In Cooperation with National Park Service, Point Reyes National Seashore 

Investigation of Wind and Water Level for the Giacomini 

Wetland Restoration Project, Point Reyes National 

Seashore 

By John R. Dingler and Roberto J. Anima 

2007 

Open-File Report 2007-1151 

U.S. Department of the Interior 

U.S. Geological Survey 
U.S. Department of the Interior 

DIRK KEMPTHORNE, Secretary 

U.S. Geological Survey 

Mark D. Myers, Director 

U.S. Geological Survey, Reston, Virginia 2007 

For product and ordering information: 

World Wide Web: http://www.usgs.gov/pubprod

Telephone: 1-888-ASK-USGS 

For more information on the USGS—the Federal source for science about the Earth, 

its natural and living resources, natural hazards, and the environment: 

World Wide Web: http://www.usgs.gov

Telephone: 1-888-ASK-USGS 

Suggested citation: 

Dingler, John R., and Anima, Roberto J., 2007, Investigation of wind and water level for the Giacomini wetland r

estoration project, Point Reyes National Seashore: U.S. Geological Survey Open-File Report 2007-1151 

[http://pubs.usgs.gov/of/2007/1151/]. 

Any use of trade, product, or firm names is for descriptive purposes only and does not imply 

endorsement by the U.S. Government. 

Although this report is in the public domain, permission must be secured from the individual 

copyright owners to reproduce any copyrighted material contained within this report. 

ii
Contents 

Introduction .........................................................................................................................................................................1

Setting...............................................................................................................................................................................1

Wind ..................................................................................................................................................................................1

Tides and Tide Stations .................................................................................................................................................2

Giacomini Wetland Restoration ...................................................................................................................................2

USGS Involvement..........................................................................................................................................................2

Instrument Installation and Operation............................................................................................................................3

Data Collection....................................................................................................................................................................3

Wind ..................................................................................................................................................................................3

Water Level......................................................................................................................................................................3

Analysis and Discussion ...................................................................................................................................................4

Wind ..................................................................................................................................................................................4

Water Level......................................................................................................................................................................5

Conclusions and Recommendations...............................................................................................................................6

References Cited ................................................................................................................................................................6

Figures ..................................................................................................................................................................................8

Tables .................................................................................................................................................................................10

Figures 

Figure 1. Point Reyes National Seashore.......................................................................................................................8

Figure 2. Topographic map of Point Reyes National Seashore and Tomales Bay with instrument locations 

and sites of NOAA tidal stations......................................................................................................................................8

Figure 3. Meteorology tower and water-level recording station on the Giacomini levee....................................8

Figure 4. Sampling times for the Giacomini Levee meteorology station..................................................................8

Figure 5. Polar scatterplot showing wind speed as a function of wind direction by month at the Giacomini 

Levee.....................................................................................................................................................................................8

Figure 6. Polar graph showing mean resultant length for wind direction at the Giacomini Levee .....................8

Figure 7. Polar histogram showing wind speed as a function of wind direction at the Giacomini Levee .........8

Figure 8. Polar scatterplot showing wind speed as a function of wind direction at the Giacomini Levee........8

Figure 9. Water level measurements in December 2002 at the Point Reyes Tidal Station, Sacramento 

Landing, and Giacomini, and the predicted tide at the Point Reyes Tidal Station..................................................8

Figure 10. Water level measurements in December 2004 at the Point Reyes Tidal Station, Sacramento 

Landing, and Giacomini, and the predicted tide at the Point Reyes Tidal Station..................................................8

Figure 11. One year of water-level measurements at Giacomini Levee and Sacramento Landing....................8

Figure 12. Quantile plots of water level at the Giacomini Levee and Sacramento Landing versus that at the 

Point Reyes Tidal Station. .................................................................................................................................................9

 

iii
Tables 

Table 1. Tidal elevations for 9415020 (Point Reyes, Calif.) .......................................................................................10

Table 2.Spreadsheet array of available data from the Giacomini Levee meteorology station..........................10

Table 3. Spreadsheet array of available data from the Giacomini Levee and Sacramento Landing water 

level stations......................................................................................................................................................................11

Table 4. Giacomini Lvee wind statistics ......................................................................................................................11

Table 5. Giacomini Levee water-level percentiles for four dates ..........................................................................12

iv
Investigation of Wind and Water Level for the 

Giacomini Wetland Restoration Project, Point Reyes 

National Seashore 

By John R. Dingler and Roberto J. Anima1

Introduction 

Setting 

Point Reyes National Seashore (PRNS), comprising unique elements of geological, 

biological, and historical interest, is located on the central California coast approximately 60 km 

northwest of San Francisco (fig. 1). The National Seashore contains nearly 130 km of exposed and 

protected shorelines, spectacular coastal cliffs and headlands, lagoons, open grasslands, bushy 

hillsides, and forested ridges. Approximately 30 km of the shoreline are coastal-dune habitat that 

supports 11 federally listed species, including the threatened western snowy plover and the 

endangered plants Tidestrom’s lupine (Lupinus tidestromii) and beach layia (Layia carnosa). The 

San Andreas Fault, a right-lateral strike-slip fault, trends northwest along the northeastern side of 

the park. 

