g02. construction of 3dep in the coastal zone as the

Authors: Jeffrey J. Danielson, John C. Brock, Gayla A. Evans, and Dean J. Tyler

G02. Construction of 3DEP in the Coastal Zone

as the Coastal Component of the 3D Elevation

Program

Coastal GeoTools 2015

Topobathymetric Elevation Models

Many applications of geospatial data in coastal environments require detailed

knowledge of near-shore topography and bathymetry as physical processes in

the coastal environments are controlled by the geomorphology of both “over-

the-land” topography and “underwater” bathymetry.

Topobathymetric models provide a required seamless elevation product for

several science application studies such as shoreline delineation, coastal

inundation mapping, sediment-transport, sea level rise, storm surge models,

tsunami impact assessment, and also to analyze the impact of various climate

change scenarios on coastal regions.

The Coastal National Elevation Database (CoNED) Applications Project is

integrating many disparate lidar and bathymetric data sources into a common

seamless database aligned both vertically and horizontally to a common

reference system to construct 3DEP in the Coastal Zone topobathymetric

models.

Topobathymetric Elevation Models (Con’t)

This multi-temporal, multi-scale, and multi-resolution database permits an easy

portability to geomorphological and hazard vulnerability applications but at the

same time extends the framework of the 3DEP Bare-Earth Digital Elevation

Models (DEMs) offshore into the intertidal, submarine estuarine and littoral

zones.

Strengths of the coastal elevation database are its multi-temporal / multi-scale

capability for assessing geomorphic change detection, the maintaining of

critical topographic features such as, levees and embankments and finally the

accurate mapping of shoreline and wetland elevations.

Topobathymetric Elevation Models

Topobathymetric elevation models are a merged rendering of both

topography (land elevation) and bathymetry (water depth) to provide a

seamless elevation product

Data sources

Light Detection and Ranging (Lidar) Airborne (NIR-1064nm)

Terrestrial Ground-Based (NIR-1064nm)

Topobathymetric (EAARL-B and CZMIL)

(Green-532nm)

Bathymetric Sonar (Acoustic) Multi-Beam

Single-Beam

Swath

Hydrographic Surveys

terrestrial marine intertidal

3DEP in the Coastal Zone

• 39% of the nation’s total

population lives in

coastal shoreline

counties (NOAA).

• Coastal areas are highly

dynamic: shoreline

erosion, rapid wetland

loss, hurricane impacts,

and sea-level rise.

• Rapid urban

development and

population growth in the

coastal zone=

increasing human

vulnerability to natural

hazards.


Focus Regions (Current Status)

Sandy

Region

Coastal Change and Hazard Applications: Earthquake Tsunamis Storm Surge

Sea Level Rise Wetland Loss Cliff Erosion

Habitat Quality Coral Bleaching Ocean Acidification

Water Quality

San Francisco Bay

Northern Gulf of Mexico

An Elevation Data Foundation for Understanding

Coastal Vulnerability and Change Pacific

Northwest

Pilot

Pacific Islands Pilot

Alaska

North Slope

Marshal

l Islands

Hawaiian

Islands

NJ/DE


Topobathymetric Elevation Models - Specifications

Definition: Extends from the open coast to the landward boundary of coastal watersheds (USGS Watershed Boundaries Dataset) Includes inland bathymetry where available

Spatial Specifications:

Projection / Coordinate System: Universal Transverse Mercator (UTM) and Geographic

Horizontal datum: NAD83 (2011)

Vertical datum: NAVD88 (Geoid12A)

Cell sizes: 3 Meter, 2 Meter, and 1 Meter

Accuracy Specifications:

Lidar: Quality Level 2 (QL2) - 2 points per sq. meter – 10cm RMSE

Spatial Organization– Consistent gridding/interpolation, resampling, and cell alignment

Multi-temporal – Repeat Lidar Acquisitions over Site-Specific Coastal areas

Updating – Spatially Referenced Metadata

Elevation Reference Systems

Topobathymetric Model Development Workflow

• Removing elevations from the tops of selected drainage

structures (bridges and culverts) in a lidar-derived DEM

to depict the terrain under those structures so that

channels flow down slope

(Poppenga 2010, 2012, 2013, 2014)

Hydrologically-Enforced (Hydro-Enforced)

• Objective: The minimum convex hull boundary

is a mask created from the classified ground

lidar points that extracts the perimeter of the

exterior lidar points.

