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

Bathymetric Surveys on Ponds 3, 4, & 5, Napa-Sonoma Marshes U.S. Geological Survey

John Y. Takekawa, Lacy M. Smith, & Nicole D. Athearn

Bathymetric Survey Overview

Goal: Document geomorphologic changes that have occurred since restoration of tidal flow New baseline data – Post-Breach Ponds 4 and 5 Comparable data

Pond 3: 2001 (Towill) vs. 2009, 2001 vs. 2005, 2005 vs. 2009

Ponds 4 & 5: 2001 (Towill) vs. 2009

Additional mapping of original South Slough breach, all pond breaches, and pond islands.

Bathymetry Survey Methods

Pelican Case with Navisound

RTK Antenna

Console with

laptop & RTK

Transducer

Bathymetry Survey Methods

200 m East-West & North-South transects

Pond 3

Pond 4

Bathymetry Survey Methods

South Slough and Breaches

Pond 3 ~ 2002 South Slough Breach

Mean elevation 2006: -3.122 ± 0.032 m (mean ± SE) NAVD 88 Mean elevation 2009: -3.108 ± 0.031 m

2006 2009

Pond 3 ~ 2002 South Slough Breach

Net sediment gain of 46 m3 or a 1.4 cm thick layer across the area

South Slough

Mean elevation of South Slough region only: -2.85 ± 1.52 m

Pond 5 ~ Current Elevation

Mean elevation: 0.85 ± 0.003 m (mean ± SE) NAVD 88

Elevation Range: -1.50 to 1.53 m

Pond 5 ~ 2001 - 2009

2001: 0.78 ± 0.003 m (mean ± SE) 2009: 0.85 ± 0.003 m

Pond 5 ~ Change in Elevation

Net sediment gain: 217,625 m3

7.6 cm layer of sediment throughout the pond

Pond 4 ~ Current Elevation

Mean elevation: 0.81 ± 0.004 m

Elevation Range: -2.1 to 1.97 m

Pond 4 ~ 2001 - 2009

2001: 0.82 ± 0.003m (mean ± SE) 2009: 0.81 ± 0.004m

Pond 4 ~ Change in Elevation

Net sediment gain: 19,700 m3

5.4 cm layer of sediment throughout the pond

Pond 3 ~ Current Elevation

Mean elevation: 1.05 ± 0.003 m

Elevation Range: -1.60 to 1.90 m

Pond 3 ~ 2001 to 2009

2001: 1.17 ± 0.002 m (mean ± SE) 2009: 1.05 ± 0.003 m

Pond 3 ~ Elevation Change 2001-2009

Net sediment loss: 594,900 m3

12 cm layer of sediment throughout the pond

Pond 3 ~ 2005 - 2009

2005: 0.96 ± 0.002m (mean ± SE) 2009: 1.05 ± 0.003m

Pond 3 ~ Change in Elevation 05-09

Net sediment gain: 473,800 m3

9 cm layer of sediment throughout the pond

Vegetation

See Google Earth

Summary

0.6

0.8

1

1.2

1.4

2000 2002 2004 2006 2008 2010

Me

an

Ele

va

tio

n (

m)

Pond 3

Pond 4

Pond 5

Future Research

Additional bathymetric surveys over time Bathymetric survey on 9 & 10 Aerial and Ground vegetation surveys Elevation survey of colonizing plants Continued monitoring of bird pond use

Acknowledgements

Funding provided by USGS and CA State Coastal Conservancy

Project support provided by: I. Woo, K. Spragens, K. Thorne, J. Shinn, A. Brand, K. Brailsford, C. Daggett, P. Gibson, T. Edgarian, S. Bishop, S. Piotter, K. Hirsch, and H. Haselbach