Tomales Bay (fig. 2), which is straight, long, narrow, and shallow, runs along the 

northeastern boundary of PRNS. The Bay, which fills the northwestern end of a rift valley at the 

intersection of the San Andreas Fault with the coastline, is approximately 20 km long, 2 km wide, 

and 6 m deep with mountainous terrain to the southwest and rolling hills to the northeast. Tomales 

Bay is one of the cleanest estuaries on the West Coast. In winter, approximately 17,000 to 20,000 

shorebirds inhabit Tomales Bay and Bodega Bay, which lies directly to the north. 

Sa

Wind 

The Central California Coast lies on the eastern edge of the North Pacific high-pressure 

system. The location of that system throughout the year determines the predominant 

meteorological conditions for the region. Higher pressure offshore in combination with lower 

pressure in the warm inland areas results in northwesterly winds during much of the year (Mass and 

Bond, 1996; Renard, 1996). Normally, the high-pressure system shifts north during the summer 

and south during the winter. Consequently, the predominant wind direction is from the northwest 

between May and October (Halliwell and Allen, 1987) and from a westerly direction between 

November and April (Halliwell and Allen, 1987; Dorman, and others, 1995; Dorman and Winant, 

1995). 

In addition to the North Pacific High, migratory weather systems produce local climatic 

variations throughout the year. During the winter months, southeasterly to southwesterly winds 

form in advance of extratropical storms that cross the region. During the summer months, the 

 

1

 Both at U.S. Geological Survey, Menlo Park, Calif. 

1
development of higher pressure over the interior part of the state results in offshore flow (Mass and 

Bond, 1996). 

Land and sea breezes are a common component of the local wind regime. When the air 

lying over the land is cooler than the air over the ocean, a land breeze (offshore flow) develops; the 

reverse pattern of air temperatures generates a sea breeze (onshore flow). Typically, the land 

warms during the day with a maximum air-temperature difference between the ocean and valley 

occurring in mid afternoon. This produces a surface pressure differential between the ocean (high) 

and valley (low) that generates a strong, steady sea breeze. As day ends the land begins to cool, 

and sometime after sunset the two temperatures equalize and the wind dies. Further cooling 

generates a land breeze, which, in general, is weaker than the preceding sea breeze. In central 

California, this pattern occurs throughout the year, producing large diurnal changes in coastal 

weather (Banta and others, 1993). 

Tides and Tide Stations 

Tides along the California coast are semi-diurnal in nature (two highs and two lows a day) 

with a strong diurnal inequality (unequal heights in successive high or low waters). The nearest 

NOAA primary control tidal station used for this study is adjacent to a pier at the end of Chimney 

Rock Road at the western end of Drake’s Bay (referred to as the ‘Point Reyes Tidal Station’ in this 

report). Both predicted water levels and measured water levels are available from NOAA for the 

Point Reyes Tidal Station2

. Table 1 summarizes the tidal datums for that station. Only predicted 

water levels are available for the subordinate tide stations at Marshall and Inverness.

Giacomini Wetland Restoration 

At the head of Tomales Bay, the Giacomini Ranch comprises 563 acres of pastureland 

currently being used for grazing dairy cattle. After more than 50 years of operation as a dairy, the 

National Park Service acquired the Giacomini property (fig. 2) with the intention to restore most of 

it and the nearby Olema Marsh to tidal wetland. Restoration will add approximately 4% to the 

existing coastal wetlands in California. The project will return the headwaters of Tomales Bay and 

two major stream intersections to an intertidal marsh environment, enhancing habitat for both 

wildlife and fish populations and contributing to the long-term health of Tomales Bay.

Prior to the establishment of the ranch, the area was primarily salt marsh that formed as the 

delta of Lagunitas Creek expanded into Tomales Bay. In converting the salt marsh to dairy land, 

levees and tide gates were constructed to prevent tidal incursion and stream flooding. Those levees 

have significantly altered the patterns of estuarine circulation and sediment deposition. To restore 

natural hydrologic processes within the area and to promote the return of ecological functions and 

processes, the levees will have to be breached or removed.

