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HomeMy WebLinkAboutH_5230_SCOASTAL FRONTIERS ,. Tom Rossmiller Harbor Resources Manager City of Newport Beach 829 Harbor Island Drive Newport Beach CA, 92660 Jw1e 26, 2007 CFC-727 Subject: Newport Beach May 2007 Beach Profile Survey Mr. Rossmiller: This letter report presents the methods and results of the Newport Beach May 2007 beach profile survey. The work was performed in support of the City of Newport Beach Shoreline Monitoring Program. The sections that follow provide an overview of the monitoring program, discuss the field activities, present the results, and offer brief observations regarding the state of the City's beaches. Beach profile plots accompany lhis report in Attachment A. The vertical datum used throughout this report is MLLW based on the National Tidal Datum Epoch (1983-200 I). The horizontal datum is the North American Datum of 1983 (NAD 83), California State Plane Zone 6, with units in US Survey Feet. Overview The May 2007 beach profile survey represents the second semi-annual survey conducted as part of the City's shoreline monitoring program since its inception in October 2006. The program consists of 13 shore-perpendicular beach profile transects located between the Santa Ana River and Corona de! Mar (Figure 1). With the exception of Transect CDM-1, which was established specifically for this monitoring program, each of the profile locations corresponds to a historical transect surveyed by the U.S. Army Corps of Engineers (USACE) as part of the Coast of California Storm and Tidal Waves Study for Orange County (CCSTWS-OC) or the Santa Ana River Nearshore Disposal monitoring project. The objective of the current monitoring program is to develop a quantitative understanding of changes in the condition of the City's beaches. The Newport area beach profile transects were surveyed on behalf of the U.S. Army Corps of Engineers and the County of Orange on multiple occasions during the 1990's and as recently as 2002. In December 2004, Coastal Frontiers conducted a pre-nourishment survey in support of the Santa Ana River Nourishment Project (which did not provide Coastal Frontiers Corporation 9420 Topanga Canyon Blvd, Suite 101 Chatsworth, CA 91311-5759 (818) 341-8133 Fax (818) 341-4498 Mr. Tom Rossmiller June 26, 2007 Page 2 significant amounts of material to the beach). A post-storm survey was performed in January 2006. These data provide a historical context by which to judge the changes observed in the shorezone as part of the current monitoring program. The first survey carried out as part of the current monitoring program was conducted in October 2006. Data obtained as part of this survey indicated that short-and long-term shoreline changes were similar. Shoreline advance predominated in the region bound by Transects SA-18 and SA-12; whereas, modest shoreline retreat was observed at those transects near Balboa Pier and Corona de! Mar. Figure 1. Location Map Field Activities Field activities were conducted ou May 17, 2007 using methods identical to those employed for the preceding three surveys conducted by Coastal Frontiers. In consequence, the results are directly comparable. The following sections discuss the data acquisition and reduction methods used for the survey. Mr. Tom Rossmiller June 26, 2007 Page 3 Beach Profile Data Acquisition The survey was conducted under ideal conditions, with light winds and waves typically less than 2 ft. The wading and bathymetric portions of the surveys were performed concurrently by two crews. Data were acquired along each transect from the back beach to the 45-ft isobath, Mean Lower Low Water (MLLW) Datum. The beach and surf zone were surveyed using a total station and a survey rodman. The total station was used to determine the position and elevation of the beach at each location occupied by the rodman. Each transect was surveyed from the back beach seaward through the surf zone until the survey rod no longer protruded above the water surface when held erect. This location, typically