Prepared for: John Stachelhaus Department of Administration State of Rhode Island
12/10/07
Prepared by: Sudha Maheshwari 455 E. Eisenhower Parkway, Suite 240, Ann Arbor, MI 48108
1 PURPOSE OF DOCUMENT 3 2 GENERAL DESCRIPTION 3 2.1 STATEWIDE LAND COVER/LAND USE DATA (RI_LCLU) 3 2.2 STATEWIDE IMPERVIOUS DATA (RI_IMPV) 4 3 PROJECT LIFE CYCLE 4 4 OVERALL PROCESS STEPS 5 4.1 EXTRACT IMPERVIOUS 6 4.2 LABEL IMPERVIOUS 7 4.3 BUFFERING LABELED IMPERVIOUS DATA 7 4.4 CREATE PERVIOUS CLASSIFICATION 9 4.5 LABEL PERVIOUS DATA 10 4.6 SECONDARY BUFFER 10 4.7 CLEAN DATA 12 4.8 QC 13 4.9 OTHER GENERAL PROCESSING STEPS 13 5 CLASSIFICATION SCHEMA 13 6 REFERENCE DATA USED 19 7 PROJECT PERSONNEL 20
1 Purpose of Document
The purpose of this document is to provide a detailed description of the Rhode Island land cover/land use project and particularly the various steps that were used to delineate the 2003-04 land use land cover boundaries for the state. An overview of the process is also provided in the metadata as well, however, detailed instructions on each step are provided in this document. Section 2 provides a general description of the final products that came out this project including attributes associated with the data. Section 3 provides an overview of the project cycle. Section 4 provides the overall process steps followed by sub-sections on the details of each step. Section 5 provides the final classification scheme used. Section 6 discusses the project personnel involved and Section 7 lists the ancillary data used in creating these data. 2 General Data Description
This project involved the creation to two datasets: 2.1 Statewide Land Cover/Land Use Data (RI_LCLU) This is a statewide, seamless digital dataset of the land cover/land use for the State of Rhode Island derived using semi-automated methods and based on imagery captured in 2003-2004 2 ft pixel resolution. (Aerial Photography for areas East of the RISPC easting meridianal value 340,000 and for Block Island was obtained in March and April of 2003. Photography for areas west of RISPC easting 340,000 was obtained in April of 2004.) The project area encompasses the State of Rhode Island and extends approximately 1/2 mile into the neighboring states of Connecticut and Massachusetts. Geographic feature accuracy meets general National Mapping Standards for 1:5000 scale mapping with respect to base level data (roads, hydrography, and ortho imagery). The minimum mapping unit for this dataset is .5 acre. The land use classification used for these data was based on the Anderson Level III modified coding schema used in previous land use datasets in Rhode Island (1988 & 1995) with some modifications for the 2003 classification. The dataset is intended to be incorporated into the Rhode Island Geographic Information System database for use by federal, state and local government and made available to the general public under established RIGIS licensing procedures. The data were delivered to the State of Rhode Island, Department of Administraiton, Statewide Planning Program on one external disk dirve in an ArcInfo coverage format.
This dataset as delivered includes the following attribute fields: *
Table 1: Data Dictionary for RI_LCLU Data Field Name Field Type Description FID ESRI Internal Field Sequential unique whole numbers that are automatically generated Shape Feature Geometry Coordinates defining the features Area Area in sq ft generated by ESRI Perimeter Perimeter of feature in ft generated by ESRI RI_LCLU# ESRI Internal Field Sequential unique whole numbers that are automatically generated RI_LCLU-ID ESRI Internal Field LCLU Binary 3-digit Land Use Code (Code descriptions provide in Section 5) Description Text Abbreviated description of land use * Acres * Numeric * Area in Acres as calculated from Area Field (in sq ft) (* Added after delivery) 2.2 Statewide Impervious Data (RI_IMPV) This is a statewide, seamless digital dataset of the impervious surfaces for the State of Rhode Island derived using semi-automated methods and based on RIGIS/RIDOT imagery captured in 2003-2004. (Aerial Photography for areas East of the RISPC easting meridianal value and for Block Island was obtained in March and April of 2003 and areas west of RISPC easting was obtained in April of 2004.) The project area encompasses the State of Rhode Island and extends 1/2 mile into the neighboring states of Connecticut and Massachusetts or to the limits of the available orthophotography. Geographic accuracy of the source data meets the National Mapping Standards for 1:5000 scale mapping with respect to base level data (roads, hydrography, and orthos). This raster dataset has two classes - pervious and impervious. Impervious surfaces are man made or created surfaces that do not allow water to permeate through them. Impervious features include paved surfaces such as buildings, roads, sidewalks, driveways, parking lots, swimming pools, tennis courts, compacted dirt roads, athletic track, water treatment facilities, etc. They do not include structures over water such as docks, bridges, etc. and railroads. Natural occurring impervious surfaces such as rock outcrops, etc. were not considered impervious for this dataset.
The impervious surface data were delivered to the State of Rhode Island as an ESRI grid format data set with a 2 ft spatial resolution.
3 Project Life Cycle
The project was initiated by conducting an analysis of a 1 square mile sample area (Wickford, RI) to establish the methodology and buffering rules to be used throughout the overall process. A second sample tile (Block Island) was then developed and used to determine if and when modifications might be necessary for less developed landscapes. A third sample tile (East Providence) was then developed as representing a highly developed urban area for further modifications to the processes. These second and third sample areas were included and incorporated as tiles 9 and 10 in the production process. The production process then proceeded from the north to the south and west to east starting in the Northwest corner of the state for the remaining 8 tiles comprising the overall 10 tile project area. The data development process started in August of 2006 and final edits were completed in December of 2007.
4 Overall Process Steps
The land cover/land use dataset was created using semi-automated methods for classification of the color ortho imagery from 2003-04 for RI and through using attributes from the 1995 LC/LU dataset that was compiled manually through photo-interpretation.
1. For urban classes (i.e. classes that involved urban uses of land such as residential, commercial, etc.), the impervious data were extracted from the RIGIS/RIDOT 2003/04 orthophotgraphy
2. Labels for the land use were pulled from the RIGIS1995 land use data where no change took place and were assigned manually for areas where change occurred from 1995-2003.
