a of a of a o/a ols rooky pr1off21 2/28/2001 588936.40320 4090757.03541 7.33 91.94 0.73 1.6, 3.5 1.29 poorly medium sand pr2off 1 3/312001 588320.6968 4090894.947 0.05 84.70 15.26 4.10 3.53 moderately well very fine sand pr20ff 2 31312001 588374.921 4089971.672 0.00 82.93 17.07 4.00 3.24 poorly very fine sand pr2off3 31312001 587671.5155 4090413.091 2.48 91.40 6.12 3.90 2.66 poorly fine sand pr2off 4 3/312001 587127.1109 4090649.5 0.00 99.75 0.25 3.00 2.51 well fine sand pr2off 4r 3/312001 587127.1109 4090649.5 0.00 99.73 0.27 3.00 2.53 well fine sand pr2off 5 3!312001 587372.9152 4089831.008 of a of a of a of a of a of a shell hash shell pr2off6 31312001 586752.8394 4089225.525 22.46 77.54 0.00 0.00 ..0.07 poorly hash/pebbles pr2off7 31312001 587619.349 4088964.486 31.80 67.28 0.91 -1, 2 ..0.13 poorly pebbly pr2off 8 3/312001 588952.1935 4089250.695 3.21 96.74 0.05 1.60 0.83 moderately coarse sand pr2off 9 31312001 590275.4221 4069261.142 13.37 74.36 12.27 -1, 2, 4 2.46 very poorly sorted very fine sand pr2ofl' 10 3/3/2001 591501.9939 4089275.101 o/a of a of a o/a nls nla rodcy pr2off 11 31312001 591572.9462 4089838.315 ola of a of a o/s of a o/s rocky pr2off 12 31312001 590716.4856 4089987.874 of a of a ola of a of a of a rooky pt2off 13 31312001 590195.2129 4090439.698 0.17 99.50 0.33 3.00 2.40 moderately well fine sand pr2off 13r 313/2001 590195.2129 4090439.696 0.48 99.21 0.31 3.00 2.37 moderately fine sand pr2off 14 3/312001 569750.1444 4090434.976 0.00 95.52 4.48 3.90 3.04 moderately very fine sand pr2off 15 31312001 589608.6556 4069977.813 0.04 99.60 0.36 2.00 1.67 moderately well medium sand pr2off 16 313/2001 589223.784 4069972.789 0.00 81.35 18.65 2. 4 3.01 poorly very fine sand pr2off 17 313/2001 588954.6059 4090439.134 0.00 91.50 650 4.00 3.29 moderately well very fine sand pr2off 18 3/312001 589305.0935 4090432.853 0.00 89.89 10.11 3.90 3.25 moderately very fine sand pr2off 19 31312001 589543.6553 4090587.014 of a of a o/B of a o/a of a rooky pr2off20 313/2001 589283.6356 4090758.464 0.05 88.20 11.75 3.90 3.28 moderately vary fine sand pr2off 21 313/2001 586927.4981 4090757.164 0.26 92.04 7.68 4.00 3.18 moderately vary fine sand pr3off 1 31712001 588311.6218 4090883.649 0.00 87.51 12.49 4.00 3.47 moderately well very fine sand pr3off2 317/2001 588410.4086 4089967.127 0.08 96.92 2.99 2.70 2.51 poorly fine sand pr3orf 3 31712001 587916.2£11 4090391.365 0.15 82.10 17.76 3.90 3.15 poorly very fine sand pr3off 4 31712001 587156.4612 4090678.649 1.28 98.24 0.48 3.00 2.51 moderately well fine sand pr3off 5 317/2001 587193.2396 4089958.97 0.13 99.70 0.17 2.90 2.16 moderately well fine sand very coarse sand (shelly, pr3off6 3/712001 586665.4722 4089224.143 14.81 85.07 0.12 0.20 .0.11 moderately pebbly) pr3off7 317/2001 587735.1624 4089244.865 0.05 92.47 7.48 3.50 2.91 moderately fine sand pr3off 8 317/2001 589050.0543 4089260.046 3.24 96.62 0.14 1.60 1.01 moderately medium sand pr3off9 317/2001 590289.3858 4089287.93 0.00 94.06 5.94 2.1, 3.9 2.63 moderately fine sand pr3off 10 317/2001 591537.3484 4089285.843 of a o/a of a of a of a o/a rocky pr3off 11 31712001 591556.3671 4069996.795 of a ols of a of a nls of a rodty pr3off 12 3f7/2001 590814.7433 4089959.234 0.00 99.62 0.38 