understanding the landscape of Saratoga County, NY

Descriptions of Data and Analyses used to Create Map Series

K.Seleen and M. Trabka  10/25/2013

The Landscape of Saratoga County, encompassing  844 square miles (540,160 acres), varies widely in its terrain, land cover, uses, and distribution of Conservation Resources. The Conservation Resources that Saratoga PLAN is trying to better understand through this landscape analysis are: Agricultural Lands, Natural Habitats, Water Resources, and potential Trail Networks.

As the basis of the landscape analysis, Saratoga PLAN, working with GIS Consultant Kirsten Seleen of Seleen Associates, created a series of maps. We used the best data sources that we could find and/or create that were applicable to the scale of the county. Maps depicting the distribution and quality of Conservation Resources, as well as informational maps for reference, were created by selecting and utilizing the data sources to create map layers. In addition to mapping and ranking Natural Habitats, Water Resources, Agricultural Lands, and Trail Networks, we are also learning a lot by studying maps depicting physiography, aerial photoimagery, current land cover types, projected future development patterns, grey infrastructure (i.e. sewer lines), green infrastructure (i.e. groundwater recharge), watershed quality, and other factors.

Saratoga PLAN’s goal in creating these maps is multi-fold:

  • to better understand the diversity, geographic distribution, and characteristics of the landscape of Saratoga County;
  • to help property owners understand their land’s conservation values and its context;
  • to evaluate conservation opportunities and investments; to guide our outreach and educational programs and services; and
  • to make this information widely available to partners, local governments, planners, developers, educators, students, businesses, and other conservation organizations.

The following descriptions describe how the maps were created and what they attempt to portray, where the data came from for each map and how we used them to depict, classify, and rank various factors that affect the distribution and quality of the Conservation Resources we are trying to understand throughout Saratoga County.

General Reference

This map was created to be used as general reference to help with orientation when viewing the other maps. Commonly known features such as town, city and village boundaries and names, major roads, and major lakes and rivers, with some hillside shading to indicate topography and elevation. Many of these same features were repeated on the other maps so that users could compare locations to the General Reference Map.

Aerial Imagery

Photos were taken from the air in the fall of 2011 when leaves were on and georeferenced in order to correct for perspective and curvature of the earth’s surface.

Physiography

This map image is used as a reference to help us understand the basic landform of the county through shaded topography and colored elevation. The relatively level sandplains created by glacial lake outwash sediments are evident in the eastern half of the county, as are the Adirondack foothills in the northwest. The basic drainage pattern throughout the county is also easy to see in the physiography map. You can even tell where the Hudson used to flow south and east through what is now the Kayaderosseras drainage and how the Mohawk flowed north, first joining the ancient Hudson west of Saratoga Lake out through what is now Fish Creek, and later through Ballston Creek and Lake, Round Lake and the Anthony Kill (Tenandeho).

Land Cover

Land Cover is a foundational dataset that was used for as a basis for mapping the Agricultural lands and the Natural Habitats.

Using existing data layers as a starting point, Natural Habitat Complexes (forest cover, wetlands, surface water) and Agricultural Lands (mapped agriculture and pasture land cover types) were screen digitized at an approximate scale of 1:5,000. Spring and fall 2011 aerial images were used as the base layers for delineation.

We were able to obtain an early release of the 2011 National Land Cover Dataset Impervious Surface product from USGS.  It is classified from 2011 Landsat satellite imagery with a resolution, or smallest detectable area, of 30 square meters (1/4 acre).  It is an accurate representation of surfacing (i.e. roads, buildings, rooftops, parking lots, etc.) that does not allow water to permeate into the soil, instead producing runoff.

USGS did not have a completed Land Cover product they were ready to release early, so we achieved the Land Cover map by combining the digitized natural habitats and agricultural lands with 2011 impervious surfaces data and 2006 open water data, resulting in a 30 meter resolution (1/4 acre) land cover layer with 5 classes or categories of land cover types – natural habitats, water, agricultural lands, low density residential/managed land, high density development (including impervious surfaces).

Saratoga County’s Land Cover is 10.19% densely developed, 10.77% lightly developed, 10.77% agricultural, 3.4% water, 8% wetlands, and 57% uplands (woodland, shrubland).

Night Sky

A georeferenced NASA satellite image of the night sky from Oct 12 2012 was acquired, showing the ground reflectance/lights from space at night. The night sky image illustrates the relative level and pattern of developed areas. Night-time lights negatively affect bird migration and reproduction in some moth species, which are drawn to the lights. Moths are important pollinators and prey species in the food chain, particularly for song birds.

Conserved Lands

The Conserved Lands Map depicts the current amount of land that is thought to have some level of protection within the county.

Lands considered to be protected in the short-term, or non-permanently, are the lightest green and amount to 77,340 acres or 14% of the county’s land mass.

Short-term protection includes woodlands enrolled in the 480A tax abatement program for working forestland; other non-permanently protected properties are also included.

