Shoreline Situation Reports (SSR) were first generated by VIMS in the 1970's to report the condition and status of the shore lands. The SSR series were published in hardcopy on a county by county basis for each Tidewater Virginia localities. The reports were intended to assist planneres, managers, and regulators in decisions pertaining to management of coastal areas and natural resources therein. This Shoreline Inventory report continues a process which updates and expands the earlier reports. Data collected reports the conditions in the immediate riparian zone, the bank, and along the shoreline.
To inventory Virginia's tidal shoreline conditions.
There are three shapefiles that are part of the City of Chesapeake Inventory database: ches_lubc, ches_astru, ches_sstru. Ches_lubc (land use and bank cover for City of Chesapeake) is an linear shapefile containing data about land use, bank height, erosion, marsh, and beach status along the shoreline. Ches_sstru (City of Chesapeake shoreline structures) is an linear shapefile delineating hard structures in place for shoreline protection (bulkhead, riprap, groin fields). Ches_astru (City of Chesapeake structures) is a point shapefile with locations of docks, ramps, and boathouses. The attributes of these three shapefiles are explained in the Entity and Attribute Information section below.
ground condition at time of survey
These data should not be used for jurisdictional permit determinations beyond providing general shoreline condition or status information. These data have not been surveyed to property boundaries.
Greate Road
The attributes were compared to original GPS data logs for accuracy. Errors were corrected where noted.
Chain-node topology present. Linear coverages were built for line and point coverages were built for points.
All shoreline of the City of Chesapeake that has a minimum depth of 2 feet at mean low water was surveyed. If tidal influences prevented access, some shoreline was coded remotely.
Shoreline structures were recorded with a GPS unit as the boat moved along the shoreline. Data was transferred from the GPS boat track to an existing digital shoreline coverage by projecting data to the shoreline at a 90 degree angle from the boat track. Rectified digital orthophoto quads were used as a background coverage to aid in data positioning. Dock and boathouse point data were aligned with docks on the images. Land use features were placed along the shore so changes in land use were coincident with changes illustrated in the imagery. Positional accuracy for data that has been corrected with imagery is .3 meters (equivalent to image resolution). Data not visable on the imagery (bulkheads, riprap, etc.) has a positional accuracy of 11 meters. Accuracy was determined by comparing digitally processed data locations to onsite GPS ground surveys collected at random.
Imagery (2007) serves as a background in the map portfolio. Imagery is used to update land use and structure data as well as to remotely code areas not previously surveyed in the field. The VBMP shoreline was also used and adjusted using the imagery where needed.
Data was collected by a two-person field crew (one person collecting land use and bank condition data and one boat operator also collecting shoreline features) using two hand-held Trimble GeoExplorers GPS Units, while navigating along the shoreline. A data dictionary designed for the inventory was installed on each GPS Unit. One data collector records natural features including land use, bank height, presence of marsh or beach, and shoreline stability. A second person collects data on the hardened structures: riprap, bulkheads, docks, boatramps, etc. Point features (docks, boathouses, ramps) were surveyed with a ten second observation recorded at 1 reading/second. Linear features were surveyed kinematically at a rate of one observation every 3 seconds.
Data from the GPS units were postprocessed on a PC with Trimble Pathfinder Office software. Postprocessing includes differential correction using base station data collected at the VIMS laboratory. Corrected data is converted to shapefiles for further processing.
In the ArcMap environment, boat-track arcs were manually shifted to the base shoreline (VBMP). Arcs were split and moved to locations on the shoreline perpendicular to the original locations on the boat-track. Shoreline arc segments were coded, and the shapefiles were visually checked for attribute accuracy between coded shoreline and boat-track data.
In ArcMap, boat-track points were manually shifted to the base shoreline (VBMP). Points were moved to locations on the shoreline perpendicular to the original locations on the boat-track. Points were coded and the access structure (astru) was visually checked for attribute accuracy between coded shoreline and boat-track data.
Land use, dock, and boathouse locations were digitally checked and repositioned if necessary with VBMP imagery displayed as a background coverage. This was done using ArcMap capabilities. Areas inaccessible by boat due to low tide were coded based on features observed on the imagery. The "remote" coded areas were given the item REMOTE = "yes" to distinquish them from GPS collected data.
Land use and structures were digitally checked and updated, repositioned, or added, if necessary, with 2007 VBMP imagery displayed in the background. This was done using ArcMap version 9.2. New piers, boat houses, and ramps added based upon the updated 2007 VBMP imagery are coded as item REMOTE = "yes" to distinquish them from GPS collected data.
A portfolio containing ten 1:12,000 scale plates was created for the City of Chesapeake. Each plate shows four maps: riparian land use, bank conditions, shoreline features, and natural buffers. VBMP 2007 imagery is displayed in the background to provide users with additional information.
Metadata imported.
Internal feature number.
ESRI
Feature geometry.
ESRI
coded in the lab using background imagery
Two other shapefiles combine with _lubc to complete the City of Chesapeake Shoreline Inventory. The complete set includes _lubc, _astru, and _sstru. Attributes in the _lubc file include: FEATURE or land use contains the following values: agriculture, commercial, forest, grass, paved, residential, scrub-shrub, industrial, military, multifamily dwelling, and bare; HEIGHT is the bank height with 0 - 5 feet, 5 - 10 feet, and 10 - 30 feet, and >30; EROSION or bank erosion can have the values: low or high or undercut; MARSH values are Yes(Erosion), Yes(No_Erosion), No, or a blank field; BEACH defines the presence and condition of the beach: Yes(Eroding), Yes(No_Erosion), No, or blank field; Cover is bank cover and defined as bare, partial, and total coverage; and REMOTE refers to how the data was gathered: a blank value indicates the data was collected with the GPS unit, a "y" indicates that the shoreline attributes where determined from the 2007 VBMP imagery. Phragmites australis is coded as 'yes' where its presence is noted. Attributes in the _astru (access structure shapefile) are: PNTSTRUC contains access structures such as boathouse, dock, dilapidated dock, outfall, and public or private ramp; and REMOTE. Attributes found in the _sstru shapefile are: STRUCTURE (erosion control) with values such as breakwater, bulkhead, dilapidated bulkhead,groin, jetty, marina, miscellaneous and riprap; and REMOTE.
The Comprehensive Coastal Inventory Program (CCI) at VIMS performs a service by distributing data generated by either CCI or public agencies which offer data without restriction or charge. CCI assumes no responsibility for data accuracy or precision, metadata completeness or correctness for digital information. CCI assumes no liability for misuse of any data which may arise as a result of any alteration, conversion, or combination with other data sources. As well, the timeliness and scale of these products must be considered when evaluating appropriate use.
Greate Road