2.40 2.34 moderately fine sand pr3off 13 317/2001 590185.9795 4090470.664 0.23 98.64 1.12 360 270 moderately fine sand pr3off 14 31712001 589844.723 4090467.043 0.08 74.27 25.65 4.00 3.73 poorly very fine sand pr3off 15 31712001 589659.0477 4089946.944 0.25 99.45 0.30 2.00 1.54 moderately well medium sand pr3off 16 3f712001 589181.6537 4090016.249 0.02 98.02 1.96 2.30 2.19 moderately fine sand S.G. Watt, 2003 86 pr3off 16r 3f712001 589181.6537 4090016.249 0.09 98.37 1.54 2.10 2.07 moderately fine sand pr3off 17 3f712001 588948.8339 4090420.656 0.00 84.39 15.61 4.00 2.76 poorly fine sand pr3off 18 31712001 589355.4407 4090424.929 0.11 87.26 12.61 4.00 3.44 moderately well very fine sand pr3off 19 3f712001 589564.261 4090575.027 0.17 97.12 272 3.90 3.09 moderately we\\ very fine sand pr3off20 31712001 589277.713 4090756.926 0.00 90.90 9.10 4.00 3.33 moderately wall vary fine sand pr3off21 31712001 588921.4076 4090771.634 0.20 95.94 3.85 3.00 2.66 moderately we\\ fine sand pr4off1 312712001 586296.86559 4090894.56840 0.00 93.36 6.64 2.1, 3.7 2.12 poorly fine sand pr4off2 312712001 588401.46254 4089971.10544 0.22 92.18 7.60 320 2.71 moderately fine sand pr4off 14 312712001 589712.32262 4090354.69208 0.05 97.50 2.45 3.90 3.05 moderately wall Vel)' fine sand pr4off 14r 312712001 589712.32262 4090354.69208 0.06 97.72 222 3.90 3.03 moderately well very fine sand pr4off15 312712001 589565.64326 4089983.52541 0.71 99.23 0.05 2.10 209 moderately fine sand pr4off16 3127/2001 589216.18209 4089975.92696 0.00 81.71 18.29 4.00 3.62 moderately well very fine sand pr4off 17 3127/2001 588898,22.512 4090434.86213 0.00 76.85 23.15 4.10 3.71 moderately very fine sand pr4off 18 3127/2001 589290.00028 4090429.75496 0.29 95.60 4.11 3.90 3.16 moderately wall very fine sand pr4off 19 3127/2001 589555.22237 4090615.61668 ola ola ola ola ola rocky pr4off20 3/27/2001 589270.29695 4090756.84797 0.00 88.98 "''11.02 4.00 3.48 moderately well very fine sand pr4off21 312712001 588912.75631 4090747.54544 0.39 97.98 1.83 3.10 2.55 moderately watt fine sand Experiment Sediment Samples d1off1 3/2812001 586384.4049 4090896.388 0.00 97.17 2.83 4.00 3.37 ~II very fine sand d1off2 3126/2001 588440.0923 4089964.108 0.00 65.06 14.94 4.00 3.24 moderately well very fine sand d1off14 312812001 sa9no.6232 4090432.976 0.12 99.09 0.80 2.10 1.97 moderately medium sand d1off14r 3/26/2001 589770.8232 4090432.976 0.09 99.19 0.72 2.10 1.94 moderately medium sand d1off15 312812001 589568.0313 4069964.844 0.04 93.84 6.12 2, 4 2.23 poorly fine sand d1off 16 3128/2001 589205.8037 4089972.123 0.00 75.07 24.93 4.10 3.76 moderately vary fine sand d1off 17 312812001 586939.9156 4090422.005 0.37 86.61 13.02 4.00 3.48 moderately vary fine sand d1off18 3126/2001 589290.0531 4090427.902 0.00 93.96 6.04 3.90 3.08 moderately vary fine sand d1off 19 312812001 589576.9471 4090617.709 ola ola ola ola rua ola rod d2off1 312912001 586296.2753 4090902.003 0.81 97.47 1.72 3.70 2.87 moderately wall fine sand d2off 2 3129/2001 588334.4934 4089988.859 0.03 67.28 12.68 3.90 3.21 moderately vary fine sand d2off2r 3129/2001 566334.4934 4089988.859 0.00 68.44 11.56 3.90 3.14 moderately very fine sand d2off 14 3129/2001 589738.2109 4090432.631 0.00 90.63 9.37 4.00 3.23 