Lands with permanent or long-term protection are medium green and comprise 9% or 49,931 acres in the county. State forests and state forest preserves are considered to be protected long-term or permanently. Some of the largest examples are labeled on the map such as the Saratoga National Historical Park (Battlefield), Moreau Lake State Park, Wilton Wildlife Preserve, Vischer Ferry Preserve, and Saratoga Spa State Park.
Lands that Saratoga PLAN currently stewards as conservation easements or under ownership or management are shown in dark green and amount to 3,566 acres or 0.66% of the county.

The blue line for the Adirondack Park is also shown in the northwest portion of the county, since there are additional restrictions on land use in the park.

The Conserved Lands Map may be incomplete; please contact Saratoga PLAN if you know of other lands in the county that are conserved in some way and are not shown.

Groundwater Recharge

A GIS-based soil-water balance model developed by USGS out of Wisconsin, was used to generate a map of mean annual Groundwater Recharge rates for Saratoga County.  This approach relies heavily on soils, direction of flow and climate information (10 years of daily climate data) as well as taking into consideration land use/land cover.  Expected recharge averages would be in the 6 -12 inches/year range, therefore areas of “high recharge” were mapped as those greater than 12 inches/year.

Groundwater recharge is an essential phase of the hydrologic cycle and something that open soils make possible. As rainwater seeps into the ground, it is cleansed by the soil, replenishes aquifers, is extracted for human use utilizing public and private wells, and slowly seeps into streams, wetlands and lakes, providing a clean and steady base flow to aquatic habitats. When open soils with high groundwater recharge are paved over, none of these essential services can be provided to people or to water-dependent species. In addition, surface runoff increases, polluting receiving waters and contributing to flooding.

Because of its importance to human and native species, the ability of places to recharge groundwater was factored into rankings for Agricultural Lands and Natural Habitat Complexes.

Subwatersheds

The Subwatersheds map was created as a reference to help read and understand the Aquatic Habitats map. In the Subwatersheds map, we tried to show the continuous flow of within Subwatersheds and the groupings of Subwatersheds comprising the watersheds.

For example, the Kayaderosseras-Saratoga Lake- Fish Creek watershed flows generally east toward the Hudson River and is comprised of the following subwatersheds: Upeer Kayaderosseras Creek, Middle Kayaderosseras Creek, Gloweegee Creek, Lower Kayaderosseras Creek, Geyser Brook, Bog Meadow Brook, Drummond Brook-Fish Creek, and Fish Creek.

Impervious Surfacing and Development in Subwatersheds

Each Subwatershed was measured for the amount of impervious surfacing and development within it. As discussed in the Groundwater Recharge Map significant impacts to water quality, quantity and cycles are impacted by hard surfaces non-absorptive surface runoff conditions in the Subwatersheds.

Predicted Growth and Grey Infrastructure

This map helps to inform where Conservation Resources are highly threatened with conversion to other uses. It also portrays where public investments have been made in roads and water and sewer lines. Therefore, Predicted Growth and Infrastructure may drive conservation resources toward or away from areas of predicted growth, depending on the significance of the Conservation Resource. These areas also offer opportunities for conserving land for parks and public recreation close to where people live and work.

Transportation Analysis Zones, Predicted Growth, and Supplemental Growth Predictors were used to rank areas of the county as High, Medium, or Low Combined Predicted Growth.

Transportation Analysis Zones – Capital District Regional Planning Commission predicted population change at a coarse scale. In processing for the purposes of our use, percent population change was calculated based on the difference in predicted population change from 2010 to 2050. The Analysis Zones were then grouped in High, Medium and Low categories. The threshold for the low category was based on the growth rate, from 2000 to 2010, of Saratoga County’s Metropolitan Statistical Area (5.4%), so anything equal or lower than the “going rate” of the economically similar surrounding area was considered low predicted growth. The high category was based on double the national average rate of growth for the same period (9.7%), so anything higher than 19.4%.

Supplemental Growth Predictors – Several factors that have been identified in previous impact assessments and in literature were pulled from an Audubon dataset to augment the very spatially coarse units of the Transportation Analysis Zones. These factors included Slope, Regulated Wetlands, Proximity to Roads, School District Ranking, Proximity to Recreational Protected Lands, Proximity to Lakes and Streams and Relative Elevation (position –high/low- in the landscape relative to the immediate surrounding area – i.e. “does this location have a view?”).

Infrastructure – Sewer Lines, Water Lines, Primary Roads, Interstate Corridor and Interchanges – Data provided by the Sewer Commission and former consultants who worked on planned expansions allowed us to update to the best available sewer and water line information. The roads, interstate and exits were available through the NYS GIS Clearinghouse.

Terrestrial Resiliency

Resiliency concerns the ability of a living system to adjust to climate change, to moderate potential damages from disturbances (fire, flood, high winds), to take advantage of opportunities, or to cope with consequences; in short, its capacity to adapt. The Nature Conservancy’s resilience analysis develops an approach to conserve biological diversity while allowing species and communities to rearrange in response to a continually changing climate and environmental factors. The most resilient examples of key geophysical settings were identified, to provide managers and scientists with a nuanced picture of the places where conservation is most likely to succeed over centuries.