3. Rule sets as shown in Tables 2 an 3 were used to buffer the labeled impervious.
4. The pervious uses were classified separately through a segmentation process using Difiniens's eCognition© software.
5. The labels for pervious classes were also pulled from the RIGIS 1995 data and flagged for correction where necessary.
6. The buffered impervious data and the pervious data were combined using ESRI ArcGIS© software. RIGIS (E911rds04) road centerline data were used to provide break points between land use classes to the left and right of roads. Likewise RIGIS active railroads rirail02 were used to delineate railroad corridors.
7. Filters were applied to smooth the polygon boundaries as needed and to maintain the minimum mapping unit (mmu) of .5 acre. Although the mmu of .5 acre was adhered to in most instances, in some cases, polygons lesser than .5 acres were delineated - these included polygons from the hydrography data (which was directly burned into the classification) and polygons with urban uses in rural areas with isolated residential or commercial uses less than .5 acres.
8. Manual review of the data was performed and polygons that did not delineate appropriately through the automated land use were corrected both in terms of geometry and in terms of labels.
9. Extensive QC was performed on the data and edits were done as needed. The State of Rhode Island provided input for QC on specific polygon delineation and land cover/land use coding based upon local knowledge of delivery areas as they were delivered for review. No onsite field verification was conducted by either Sanborn or the State of Rhode Island during this project.
Data were delivered to the client in 10 delivery areas in Rhode Island. A graphic of the tile structure for the 10 tile delivery area is included in Section 3. Most production was done in smaller production areas in order to meet limitations in various software tools. Production areas were edge-matched to produce a seamless data set for the State of Rhode Island for final delivery.
4.1 Extract Impervious Semi-automated impervious data were generated using a Feature Analyst extension for ESRI ArcGIS. Training samples based on the 2003/2004 imagery were used within Feature Analyst to generate extraction models which classified impervious features. Automated impervious extractions were then manually reviewed and edited for mapping at a 1:5000 scale. Impervious features include paved surfaces such as buildings, roads, sidewalks, driveways, parking lots, swimming pools, tennis courts, compacted dirt roads, athletic track, water treatment facilities, etc. They do not include structures over water such as docks, bridges, etc. and railroads. Impervious surfaces are human-made and not natural impervious surfaces such as mountains, rock outcrops, etc. Railroads were not considered impervious and neither were bridges over water, etc. Compacted dirt roads were considered impervious and also tennis courts, swimming pools and other paved sporting facilities such as sports track, etc. The impervious surface data in an ESRI grid format was delivered on a tile by tile basis to the client and later edge-matched and combined in a statewide data set for final delivery to State of Rhode Island.
4.2 Label Impervious
This step involved the labeling of the cleaned up impervious data set. Before labeling, the road centerlines were buffered by 20' resulting in an overall 40 foot width and used to mask out any underlying impervious to separate impervious features to the left and right of road networks. Labels were then applied to the impervious data set from the RIGIS 1995 land use data in a raster conditional modeling process. A semi-automated process was used to clean labels where misalignment occurred between the two data sets using standard processing tools in ArcGIS such as Eliminate. Manual review and labeling was performed where land use changed between 1995 and 2003 from pervious to impervious uses and where automated cleanup was not sufficient. The labeled impervious data were also reviewed against ancillary data such as location of schools, government facilities, waste sites, etc. The labeled impervious features did not contain any roads data for roads less than 200 feet in width. (with the exception of major limited access highways (interstates) and as identified in previous RIGIS LCLU data sets as described in Section 5.) 4.3 Buffering Labeled Impervious Data
This step entailed the buffering of labeled impervious data to produce the preliminary boundaries of the land uses for urban classes. Before buffering, free standing impervious clumps of less than 200 sq feet were removed in order to remove sheds, detached garages or small structures at the end of people's property.
The labeled impervious data were buffered based on the assigned LC/LU code. For classification codes, buffer distances and buffer priority, refer to Table 2 below).
Table 2: Buffer Rules for 1st Buffer Land Use Buffer Distance Rules Residential (111, 112, 113) 30 feet All subtypes of residential are equal - e.g. when buffers of medium density and low density overlap, they divide in the center. Residential buffers override developed recreation and transitional areas. Residential buffers are trumped by all other urban class buffers. Residential (114, 115) 60 feet Commercial (120) 10 feet Commercial is same priority as industrial, commercial/residential mix, commercial/industrial mix and cemeteries and when the buffers for these classes overlap, they divide in the center. Commercial buffers override all other urban class buffers. Industrial (130) 10 feet Industrial is same priority as commercial, commercial/residential mix, commercial/industrial mix and cemeteries and when the buffers for these classes overlap, they divide in the center. Industrial buffers override all other urban class buffers. Roads (141) 20 feet Road priority is same as railroads, power lines and other transportation and when the buffers for these classes overlap, they divide in the middle. Roads buffers are trumped by commercial, industrial, commercial/residential and commercial/industrial. Road buffers override all other urban class buffers. Airports (142) 50 feet Airports are trumped by commercial, industrial, commercial/residential, commercial/industrial, roads, railroads, power lines and other transportation. Airport buffers override all other classes. Railroads (143) 20 feet Railroad priority is same as roads, power lines and other transportation and when the buffers for these classes overlap, they divide in the middle. Railroad buffers are trumped by commercial, industrial, commercial/residential and commercial/industrial. Railroad buffers override all other urban class buffers. Water and Sewage Treatment (144) 50 feet Water and sewage treatment is same priority as waste disposal, and when the buffers for these classes overlap, they divide in the center. Water and sewage treatment buffers override mines, quarries and gravel