moderately vary fine sand d2off15 3129/2001 589596.1119 4089976.236 0.03 97.94 2.03 2.1, 4.0 2.20 moderately fine sand d2off15r 312912001 589596.1119 4089976.236 0.00 97.45 2.55 2.1,4.0 2.26 moderately fine sand d2off 16 3/2912001 569211.6525 4089983.28 0.00 80.51 19.49 2.0,4.0 3.09 moderately vary line sand d2off17 312912001 586938.8126 4090385.38 0.05 88.49 11.46 4.00 3.38 moderately well vary fine sand d2off 17r 3/29/2001 588938.8126 4090365.38 0.05 88.49 11.46 400 3.48 moderately wen very fine sand d2off 16 3129/2001 589306.5016 4090419.199 0.90 90.90 8.20 2.0, 4.0 2.89 poorly fine sand d2off19 312912001 5895n.7922 4090586.265 0.00 97.40 2.60 3.60 3.03 moderately well very fine sand d2off 19T 312912001 569577.7922 4090566.265 0.00 97.34 2.66 3.90 3.02 moderately well very fine sand d2off20 312912001 589260.811 4090747.672 0.00 85.59 14.41 4 3.53 moderately well vary fine sand d2off21 3129/2001 588940.893 4090753.421 0.00 97.66 2.34 3.10 2.74 moderately well fine sand d3off 1 3/3012001 588325.54194 4090848.62114 0.44 93.57 6.00 4.00 3.00 moderately fine sand d3off1r 3130f2001 588325.54194 4090848.62114 0.84 93.23 5.93 4.00 2.93 moderately very fine sand d3off2 313012001 588428.25657 4089963.20771 0.10 96.86 3.02 210 219 moderately fine sand d3off 14 3130/2001 589741.35168 4090416.02139 0.13 94.13 5.74 2,4 2.97 moderately fine sand d3off 15 3/3012001 589541.97131 4089989.66779 0.00 91.60 8.40 2, 4 3.22 moderately vary fine sand d3off15r 3130/2001 589641.97131 4089989.66779 0.00 91.47 8.53 2, 4 3.21 modarataely very fine sand d3off 16 3130/2001 589220.59459 4089979.71235 0.00 99.40 0.60 2.50 2.05 moderately well fine send d3off 17 3130/2001 588940.18963 4090423.89418 2.69 64.01 13.30 4.00 3.26 poorly very fine sand d3off 17r 3130/2001 568940.16963 4090423.89418 2.94 83.02 14.04 4.00 3.25 poorly very fine send d3ofrf 18 313012001 569290.05643 4090430.12106 0.13 88.38 11.49 4.00 3.21 moderately very fine sand d3off19 313012001 569517.46494 4090537.58676 ola ola ola ola noretum d3off20 3130/2001 5892n.71299 4090756.92602 0.00"'' 90.28 9.72 4.00'"' 3.30 moderatelywell very fine sand d3off21 3130/2001 588929.21977 4090734.77023 0.66 93.82 5.52 3.70 2.93 moderately fine sand Post-Experiment Sediment Samples pt1off 1 412/2001 568371.0753 4090895.471 0.00 88.69 11.31 3.90 3.39 moderately well very fine sand pt1off2 41212001 588347.8484 4089989.031 0.00 68.04 11.96 3.90 2.92 poorly fine sand pt1off 3 41212001 587664.0992 4090413.014 0.33 91.31 8.36 3.70 2.77 poorly fine sand pt1off 3r 41212001 587864.0992 4090413.014 0.21 91.54 8.25 3.60 2.85 poorly fine sand pt1off4 41212001 587154.9667 4090679.377 1.07 96.64 0.29 3.10 2.37 moderately well fine sand pt1off 5 412/2001 587218.6461 4089951.467 0.00 99.97 0.03 2.10 1.82 moderately wen medium sand pl1off6 41212001 566628.235 4089216.705 21.32 78.38 0.32 0.90 -0.16 pooriy shall hash pt1off7 41212001 557742.7109 4089235.701 0.00 73.67 28.33 2.1, 4.1 3.54 poorly silty sand pt1off 7r 412/2001 587742.7109 4069235.701 0.00 75.24 24.76 2.1, 4.0 3.50 poorly vary fine sand pt1off 8 41212001 589057.5842 4069249.396 0.08 97.29 2.63 2.10 2.13 moderately sorted fine sand pt1off 6r 41212001 589057.5842 4069249.396 0.00 97.87 2.13 2.10 2.08 moderately fine