2011 Bombay Hook National Wildlife Refuge DMC Imagery

The NOAA Bombay Hook Project covers 177 square kilometers of the Bombay Hook National Wildlife Refuge and surrounding areas in Kent County, Delaware. Dewberry produced Ortho Mosaics for 101 tiles (1700 m x 1700 m) covering this area. The Orthos were created with a 25cm cell size.

Original contact information:

Contact Org: NOAA Office for Coastal Management

Phone: 843-740-1202

Email: coastal.info@noaa.gov

These Orthos provide a snapshot in time that depicts the ground surface and water features for use in coastal management. These DEMs are created to the specifications outlined by NOAA OCM in partnership with the Delaware Department of Natural Resources and Environmental Control (DNREC).

11351

A complete description of this dataset is available in the Final Project Report submitted to NOAA OCM.

Users must assume responsibility to determine the usability of these data.

None

Data set is not for use in litigation. While efforts have been made to ensure that these data are accurate and reliable within the state of the art, NOAA, cannot assume liability for any damages, or misrepresentations, caused by any inaccuracies in the data, or as a result of the data to be used on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.

Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 3; ESRI ArcCatalog 9.3.1.1850

AT was performed using Surveyed control points, Dewberry and Davis, LLC used Trimble R-8 GNSS receivers, which is a geodetic quality dual frequency GPS receiver, to collect data at each surveyed location. The required accuracy is 2 m or better at the 95% confidence level as computed in accordance with the FGDC National Standard for Spatial Data Accuracy (NSSDA).; Quantitative Value: 2 meters, Test that produced the value: The ground control was captured using Trimble R-8 GNSS receivers, which is a geodetic quality dual frequency GPS receiver. All locations were occupied once with approximately 38% of the locations being re-observed. All re-observations matched the initially derived station positions within the allowable tolerance of 5cm or within the 95% confidence level. 2 m or better at the 95% confidence level as computed in accordance with the FGDC National Standard for Spatial Data Accuracy (NSSDA).

The DEMs are derived from the source LiDAR. Vertical accuracy is not tested on the DEMs. The vertical accuracy of the LiDAR was tested by Dewberry with 8 independent survey checkpoints. The survey checkpoints were evenly distributed throughout the project area. All 8 checkpoints were used to compute the Fundamental Vertical Accuracy (FVA). Project specifications required a FVA of 18 cm (0.18 m) based on a RMSEz (9 cm/ 0.09 m) x 1.9600. All checkpoints were also used to compute the Consolidated Vertical Accuracy (CVA). Project specifications required a CVA of 18 cm (0.18 m) based on the 95th percentile.; Quantitative Value: 0.14 meters, Test that produced the value: The DEMs are derived from the source LiDAR. Vertical accuracy is not tested on the DEMs. Based on the vertical accuracy testing conducted by Dewberry, using NSSDA and FEMA methodology, vertical accuracy at the 95% confidence level (called Accuracyz) is computed by the formula RMSEz x 1.9600. The dataset for the Bombay Hook project satisfies the criteria: Lidar dataset tested 0.14 m vertical accuracy at 95% confidence level, based on RMSEz (0.07 m) x 1.9600. Based on the vertical accuracy testing conducted by Dewberry, using NDEP and ASPRS methodology, consolidated vertical accuracy at the 95% confidence level is computed using the 95th percentile method. The dataset for the Bombay Hook project satisfies the criteria: Lidar dataset tested 0.11 m vertical accuracy at 95% confidence level in all land cover categories combined.

Cloud Cover: 0

A visual qualitative assessment was performed to ensure data completeness and compliance with project specifications. No void or missing data exists. Multiple tiles were added to the tile grid to fully cover the project boundary.

Data covers the tile scheme provided for the project area.