pits, residential, developed recreation, vacant land and transitional areas. Water and sewage treatment buffers are trumped by all other urban class buffers. Waste Disposal (145) 50 feet Waste disposal is same priority as water treatment, and when the buffers for these classes overlap, they divide in the center. Waste disposal buffers override mines, quarries and gravel pits, residential, developed recreation and transitional areas. Waste disposal buffers are trumped by all other urban class buffers. Power Lines (146) 20 feet Power line priority is same as roads, railroads and other transportation and when the buffers for these classes overlap, they divide in the middle. Power line buffers are trumped by commercial, industrial, commercial/residential and commercial/industrial. Power line buffers override all other urban class buffers. Other Transportation (147) 20 feet Other transportation priority is same as roads, power lines and railroad and when the buffers for these classes overlap, they divide in the middle. Other transportation buffers are trumped by commercial, industrial, commercial/residential and commercial/industrial. Other transportation buffers override all other urban class buffers. Commercial/Residential Mix (151) 10 feet Commercial/residential mix is same priority as industrial, commercial, commercial/industrial mix and cemeteries and when the buffers for these classes overlap, they divide in the center. Commercial/residential buffers override all other urban class buffers. Commercial/Industrial Mix (152) 10 feet Commercial/industrial mix is same priority as industrial, commercial, commercial/residential mix and cemeteries and when the buffers for these classes overlap, they divide in the center. Commercial/industrial buffers override all other urban class buffers. Developed Recreation (161) 60 feet Developed recreation buffers override transitional areas. Developed recreation buffers are equal in priority to vacant land. The buffers are trumped by all other urban class buffers. Vacant Land (162) 60 feet Vacant land buffers override transitional areas. Vacant Land buffers are equal in priority to developed recreation. The buffers are trumped by all other urban class buffers. Cemeteries (163) 10 feet Cemetery buffers override water and sewage treatment, waste disposal, mines, quarries and gravel pits, residential, developed recreation, vacant land and transitional areas. Cemetery buffers are trumped by all other urban class buffers. Institutional (170) 15 feet Institutional buffers override residential, cemeteries, mines, quarries and gravel pits, water and sewage treatment, waste disposal, developed recreation and vacant land. Institutional buffers are trumped by all other urban class buffers. Waste Disposal (145) 50 feet Waste disposal trumps developed recreation and vacant land. Waste disposal is same priority as 'mines, quarries, gravel pits' and when buffers for these classes overlap, they divide in the center. Mines, Quarries and Gravel Pits (740) 50 feet Mines, Quarries and Gravel Pit buffers trump residential, developed recreation, vacant land and transitional areas. Mines, Quarries and Gravel Pit buffers are trumped by all other urban class buffers. Transitional Areas (750) 100 feet Transitional area buffers are trumped by all urban class buffers. 4.4 Create Pervious Classification
The 2003/2004 imagery was segmented and classified with Difiniens eCognition software using a process tree model. The imagery was classified into seven pervious classes:
Grassland and Shrubland - Code 300 Water (water was burned in from the Hydrography layer provided by the State of Rhode Island and larger bodies of water that were greater than the minimum mapping unit and not in the hydrography layer were flagged for manual review) - Code 500 Deciduous Forest - Code 410 Coniferous Forest - Code 420 Mixed Forest - Code 430 Barren - Code 700
The coding schema applied in this project differs from previous RIGIS land cover/land use coding schema in that the previous data sets from 1988 and 1995 erroneously had forest types as 300 codes and brushland as 400 codes. These were numerically corrected at the direction of the State of Rhode Island. Data Land Cover codes used in this project result in a schema complying with the correct Anderson coding whereby brushland is code 300 and forest types are coded 400.
The segmented classification was then exported to a grid format and a series of filters were applied to the data in order to generalize/smooth the pervious land use class boundaries. Features below the ½ acre minimum mapping unit were dissolved into surrounding features.
4.5 Label Pervious Data
This step entails the labeling of the pervious classification from Step 4 before using the 1995 land use data. This was done by combining the pervious classification with the 1995 land cover dataset and pulling in the labels of use based on the 1995 classification - for example, where the pervious classification is grass or shrub, and the label in the land use classification is wetland, the grass/shrub segments is labeled as a wetland- based on a zonal majority rule (i.e. the segment gets labeled with the class which contains the largest proportion of the segment. For example, if a given segment is 30% within forest, 30% within brush and 40% within wetland class, that segment will be labeled wetland). Where logical label combinations occurred, the pervious data were labeled with an appropriate land use code between 111 and 750. Where illogical label combinations occurred, the pervious data were labeled with a flagged value of 900 for manual review. Illogical calls include calls such as grass in the new classification in areas where there was forest in 1995 - while possible (due to deforestation), these polygons were reviewed manually to determine the correct call. Forested wetlands were not classified in the 1995 data. Wetlands in 1995 included forested wetlands and were all of one flavor (Code = 600). Labels for non-forested wetlands were pulled based on a zonal majority rule to the segment boundary (as discussed above). Thus, non-forested wetland boundaries were improved based on the image characteristics.
4.6 Secondary Buffer
Through this step, the buffered labeled impervious and the labeled pervious data were combined through a secondary buffer. The purpose of this buffer is to incorporate natural classes into urban class delineations where appropriate - for example lawns in residential. The secondary buffer only allows impervious features of certain classes to grow into pervious regions of specific classes. The buffers grew at a specified distance beyond the edge of buffer 1. The buffer distances and class hierarchy were specified within an automated model. Road centerlines were buffered 2' and coded in as 999 in order to provide a mask to prevent land use classes from expanding across roads. For classification coded, buffer distances and buffer priority, refer to Table 3 below.