sand pt1off 9 41212001 590295.2937 4089262.474 0.00 93.95 6.05 3.90 3.35 moderately vary fine sand pt1off 10 41212001 591516.6829 4089275.557 ola ola ola '"' ola ola rocl1y S.G. Watt, 2003 87 pt1off 11 41212001 591496.4767 4090000.198 0.02 99.81 0.17 2.50 2.09 moderately fine sand pt1off 11r 41212001 591498.4767 4090000.198 0.03 99.82 0.15 2.60 2.10 moderately fine sand pt1off 12 41212001 590720.9345 4089988.187 0.00 98.04 19£ 3.90 3.09 moderately wall very fine sand pt1off 13 4/212001 590164.8534 4090492.842 0.36 95.25 3.39 2.1, 3.9 2.77 moderately fine sand pt1off14 41212001 589720. 5632 4090419.973 0.10 91.79 6.11 2.1, 4.0 3.15 moderately very fine sand pl1off15 41212001 589661.3436 4089982.472 6.50 93.26 0.24 1.9, 3.8 0.89 poorly coarse sand pt1off16 412/2001 589211.7691 4089972.185 0.17 87.49 12.34 2.0, 4.1 2.46 poorly fine sand pt1off17 412/2001 588913.1829 4090423.944 0.07 85.25 14.69 4.10 3.47 moderately well very fine sand pl1off 18 41212001 589293.0558 4090427.712 0.00 87.34 12.66 4.00 3.57 moderately well very fine sand pttoff 19 41212001 589567.4113 4090586.155 2.62 96.72 0.66 2.30 2.00 poony medium sand pt1off20 41212001 589285.1773 4090753.266 0.04 89.01 10.94 3.90 3.32 mOderately well very fine sand pt1off21 41212001 588936.3838 4090758.888 1.44 94.85 3.71 3.60 2.61 moderately fine sand pt2off 1 4/5/2001 588311.8992 4090876.216 0.09 91.41 8.50 4.00 3.44 moderately well very fine sand pt2off2 4/512001 588344.9605 4089981.612 0.07 95.50 4.43 2,3.9 1.98 poorly medium sand pl2off 3 4/5/2001 587832.9535 4090411.216 0.11 90.40 9.49 3.20 2.81 poorly fine sand pl2off 4 4(5/2001 587186.5751 4090633.469 0.00 99.14 0.86 3.00 2.49 modaralely well fine sand pl2off 5 415/2001 587174.3474 4089949.123 0.13 99.54 0.33 3.00 2.28 moderately well fine sand shell hash/fine pt2off6 4/5/2001 586622.6547 4089183.477 0.11 98.88 1.01 2,3.9 2.02 poorly sand pt2off7 4/512001 587780.2463 4089193.562 3.81 95.80 0.39 1.60 0.90 moderately coarse sand pt2off8 4/5/2001 58a981.7927 4089256.002 1.04 97.68 1.27 2.00 1.52 moderately medium sand pt2off9 415!2001 590264.2817 4089247.721 0.19 94.66 5.15 2, 4 2.25 moderately fine sand pt2off 10 41512001 591513.3589 4089308.806 ofa ofa of a of a of a of a no return pl2off 11 415/2001 591529.6511 4089999.458 ofa ofa o/a ofa ofa of a rocky pt2off 12 4/512001 590713.6781 4090000.603 0.00 99.28 0.72 3.50 2.54 moderately fine sand pt2off 13 4/512001 590177.1157 4090466.875 0.30 97.59 2.11 3.80 2.89 moderately fine sand pt2off 14 4/5/2001 589752.9282 4090443.693 0.31 91.19 8.50 2, 4 292 poorly fine sand pt2off 15 41512001 589609.1426 4090009.658 0.31 91.18 8.51 2,4 250 poorly fine sand pt2off 16 41512001 589159.776 4089977.187 0.03 77.43 22.54 2,4 3.45 poorty very fine sand pt2off 17 4(512001 568929.2318 4090421.893 0.00 84.48 15.52 4.00 3.52 modaralely well very fine sand pl2off 18 4/512001 589318.206 4090434.855 0.02 97.90 2.08 3.90 2.98 moderately well very fine sand pt2of 19 4/512001 589562.2862 4090621.239 ofa ola ofa of a ola ola rocky pt2off20 4/512001 589263.1804 4090730.844 0.16 90.49 9.35 4.00 3.32 moderately well very fine send pt2off21 4f51200t 588924.2256 4090786.498 0.22 90.07 9.71 4.00 322 moderately very fine sand pt3off 1 411212001 588311.5139 