USGS Involvement 

Developing a successful restoration strategy requires knowledge of elevations within the 

pastureland and the range of water depths that can be expected from tidal, river, and wind action. 

In support of the restoration program, the USGS provides technical assistance to PRNS in the form 

of a scientific study focusing on understanding the physical processes that could affect the 

Giacomini wetland restoration. The study will yield scientific products that NPS resource 

managers can use in designing and implementing the restoration project. Research elements 

include: 

 

2

http://tidesandcurrents.noaa.gov/data_menu.shtml?type=Historic+Tide+Data&mstn=9415020

2
• Develop a Geodetic Control Network (GCN) throughout PRNS that meets the standards specified National 

Geodetic Survey data base (the NGS “Bluebook”). The grid will allow this and future studies to be conducted to a 

precision commensurate with the expressed goals of PRNS. The survey will consist of three steps: (1) verify 

existing GPS control monuments in the area; (2) tie control monuments in the study areas to the GPS control 

monuments; and (3) establish NAVD88 elevations using a digital electronic level. 

• Conduct a detailed survey of the Giacomini site to produce an accurate topographic map of the property. The site 

survey can be coupled with on-site water-level measurements to produce an empirical flooding model. 

• Measure water level and wind regime at the Giacomini site. The water-level range is critical to determining the 

wetland types based on the elevation of the dairy land. Water level at Sacramento Landing, in central Tomales 

Bay, will also be measured for comparison. 

As of November 2005, we have created a GCN, produced a detailed topographic map of the 

Giacomini site, and collected approximately three years of water-level and wind data at the 

Giacomini site and over one year of usable water-level data at the Sacramento Landing pier. 

Instrument Installation and Operation 

A meteorological tower and water level-gauge3 were installed on the levee adjacent to 

Lagunitas Creek near the bayward end of the Giacomini property (figs. 2, 3). Mounted on the 10-m 

tower are a suite of sensors to measure wind speed and direction, barometric pressure, air 

temperature, and rainfall. Cup anemometers mounted one, two, four, and eight meters above the 

ground and a wind direction vane mounted at the top of the tower, have threshold speeds of 1 m/s. 

The sample rate was 1 Hz, and each record consisted of fifteen-minute average values and standard 

deviations for each sensor. 

The water-level gauge uses a gas purge system to measure the water level above the tip of a 

small inside-diameter tube that was installed underwater in the creek. The elevation of the end of 

the tube was determined so that the water level can be related to a chosen datum such as NAVD88. 

A similar water-level gauge was mounted to the pier at Sacramento Landing (fig. 2) using the same 

surveying methods to tie the elevation of the end of the tube to the NAVD88 reference point. 

Data Collection 

Wind 

The collection of wind data at the Giacomini site started on 6 November 2002 at 1530 PST 

(fig. 4). The data logger samples all input channels once a second and then calculates averages for 

each channel at the end of the specified averaging period. Initially, the period was 10 minutes; on 6 

March 2003 at 1530 PST, the period was reset to 15 minutes. All the wind data are stored in an 

Excel spreadsheet (column headings shown in table 2). For each sensor, successive columns 

represent the average and standard deviation (SD) during the sampling period 

Water Level 

The water level sensor measures the pressure needed to push a gas bubble out of the tube 

and converts that pressure to a water depth at the tip of the tube. Samples were taken every two 

 

3

 Information on the instruments can be found at: 

http://www.nrgsystems.com/store/products.php?cd=11&ProdGrp=STND (wind) 

http://www.waterlog.com/products/H355/h_355.html (water level gauge) 

http://www.waterlog.com/products/H350XL/H-350XL.html (water level recorder) 

3
seconds for fifteen minutes (450 samples), and the average and standard deviation of those samples 

recorded. At the Giacomini Levee, the tip of the tube was situated in Lagunitas Creek below 

MLLW. The sensor operated continuously from 13 December 2002 through 30 October 2005. 

Data from the period between 29 August and 22 November 2004 were lost because of a collection 

error. At Sacramento Landing, the tip was mounted below MLLW on a pipe attached to a pier 

piling. Because of fouling by marine organisms, the data were unreliable before 23 October 2004 

when an effective cleaning technique was developed. Subsequent data were complete and reliable. 

All of the water-level data for each location are stored in an Excel spreadsheet (column 

headings shown in table 3). The spreadsheet also contains the Inverness, Marshall, and Point Reyes 

Tidal Station predicted tides as well as the measured values at the Point Reyes Tidal Station. The 

corrected depth, H2, is derived by correcting the measured depth, H1, to the NAVD88 datum. Hpr,

the measured depth from the Point Reyes Tidal Station gauge, is also based on NAVD88 assuming 

that datum and MLLW are the same at that station (table 1). 