Table 3: Buffer Rules for 2nd Buffer Land Use Buffer Distance Rules Residential (111 &112) 100 feet Buffer permeates non-woody and barren. The buffer does not extend over water and forests. The buffer overrides water and sewage treatment, waste disposal, mines quarries and gravel pits. The buffers are trumped by all other secondary urban buffers. Residential (113, 114, 115) 150 feet Industrial (130) 50 feet Buffer permeates non-woody and barren. The buffer does not extend over water and forests. Industrial is equal in priority with commercial, commercial/residential mix, commercial/industrial mix. The buffer is trumped by roads, railroads, power lines and other transportation. The buffer overrides all other urban class buffers. Roads (141) 0 feet Roads are not expanded with a second buffer. Roads are not affected by secondary buffers of other classes. Airports (142) 100 feet Buffer permeates non-woody and barren. The buffer does not extend over water and forests. The buffer is trumped by roads, railroads, power lines, other transportation, developed recreation, transitional areas, commercial, industrial, commercial/industrial, commercial/residential and institutional. The buffer overrides all other urban class buffers. Railroads (143) 0 feet Railroads are not expanded with a second buffer. Railroads are not affected by secondary buffers of other classes. Water and Sewage Treatment (144) 50 feet Water and sewage treatment is equal in priority to waste disposal. The buffer expands into non-woody and barren. The buffer does not extend over water and forests. The buffer trumps mines quarries and gravel pits, and developed recreation. The buffer is trumped by all other urban class buffers. Waste Disposal (145) 100 feet Waste disposal is equal in priority to water and sewage treatment. The buffer expands into non-woody and barren. The buffer does not extend over water and forests. The buffer trumps mines quarries and gravel pits, and developed recreation. The buffer is trumped by all other urban class buffers. Power Lines (146) 0 feet Power lines are not expanded with a second buffer. Power lines are not affected by secondary buffers of other classes. Other Transportation (147) 30 feet Other transportation is equal in priority to roads, railroads and power lines. The buffer expands into non-woody and barren. The buffer does not extend over water and forests. The buffer overrides all other urban class buffers. Commercial/Residential Mix (151) 50 feet Buffer permeates non-woody and barren. The buffer does not extend over water and forests. Commercial/residential mix is equal in priority with industrial, commercial, commercial/industrial mix. The buffer is trumped by roads, railroads, power lines and other transportation. The buffer overrides all other classes. Commercial/Industrial Mix (152) 50 feet Buffer permeates non-woody and barren. The buffer does not extend over water and forests. Commercial/industrial mix is equal in priority with industrial, commercial, commercial/residential mix. The buffer is trumped by roads, railroads, power lines and other transportation. The buffer overrides all other classes. Developed Recreation (161) 50 feet Buffer permeates non-woody and barren. The buffer does not extend over water and forests. The buffer is trumped by roads, railroads, power lines and other transportation. The buffer overrides all other urban class buffers. Vacant Land (162) 50 feet All non-woody and barren gets labeled as vacant land if the underlying polygon from 95 land use is vacant land. Vacant land is trumped by all other secondary buffers. The buffer does not extend over water and forests. Cemeteries(163) 50 feet Buffer permeates non-woody and barren. The buffer does not extend over water and forests. The buffer trumps residential, water and sewage treatment, waste disposal, mines, quarries and gravel pits and vacant land. The buffer is trumped by all other urban class buffers. Institutional (170) 50 feet Buffer permeates non-woody and barren. The buffer does not extend over water and forests. The buffer overrides airports, cemeteries, residential, water and sewage treatment, waste disposal mines, quarries and gravel pits and vacant land. Mines, Quarries and Gravel Pits (740) 100 feet Buffer permeates non-woody and barren. The buffer does not extend over water and forests but overrides vacant land. It is trumped by all other urban class buffers.
4.7 Clean Data
This step entails the generalization of data to remove sharp edge polygons, and polygons that fall below the minimum mapping unit, and incorporate the road centerlines. The generalization was done in the raster environment using a series of filters and smoothing algorithms and in the vector environment using the eliminate tool. Although a 1/2 acre minimum mapping unit was used, certain urban land use polygons of less than 1/2 acre were captured in order to keep all the urban polygons delineated as urban particularly in rural areas.
Final review was performed manually where all the flagged values were assigned the correct land use codes, any misclassified polygons were correctly delineated. Due to the nature of automated classifications, and the poor quality of the imagery, some uses did not classify correctly and manual delineation was performed to accurately represent those classes. Wetlands were not delineated correctly in many instances and had to be hand digitized keeping in mind the rules of automated delineation for these classes. Likewise, mixed forest delineation showed a lot of confusion and was corrected as needed.
The coastline was based on the coastline data provided by the State of Rhode Island. Therefore in some areas, the coastline does not follow the imagery.
4.8 Quality Control
The data went through an internal Quality Control at Sanborn and was subjected to an external quality control processes at the State of Rhode Island and a third party contractor (Mapping and Planning Services Inc) employed by the State. No on site field verification was conducted by either Sanborn, Rhode Island or the consultant during this project. Extensive use of RIGIS ancillary data and local knowledge was employed during the overall QC process. This included orthophotography, municipal parcel data and RI E911 building site data. Issues pointed out during the QC process were resolved on a tile by tile basis and finalized as data were merged into the final statewide data set.
4.9 Other General Processing Steps
In order to process information, the area had to be subdivided into smaller production areas. Deliveries to Rhode Island were made by Delivery Areas (See Section 7) (each delivery area was comprised of a number of production areas). Internal production and QC were done using production areas. The production areas were edge-matched, QCed and then external QC was performed on it. Deliveries to Rhode Island were also provided by Delivery Areas and comments addressed. All the final comments were incorporated and edge-matching was done to ensure a seamless dataset. The final data were updated using the coastline data provided by Rhode Island.
5 Classification Schema
This coding schema for Land Cover/Land Use type is derived from the Anderson (modified) coding schema used by RIGIS in previous (1988 and 1995) land cover/land use data sets. It includes level 3 coding for Urbanized Developed areas (100 Codes); level 2 coding for agricultural (200 Codes), Forested lands (400 Codes), and Barren Lands (700 Codes); and Level 1 coding for Brushland (300 Code), Open Water (500 Code), and Wetlands (600 Code). This numerical coding schema differs from previous RIGIS land cover/land use coding schema in that the previous data sets from 1988 and 1995 erroneously had forest types as 300 codes and brushland as 400 codes. These were numerically reversed at the direction of the State of Rhode Island. The resulting schema for data created for this project as shown above complies with the true Anderson coding schema.
111...High Density Residential (8 houses or more per acre) 112...Medium High Density Residential (4 - 8 houses per acre) 113...Medium Density Residential (1 - 4 houses per acre) 114...Medium Low Density Residential (1 house per 1 to 2 acre) 115...Low Density Residential (>2 acre lots)
DESCRIPTION: All residential categories are based on the size of the maintained lot and include the house and the yard area. Lot sizes are visually determined by comparing the houses in an area to the surrounding houses, observing the spacing between the houses and the relative amount of yard space between them. Other land cover types (such as forest, wetland or water bodies), even though they may be on a residential property, are mapped separately if they exceed the minimum mapping unit. Duplexes (usually with 2 front doors/pathways and sometimes 2 driveways) will be factored into this calculation while multi-unit complexes will generally be classified as high density residential unless surrounded by a significant amount of maintained yard (such as some condos), in which case it may calculate out to a lower density category. Building sizes of residences (except for some duplexes and multi-unit complexes) are significantly smaller than almost all commercial and industrial buildings.
120...Commercial (sale of products and services)
DESCRIPTION: Large commercial facilities (such as malls, shopping centers and larger strip commercial areas) are typically well landscaped with parking strategically arranged around the building in multiple areas. There are often a few loading docks. These land uses are usually found in residential areas or grouped with other commercial facilities. Parking areas are included. Smaller commercial facilities (such as neighborhood stores or smaller strip commercial areas) often look similar to residential areas but are sometimes distinguishable by their larger parking areas (compared to residential parking) often behind the building down a driveway with spaces for 5 or 10 vehicles or if in a dense residential area, they may actually be commercial at the ground level and apartments above. Without any of these distinguishing features, these will probably be classified as residential. Also included in this category are office parks, medical offices and lawn and garden centers that do not produce or grow the product (not part of nurseries). Commercial buildings are almost always larger than residential structures.