in a water depth of 10 to 12 ft below MLL W, provided substantial overlap with the landward portion of the bathymetric survey. Bathymetric data were collected with a digital acoustic echo sounder operated from a shallow-draft inflatable survey vessel. A dynamic motion sensor, which provides real-time corrections to the echo sounder for wave-induced vessel heave, also was utilized. A OPS receiver was used to determine the position of each sounding. To improve the accuracy of each position, differential corrections transmitted in real-time from U.S. Coast Guard beacons were utilized (DGPS). All systems were interfaced to a laptop computer using the Hypack Max survey package. The boat traveled along each transect guided by DGPS navigation. Soundings were acquired on a continuous basis (approximately 3 soundings per second), while positions were recorded at I-second intervals. The DGPS position data and sounding data were merged using the Hypack software, with interpolated positions being assigned to the soundings acquired between position fixes. The calibration of the echo sounder was checked at periodic intervals during the survey using a standard "bar check" procedure. Measurements of the speed of sound in sea water also were obtained at the offshore end of each transect using a device that records conductivity, temperature, and depth (CTD) along a vertical profile within the water column. Beach Profile Data Reduction The data from the wading portion of the survey were processed using software developed by Trimble. The raw total station data were read by the software, and the coordinates and elevation of each data point were calculated and inserted into a CAD drawing. The raw data from the bathymetric portion of the survey consisted of Hypack files containing the position data and heave-compensated soundings. These data were edited for Mr. Tom Rossmiller June 26, 2007 Page 4 outliers using the Hypack Single-Beam Processing Module. The dynamic motion sensor utilized during the survey removed the wave contamination from the record in real time. Corrections for the draft of the transducer and the measured speed of soW1d in sea water then were applied to the measured depths. The speed-of-sound profiles were confirmed using the results of the "bar check" calibration procedure. Finally, the corrected soundings were adjusted to MLLW datum using tide measurements made by the U.S. Department of Commerce, NOAA, at Los Angeles Harbor. To provide a more accurate representation of local tide conditions, the water levels recorded at Los Angeles were adjusted using the average time and height differences for Balboa Pier published by NOAA. The adjusted soundings were thinned to a nominal interval of 10 ft to produce a manageable file size suitable for developing beach profile plots. The resulting x, y, z data ( easting, northing, and elevation) were inserted into the CAD drawing containing the wading data. As indicated above, the field work was conducted in such a manner as to provide substantial overlap between the wading and bathymetric portions of the survey. The processed data were examined in this region to insure that the two data sets were compatible. Once this confirmatory inspection had been completed, only the more detailed data in the region of overlap were retained (typically the bathymetric data). The less detailed data were purged, after which the wading and bathymetric data were merged to create a single digital file. Based on past experience, the vertical accuracy of the processed soundings is approximately ±0.5 ft. According to the GPS equipment specifications, the root mean square (RMS) accuracy of horizontal positions obtained in the manner described above is 3.1 ft. The electronic total station used to conduct the survey is capable of measuring elevation differences to within ±0.1 ft and ranges to within ±0.5 ft. However, because the swimmer was subjected to waves and currents in the surf zone, the horizontal accuracy perpendicular to each transect (parallel to the shoreline) varied from minimal