Analysis and Discussion 

Wind 

The primary goal of the meteorology measurements at the Giacomini site was to assess the 

affect of wind on water level especially during periods of high water when flooding of roads and 

property adjacent to the restored wetland was most likely to occur. Although the wind data clearly 

show the pattern of speed and direction and wind shear at the levee, no correlation with overall 

water level was found. 

Wind blows primarily from the northwest and southeast with a southwest component during 

some times of the year (figs. 5, 6) at speeds up to 17 m/s (figs. 7, 8). Northwest winds predominate 

from April through October and southeast winds from November through February with a notable 

southwest component between May and September (fig. 5). Northwest winds are indicative of the 

summer regional wind pattern for the northern Pacific, southeast winds of winter storms, and 

southwest winds of the summer sea breeze. The axis of Tomales Bay aligns with the predominant 

summer winds from the northwest and the winter storm winds from the southeast. Although it is 

protected from sea breezes by the mountainous topography of the Inverness Ridge, some winds 

reach the bay through gaps along the ridge. 

Nonetheless, there is a large variability in wind direction at the Giacomini Levee that can 

only be quantified by the use of statistics for cyclic data (i.e., the beginning and end of the scale 

coincide: 0° = 360°). Because of the circular nature of directional data, the classic arithmetic mean 

is likely to be a poor summary statistic (e.g., the mean of 1° and 359° is not 180°). The equivalent 

circular parameter the mean resultant length, R, defined by 

 R 2 = (S2+C2)/N2 (0 ≤ R ≤ 1)

where θ is the wind direction and there are N observations, each with unit weight, and 

S = C = . ∑N

1 θ )sin( ∑N1 θ )cos(

If R not equal to zero, the circular mean, Θ, is defined by 

Θ = arctan(S/C). 

As R approaches 1, the observed directions cluster about Θ; as R decreases, the observed 

values become widely dispersed or from opposite directions, and Θ loses significance. With 

respect to the Giacomini Levee wind data, R notably varies with month and wind speed (fig. 6). 

4
On a monthly basis, R is 0.5 or greater in May and September, which are transition months between 

summer and winter wind patterns. In January, March, April, October, and November, R is 

between 0.25 and 0.5. In the other months, R less than 0.25. Considering wind speed categories, 

when U8 is greater than or equal to 10 m/s, R is approximately 0.5. When U8 is greater than 5 m/s, 

R is 0.25. 

The maximum wind speed measured at the 8-m anemometer (U8

) exceeded 17 m/s (table 4). 

Wind speeds greater than 10 m/s occur 1.2% of the time and only come out of the southeast and 

northwest (fig. 7) with the predominant direction being the southeast, probably as a result of winter 

storms (fig. 8).

Water Level 

Using data from the Point Reyes Tidal Station and the water-level gauges at Sacramento 

Landing and the Giacomini Levee (fig. 2) allows us to look at tidal differences between the open 

ocean, central Tomales Bay, and the head of the bay (figs. 9, 10). Clearly, the tide is the largest 

contributor to the water level, as the three curves have a shape and periodicity that is consistent 

with a tidal cycle. The major differences are that there is a shift in the times of highs and lows 

between the sites and there is an elevation of the highs and truncation of the lows at Giacomini 

relative to the other sites. Data from the water level gauge at Sacramento Landing show a floodtide lag of approximately 2 hours between the tidal peak at Sacramento Landing and Point Reyes 

Tidal Station (temporal offset) and an ebb-tide lag of approximately 3 hours. Tidal ranges are 

approximately equal at the two locations. At the Giacomini Levee, the lag is approximately 1 hour 

for the flood tide and 4 hours for the ebb. Elevations are not equal; the peaks match with slightly 

higher elevations at the Levee, but the troughs at the Giacomini Levee are significantly truncated 

relative to those at Sacramento Landing (fig. 11). The truncation could be caused by an increased 

impact of the flow in Lagunitas Creek during the ebb tide and/or modification of the low-tide flow 

over the mud flat. 

Quantile plots further elucidate water-level differences between the sites (figs. 12, 13). 

Quantiles are points taken at regular intervals from the cumulative distribution function of a 

random variable. Dividing ordered data into q equal-sized data subsets is the motivation for qquantiles; the quantiles are the data values marking the boundaries between consecutive subsets. 