130...Industrial (manufacturing, design, assembly, etc.)
DESCRIPTION: Industrial areas are typically not landscaped as thoroughly as a commercial facility. Parking is often in one large lot. These areas generally have many loading docks and there are often truck trailers parked on-site. These facilities are often far from residential areas, often surrounded by forests, but typically near major roads or highways. Parking areas are included. Industrial buildings are almost always larger than residential structures.
141...Roads (divided highways >200' plus related facilities)
DESCRIPTION: Related facilities would include rest areas, highway maintenance areas, storage areas, on/off ramps, and maintained grassy areas adjacent to the roadway. Also included is the grass or wooded median strip between the roads. Roads less than 200 feet in width that are the center of two differing land use classes will have the land use classes meet at the center line of the road. Bridges that are greater than 200 feet wide will be included in this category.
142...Airports (and associated facilities)
DESCRIPTION: Airport facilities include runways, maintained grassy areas adjacent to runways, hangars, terminals, freight storage areas and buildings, roads, short and long term parking lots, observation towers and on-site commercial facilities. Abandoned airports should be classified as another use such as Vacant Land (162) or Transitional Land (750) depending on its current use.
143...Railroads (and associated facilities)
DESCRIPTION: Railroad facilities include all tracks, maintained rights-of-way adjacent to the tracks, terminals, stations, switching yards, storage facilities and buildings, and parking lots around the station.
144...Water and Sewage Treatment
DESCRIPTION: Water and sewage treatment facilities are typically characterized by circular sedimentation and aeration tanks, associated facilities include pump houses, filtration and aeration buildings, water storage tanks /standpipes as well as parking lots.
145...Waste Disposal (landfills, junkyards, etc.)
DESCRIPTION: Landfills often can be mistaken for sand and gravel pits (740) but do not have the "spider" shaped sorting/conveyor apparatus associated with sand and gravel operations. There is usually an area of recent activity with disturbed earth and piles of material (waste and cover material) nearby. There will often be large areas that haven't been disturbed for a while. Associated facilities for landfills, junkyards, and automobile dumps include all buildings, roads and parking areas. There are usually construction machines (such as front bucket loaders, road graders, bulldozers and dump trucks) on site. Once landfills are closed, they are covered, graded and often times venting pipes for methane gas can be seen arranged systematically throughout the landfill. There will generally be a high point in the middle of the landfill with moderate slopes out to the edges. Some capped landfills may have been converted to another use, such as Developed Recreation (161).
146...Power Lines (100' or more width) DESCRIPTION: Power lines generally follow straight lines across the landscape. Usually, the support towers are visible at a set interval and often, wires can be seen on an aerial photograph between the towers. Also included in this category are underground pipeline corridors. In both cases, the feature is mapped to the edge of the maintained vegetation. Where power lines or utility corridors pass over or through other land use categories, the other category takes precedence unless the area is managed specifically for the power line (such as forest).
147...Other Transportation (terminals, docks, etc.)
DESCRIPTION: This category is used for land-based truck terminals and warehouses (with many loading docks) as well as water-based docks and associated buildings used for industrial or commercial purposes not associated with other categories (such as recreation docks used at marinas), but includes commercial fishery facilities. Adjacent parking areas and storage facilities are included. This category takes precedence over Industrial (130) if the primary use is to transport goods.
151...Commercial/Residential Mixed (New not in 1995- There are minimal polygons identified or coded in this category. The intention for inclusion of the category were suggested by Rhode Island to allow for future use.)
DESCRIPTION: This category is used for land uses that are a mix of both commercial and residential. Although difficult to tell from aerial photographs, ancillary data may be provided to help classify areas into this type.
152...Commercial/Industrial Mixed (Coded as 150 in 1995)
DESCRIPTION: Some facilities are not obviously commercial or industrial but a mix of the two. They are nicely landscaped yet have distinguishing characteristics of both commercial and industrial areas. Parking lots are included. Commerce Parks will fit into this category.
161...Developed Recreation (all recreation)
DESCRIPTION: Developed recreation facilities include stadiums, ball fields, tennis courts, urban parks, basketball courts, ski areas, golf courses, marinas, playgrounds, zoos, amusement parks, developed beach areas, drive-in theaters, fairgrounds, bike paths, race tracks and swimming pools plus associated parking lots. It does not include passive recreation areas such as state forests or parks, except for the developed facilities associated with these areas. These facilities, when associated with institutional land uses, will be pulled out into this category.
162...Vacant Land
DESCRIPTION: Land is classified as vacant if it is abandoned land that isn't being used for any other land use. It isn't being prepared for another use (see 750 Transitional Area below) and does not have enough tree growth to be classified as forest or enough vegetation to be classified as brushland (300). It may include structures and indicates that the land was previously used for one of the urban categories.
163?Cemeteries
DESCRIPTION: From small to large cemeteries, these features are obvious by the orderly grid of gravestones, monuments and road networks. Quite often, they are noted on USGS topographic maps. This category includes associated buildings, roads and parking areas.
170...Institutional (schools, hospitals, churches, etc.)
DESCRIPTION: Institutional land and buildings are public or quasi-public facilities with or without green space designed to serve large numbers of people such as government buildings, schools, colleges, hospitals, prisons, churches, town halls, public works facilities, police stations or fire stations. The maintained areas around the facilities are included as are parking facilities. Some of the facilities at a large college, for example, may be pulled out into other categories (such as an athletic field - 161). However, all dormitories, family and faculty housing and other buildings are included in this category as are grassy areas that are on the property of the institution as are usually noted on USGS topographic maps.
210...Pasture (agricultural not suitable for tillage)
DESCRIPTION: Pasture land is generally used for grazing of animals and for the growing of grasses for hay. It is often hilly, may have poor drainage or stoniness, and the field boundaries may be less defined than cropland. There may be scattered trees or shrubs in the field. Associated facilities include barns and other outbuildings.
220...Cropland (tillable)
DESCRIPTION: Cropland is generally tilled land used to grow row crops. There is usually evidence of intense land management. The land is often flat, well drained and the field boundaries are generally very well defined. This category also includes turf farms that grow sod. Associated facilities include barns and other outbuildings.