4090913.225 0.00 96.68 3.32 4.00 3.34 wen very fine sand pl3off2 4/1212001 588425.2348 4089971.386 0.00 80.74 19.25 4.00 3.29 moderately -very fine sand pt3off3 4/1212001 587828.1613 4090444.074 0.06 68.61 13.33 3.10 3.42 moderately -very fine sand pt3off 3r 411212001 587828.1613 4090444.074 0.06 79.62 20.32 4.00 3.33 moderately very fine sand pt3off 4 4/1212001 587156.6435 4090660.899 0.00 99.02 0.98 3.00 2.60 well sorted fine sand pt3off 5 411212001 587240.0368 4089910.966 1.48 98.11 0.41 2.80 1.89 moderately medium sand pt3off6 4/1212001 586629.4955 4089240.907 0.11 97.93 1.95 1.9, 3.9 1.76 poorly medium sand p\3off7 4/1212001 587845.5015 4089201.627 0.00 85.08 14.92 2.1, 3.9 2.75 poorly fine sand pt3off8 4/1212001 589043.0986 4089215.959 0.08 95.12 4.80 2, 3.9 224 moderately medium sand pt3off 8r 4/12/2001 589043.0986 4089215.959 0.07 94.42 5.51 2, 4 2.34 moderately fine sand pt3off9 4/1212001 5902.97.8492 4089262.501 0.00 95.33 3.67 2.1,3.9 2.45 moderately fine sand pt3off10 4/12/2001 591547.9141 4089269.791 ola of a of a o/a ofa o/a cocky pt3off11 411212001 591530.4169 4089928.458 ola of a ofa ola ola pt3off12 4/1212001 590764.4013 4089947.934 0.00 94.09 5.91 4.00 "''3.36 well "'"''very fine sand pt3off13 411212001 590211.576 4090435.765 0.00 97.34 2.66 4.00 3.18 moderately well very fine sand pt3off14 4/1212001 589728.692.1 4090462.12 0.23 95.06 4.72 2, 4 2.75 moderately fine sand pt3off 15 4112/2001 589672.439 4089971.494 0.16 99.46 0.37 2.00 1.61 moderately well medium sand pt3off 16 4/1212001 589192..3389 4089984.929 0.00 74.51 25.49 4.00 3.77 moderately silly sand pt3off 17 4/1212001 588939.8295 4090430.215 0.00 84.77 15.23 4.00 3.44 moderately well very fine sand :pt3olf18 411212001 589290.5857 4090379.833 0.00 86.73 13.27 4.00 3.55 well vary fine sand pt3off 19 4/1212001 589540.9561 4090561.833 o/a ofa of a of a of a ofa cod S.G. Watt, 2003 88 Appendix C. Deep-Water Marine Benthic Habitat Classification Scheme Explanation for Habitat Classification Code (Greene et a! .. , 1999) S.G. Watt, 2003 89 Habitat Classification Code A habitat classification code, based on the deep-water habitat characterization scheme developed by Greene et al .. ( 1999), was created to easily distinguish marine benthic habitats and to facilitate ease of use and queries within GIS (e.g., ArcView®, TNT Mips®, and ArcGIS®) and database (e.g., Microsoft Access® or Excel®) periods. The code is derived from several categories and can be subdivided based on the spatial scale of the data. The following categories apply directly to habitat interpretations determined from remote sensing imagery collected at the scale of 1Os of kilometers to 1 meter: Megahabitat, Seafloor Induration, Meso/Macrohabitat, Modifier, Seafloor Slope, Seafloor Complexity, and Geologic Unit. Additional categories of Macro/Microhabitat, Seafloor Slope, and Seafloor Complexity apply to areas at tl1e scale of 10 meters to centimeters and are determined from video, still photos, or direct observations. These two components can be used in conjunction to define a habitat across spatial scales or separately for comparisons between large and small-scale habitat types. Categories are explained in detail below. Not all categories may be required