The Nature Conservancy’s resilience analysis had four parts. The project:

  1. Mapped geophysical settings across the entire area,
  2. Within each geophysical setting, located areas that have complex topography and are highly connected by natural cover,
  3. Compared the identified sites with The Nature Conservancy’s portfolio of important biodiversity sites,
  4. Identified key linkages between sites.

The final products identify sites with high or low estimated resilience to climatic changes or other environmental disturbances relative to their setting.

In the study, each location was rated according to how connected its surrounding neighborhood was.  Local Connectedness measured each location on the map according to how easily a species or ecological process can move into adjacent areas where similar land cover classes (forest & forested wetland) facilitated movement and very different classes (natural cover & developed) impeded or slowed down movement.

In the same study, landscapes were evaluated for Regional Flow, a measurement of broad scale, regional movements (such as migration, dispersal and range shifts), making it particularly useful for identifying  pinch-points or linkage areas that may be important for maintaining permeability across the whole region.

Conservation Resource: Upland and Wetland Natural Habitat Complexes

Upland and wetland natural habitat complexes are areas of forest, woodland, shrubland, surface water, and wetland cover. The Land Cover map (described elsewhere) was used as the basis of determining where these natural habitats occur.

One of the primary factors used to rank natural habitat complexes was the size of the contiguous patch of natural habitats on the landscape. Size is an important factor because a larger patch typically supports functioning ecological processes such as pollination, ability to respond to dynamic changes, etc. as well as a more diverse assemblage of species, including both “edge” and “interior” species. Smaller patches provide habitat for wildlife species and native flora, especially those adapted to “edge” habitats, and the quality of the habitat suffers from fragmentation. Fragmentation and small patch size makes species vulnerable to population isolation and inbreeding, roadkill, invasive species introductions, and other stresses.

Each patch or polygon of natural habitat complex was evaluated and assigned a value for: 1) size, 2) amount and percent of higher than average terrestrial resilience (described in Terrestrial Resiliency map), and 3) amount and percent of high groundwater recharge (described in Groundwater Recharge Map).  Indices based on percent were included since looking at area or size alone would skew results towards only large polygons, overlooking smaller but possibly important linking patches (i.e. how much of a patch is made up of high connectivity, flow and/or recharge area regardless of size).

Conservation Resource: Agricultural Lands

Patches or polygons of agricultural land were assigned a ranking based on two criteria: prime or statewide significant farmland soil (amount  and percent) and high groundwater recharge (amount and percent). A density of farmland map was created to show aggregations or areas of rural landscape concentration and can be used for context information for farmland.

Conservation Resource: Trail Networks

Using the Trails Network in Saratoga County’s 2006 Green Infrastructure Plan, this map shows the main arteries of a countywide system.

The trails on the map are coded as: existing  (solid) versus proposed (dashed lines) and for the relative timeframe for when they might be planned. Immediate means they are currently being worked on by Saratoga PLAN’s Countywide Trails Committee of all trail users – hikers, bicyclists, snowmobilers, horseback riders, etc. The locations of unbuilt, unplanned trails are representational, with the accuracy of their location indicated by the width of the Accuracy Zone surrounding them. The accuracy zones range from 2 miles on either side of the dashed line shown on the map, 1.0 miles on either side, O.5 mile on either side, to 0.1 mile on either side of the dashed line.

Note: Only the major arteries of a countywide Trails Network are mapped. There are many localized and shorter trails existing, too. A full dataset of existing trails can be downloaded for use with Google Earth from Saratoga PLAN’s website: www.saratogaplan.org.

Conservation Resource: Aquatic Habitats

New York State Freshwater Conservation Blueprint Project – New York Natural Heritage program was tasked in 2011 with creating GIS datasets that “identify the locations and status of critical freshwater targets (habitats and species) in New York” in order to support spatially explicit planning and inform decision making for regulatory agencies and conservation organizations. They produced many layers of biodiversity information using both observation and modeled data. For our purposes, we focused on indicators of aquatic health and function, occurrences of rare or significant species or natural communities, regionally identified conservation priorities, and critical floodplain areas.  These pieces of information were assigned to each aquatic system. We pulled out the parts that were useful at a county level and combined them into a single “blueprint rank”.

Riparian Natural Cover – the river and stream systems were buffered to represent a 100m streamside zone. Percent natural cover (based on our updated digitized Land Cover layer) was calculated for each reach of the river or stream. Based on distribution of natural cover with the riparian zones throughout the county, ranks were assigned as low, medium or high.

Stream and River Corridors – Combining the blueprint rank and the health of the riparian area, an overall rank was assigned to stream reaches.

Lakes – Also shown on the map were lakes shaded by DEC water quality inventory category, however these data weren’t used in any ranking process because they are very incomplete across the county.

Overlap of Conservation Resources

The overlap map is a composite of all four ranked Conservation Resources:  Agricultural Lands, Natural Habitat Complexes, Aquatic Habitats, and Trail Networks. It shows the geographic relationship between the Conservation Resources and where they overlap or are in close proximity to one another, as well as to lands that are under conservation.