Put another way, the kth q-quantile is the value x such that the probability that a random variable 

will be less than x is at most k/q and the probability that a random variable will be less than or 

equal to x is at least k/q. There are q − 1 quantiles, with k an integer satisfying 0 < k < q. Some 

quantiles have special names: the 100-quantiles are called percentiles and the 4-quantiles are called 

quartiles.”4

 In quantile scatterplots, the quantiles of one variable are plotted against the quantiles of 

another variable to assess the similarity of the empirical distributions of the two variables (fig. 12). 

If the data points fall on the regression line, then it can be concluded that the two variables follow 

the same distribution. Plotting each Hg

 (H2 at the Giacomini Levee) and Hs (H2 at Sacramento 

Landing) against Hpr (water level at the Point Reyes Tidal Station) shows the difference between the 

water-level patterns at the Levee and Sacramento Landing. The Hs-Hpr curve falls on the normal 

regression line except for the largest values, indicating that the peaks are higher in Tomales Bay 

than at the Point Reyes Tidal Station. However, the Hg

-Hpr curve does not match the regression line 

at all, and its shape indicates that both low and high water are higher at the Giacomini Levee. 

In quantile-quantile plots, which are different from quantile scatterplots, the observed 

values of a variable are plotted against the theoretical quantiles of that variable. Such a plot would 

indicate a good fit of the theoretical distribution to the observed values if the plotted values fall 

 

4

 Wikipedia: 7 June 2006 

5
onto a straight line. In figure 13, the deviation from a straight line in all three curves—Hg, Hs, and 

Hpr—is consistent with a tidal pattern. Again, the sharp deviation in the lower part Hg curve 

shows that low water is much different than would be expected from tidal action. 

Water elevations over the Giacomini site after the levees are opened are based on the 

percentile values of the water-level data at the levee (table 5 and fig. 14). In this case, percentile 

values represent the amount of time the water level is above that value. Thus, the 50th percentile, or 

median, value is the elevation that is exceeded 50% of the time. The minimum and maximum 

values are the lowest and highest water-level elevations (one data point). Contouring the 

topographic map using these percentile values shows the percentage of time that the water will 

equal or be greater than the given elevation. The map shows that most of the Giacomini Ranch site 

would be flooded less than 50% of the time if there were openings in the levees. 

Because the wind predominantly blows along the axis of Tomales Bay, strong winds 

possibly could increase or decrease high water levels. For example, a strong northwest wind 

blowing at a higher-high tide could increase the water level over the wetland. The reverse could be 

true of a southeast wind. However, we found no correlation between wind and water level at the 

levee site when we compared wind speed with high water levels (fig. 15). Likely, any affect of 

wind on water level would be masked by the large tidal signal. Furthermore, the affect of creek 

flow is unknown and the influence of the mud flat on controlling the water level is not quantifiable 

with our data. Qualitatively, the strong winds that are associated with winter storms would either 

have no affect on water level or would push water away from the head of the bay, thus lowering the 

effective water level over the wetland. 

Conclusions and Recommendations 

The objective of this study was to gather topographic, wind, and water-level data at the 

Giacomini Ranch to be able to predict flooding levels if PRNS converts the property to an intertidal 

marsh environment. Three years of data show the property would be flooded less than 50% of the 

time if the levees were breached and the maximum water level would not result in flooding of 

adjacent property. A caveat, though, is that these data do not consider the affect of a large flood in 

Lagunitas Creek during times of highest water. A guess is that the increased area resulting from 

opening the levees would accommodate the excess water without flooding. To better evaluate the 

flooding affect, one would need to know the increased volume of water and how the creek and tide 

interact. 

We recommend that the Giacomini water-level station be operated for at least two years 

after the levee is breached. Those data can be compared with the pre-breach data (fig. 14) to see 

how increasing the area exposed to tides alters maximum water levels. The wind and water-level 

stations could also be modified to transmit their data to the visitor center for real-time display. 

Besides being of public interest, such a display would alert park personnel before extreme water 

levels are reached. 

References Cited 

Banta, R.M., Olivier, L.D, and Levinson, D.H., 1993, Evolution of the Monterey Bay sea-breeze 

layer as observed by pulsed Doppler lidar: Journal of Atmospheric Science, v. 50, p. 3959-

3982. 

Dorman, C.E., and Winant, C.W., 1995, Buoy observations of the atmosphere along the west coast 

of the United States, 1981-1990. Journal of Geophysical Research, v. 100, p. 16029-16044. 

6
Dorman, C.E., Enriquez, A.G., and Friehe, C.A., 1995, Structure of the Lower Atmosphere over the 

Northern California Coast during Winter. Monthly Weather Review, v. 123, p. 2384–2404. 