230...Orchards, Groves, Nurseries DESCRIPTION: This category includes fruit orchards, greenhouses, plant nurseries, Christmas tree farms, vine crops (such as vineyards, strawberry and blueberry patches), and cranberry bogs (including sandy areas adjacent to the bogs that are used in the growing process). The orderly pattern of the vegetation generally indicates that one or more of these land uses is present. Associated facilities include barns, other outbuildings and parking lots. Orchards and greenhouses are often symbolized on USGS topographic maps. Commercial lawn and garden centers that do not produce or grow the product will be considered Commercial (120).
240...Confined Feeding Operations
DESCRIPTION: Confined feeding operations are intensive facilities used for raising livestock or poultry in a small space where there are minimal adjacent grazing lands. This category includes the feeding areas, stables, barns, outbuildings and waste management facilities as well as equipment storage areas.
250...Idle Agriculture (abandoned fields and orchards)
DESCRIPTION: When pasture, cropland and other agricultural uses have not been active for a few years, it is classified as idle agriculture. Often, early successional vegetation is seen growing in around the edges and there is no evidence of any land or vegetation management. Eventually, it will become brushland (300).
300...Brushland (shrub and brush areas, reforestation) (Formerly coded as 400 in 1995) DESCRIPTION: Brushland is characterized by lots of shrubs and very few trees (< 50% canopy). It includes areas that are being reforested but the trees are not large or dense enough to be classified as forests. It also includes areas that are more permanently shrubby, such as heath areas, wild blueberries or mountain laurel.
400?Forest Lands (Formerly coded as 300 in 1995) 410...Deciduous Forest (>80% hardwood) (Formerly Brushland in 1995) 420...Coniferous Forest (>80% softwood) 430...Mixed Forest
DESCRIPTION: Trees are classified as forests when the tree canopy covers at least 50% of the space when viewed from above on an aerial photograph. The three different categories depend upon the composition of deciduous vs. coniferous trees. On an aerial photograph, most coniferous trees have conical shapes (except for pines) with dense needles and tight branching with dark spectral signatures whereas deciduous trees have a more open or freeform shape with leaves (during the growing season) that give the tree a coarser texture or pattern and a looser or more open branching arrangement. Deciduous spectral signatures are generally lighter than coniferous signatures.
500...All Open Water Bodies DESCRIPTION: This category includes open water, such as lakes, ponds, lagoons, bays or rivers wide enough to be mapped as a polygon instead of a line. This includes any open water feature on the land side of the ocean coastline. (In the 1995 landuse 500 was latter recoded as 510-Fresh Water and 520 for salt and brackish water.) 600...Wetland (Non-Forested)
DESCRIPTION: Visible grassy or vegetated areas often near or adjacent to open water bodies or streams and or visibly scoured areas that may be associated with tidal flow or flooding. Forested wetlands will be treated as Code 400 forest types. Dead forest wetlands will also be delineated as Code 400 forest types.
710...Beaches
DESCRIPTION: This category includes fresh and saltwater sandy beaches. If it is a highly developed beach facility with buildings and parking lots, it should be classified as Developed Recreation (161).
720...Sandy Areas (not beaches) DESCRIPTION: These are sandy areas that are not beaches, with very little visible vegetation. These are generally small patches of sand in shrub-scrub areas that indicate highly permeable soils with very little organic material.
730...Rock Outcrops
DESCRIPTION: These are areas of rock with very sparse visible vegetation, usually found in steep areas with a lot of topographic relief, usually cliffs.
740...Mines, Quarries and Gravel Pits
DESCRIPTION: Sand and gravel pits usually have a "spider" shaped sorting/conveyor apparatus. Mines and quarries usually have very steep sides where there is evidence of some sort of extraction activity. Associated facilities include all buildings, roads and parking areas. There are usually construction machines (such as front bucket loaders, bulldozers and dump trucks) on site. USGS topographic maps will usually mark these features with appropriate symbols.
750...Transitional Areas (urban open)
DESCRIPTION: Some areas are in the process of being developed from one land use to another. Since these are transitional lands, it is not always apparent what the new land use will be so they are classified as this category. Typically, these areas are being developed for residential, commercial or industrial use. Comparison to older imagery shows that it was previously another land use or land cover category.
760...Mixed Barren Areas
DESCRIPTION: Mixed barren areas are areas that are very sparsely vegetated but clearly can not be classified as either rock outcrops or sandy areas. They may be a combination of rock and sand but are characterized by little or no vegetation and a visible rock or sandy surface.
6 Reference Data Used Data provided from the RIGIS Database as Maintained by the University of RI, Environmental Data Center as of 07/15/06
Rilu95c (Land Use1995) StateFacs E911rds04 Saltwater Streams5k MARoads (downloaded from MassGIS website) Ponds5k Esites06 and Esites06x (used for Quality Control only) Airport Electran CTRoads (downloaded from MAGIC - Map and Geographic Information Center at University of Connecticut) Gasline Landfill_and_Waste_Disposal_Facilities Library Medfacs Drvwy04a Schools01 Munifacs Pubsafe Rail Ritown5k 2003/2004 ORTHOIMAGES (Aerial Photography for areas East of the RISPC easting meridianal value 340,000 and for Block Island was obtained in March and April of 2003 and areas west of RISPC easting 340,000 was obtained in April of 2004.) 7 Project Personnel
The following persons worked on this project at Sanborn:
Andrew Brenner, General Manager, Sanborn Ann Arbor Sudha Maheshwari, Operations Manager, Sanborn Ann Arbor Mark Irwin, Analyst, Sanborn Ann Arbor Eddie Luthy, Analyst, Sanborn Ann Arbor
External QC for Sanborn was conducted by: David Goodwin, GIS/Data Manager, Department of Conservation and Recreation, State of Massachusetts
The following persons worked on this project for the State of Rhode Island:
John Stachelhaus, Project Manager, GIS Specialist, RI Dept. of Administration, Division of Information Technology and Statewide Planning Program Nancy Hess, Principle Environmental Planner, RI Dept. of Administration, Statewide Planning Program Paul Jordan, GIS Specialist, RI Dept. of Environmental Management Mary Hutchinson, GIS Professional, Mapping and Planning Services, Inc Peter August, Director, The Coastal Institute, The University of Rhode Island Charles Labash, Director, Environmental Data Center, The University of Rhode IslandThe land cover/land use dataset was created using semi-automated methods for classification of the color orthophotos from 2003-04 for RI and through using attributes from the 1995 LC/LU dataset that was compiled manually through photo-interpretation. See Process Document Report in Attribute Overview in this metadata
1. For urban classes (i.e. classes that involved urban uses of land such as residential, commercial, etc.), the impervious data were extracted
2. Labels for the land use were pulled from the 1995 land use data where no change took place and were assigned manually for areas where change occurred from 1995-2003.
