mapping and analyzing shoreline change - coastal...

Aerial Photography For Analyzing Shoreline Change and Inlet Migration

Marcus Gruver - Geospatial Analyst Alex Ferencz – GIS Assistant

Stockton University: Coastal Research Center

• Project • Study Area • Overview of Georeferencing • Problems and Solutions • Shoreline Analysis • Limitations and Error

Overview

• Funded by the New

Jersey Department of Environmental Protection, Department of Coastal Engineering.

• New addition was for inlet monitoring.

• Tasked with georeferencing historical aerial datasets of NJ and delineating shorelines for Corson and Hereford Inlet.

New Jersey Beach Profile Network

Study Area: Corson Inlet, NJ

Images taken from Google Earth

Importance

• Snap shot in time of conditions

• From this coastal geomorphic information can extracted o High Water Line (Wet/Dry line) o Dune/Beach width o Position of the shoreline

• Provides clues on the geomorphic processes occurring

• Help Coastal Zone managers make decisions.

Historical Aerial Datasets • Aerial Data sets at the Coastal

Research Center;

• Considerations

o Aircraft type/Camera type o Time of collection

o 1970 o 1974 o 1977 o 1987 o 1995 o 2000 o 2002

o 1920 o 1931 o 1933 o 1940 o 1944 o 1955 o 1962

What is Georeferencing? • As defined by ESRI’s GIS dictionary

o “[coordinate systems] Aligning geographic data to a known coordinate system so it can be viewed, queried, and analyzed with other geographic data. Georeferencing may involve shifting, rotating, scaling, skewing, and in some cases warping, rubber sheeting, or orthorectifying the data.” (http://support.esri.com/en/knowledgebase/GISdictionary/popup/georeferencing)

• Web map service (WMS) provided by New Jersey Geographic

information Network: 2012 digital orthophotography.

Georeferencing: Control Map

• Be precise as possible • Evenly Distribute CPS

throughout • When in doubt add

more CP’s

Ground Controls Points

Types of Transformations

• Zero order polynomial o 1 link

• First order polynomial o Minimum of 3 links

• Second order polynomial o Minimum of 6 links

• Third order polynomial o Minimum of 10 links

• Also spline, protective transformation, adjust

•Residual Error •Total Error is a Root mean square (RMSE) of all the residual errors.

Transformation&Error (RMSE)

Error RMSE

Taken from ERSI HELP

• Do to lens distortion RMSE values in some areas where high

• Choosing CP’s in locations where construction has occurred.

• Having Historical Images where salt marsh or water are the majority of the image. Or where there is lack of development of coast at the period of time

Issues, Problems and some Solutions

Underdeveloped Areas: Salt Marshes

Geomorphic Control Points

Analysis and Limitations

o Beach nourishment projects may influence the shorelines.

o Inlet channel dredging may also influence the movement of the spit.

o Some historic aerial photographs were taken Immediately after damaging storm events.

o Historic aerial photographs are at varying Time periods.

Sources of Error

o Heads Up shoreline delineation of the Wet/Dry line.

o Tidal positions of the Wet/Dry line.

o Error associated with georeferenced aerial photographs.

o Positional accuracy of Survey data.

o Uncertainty involved with interpolating DEMs from survey data.

References • ESRI. 2014. ArcGIS 10.1 Desktop Help – Fundamentals of georefencing a raster

dataset. ONLINE. Available at:http://resources.arcgis.com/en/help/main/10.1/index.html#//009t000000mn000000. 5/18/2014

• USGS, Thieler, E.R., Himmelstoss, E.A., Zichichi, J.L. and Ergul, Ayhan. 2009. Digital Shoreline Analysis System (DSAS) version 4.0- An ArcGIS extension for calculating shoreline change. U.S. Geological Survey Open-File Report 2008-1278

• Cowart, Lisa, Analyzing Estuarine Shoreline Change in Coastal North Carolina. http://192.168.1.1:8181/http://thescholarship.ecu.edu/bitstream/handle/10342/1897/Cowart_ecu_0600M_10039.pdf?sequence=2&isAllowed=y July, 2009