Halliwell, G.R., and Allen, J.S., 1987, Wavenumber-frequency domain properties of the coastal sea 

level response to alongshore wind stress along the west coast of North America, 1980-84. 

Journal of Geophysical Research, v. 92, p. 11761-11788. 

Mass, C.F., and Bond, N.A., 1996, Wind Reversals along the United States West Coast during the 

Warm Season. Part II:Synoptic Evolution. Monthly Weather Review, v. 125, p. 1692-1694. 

Renard, R.J., 1996, and earlier years, Monterey Peninsula Monthly Weather Summaries: 

Unpublished documents available from Department of Meteorology, Naval Postgraduate 

School, Monterey, CA 93943. 

7
Figures 

Figure 1. Point Reyes National Seashore, (box at the top left corner of the image) is approximately 

60 km northwest of San Francisco. The San Andreas Fault trends from southeast to northwest along 

the northeast boundary of the National Seashore (red lines mark Bay-Area faults). 

Figure 2. Topographic map of Point Reyes National Seashore and Tomales Bay with instrument 

locations and sites of NOAA tidal stations. 

Figure 3. Meteorology tower and water-level recording station on the Giacomini levee. The tower 

is 10-m high with anemometers at 1, 2, 4, and 8 m and a wind vane on top. A tube runs from the 

water-level box to Lagunitas Creek (background). 

Figure 4. Sampling times for the Giacomini Levee meteorology station. Breaks in the line 

represent times of no data. 

Figure 5. Polar scatterplot showing wind speed (U8

, m/s) as a function of wind direction (°TN) by 

month at the Giacomini Levee. For clarity the radial axis (U8) is reversed, placing the minimum speed 

at the graph’s circumference. 

Figure 6. Polar graph showing mean resultant length for wind direction (°TN) at the Giacomini 

Levee. Data points represent selected averages: each month, U8 greater than 5 m/s, U8 greater than 

10 m/s, and all the data. 

Figure 7. Polar histogram showing wind speed (U8, m/s) as a function of wind direction (°TN) at 

the Giacomini Levee. Wind speed is broken into four categories. 

Figure 8. Polar scatterplot showing wind speed (U8, m/s) as a function of wind direction (°TN) at 

the Giacomini Levee. For clarity the radial axis (U8

) is reversed, placing the minimum speed at the 

graph’s circumference 

Figure 9. Water level measurements in December 2002 at the Point Reyes Tidal Station (Hpr), 

Sacramento Landing (Hs

), and Giacomini (Hg) and the predicted tide at the Point Reyes Tidal Station 

(Tpr). (B) a two-week period; (A) two days to dramatize the truncation of the low water at Giacomini 

and the temporal offsets of the highs and lows between the sites, and the strength of the tidal 

signal. 

Figure 10. Water level measurements in December 2004 at the Point Reyes Tidal Station (Hpr), 

Sacramento Landing (Hs

), and Giacomini (Hg) and the predicted tide at the Point Reyes Tidal Station 

(Tpr). (B) a two-week period; (A) two days to dramatize the truncation of the low water at Giacomini, 

the temporal offsets of the highs and lows between the sites, and the strength of the tidal signal 

Figure 11. One year of water-level measurements at Giacomini Levee (black) and Sacramento 

Landing (red). Clearly, truncation of the tidal lows consistently occurs throughout the year. 

8
Figure 12. Quantile plots of water level at the Giacomini Levee and Sacramento Landing versus 

that at the Point Reyes Tidal Station. In quantile scatterplots, the quantiles of one variable are 

plotted against the quantiles of another variable to assess the similarity of the empirical 

distributions of the two variables. If the data points fall on the regression line (red line), then it can 

be concluded that the two variables follow the same distribution. Clearly, the Giacomini Levee 

water level does not match that at the Point Reyes Tidal Station as well as the Sacramento Landing 

water level does. 

Figure 13. Quantile-Quantile plots of water level at the Point Reyes Tidal Station (Hpr), Sacramento 

Landing (Hs), and Giacomini (Hg). In quantile-quantile plots, the observed values of a variable are 

plotted against the theoretical quantiles. A good fit of the observed values to the theoretical 

distribution would be indicated if the plotted values fall onto a straight line. The curves at the ends 

of each of the plots represent low and high tides. The fact that the Hpr and Hs

 match indicates that 

water fluctuations at those sites is similar. The shift to the right in the upper part of Hg suggests a 

slight delay in the flood cycles relative to the other sites, and the extreme variation at the lower end 

represents flow truncation during the ebb cycles.

Figure 14. Predicted inundation levels if the Giacomini Levees are opened. Contours are based 

on all available water-level data from the Giacomini Levee station. Contours are produced by colorcoding the topographic map of the property using water-level percentiles. 