at short ranges to approximately ±15 ft at the offshore end. Results The beach profile plots developed from the May 2007 survey data are provided in Attachment A. To provide historical context, each plot also contains profiles from the October 2006, January 2006, December 2004, March 2002, November 1992, and May 1992 surveys where such data are available. The range on each plot represents the distance in feet seaward of the transect origin measured along the transect alignment, and the elevation is given in feet relative to MLL W. It should be noted that Transects SA-18 through SA-01 are registered to the origin used in the Orange County surveys conducted for the Corps in March 2002, Transects OC-27 through OC-30 are registered to the origin used in the Mr. Tom Rossmiller June 26, 2007 Page 5 CCSTWS-OC, and Transect CDM-1 is registered to the established origin. All historical data were adjusted to the new National Tidal Datum Epoch (1983-2001). The May 2007 beach profile data are included in digital form on an accompanying CD-Rom, which contains a digital copy of this report along with ASCII files of: ( 1) range and elevation for each profile, and (2) northing, easting, and elevation triplets (n,e,z) for the entire survey. Elevations are provided relative to MLLW Datum (1983-2001) and geo- referenced positions are given in U.S. Survey Feet relative to California State Plane Zone 6, NAD 83. Observations A detailed analysis of the state of the City's beaches exceeds the present Scope of Work. General observations are offered, however, based on the beach profile plots (Attachment A) and the MSL shoreline changes presented in Table 1, Figure 2, and Figure 3. Table 1. MSL Shoreline Changes MSL Shoreline Change Transect Seasonal Long-Term Oct. 2006 to May 2007 May 1992 to May 2007 SA-18 -144 119 SA-15 -117 120 SA-12 -64 88 SA-09 13 33 SA-08 6 7 SA-06 34 -31 SA-04 20 20 SA-01 -53 -23 OC-27 -16 -41 OC-28 48 9 OC-29 -20 -16 OC-30 3 2 CDM-1 -6 - Mr. Tom Rossmiller June 26, 2007 Page 6 Figure 2. Seasonal MSL Shoreline Changes (October 2006 -May 2007) g f 100 f 00 ,:i 0 .., i -00 =:::~g: ~ ,\0 ;!j .... r--~ Ot,,,~ ;jj;jj;jj;jj i ; ;ii ; § 8 88 Figure 3. Long-Term MSL Shoreline Changes (May 1992 -May 2007) 0 -SO -150 100 00 0 -so Mr. Tom Rossmiller June 26, 2007 Page 7 Profile Changes 1. Santa Ana River Nearshore Mound: The May and November 1992 profiles at Transects SA-18, SA-15, and SA-12 show the nearshore berm that was created from the placement of approximately 1.2 million cubic yards of sediment during 1992. The most recent profiles obtained at these transects (March 2002 through May 2007) indicate that the nearshore berm has been dispersed. It is possible that this material contributed to the long-term (1992-2007) shoreline advance in this region (Table I). 2. Seasonality: Nearshore bars are evident in beach profiles obtained during the late winter and spring at the majority of the West Newport Beach transects (Transects SA-18 through SA-01). However, these bars are absent in profiles obtained during the fall and early winter. This finding is consistent with the seasonal pattern of offshore transport of sand that typically occurs in response to winter storm waves. The predominance of shoreline retreat observed from October 2006 to May 2007 (Table I) further supports this observation. Shoreline Changes 1. Seasonal Shoreline Changes: Between October 2006 and May 2007 the shoreline retreated at six transects, advanced at four sites, and remained essentially unchanged (10 ft or less) at three locations. The average change in the West Newport Beach area (Transects SA-18 through SA-0 I) was a shoreline loss of 3 8 ft. An average shoreline gain of 16 ft occurred at the two Balboa Peninsula sites (Transects OC-27 and OC-28), while an average shoreline loss of 8 ft was recorded at the Corona de! Mar locations (Transects OC-29 through CDM-1). The greatest change, a loss of 144 ft, occurred at Transect SA-18. As indicated above, these shoreline losses are consistent with the seasonal trend of offshore sediment transport that typically occurs in response to winter storm waves. 