New Hampshire Department of Environmental Services
20090722
New Hampshire Buffer Gap Analysis - Hillsborough County
One
vector digital data
Concord, New Hampshire
New Hampshire Department of Environmental Services
For Tiers 1 to 3, final output dataset depends upon the currentness of the source data layers including
Conservation Lands (conslands.shp) and the National Hydrography Network and "local protections" tabular
data in MS Access and related geodata developed and maintained by DES. Contact DES for more details.
Note: At the end of October 2009, two major updates were applied to the dataset. The first was an
adjustment to the Tier classification based on updates on local municipal regulations that were provided
by the Piscataqua Region Estuaries Partnership. The second update was based on the overlay of an updated
Conservation Lands dataset in which situation stream segments with conservation lands were classified
as Tier 1.
<URL:http://www.granit.unh.edu/cgi-bin/nhsearch?dset=des_buffergapanalysis/buffergapanalysis11>
Some river and lake riparian buffers are currently protected under existing local ordinances or by conservation
lands and easements. The state Comprehensive Shoreline Protection Act protects public waters including “great ponds”
(waterbodies greater than 10 acres) and rivers with a stream-order of four or greater. This analysis identifies and
measures where protections occur and where they are absent along river and lake shoreline frontage. The analysis
categorizes all of the state’s rivers or lakes into six levels of protection as defined in the Entity_and_Attribute_Information
section below, where tier 1 is the highest level of protection.
To identify gaps in riparian buffer protection and to measure and report the river and lake shoreline frontage protected by conservation
land, local zoning ordinances, or the Comprehensive Shoreline Protection Act (CSPA), in effect as of July 1st, 2008 under New Hampshire
Statutes, Title L., Chapter 483-B
Data distribution tile: county
2009
Publication Date
As needed
-72.063019
-71.243676
43.205203
42.697010
None
Hydrography
Flowing Water
Watershed Planning
Stream Order
Shoreline Protection
ISO 19115 Topic Category
planningCadastre
None
United States
Northeast
New England
New Hampshire
Hillsborough County
None
Not for legal use.
Pierce Rigrod
New Hampshire Department of Environmental Services
Drinking Water and Groundwater Bureau
mailing and physical address
29 Hazen Drive, PO Box 95
Concord
NH
03302
US
603-271-0688
603-271-3305
pierce.laskey-rigrod@des.nh.gov
Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 3; ESRI ArcGIS 10.0.3.3600
n/a
The data are complete as of the publication date.
The process to classify the stream segments is built on ESRI’s Model Builder – to perform the multiple steps
required to conduct the analysis – and a geodatabase to retain “scratch” or “temp” files that are generated
during the analysis. The final output from the Model Builder is stored in a second geodatabase that is used
to distribute model results. All analysis based on vector datasets.
The classification system is hierarchical with Tier 1 at the top of the list and Tier 6 at the bottom.
The assignment of Tier protection values (1-6) has been done so that river or lake segments are assigned
the highest protection (Tier) value if they meet that Tier’s criteria. Accordingly, river or lake frontage
meeting Tier 1 criteria and also meeting Tier 2 or other criteria has been assigned a final Tier value = 1
(its highest level of protection). This order of precedence (1 over 2, 2 over 3, etc) results in no overlap
between Tier protection classes (no double counting) in order to better estimate protected frontage as a
percentage of all frontage in the watershed.
Tier 1 and 2:
The two primary datasets for Tier 1 and Tier 2 analysis is the Conservation polygon shapefile (provided by NH GRANIT)
and the National Hydrography Dataset provided by UNH, edited by DES. The method for generating the conservation lands
dataset was a combination of converting vector data to raster and employing Spatial Analyst to identify segments whose
buffers would intersect conservation lands. Conservation land parcels with no Primary Protection Type (PPTYPE field is NULL)
were excluded from this analysis (see Known Issues below) and the stream segments for these parcels would be subject to Tier 3
or higher analysis.
NOTE 1: Most common error within Tier 1 and 2 coding was misclassifications of short stream segments to Tier 6 within
conservation lands or coding of short segments outside conservation lands boundaries as Tier 1. To correct all Tier 6 records
were isolated and an overlay analysis was used to identify which stream segments intersected the conservation land polygon
(excluding parcels with no PPTYPE listed). The selected stream segments within conservation land parcels coded as Tier = 6
(no protection) were corrected from Tier 6 to Tier 1. Those short segments extending beyond the conservation land boundaries
remain in the data as errors and may be manually corrected or further geoprocessed to correct.
Tier 3 (CSPA):
Tier 3 includes rivers with a stream order of 4 or greater, or great ponds not assigned a Tier 1 or 2 (i.e. not protected
by conservation land). A simple query was used to identify NULL classifications (after the Tier 1 and Tier 2 classification)
and to identify stream orders of 4 or greater.
NOTE 2: In the original creation of the dataset the generation of double lines (that is, 2 lines for one stream segment
representing each river bank of the segment) from the hydrography dataset did not generate the proper stream order for
particular segments associated with double lined hydrography. However, spot checks were conducted on the major rivers to
correct for this. Later iterations and methods for generating this dataset will be corrected to ensure that this will
no longer be an issue.
Tier 4 and Tier 5 (Local Regulations):
Tier 4 and Tier 5 is based on the presence of local zoning regulation for stream segments that do not fall into the
Tier’s 1 – 3 criteria. The base data layer that identifies these communities with buffer protections in zoning ordinance
was conducted in previous analysis and its results incorporated into this analysis. Stream segments were assigned to the
Tier’s 4 or 5 if local zoning protected buffers according to the Tier 4 or 5 criteria and the stream/pond frontage was
not assigned a higher Tier value (e.g. 1 – 3).
Tier 6 (No Protection):
A Tier 6 classification indicates no protection for a stream segment. It is assigned to the all remaining river or pond
frontage without protection identified and coded in the previous steps.
2009
State Plane Coordinate System 1983
New Hampshire
0.999967
-71.666667
42.500000
984250.000000
0.000000
Coordinate pair
0.000208
0.000208
Survey Feet
North American Datum of 1983
GRS 80
6378137.000000
298.257222
hillsborough_buffer_gap
Stream segments based on National Hydrography Dataset
NHDES
FID
Internal feature number.
ESRI
Sequential unique whole numbers that are automatically generated.
SHAPE
Feature geometry.
ESRI
Coordinates defining the features.
StreamOrde
Strahler stream order to define stream size based on hierarchy of tributaries.
NHDES
Stream order
Tier
Tier classification of the stream segment
NHDES
1
Conservation Land in excess of 300 feet from river/lake frontage
NHDES
2
Conservation Land greater than or equal to 100 feet but less than 300 feet from river/lake frontage
NHDES
3
CSPA Protection (150 ft Natural Woodland Buffer)
NHDES
4
Local Protection Ordinance, buffer greater than or equal to 100 feet
NHDES
5
Local Protection Ordinance, buffer greater then or equal to 50 feet, but less than 100 feet
NHDES
6
No Protection (meeting the criteria in the above 5 Tiers)
NHDES
Shape_Leng
Length of stream segment
NHDES
Length of stream segment in feet
20120315
NH Department of Environmental Services
Pierce Rigrod
Mailing and physical address
29 Hazen Drive, PO Box 95
Concord
NH
03302
603-271-0688
603-271-0688
603-271-3305
FGDC Content Standards for Digital Geospatial Metadata
FGDC-STD-001-1998
local time