Figure 15. Wind speed at the Giacomini Levee, U8

, versus water level, Hg. The minimum water 

level shown on the abscissa, 1.8 m, corresponds to the 90th percentile of all data (10 % of all water 

levels were greater than 1.8 m). The data are broken out by three-month periods to better show 

levels during stormy and fair seasons. There is no obvious correlation.

9
Tables 

Table 1. Tidal elevations for 9415020 (Point Reyes, Calif.)4 

Latitude: 37° 59.8’ N, Longitude: 122° 58.5’ W 

Maximum Water Level 2.61 m 

Mean Higher High Water (MHHW) 1.76 m 

Mean High Water (MHW) 1.55 m 

Mean Tide Level (MTL) 0.96 m 

Mean Sea Level (MSL) 0.95 m 

Mean Low Water (MLW) 0.36 m 

Mean Lower Low Water (MLLW) 0.00 m 

Minimum Water Level -0.82 m 

NAVD88 Elevation 0.01 m 

Table 2. Spreadsheet array of available data from the Giacomini Levee meteorology station 

[SD = Standard Deviation] 

COLUMN VALUE COLUMN VALUE 

1 Julian Day 16 (Unused) 

2 Date 17 (Unused) 

3 Time 18 Direction 

4 Housing Temperature 19 SD Direction 

5 Battery 20 (Unused) 

6 WIND SPEED (U1, m/s) 21 (Unused) 

7 SD U1 22 (Unused) 

8 WIND SPEED (U2, m/s) 23 (Unused) 

9 SD U2 24 Temperature 

10 WIND SPEED (U4, m/s) 25 SD Temperature 

11 SD U4 26 Barometer 

12 Rain Gauge 27 SD Barometer 

13 SD Rain Gauge 28 (Unused) 

14 WIND SPEED (U8, m/s) 29 (Unused) 

15 SD U8

4

 the station description is available at the NOAA website: 

http://140.90.121.76/cgi-bin/station_info.cgi?stn=9415020+Point+Reyes+,+CA

10
Table 3. Spreadsheet array of available data from the Giacomini Levee and Sacramento Landing 

water level stations 

COLUMN VALUE COLUMN VALUE 

1 Day 6 H2 (corrected depth, m) 

2 Time 7 Ti (Inverness tide, m) 

3 H1 (measured depth, m) 8 Tm (Marshall tide, m) 

4 Julian Date 9 Tpr (Point Reyes tide, m) 

5 Date 10 Hpr (Point Reyes depth, m) 

Table 4. Giacomini Lvee wind statistics (75,869 samples at four samples per hour) 

U1 (m/s) U2 (m/s) U4 (m/s) U8 (m/s) 