3. Various rule sets were used to buffer the labeled impervious.
4. The pervious uses were classified separately through segmentation in eCognition
5. The labels for pervious classes were also pulled from the 1995 data and flagged for correction where necessary.
6. The buffered impervious data and the pervious data were combined using ArcGIS. The road centerline data were used to provide break points between land use classes to the left and right of roads. Likewise active railroads were used to delineate railroad corridors.
7. Filters were applied to smooth the polygon boundaries as needed and also to maintain the minimum mapping unit of .5 acre. Although the MMU of .5 acre was adhered to in most instances, in some cases, polygons lesser than .5 acres were delineated - these included polygons from the hydrography data (which was directly burned into the classification) and polygons with urban uses in rural areas with isolated residential or commercial uses less than .5 acres.
8. Manual review of the data was performed and polygons that did not delineate appropriately through the automated land use were corrected both in terms of geometry and in terms of labels.
9. Extensive QC was performed on the data and fixes were done as needed.
Data were delivered to the client in 10 delivery areas in Rhode Island. Most production was done in smaller production areas in order to meet limitations in various software tools. Production areas were edge-matched before delivering to Rhode Island and likewise delivery areas were edge-matched to produce a seamless data for the State of Rhode Island.
Clipped to a 1000 foot buffered county line data set by Statewide Planning after delivery of final data set submission from Sanborn
111...High Density Residential (<1/8 acre lots) 112...Medium High Density Residential (1/4 to 1/8 acre lots) 113...Medium Density Residential (1 to 1/4 acre lots) 114...Medium Low Density Residential (1 to 2 acre lots) 115...Low Density Residential (>2 acre lots) DESCRIPTION: All residential categories are based on the size of the maintained lot and includes the house and the yard area. Lot sizes are visually determined by comparing the houses in an area to the surrounding houses, observing the spacing between the houses and the relative amount of yard space between them. Other land cover types (such as forest, wetland or water bodies), even though they may be on a residential property, are mapped separately if they exceed the minimum mapping unit. Duplexes (usually with 2 front doors/pathways and sometimes 2 driveways) will be factored into this calculation while multi-unit complexes will generally be classified as high density residential unless surrounded by a significant amount of maintained yard (such as some condos), in which case it may calculate out to a lower density category. Building sizes of residences (except for some duplexes and multi-unit complexes) are significantly smaller than almost all commercial and industrial buildings.
120...Commercial (sale of products and services) DESCRIPTION: Large commercial facilities (such as malls, shopping centers and larger strip commercial areas) are typically well landscaped with parking strategically arranged around the building in multiple areas. There are often a few loading docks. These land uses are usually found in residential areas or grouped with other commercial facilities. Parking areas are included. Smaller commercial facilities (such as neighborhood stores or smaller strip commercial areas) often look similar to residential areas but are sometimes distinguishable by their larger parking areas (compared to residential parking) often behind the building down a driveway with spaces for 5 or 10 vehicles or if in a dense residential area, they may actually be commercial at the ground level and apartments above. Without any of these distinguishing features, these will probably be classified as residential. Also included in this category are office parks and medical offices. Commercial buildings are almost always larger than residential structures. 130...Industrial (manufacturing, design, assembly, etc.) DESCRIPTION: Industrial areas are typically not landscaped as thoroughly as a commercial facility. Parking is often in one large lot. These areas generally have many loading docks and there are often truck trailers parked on-site. These facilities are often far from residential areas, often surrounded by forests, but typically near major roads or highways. Parking areas are included. Industrial buildings are almost always larger than residential structures.
141...Roads (divided highways >200' plus related facilities) DESCRIPTION: Related facilities would include rest areas, highway maintenance areas, storage areas, on/off ramps, and maintained grassy areas adjacent to the roadway.
142...Airports (and associated facilities) DESCRIPTION: Airport facilities include runways, maintained grassy areas adjacent to runways, hangars, terminals, freight storage areas and buildings, roads, short and long term parking lots, observation towers and on-site commercial facilities.
143...Railroads (and associated facilities) DESCRIPTION: Railroad facilities include all tracks, maintained rights-of-way adjacent to the tracks, terminals, stations, switching yards, storage facilities and buildings, and parking lots around the station.
144...Water and Sewage Treatment DESCRIPTION: Water and sewage treatment facilities are typically characterized by circular sedimentation tanks, associated facilities include pump houses, filtration and aeration buildings, as well as parking lots.
145...Waste Disposal (landfills, junkyards, etc.) DESCRIPTION: Landfills often can be mistaken for sand and gravel pits but do not have the "spider" shaped sorting/conveyor apparatus associated with sand and gravel operations. There is usually an area of recent activity with disturbed earth and piles of material (waste and cover material) nearby. There will often be large areas that haven't been disturbed for a while. Associated facilities for landfills, junkyards, and automobile dumps include all buildings, roads and parking areas. There are usually construction machines (such as front bucket loaders, road graders, bulldozers and dump trucks) on site. Once landfills are closed, they are covered, graded and often times venting pipes for methane gas can be seen arranged systematically throughout the landfill. There will generally be a high point in the middle of the landfill with moderate slopes out to the edges. 146...Power Lines (100' or more width) DESCRIPTION: Powerlines generally follow straight lines across the landscape. Usually, the support towers are visible at a set interval and often, wires can be seen on an aerial photograph between the towers. Also included in this category are underground pipeline corridors. In both cases, the feature is mapped to the edge of the maintained vegetation. Where power lines or utility corridors pass over or through other land use categories, the other category takes precedence unless the area is managed specifically for the power line (such as forest).
147...Other Transportation (terminals, docks, etc.) DESCRIPTION: This category is used for land-based truck terminals and warehouses (with many loading docks) as well as water-based docks and associated buildings used for industrial or commercial purposes not associated with other categories (such as recreation docks used at marinas), but includes commercial fishery facilities. Adjacent parking areas and storage facilities are included.