or possible given the study objectives, data availability, or data quality and in these cases categories may be omitted. Explanation of Attribute Categories and their Use Determined from Remote Sensing Imagery (for creation of large-scale habitat maps) 1) Megahabitat - This category is based on depth and general physiographic boundaries and is used to distinguish regions and features on a scale of 1Os of kilometers to kilometers. Depth ranges listed for category attributes in the key are given as generalized exan1ples. This category is listed first in the code and denoted with a capital letter. 2) Seafloor Induration- Seafloor induration refers to substrate hardness and is depicted by the second letter (a lower-case letter) in the code. Designations of hard, mixed, and soft substrate can be further subdivided into distinct sediment types, and are then listed inlmediately afterwards in parentheses either in alphabetical order or in order of relative abundance. 3) Meso/Macrohabitat - This distinction is related to the scale of the habitat and consists of seafloor features ranging from 1 kilometer to 1 meter. Meso/Macrohabitats are noted as the third letter (a lower-case letter) in the code. If necessary, several Meso/Macrohabitats can be included either alphabetically or in order of relative abundance and separated by a backslash. 4) Modifier - The fourth letter in the code, a modifier, is noted with a lower-case subscript letter or separated by an underline in some GIS periods (e.g., ArcView®). Modifiers describe the texture or lithology of the seafloor. If necessary, several modifiers can be included alphabetically or in order of relative abundance and separated by a backs lash. S.G. Watt, 2003 90 5) Seafloor Slope - The fifth category, listed by a number following the modifier subscript, denotes slope. Slope is calculated for a survey area from x-y-z multibeam data and category values can be modified based on characteristics of the study region. 6) Seafloor Complexity - Complexity is denoted by the sixth letter and listed in caps. Complexity is calculated from slope data using neighborhood statistics and reported in standard deviation units. As with slope, category values can be modified based on characteristics of the study region. 7) Geologic Unit- When possible, the geologic unit is determined and listed subsequent to the habitat classification code, in parentheses. Determined from video, still photos, or direct observation (for designation of small-scale habitat types) 8) Macro/Microhabitat -Macro/Microhabitats are noted by the eighth letter in the code (or first letter, if used separately) and preceded by an asterisk. This category is subdivided between geologic (surrounded by parentheses) and biologic (surrounded by brackets) attributes. Dynamic segmentation can be used to plot macroscale habitat patches on Mega/Mesoscale habitat interpretations (Nasby 2000). 