Hypsometric curves of the Duplin River Dr. Jackson O. Blanton Skidaway Institute of Oceanography

10 Ocean Science Circle Savannah Georgia 31411 USA

jack.blanton@skio.uga.edu http://www.skio.peachnet.edu/faculty/blanton.html Georgia Coastal Ecosystems LTER Project

Dept. of Marine Sciences University of Georgia Athens Georgia 30602-3636 USA

gcelter@uga.edu https://gce-lter.marsci.uga.edu/ Dr. Jackson O. Blanton Skidaway Institute of Oceanography

10 Ocean Science Circle Savannah Georgia 31411 USA

jack.blanton@skio.uga.edu http://www.skio.peachnet.edu/faculty/blanton.html Principal investigator 2004-01-01 2007-12-31 Francisco Andrade University of Lisbon

University of Lisbon Marine Laboratory of Guia Estrada do Guincho Cascais 2750 Portugal

Co-investigator 2004-01-01 2007-12-31 Julie Amft Skidaway Institute of Oceanography

10 Ocean Science Circle Savannah Georgia 31411 USA

julie.amft@skio.uga.edu Co-investigator 2004-01-01 2007-12-31 Dr. Marie Adelaide Ferreira IMAR-Marine Laboratory

IMAR-Marine Laboratory Portugal

Co-investigator 2004-01-01 2007-12-31 2026

J.Blanton (SkIO) is worked in collaboration with F. Andrade (Univ. of Lisbon), M. Adelaide Ferreira (IMAR-Marine Laboratory, Portugal) and J. Amft (SkIO) to construct a high resolution DEM for the system. They completed the classification and analysis of a series of 7 aerial infrared images of the Duplin River, covering low water (LW) to high water (HW). For each pass, a total of eight images were obtained on infrared (IR) film. The photographs were processed to yield the water surface area as a function of time. Subsurface pressure gages deployed along the tidal creek were used to determine the vertical reference level for the corresponding flooded area. The analyses of these images were used to construct curves relating flooded area to water level (Figure 5). J. Blanton (SKIO) and J. Amft (SKIO) used aerial photos to delineate tributary tidal creeks and their drainage areas along the Duplin River. They defined polygons for low-water and high-water areas for 12 tributary creeks and their intertidal area (Fig. 2). The implied assumption for each polygon is that no water crosses the drainage boundaries. While some cross-boundary transport may occur at extreme high tides, the volumes involved are quite small compared to the creek fluxes draining the intertidal areas. Estimates of the low water and high water areas of each polygon are being used to estimate the relative magnitude of tidal water storage in various parts of the Duplin intertidal area. The hypsometric curves produced from this analysis (Figure 6) have a consistent pattern of growth in water level versus time based on following the evolution of water area during a flood tide. Eleven of 16 prisms show relatively slow growth rates and small initial volumes. The largest tidal prisms are found for Polygon 1 (Barn Creek) and Polygon 5 (Marsh along the east fork north of Hunt Camp). Careful study of the individual hypsometric curves as well as those describing the growth in water volume is likely to reveal morphological details throughout the Duplin River intertidal area that would be relevant to the distribution of plants and animals as well as residence time of water. Numerical models of water circulation in the river may simulate tidal currents more accurately by incorporating the DEM into their model grids.

Question 2: How do the spatial and temporal patterns of biogeochemical processes, primary production, community dynamics, decomposition, and disturbance vary across the estuarine landscape, and how do they relate to environmental gradients? (more information)

LTER NSF Duplin River Georgia GCE aerial imagery DEM eleveation infrared intertidal Overall geographic extent of the research project -81.301987 -81.263124 31.486493 31.410854 2004-01-01 2007-12-31

National Science Foundation grant numbers OCE-9982133 and OCE-0620959

estuary marsh complex Duplin River - Duplin River transect used for GCE quarterly hydrographic monitoring surveys. Nominal profiling stations are defined at various locations along the Duplin River west of Sapelo Island, Georgia. -81.301987 -81.263124 31.486493 31.410854 Blanton, J.O., Andrade, F. and Adelaide Ferreira, M. 2006. The relationship of hydrodynamics and morphology in tidal-creek and salt-marsh systems in South Carolina and Georgia. Pages 93-107 in: Kleppel, G.S., DeVoe, M.R. and Rawson, M.V. (editors). Implications of changing land use patterns to coastal ecosystems. Springer-Verlag, New York, NY. Andrade, F., Blanton, J.O. and Adelaide Ferreira, M. 2003. Presentation: A digital elevation model of a tidal creek and its relationship to tidal circulation. ASLO 2003, 9-14 February 2003, Salt Lake City, Utah. Figure 5. Water level curves for 15 April 2004 along the axis of the Duplin River. The red vertical lines (T1 through T7) show the times of each aerial pass. The locations of the three curves are shown in the image on the right. Water level at a given time varies within 0.1 m over a distance of 7 km, so water surface is assumed to be horizontal over the 2 min duration of a single pass of the airplane. https://gce-lter.marsci.uga.edu/public/resources/projects/waterCurvesFig5DiQ2.png Figure 6. A comparison of hypsometric curves for four polygons with one for the total drainage area. The final line segment in each plot connects water depths and areas from 2.19 to 2.30 meters. The area at 2.19 m references the largest water area calculated for the final overflight (T7). The area at 2.30 m (the water level of the NOAA published mean spring HHW) references the total polygon area. Areas for the total Duplin tidal watershed have been divided by ten to scale that curve with the polygons. https://gce-lter.marsci.uga.edu/public/resources/projects/hypsoCurvesFig6DiQ2.png GIS Raster Data: Duplin DEM https://gce-lter.marsci.uga.edu/public/app/resource_details.asp?id=332 GIS Raster Data: Duplin DEM https://gce-lter.marsci.uga.edu/public/app/resource_details.asp?id=332 Document: Measuring the topography of the intertidal area of a tidal creek Duplin River (Sapelo Island, GA) https://gce-lter.marsci.uga.edu/public/app/resource_details.asp?id=851