• Basic Processing Steps:

• Extract ground class from classified point cloud

• Generate a LAS Dataset (lidar files container) and

compute the average point spacing from point cloud

• Construct a raster whose cell values reflect the “Point

Count” spatial distribution from the LAS lidar files

referenced by a LAS dataset

• Fill small interior holes and shrink the data extent to

the exterior lidar points, convert raster extent to

polyline with assigned elevation heights

ARRA Region 1- 2011 Lidar Dataset (Overview)

Topographic Lidar (NIR-1064nm

ARRA Region 1- 2011 Lidar Dataset (Zoom)

Topographic Lidar (NIR-1064nm)

Land / Water Masking (MCHB) Minimum Convex Hull (Variable Elevation Datum)

Minimum Convex Hull – New Jersey Wetlands

Point Return Density – All Classes

Point Return Density Thresholding

3DEP in the Coastal Zone (Hurricane Sandy)


Pre-Sandy Lidar Status


Post-Sandy Lidar Status

3DEP in the Coastal Zone (Hurricane Sandy) EAARL-B Bathymetry (Barnegat Bay)

Delaware River


EAARL-B – Delaware River Basin (Inland Bathymetry)

3DEP in the Coastal Zone (New Jersey / Delaware)

Integrated Topobathymetric Elevation Model (2014)


1-Meter Integrated Topobathymetric Model Metadata


NJDE Validation – Absolute Vertical Accuracy


NJDE Validation – Absolute Vertical Accuracy (Overall)

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Min. Diff -4.499 Meters

Max. Diff 1.543 Meters

Mean Diff -0.105 Meters

Std. Dev. Diff 0.582 Meters

RMSE 0.591 Meters


GPS Control for Validation of Topobathymetric Models

Avalon, NJ Island Beach State Park,

Seaside Park, NJ

Sandy Hook, NJ


NJDE Validation – Abs. Vertical Acc. (Coastal Sources)

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Sources Min.. Diff Max. Diff Mean Diff Std. Dev. Diff RMSE

2011 Lidar -1.152 0.155 0.102 0.099 0.142

2010 Lidar -1.318 0.258 -0.855 0.603 1.046

2009 Lidar -1.461 0.076 -0.843 0.604 1.036

RMSE


NJDE Validation – Abs. Vertical Acc. (Staten Island)


NJDE Validation – Abs. Vertical Acc. (Staten Island)

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Min. Diff -2.830 Meters

Max. Diff 0.924 Meters

Mean Diff -0.063 Meters

Std. Dev. Diff 0.307 Meters

RMSE 0.313 Meters

Classified Lidar Datasets (Processed): USGS_NC_1996

USGS_NC_1997

NGS_NC_VA_Coast_Mar_2008

USACE_Currituck_Dare_Hyde_Counties_NC_Aug_2009

USGS_Cape_Hatteras_NC_Nov_2009

USGS_N_Outer_Banks_NC_Nov_2009

USGS_Dare_Hyde_Counties_NC_Dec_2009

USACE_NC_Coast_Jun_2010

USACE_VA_Coast_July_2010

NGS_Carteret_Dare_Counties_NC_Aug_2011_Post_Irene

USGS_NC_Coast_Nov_2012_Post_Sandy

USACE_VA_Coast_Nov_2012_Post_Sandy

Unclassified Datasets (Unprocessed): USGS_NC_1998

USGS_NC_1999

USGS_SC_NC_VA_1999_Post_Dennis

USGS_SC_NC_VA_1999_Post_Floyd

USGS_NC_Summer_2000

NC_Floodplain_Mapping_Program_NC_Mar_2001

USACE_NC_Coast_Jul_2004

USACE_NC_Coast_Sep_2005

• 20 Source Lidar Datasets

• 12 classified, processed

and gridded.

• 8 unprocessed (require

bare earth processing –

LP360)

• Project temporal range

1996 – 2013.

• Additional, more recent

datasets coming soon.

NC Outer Banks: Multi-Temporal Topobathy

• Spatial overlap of the 20

Lidar source datasets.

• Overlap range: 1 – 15

(temporal iterations).

• Average overlap for Outer

Banks, NC: 10

• Higher temporal density (10

– 15) on Atlantic shoreline.

• Geomorphology dynamics

will be highly visible for the

Outer Banks, NC with the

wide range of temporal data

availability.

• Natural change

• Human driven change

• Disturbance driven change


1. Aug, 2009

2. Nov, 2009

3. Aug, 2011

4. Nov, 2012


Questions

g02. construction of 3dep in the coastal zone as the

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