2008 Annual Monitoring Report (pdf 10.9MB) - Bolsa Chica ...

More documents

Recommendations

Info

Bolsa Chica Lowlands Restoration Monitoring 2008 Annual Report 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 3.0 to 3.5 m below NAVD88, 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 GPS 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. Figure 2-10. Beach profile survey operations The boat traveled along each transect from the offshore terminus to the surf zone guided by DGPS navigation. Soundings were acquired on a continuous basis (approximately 3 soundings per second), while positions were recorded at 1-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. In addition, measurements of the speed of sound in sea water also were obtained at the offshore end of each transect using a recording conductivity, temperature, and depth (CTD) instrument. Merkel & Associates, Inc. 119
Bolsa Chica Lowlands Restoration Monitoring 2008 Annual Report The data from the wading portion of each survey were processed using software developed by Trimble. The software read the raw total station data, 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 each survey consisted of Hypack files containing the position data and heave-compensated soundings. These data were edited for outliers using the Hypack Single-Beam Processing Module. The dynamic motion sensor utilized during the survey removed the majority of the wave contamination from the record in real time. To further minimize the influence of wave-induced vessel motion on several transects, however, a smooth line was faired through the echo sounder record prior to digitizing it with the Hypack software package. Corrections for the draft of the transducer and the measured speed of sound 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 NAVD88 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 Harbor were adjusted to the project site using the time and height differences published by NOAA (NOS, 2008). The adjusted soundings were thinned to a nominal horizontal interval of 3 m to produce a 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 fieldwork 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 ±15 cm. According to the Hemisphere GPS equipment specifications, the accuracy of horizontal positions obtained in the manner described above is less than 1.0 m. The electronic total station used to conduct the survey is capable of measuring ranges to within ±15 cm and elevation differences to within ±3 cm. Because the swimmer encountered waves and currents in the surf zone, however, the horizontal accuracy perpendicular to each transect (parallel to the shoreline) varied from minimal at short ranges to approximately ±5 m at the offshore end. Beach Width Measurement Program Monthly beach width measurements were acquired at each of the seven profile sites, commencing in January 2007 and continuing throughout 2008. The measurements were collected at tide heights ranging from -0.62 m to 1.96 m, NAVD. The beach width was recorded as the distance from a permanent point at the back beach to the approximate intersection of the still water line and the beach face. The foreshore slope also was measured and recorded along with the date and time of the observation. The measurements then were adjusted to approximate the MSL beach width using the foreshore slope and NOAA tide elevations. In addition, the distance from the back beach to the berm was measured. Although inherently less accurate than Merkel & Associates, Inc. 120
Page 2 and 3:
Bolsa Chica Lowlands Restoration Pr
Page 4 and 5:
Bolsa Chica Lowlands Restoration Mo
Page 6 and 7:
Page 8 and 9:
Page 10 and 11:
Page 12 and 13:
Page 14 and 15:
Page 16 and 17:
Page 18 and 19:
Page 20 and 21:
Santa Barbara Los Angeles Outer Bol
Page 22 and 23:
Page 24 and 25:
Page 26 and 27:
Page 28 and 29:
Page 30 and 31:
Page 32 and 33:
Page 34 and 35:
Page 36 and 37:
Page 38 and 39:
Page 40 and 41:
Page 42 and 43:
Page 44 and 45:
BS PM Rep3 Muted Pocket Marsh BS PM
Page 46 and 47:
Page 48 and 49:
Page 50 and 51:
Page 52 and 53:
Page 54 and 55:
Page 56 and 57:
Page 58 and 59:
Topsmelt January April July October
Page 60 and 61:
Page 62 and 63:
Page 64 and 65:
Page 66 and 67:
Page 68 and 69:
Page 70 and 71:
Page 72 and 73:
Page 74 and 75: 22 Temperature 20 Temperature (C) 1
Page 76 and 77: Bolsa Chica Lowlands Restoration Mo
Page 78 and 79: PM 50 66 47 Full Tidal Basin Future
Page 94 and 95: Zone PM 2 9 10 11 12 13 14 19 20 21
Page 108 and 109: Aug06 to Jan07 Jan07 to Jun07 assum
Page 168 and 169: Total Future Full Tidal Basin FFTB
Page 172 and 173: Western Snowy Plover Nesting at Bol
Page 174 and 175:
Western Snowy Plover Nesting at Bol
Page 176 and 177:
Page 178 and 179:
Page 180 and 181:
Page 182 and 183:
Page 184 and 185:
Page 186 and 187:
Page 188 and 189:
Page 190 and 191:
Page 192 and 193:
Page 194 and 195:
Page 196 and 197:
Page 198 and 199:
Page 200 and 201:
Page 202 and 203:
Page 204 and 205:
Page 206 and 207:
Page 208 and 209:
Page 210 and 211:
Page 212 and 213:
Page 214 and 215:
Page 216 and 217:
Page 218 and 219:
Page 220 and 221:
Page 222 and 223:
Page 224 and 225:
Page 226 and 227:
Page 228 and 229:
Page 230 and 231:
Page 232 and 233:
Page 234 and 235:
Page 236 and 237:
Page 238 and 239:
Page 240 and 241:
Page 242 and 243:
Page 244 and 245:
Page 246 and 247:
Page 248 and 249:
Page 250 and 251:
Page 252 and 253:
Page 254 and 255:
Page 256 and 257:
Page 258 and 259:
Page 260 and 261:
Page 262:
show all

2008 Annual Monitoring Report (pdf 10.9MB) - Bolsa Chica ...

Create successful ePaper yourself

Delete template?

Save as template?