MINIMUM 0.00 0.00 0.00 0.00

1ST PERCENTILE 0.35 0.35 0.35 0.35

5TH PERCENTILE 0.35 0.35 0.36 0.38

10TH PERCENTILE 0.36 0.41 0.46 0.56

25TH PERCENTILE 0.55 0.83 1.02 1.26

MEDIAN 1.46 1.88 2.22 2.54

75TH PERCENTILE 3.07 3.70 4.42 4.83

90TH PERCENTILE 4.36 5.06 6.08 6.59

95TH PERCENTILE 5.20 5.93 7.01 7.67

99TH PERCENTILE 6.88 7.75 9.15 10.26

MAXIMUM 11.73 13.99 16.14 17.38

MEAN 1.99 2.41 2.88 3.21

STANDARD DEVIATION 1.66 1.87 2.23 2.41

STANDARD ERROR 0.01 0.01 0.01 0.01

SKEWNESS 1.07 0.96 0.92 0.95

KURTOSIS 0.64 0.49 0.34 0.56

11
Table 5. Giacomini Levee water-level percentiles for four dates 

Percentile 2004.08.02 2004.12.02 2005.05.23 2005.09.29 

Minimum 0 0.47 0.47 0.47 0.47 

1 %ile 1 0.53 0.53 0.54 0.54 

5 %ile 5 0.59 0.60 0.62 0.62 

10 %ile 10 0.67 0.67 0.69 0.69 

25 %ile 25 0.84 0.85 0.87 0.86 

Median 50 1.13 1.14 1.16 1.16 

75 %ile 75 1.45 1.47 1.48 1.48 

90 %ile 90 1.75 1.76 1.77 1.79 

95 %ile 95 1.92 1.94 1.95 1.96 

99 %ile 99 2.20 2.21 2.22 2.22 

Maximum 100 2.65 2.65 2.71 2.71 

Valid N 57371 63968 80384 92764 

Mean 1.18 1.19 1.20 1.20 

Std.Dev. 0.41 0.41 0.41 0.41 

Std. Err. 0.00 0.00 0.00 0.00 

Skewness 0.50 0.50 0.50 0.50 

Kurtosis -0.36 -0.37 -0.35 -0.38 

12
Figure 1

Point Reyes National Seashore

San Andreas Fault

San Francisco

Bodega Bay
Sacramento Landing

Water Level

Giacomini Water Level

and Meteorology

Marshall Tidal Station

Point Reyes Tidal Station

Inverness Tidal Station

Figure 2

Drake’s Bay

Tomales Bay

Lagunit as Creek
Figure 3

Wind Vane

U8

U2

U1

U4
GIACOMINI LEVEE WIND DATA

11/6/02 2/26/03 6/18/03 10/8/03 1/28/04 5/19/04 9/8/04 12/29/04 4/20/05 8/10/05

Figure 4
Figure 5

JANUARY0 10 20 0 (°N)

45

90

135

180

225

270

315

FEBRUARY0 10 20 0 (°N)

45

90

135

180

225

270

315

MARCH0 10 20 0 (°N)

45

90

135

180

225

270

315

APRIL0 10 20 0 (°N)

45

90

135

180

225

270

315

MAY 0 10 20 0 (°N)

45

90

135

180

225

270

315

JUNE 0 10 20 0 (°N)

45

90

135

180

225

270

315

JULY 0 10 20 0 (°N)

45

90

135

180

225

270

315

AUGUST0 10 20 0 (°N)

45

90

135

180

225

270

315

SEPTEMBER 0 10 20 0 (°N)

45

90

135

180

225

270

315

OCTOBER0 10 20 0 (°N)

45

90

135

180

225

270

315

NOVEMBER0 10 20 0 (°N)

45

90

135

180

225

270

315

DECEMBER0 10 20 0 (°N)

45

90

135

180

225

270

315
Figure 60.0 0.5 1.0

Ř

0

45

90

135

180

225

270

315

MAY

OCTOBER

ALL MONTHS

JANUARY

SEPTEMBER

APRIL

DECEMBER

U8>=5 m/s

JULY

FEBRUARY

JUNE

AUGUST

MARCH

U8>=10 m/s

NOVEMBER
Figure 7

U8 <= 2 m/s

0

3000

6000

9000

0

45

90

135

180

225

270

315

2 < U8 <= 5 m/s 0 3000

0

45

90

135

180

225

270

315

5 < U8 <= 10 m/s 0 3000 6000

0

45

90

135

180

225

270

315

10 < U8 m/s

0

0

45

90

135

180

225

270

315

500
Figure 8

8 >= 5 m/s

69 12 15 18 U8 (m/s)

0

30

60

90

120

150

180

U8 >= 10 m/s

69 12 15 18 U8 (m/s)

0

30

60

90

120

150

180

210

240

270

300

330
Figure 9

H (m)

12/22/02 12/23/02 12/24/02

DATE

-0.5

0.5

1.5

2.5

H (m)

12/14/02 12/21/02 12/28/02

DATE

-0.5

0.5

1.5

2.5

 Hg

 Hs

 Hpr

 Tpr

B

A
Figure 10

12/22/04 12/23/04 12/24/04

DATE

-0.5

0.5

1.5

2.5

H (m)

12/14/04 12/21/04 12/28/04

DATE

-0.5

0.5

1.5

2.5

H (m)

 Hg

 Hs

 Hpr

 Tpr

A

B
Figure 11

11/13/04 1/8/05 3/5/05 4/30/05 6/25/05 8/20/05 10/15/05

DATE

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

WATER LEVEL (m)

 Hg

 Hs
Figure 12

-1 0 1 2 3

Hpr

0

1

2

3

Hs

Hs = 0.03+0.92*Hpr

Hg = 0.50+0.73*Hpr

Giacomini

Sacramento Landing
Figure 13

-1 0 1 2 3

Observed Value

-5.0

-2.5

0.0

2.5

5.0

Expected Normal Value

 Hpr

 Hg

 Hs
99 thPercentile

(2.2 m)

Above Maximum

Water Level

Below Minimum

Water Level

Maximum Water

Level (2.65 m)

10 25 50 75 90

Percentile

Figure 14
Hg (m)

Figure 15

U8 (m/s)

1.8 2.1 2.4 2.7

0

4

8

12

1.8 2.1 2.4 2.7

1.8 2.1 2.4 2.7

0

4

8

12

1.8 2.1 2.4 2.7

December - February March - May

June - August September - November