9) Seafloor Slope- The ninth category (or second category, if used separately), listed by a number denotes slope. Unlike the previous slope designation (#5), the clarity of this estimate can be made at smaller scales and groundtruthed or compared with category #5. Category values can be modified based on characteristics of the study region. l 0) Seafloor Complexitv - The designations in this category, unlike those in category #6, are based on seafloor rugosity values calculated as the ratio of surface area to linear area along a measured transect or patch. Category letters are listed in caps and category values can be modified based on characteristics of the study region. Literature Cited: Greene, H.G., M.M. Yoklavich, R.M. Starr, V.M. O'Connell, W.W. Wakefield, D.E. Sullivan, J.E. McRea Jr., and G.M. Cailliet, 1999. A classification scheme for deep seafloor habitats. Oceanologica Acta. Vol 22: 6. pp. 663-678. Nasby, N.M. 2000. Integration of submersible transect data and high-resolution sonar imagery for a habitat-based groundfish assessment ofHeceta Bank, Oregon. M.S. Thesis, College of Oceanic and Atmospheric Science, Oregon State University. S.G. Watt, 2003 91 Deep-Water Marine Benthic Habitat Classification Scheme Key to Habitat Classification Code for Mapping and use with GIS periods (modified after Greene et al.., 1999) Interpreted from remote sensing imagery for mapping purposes Megababitat- Use capital letters (based on depth and general physiographic boundaries; depth ranges approximate and specific to study .area). A= Aprons, continental rise, deep fans and bajadas (3000-5000 m) B =Basin floors, Borderland types (floors at 1000-2500 m) F =Flanks, continental slope, basin/island-atoll flanks (200-3000 m) I =Inland seas, fiords (0-200 m) P =Plains, abyssal (>5000 m) R =Ridges, banks and seamounts (crests at 200-2500 m) S = Shelf, continental and island shelves (0-200 m) Seafloor Induration- Use lower-case letters (based on substrate hardness). h = hard substrate, rock outcrop, relic beach rock or sediment pavement m = mixed (bard & soft substrate) s = soft substrate, sediment covered Sediment tvpes (for above indurations)- Use parentheses. (b) = boulder (c)= cobble (g)= gravel (h)= halimeda sediment, carbonate (m) =mud, silt, clay (p) =pebble (s) =sand Meso/Macrohabitat- Use lower-case letters (scale related). a= atoll b = beach, relic c=canyon d = deformed, tilted and folded bedrock e = exposure, bedrock f= flats g = gully, channel i =ice-formed feature or deposit, moraine, drop-stone depression k = karst, solution pit, sink I = landslide m = mound, depression n = enclosed waters, lagoon o = overbank deposit (levee) p =pinnacle r=rill S.G. Watt, 2003 92 s = scarp, cliff, fault or slump t =terrace w = sediment waves y = delta, fan zt1 = zooxanthellae hosting structure, carbonate reef 1 = barrier reef 2 = fringing reef 3 = head, bommie 4 = patch reef Modifier- Use lower-case subscript letters or underscore for GIS periods (textural and lithologic relationship). a= anthropogenic (artificial reef/breakwalllshipwreck) b = bimodal (conglomeratic, mixed [includes gravel, cobbles and pebbles]) c = consolidated sediment (includes claystone, mudstone, siltstone, sandstone, breccia, or conglomerate) d = differentially eroded r= fracture, joints-faulted g =granite h =hummocky, irregular relief i = interface, lithologic contact k =kelp 1 = limestone or carbonate m =massive o=outwash p =pavement r =ripples 5 = scour (current or ice, direction noted) u = unconsolidated sediment v = volcanic rock Seafloor