151...Commercial/Residential Mixed DESCRIPTION: This category is used for land uses that are a mix of both commercial and residential. Although difficult to tell from aerial photographs, ancillary data may be provided to help classify areas into this type.
152...Commercial/Industrial Mixed DESCRIPTION: Some facilities are not obviously commercial or industrial but a mix of the two. They are nicely landscaped yet have distinguishing characteristics of both commercial and industrial areas. Parking lots are included.
161...Developed Recreation (all recreation) DESCRIPTION: Developed recreation facilities include stadiums, ballfields, tennis courts, urban parks, basketball courts, ski areas, golf courses, marinas, playgrounds, zoos, amusement parks, developed beach areas, drive-in theaters, fairgrounds, bike paths, race tracks and swimming pools plus associated parking lots. It does not include passive recreation areas such as state forests or parks, except for the developed facilities associated with these areas. These facilities, when associated with institutional land uses, will be pulled out into this category.
162...Vacant Land DESCRIPTION: Land is classified as vacant if it is abandoned land that isn't being used for any other land use. It isn't being prepared for another use (see 750 Transitional Area below) and does not have enough tree growth to be classified as forest or enough vegetation to be classified as brushland. It may include structures and indicates that the land was previously used for one of the urban categories.
163.Cemeteries DESCRIPTION: From small to large cemeteries, these features are obvious by the orderly grid of gravestones, monuments and road networks. Quite often, they are noted on USGS topographic maps. This category includes associated buildings, roads and parking areas.
170...Institutional (schools, hospitals, churches, etc.) DESCRIPTION: Institutional land and buildings are public or quasi-public facilities with or without green space designed to serve large numbers of people such as schools, colleges, hospitals, prisons, churches, town halls, public works buildings, police stations or fire stations. The maintained areas around the facilities are included as are parking facilities. Some of the facilities at a large college, for example, may be pulled out into other categories (such as an athletic field). However, all dormitories and other buildings are included in this category. These are usually noted on USGS topographic maps.
210...Pasture (agricultural not suitable for tillage) DESCRIPTION: Pasture land is generally used for grazing of animals and for the growing of grasses for hay. It is often hilly, may have poor drainage or stoniness, and the field boundaries may be less defined than cropland. There may be scattered trees or shrubs in the field. Associated facilities include barns and other outbuildings. 220...Cropland (tillable) DESCRIPTION: Cropland is generally tilled land used to grow row crops. There is usually evidence of intense land management. The land is often flat, well drained and the field boundaries are generally very well defined. This category also includes turf farms that grow sod. Associated facilities include barns and other outbuildings.
230...Orchards, Groves, Nurseries DESCRIPTION: This category includes fruit orchards, greenhouses, plant nurseries, Christmas tree farms, vine crops (such as vineyards, strawberry and blueberry patches), and cranberry bogs. The orderly pattern of the vegetation generally indicates that one or more of these land uses is present. Associated facilities include barns, other outbuildings and parking lots. Orchards and greenhouses are often symbolized on USGS topographic maps.
240...Confined Feeding Operations DESCRIPTION: Confined feeding operations are intensive facilities used for raising livestock or poultry in a small space where there are minimal adjacent grazing lands. This category includes the feeding areas, stables, barns, outbuildings and waste management facilities as well as equipment storage areas. 250...Idle Agriculture (abandoned fields and orchards) DESCRIPTION: When pasture, cropland and other agricultural uses have not been active for a few years, it is classified as idle agriculture. Often, early successional vegetation is seen growing in around the edges and there is no evidence of any land or vegetation management. Eventually, it will become brushland. 300...Brushland (shrub and brush areas, reforestation) DESCRIPTION: Brushland is characterized by lots of shrubs and very few trees (< 50% canopy). It includes areas that are being reforested but the trees are not large or dense enough to be classified as forests. It also includes areas that are more permanently shrubby, such as heath areas, wild blueberries or mountain laurel.
410...Hardwood Forest (>80% hardwood) 420...Softwood Forest (>80% softwood) 430...Mixed Forest DESCRIPTION: Trees are classified as forests when the tree canopy covers at least 50% of the space when viewed from above on an aerial photograph. The four different categories depend upon the composition of hardwood vs. softwood trees. On an aerial photograph, most softwood trees have conical shapes (except for pines) with dense needles and tight branching with dark spectral signatures whereas hardwood trees have a more open or freeform shape with leaves (during the growing season) that give the tree a coarser texture or pattern and a looser or more open branching arrangement. Hardwood spectral signatures are generally lighter than softwood signatures.
500...Water - Burned in from Previous RIGIS Ponds5k Data -Ocean and Bay Shoreline taken from RIGIS 5K and RIDEM Shoreline Data DESCRIPTION: This category includes open water, such as lakes, ponds, lagoons, bays or rivers wide enough to be mapped as a polygon instead of a line. This includes any open water feature on the land side of the ocean coastline.
600...Wetland - Non-Forested Wetlands Only
710...Beaches DESCRIPTION: This category includes fresh and saltwater sandy beaches. If it is a highly developed beach facility with buildings and parking lots, it should be classified as 161 Developed Recreation.
720...Sandy Areas (not beaches) DESCRIPTION: These are sandy areas that are not beaches, with very little visible vegetation. These are generally small patches of sand in shrub-scrub areas that indicate highly permeable soils with very little organic material.
730...Rock Outcrops DESCRIPTION: These are areas of rock with very sparse visible vegetation, usually found in steep areas with a lot of topographic relief, usually cliffs.
740...Mines, Quarries and Gravel Pits DESCRIPTION: Sand and gravel pits usually have a "spider" shaped sorting/conveyor apparatus. Mines and quarries usually have very steep sides where there is evidence of some sort of extraction activity. Associated facilities include all buildings, roads and parking areas. There are usually construction machines (such as front bucket loaders, bulldozers and dump trucks) on site. USGS topographic maps will usually mark these features with appropriate symbols.
750...Transitional Areas (urban open) DESCRIPTION: Some areas are in the process of being developed from one land use to another. Since these are transitional lands, it is not always apparent what the new land use will be so they are classified as this category. Typically, these areas are being developed for residential, commercial or industrial use. Comparison to older imagery shows that if was previously another land use or land cover category.
760...Mixed Barren Areas DESCRIPTION: Mixed barren areas are areas that are very sparsely vegetated but clearly can not be classified as either rock outcrops or sandy areas. They may be a combination of rock and sand but are characterized by little or no vegetation and a visible rock or sandy surface.