2. Long-Term Shoreline Changes: During the 15-year period between the May 1992 and May 2007 surveys, the shoreline advanced at five of the survey sites, retreated at four, and was essentially unchanged (10 ft or less) at three. In the West Newport Beach area (Transects SA-18 through SA-01) the average shoreline change was a gain of 42 ft. The average shoreline change along Balboa Peninsula (Transects OC-27 and OC-28) was a loss of 16 ft. In Corona de! Mar (Transects OC-29 through CDM-1) the average shoreline change was a loss of 7 ft. Shoreline accretion was particularly prevalent in the region immediately adjacent to the Santa Ana River (Transects SA-18 through SA-09), with the largest shoreline advance (120 ft) Mr. Tom Rossmiller June 26, 2007 Page 8 occurring at Transect SA-15. The largest shoreline retreat, -41 ft, was observed near Balboa Pier at Transect OC-27. We have sincerely appreciated the opportunity to assist the City of Newport Beach. Please do not hesitate to contact me if you have any questions or require additional information. Sincerely, Coastal Frontiers Corporation Gregory E. Hearon, P.E. Christopher Scott Attachments: (A) Beach Profile Plots, Enclosure: Data CD-Rom Attachment A Beach Profile Plots 80 70 60 50 40 30 ~ 20 ~ ..s ID 10 © MSL '::, 0 ~ :3 -10 ls' ,-'B r:.:i -20 -30 -40 -50 -60 -70 0 May 2007 Transect SA-18 • I i I I ' _,~·"-._ ~--------" i I J~ -~, i j ~.;'.\::::-., I I ',, -.. ' I I . I " l l ~ '2'.'.~~~I I ! "'--~~-/: " ,, '"" 1\ -~~~ •• i , _~i -.......__ [ -~-.::,,., * i --r---' I -~ - I I 400 800 1200 1600 2000 2400 2800 3200 3600 4000 4400 4800 5200 Range (Feet Seaward of Transect Origin) Oct. 2006 Jan. 2006 Dec. 2004 Mar. 2002 Nov. 1992 May 1992 80 70 60 50 40 30 ~ 20 ::l ::. ...s • 10 • MSL :::, 0 ~ 0 :j -10 ~ • fJ -20 -30 -40 -50 -60 -70 0 May 2007 ' Transect SA-15 I \1'~, ' ' ' ! ""'C. ,·lee; ,_ i ' ! ' I l ' ~::'<;l" , ....... ' ~ ,, ! _{:\ '.c -, -~ '✓ ~-,\ ~ ' ! " . -" ' -"'l> ! ~ --'-·· - ' 400 800 1200 1600 2000 2400 2800 3200 3600 4000 4400 4600 5200 Range (Feet Seaward of Transect Origin) Oct. 2006 Jan. 2006 Dec. 2004 Mar. 2002 Nov. 1992 May 1992 80 Transect SA~12 70 60 ' 50 40 30 ~ 20 '""' '""' :,: 10 ..., © © MSL -'::, 0 " 0 :j -10 "' > © &l -20 J.,.,,. ii ~~'"\\ i : \ ~.\\ I i : -, I ' : i " -.., j i ~ 1', "~ '~ ~,--...... .~ ·\ : I -....._ \ -30 -,-' : -40 ---50 i -60 -70 0 400 800 1200 1600 2000 2400 2800 3200 3600 4000 4400 4800 5200 Range (Feet Sea ward of Transect Origin) May 2007 Oct. 2006 Jan, 2006 Dec. 2004 Mar. 2002 Nov. 1992 May 1992 80 70 60 50 40 30 ~ 20 ::l ::al 10 +5 ~ MSL !':'., 0 ~ 0 :j -10 ~ ~ r:r:l -20 -30 -40 -50 -60 -70 - 0 May 2007 I ~ -I \\~ I I . ~ I ~. ('.,_'\. ~ :~ "" ~.· 400 800 1200 Oct. 2006 Jan. 2006 Transect SA-09 : I ! : . . ----·;-'"" -- ' -. I -. • 1600 2000 2400 2800 3200 3600 4000 4400 4800 5200 Range (Feet Seaward of Transect Origin) Dec. 2004 Mar. 2002 Nov. 1992 May 1992 80 ' ' Transect SA-08 70 ' 60 ' 50 ' ' 40 ' 30 ~ 20 '""' '""' :al 10 +5 • ID MSL e o ~ 0 :j -10 ~ • ~ -20 ~. ' i ' I I l ' ' ' ' C "I~'\ ' ~ ' ' ' -30 ' ' . ' -40 ' -< -50 . -60 -70 0 400 800 1200 1600 2000 2400 2800 3200 3600 4000 4400 4800 5200 Range (Feet Seaward of Transect Origin) May 2007 Oct. 2006 Jan. 2006 Dec. 2004 Mar. 2002 Nov. 1992 May 1992 80 70 60 50 4{) 30 ~ 20 ::l ::a 10 +5 fil MSL .:::, 0 ~ 0 :j -10 ~ ~ ~ -20 -30 -40 -50 -60 -70 - 0 May 2007 i j i !~\ i~ i ' ' ' i ' i ·-,~1~ ! '.'.<,~➔:'\ ''-' ·~ "" ' 400 800 1200 Oct. 2006 Jan. 2006 Transect SA-06 • : i • • - ' ' ' i ' ----' i i • -- 1600 2000 24-00 2800 3200 3600 4000 4400 4800 5200 Range (Feet Seaward of Transect Origin) Dec. 2004 Mar. 2002 Nov_ 1992 May 1992 80 Transect SA-04 70 . 60 . 50 4-0 . ' 30 ~ 20 '"' '"' :,: 10 ..s © © MSL !'.:'., 0 ~ :3 -10 ~ © ~ -20 ~i¾.. ! '-1 ' ' ' ' • ' "' ~! t '" .~ i ~_,,,;,,')., ! '1' ... -' -30 ' . ' ' -40 -50 -60 -•~. -70 0 400 800 1200 1600 2000 2400 2800 3200 3600 4000 4400 4800 5200 Range (Feet Seaward of Transect Origin) May 2007 Oct. 2006 Jan. 2006 Dec. 2004 Mar. 2002 Nov. 1992 May 1992 80 70 60 50 40 30 ~ 20 ...J ...J :>I .