Tracking Marsh Elevation and Water Levels in Elkhorn Slough January 2017

Transcription

1 Tracking Marsh Elevation and Water Levels in Elkhorn Slough January Charlie Endris GIS Specialist Elkhorn Slough NERR Elkhorn Slough Foundation Central Coast Wetlands Group 2015

2 Questions Are the marshes in Elkhorn Slough drowning?

3 Questions Are the marshes in Elkhorn Slough drowning? What are the tools used to observe a drowning marsh?

4 Questions Are the marshes in Elkhorn Slough drowning? What are the tools used to observe a drowning marsh? What does the data show?

5 Questions Are the marshes in Elkhorn Slough drowning? What are the tools used to observe a drowning marsh? What does the data show? What are the potential drivers?

6 Questions Are the marshes in Elkhorn Slough drowning? Historic evidence is well documented (Van Dyke and Wasson, 2005) 1870

7 Questions Are the marshes in Elkhorn Slough drowning? Historic evidence is well documented (Van Dyke and Wasson, 2005) 2000

8 Observation Tools What are the tools used to observe a drowning marsh? Photographs

9 Observation Tools What are the tools used to observe a drowning marsh? Aerial Photographs 1931

10 Observation Tools What are the tools used to observe a drowning marsh? Aerial Photographs 1980

11 Observation Tools What are the tools used to observe a drowning marsh? Aerial Photographs 2007

12 Observation Tools What are the tools used to observe a drowning marsh? 2007 Aerial Photographs

13 Observation Tools What are the tools used to observe a drowning marsh? Aerial Photographs

14 Observation Tools What are the tools used to observe a drowning marsh? Aerial Photographs

15 Observation Tools What are the tools used to observe a drowning marsh? Water level sensors, SETs, and CORS

16 Observation Tools What are the tools used to observe a drowning marsh? Water level sensors, SETs, and CORS

17 Observation Tools What are the tools used to observe a drowning marsh? Water level sensors, SETs, and CORS Surface Elevation Table (SET)

18 Observation Tools What are the tools used to observe a drowning marsh? Water level sensors, SETs, and CORS Vertical Control Network

19 Observation Tools What are the tools used to observe a drowning marsh? GPS, Differential Leveling, TLS, and Remote Sensing Static GPS (+2 hr) Terrestrial LiDAR aka TLS (terrestrial laser scanning) Differential Leveling

20 Questions Are the marshes in Elkhorn Slough drowning? What are the tools used to observe a drowning marsh? What does the data show?

21 Data Results Remote sensing: Marsh Classification High loss Moderate loss No change Moderate recovery High recovery Very high recovery

22 Data Results Remote sensing: Marsh Classification High loss Moderate loss No change Moderate recovery High recovery Very high recovery

23 Data Results TLS and remote sensing: NDVI (normalized difference vegetation index) NDVI 2009 Marsh Transect Legend NDVI_ES_NAIP2009.tif Value High : 0.5 Low : -0.75

24 Data Results TLS and remote sensing: NDVI (normalized difference vegetation index) NDVI 2014 Marsh Transect Legend ES_NAIP2014_NDVI.tif Value High : 0.5 Low : -0.75

25 Data Results TLS and remote sensing: Elevation correlates with NDVI Elevation vs NDVI R² = NDVI Elevation

26 Data Results TLS and marsh transect data: marshes are low in the tidal frame Frequency distribution of salt marsh elevations MHW MHHW Frequency Elevation (m NAVD88)

27 Data Results Benchmark Surveys: Subsidence = 2.75 mm/yr mm Elevation Change at Benchmarks (2008 to 2016) Laser Leveling

28 Data Results SET data: Accretion outpacing elevation; Subsidence = 2.6 mm/yr

29 Data Results CORS (P210) data: Vertical plate motion P210 CORS Station Vertical Motion: Elkhorn Slough Elevation change (mm) Vertical (mm) / Present mm/yr 60 per. Mov. Avg. ( Vertical (mm)) Linear (12/ Present) -20 1/1/2006 1/1/2007 1/1/2008 1/1/2009 1/1/2010 1/1/2011 1/1/2012 1/1/2013 1/1/2014 1/1/2015 1/1/2016 1/1/2017

30 Data Results CORS (P210) data: Vertical plate motion P210 CORS Station Vertical Motion: Elkhorn Slough Elevation change (mm) mm/yr Vertical (mm) 60 per. Mov. Avg. ( Vertical (mm)) -20 1/1/2006 1/1/2007 1/1/2008 1/1/2009 1/1/2010 1/1/2011 1/1/2012 1/1/2013 1/1/2014 1/1/2015 1/1/2016 1/1/2017

31 Data Results Water Level data: Monterey Tide Station

32 Data Results Water Level data: Monterey Tide Station Source: tidesandcurrents.noaa.gov/

33 Data Results Water Level data: Monterey Tide Station Source: tidesandcurrents.noaa.gov/

34 Summary Historical and recent data suggests Elkhorn Slough s marshes are drowning Rate of local subsidence of 3 mm/yr has been fairly consistent Rate of sea level rise has dramatically increased since 2014 With sustained high water levels, significant die-off of pickleweed in Elkhorn Slough is likely Marsh restoration efforts are imperative

35 Questions?