Slope- Use category numbers. Calculated for survey area from x-y-z multibeam data. 1 Flat (0-1 ") 2 Sloping (1-30") 3 Steeply Sloping (30-60") 4 Vertical ( 60-90") 5 Overhang (> 90") Seafloor Complexity- Use category letters (in caps). Calculated for survey area from x-y-z multibeam slope data using neighborhood statistics and reported in standard deviation units. A Very Low Complexity ( -1 to 0) B Low Complexity (0 to 1) c Moderate Complexity (1 to 2) S.G. Watt, 2003 93 D High Complexity (2 to 3) E Very High Complexity (3+) Geologic Unit- When possible, the associated geologic unit is identified for each habitat type and follows the habitat designation in parentheses. Examples: ShpdlD(Q/R)- Continental shelfniegahabitat; flat, highly complex hard seafloor with pinnacles differentially eroded. Geologic unit= Quartenary/Recent. Fhd_d2C (Tmrn)- Continental slope megahabitat; sloping hard seafloor of deformed (tilted, faulted, folded), differentially eroded bedrock exposure forming overhangs and caves. Geologic unit= Tertiary Miocene Monterey Formation. Determined from video, still photos, or direct observation. Macro/Microhabitat- Preceeded by an asterik. Use parentheses for geologic attributes, brackets for biologic attributes. Based on observed small-scale seafloor features. Geologic attributes (note percent grain sizes when possible) (b) = boulder (c)= cobble (d) = deformed, faulted, or folded (e)= exposure, bedrock (sedimentary, igneous, or metamorphic) (t) =fans (g)= gravel (h)= halimeda sediment, carbonate slates or mounds (i) = interface (j) =joints, cracks, and crevices (m) =mud, silt, or clay (p) =pebble (q) =coquina (shell hash) (r) =rubble (s) =sand (t) =terrace-like seafloor including sedimentary pavements (w) =wall, scarp, or cliff Biologic attributes [a]= algae [b] = bryozoans [c] =corals [d] = detritus, drift algae [g] = gorgonians S.G. Watt, 2003 94 [n] =anemones [o] = other sessile organisms [s] = sponges [t] =tracks, trails, or trace fossils [u] = unusual organisms, or chemosynthetic communities [w] =worm tubes Seafloor Slope - Use category numbers. Estimated from video, still photos, or direct observation. 1 Flat (0-1 °) 2 Sloping (1-30°) 3 Steeply Sloping (30-60°) 4 Vertical ( 60 - 90°) 5 Overhang (90°+) Seafloor Complexity -Use category numbers. Estimated from video, still photos, or direct observation. Numbers represent seafloor rugosity values calculated as the ratio of surface area to linear area along a measured transect or patch. A Very Low Complexity (I to 1.25) B Low Complexity (1.25 to 1.50) C Moderate Complexity (1.50 to 1.75) D High Complexity (1.75 to 2.00) E Very High Complexity (2+) Examples: *(m)[w]!C- Flat or nearly flat mud (100%) bottom with worm tubes; moderate complexity. *(s/c)1A- Sand bottom (>50%) with cobbles. Flat or nearly flat with very low complexity. *(h)[c]!E- Coral reef on flat bottom with halimeda sediment. Very high complexity. Shpct1D(Q/R)*(m)[w]1 C -Large-scale habitat type: Continental shelf megahabitat; flat, highly complex hard seafloor with pinnacles differentially eroded. Geologic unit= Quartenary/Recent. Small-scale habitat type: Flat or nearly flat mud (100%) bottom with wonn tubes; moderate complexity. S.G. Watt, 2003 95