µ 10 ~ MSL t:, 0 ~ 0 :;:l -10 ~ ~ r.-:i -20 -30 -40 -50 -60 -70 "'""' 0 May 2007 ~ ; ; --s;J I ~ I ! ~! ~ 400 800 1200 Oct. 2006 Jan. 2006 Transect SA-01 ' • • -r'-r-,,,. : : ' : 1600 2000 2400 2800 3200 3600 4000 4400 4800 5200 Range (Feet Seaward of Transect Origin) Dec. 2004 Mar. 2002 Nov. 1992 May 1992 80 70 60 50 40 30 ~ 20 ::l ::E +S ID 10 m MSL !::, 0 ~ 0 :jj -10 ~ ID ~ -20 -30 ~ ' : I --" I 1, Transect OC-27 i : I : I I I I I I ' ' ~ "~ -40 ~ ~ . -50 -60 "--·"·-----: ~' -~-~~ : ! f ! -70 ' I : 0 400 800 1200 1600 2000 2400 2800 3200 Range (Feet Seaward of Transect Origin) May 2007 Oct. 2006 Jan. 2006 Dec. 2004 Nov. 1992 May 1992 3600 4000 4400 4800 5200 80 70 60 50 40 30 ~ 20 "' "' :,s +5 ID 10 <D MSL E::, 0 ~ 0 :jj -10 ~ ID ~ -20 -30 -40 -50 -60 -70 0 May 2007 7 '~ '" I ' I '·'l· ' I I ' ~I ·"'-. '""'-~ ,,,,,,__ i 400 800 1200 Oct. 2006 Jan. 2006 ' Transect OC-28 i ' ' ' I ' ' ' i ' ~J ¾ \ \ . ' 1600 2000 2400 2800 3200 3600 4000 4400 4800 5200 Range (Feet Seaward of Transect Origin) Dec. 2004 Nov. 1992 May 1992 80 Transect OC-29 70 60 ' 50 40 30 ,;-20 ,_, ,_, ::E ' 10 .., ID IJ.l MSL !':, 0 " :3 -10 ~ ID ~ -20 -30 ' ~ I ' I ' ' '< ~I i ' ' ....... ~ ~ ~~' '"'-' ! -40 -50 1,!~ , ~-• I ' ' ' ""-"· -60 '.., "'·"' -70 ' "'· 0 400 800 1200 1600 2000 2400 2800 3200 3600 4000 4400 4800 5200 Range (Feet Seaward of Transect Origin) May 2007 Oct. 2006 Jan. 2006 Dec. 2004 Nov. 1992 May 1992 80 Transect OC-30 ' 70 60 i 50 j 40 30 i ~ 20 ' ..., ..., ::. 10 .., ID v MSL '::, 0 ~ :3 -10 ~ ID ~ -20 ~ ' ... \ : ' ' I i ,, I ' f'\ ~-i I" ·,, -30 -40 -50 ~ -~ ,,__ ~· j ' ~-i j -60 -70 I'""-, ', ' ' ' ···-k 0 400 800 1200 1600 2000 2400 2800 3200 3600 4000 4400 4800 5200 Range (Feet Sea ward of Transect Origin) May 2007 Oct. 2006 Nov. 1992 May 1992 80 Transect CDM-1 70 l 60 i ( 50 40 30 ~ 20 e--0 e--0 :,: i 10 \i .s 0 w MSL '"-, i l l e o ,,~ i l ~ i :3 -10 "' ~ ,.,,,, i 0 f~ fJ: -20 \, i"--! -30 l I"'-' _, ___ l ---- ' ,__ ' ' -40 ,, -~ -50 -60 l -70 i 0 400 800 1200 1600 2000 2400 2800 3200 3600 4000 4400 4800 5200 Range (Feet Sea ward of Transect Origin) May 2007 Oct. 2006 Stein, Robert From: Sent: To: Cc: Subject: Paal, Bob [bpaal@viracon,com] Wednesday, October 03, 2007 8:54 AM Stein, Robert Badum, Steve; Rosansky, Steven Canal Dredging Follow Up Flag: Follow up Flag Status: Red Attachments: Dredging Flyer.pd! Bob, Page I of I Last March at the Newport Shores Community Association's annual meeting, we had a few top priorities for discussion from the community. One of those was dredging the canal. The community had created the T.E.R.N.S. group which was starting to gain some traction. The NSCA board of directors was supporting this group and was also willing to do what ever leg work needed to get this project done. You were kind enough to attend the NSCA annual meeting and bring us up to date on various projects including the canal. At that time many of our members asked what they can do to speed the process. You responded that it would be best if we lay low since you felt that the dredging would start in either the spring of '08, or at the latest, the fall of '08. Based on your statements, the TERNS group basically disbanded and the members felt relieved that this was being handled. I, the rest of the board, and the Newport Shores community are starting to get nervous about this project getting under way, especially since we have not heard any updates from you. One member of the community printed a few hundred copies of a flyer (attachment) which they stuffed in mailboxes throughout the community. They also asked that we print this in our next newsletter. The board determined that the best course of action would be to not print it, but rather invite you, Steve Badum, and Mayor Rosansky to our next board meeting which is held at our clubhouse November 61h at 7:00 pm. Hopefully you will bring good news to the community. Please reply to let me know if you will be able to attend our next board meeting. Regards, Bob Paal President NSCA 10/03/2007