New Jersey Rain Garden, Photograph by Tom Potterfield, Flickr
Introduction
One of the most common ways that bodies of water are polluted is through runoff from impervious surfaces, such as paved roads, concrete sidewalks, and building roofs. Although Madison is suburban by nature there are still impervious surfaces that may have runoff affecting local streams and ponds. Clean waterways are a crucial resource for reasons further than drinking water. Streams and ponds are self-contained ecosystems that provide habitats for various native species. We must keep our water bodies clean so that these species can continue to thrive and sustain our local environment. To analyze how impervious surfaces affect nearby water bodies it is important to assess their proximity to each other.
Data
In order to analyze the effect of water runoff on streams and rivers the proximity of the two variables must first be visualized. The map displayed here of Madison represents the most recent impervious surfaces estimates given by the Land Use 2012 Dataset as percentage. It also shows water bodies and streams as given by the National Hydrography Dataset (NHD).
Figure 1: Madison water bodies, and streams (data from the NJ Dept. of Environmental Protection Bureau of GIS), shown here with areas characterized as impervious surfaces by the NJDEP in 2012.
Results
In Madison, impervious surfaces ranges from 0-90 percent. The area was broken up as polygons of like-areas (streets, buildings, open areas, etc.). Darker pink colors represent a greater percentage of impervious surfaces. Streams are represented by blue lines, ponds are shown with blue circles, and pipelines and connectors are represented by black lines
Overall, ~ 31 percent of the area surrounding ponds and 36 percent of the area surrounding streams, connectors, and pipelines are marked as impervious surfaces. Water bodies in Madison are relatively well removed from the high percentage areas (caused by streets and buildings on/around main street). Because the high percentage impervious areas are distant from bodies of water and streams it is unlikely that there would be much impact, if any, from water runoff into the hydrology of Madison.
Conclusion
It is important to understand the proximity of water bodies and streams to high percentage areas of impervious surfaces in order to best care for the health of the ecosystems within and around them. Another step in assessing the health of these water bodies would be to investigate the reference of known contaminated sites to our water systems. Additionally, these observations assist in policies such as Storm water Rules and Green Infrastructure to manage storm water runoff. This is essential information for the success of Watershed and Land Management performed by the NJ Department of Environmental Protection.
About the Data
Impervious surfaces of New Jersey were mapped by the NJDEP from the Land Use 2012 Dataset. The NJDEP also recorded water bodies and streams from the National Hydrography Dataset of 2015 (NHD). The Land Use 2012 Dataset is the fifth dataset in a series of land use mapping efforts started in 1986. These maps have been updated in subsequent years using work provided by Aerial Information Systems, Inc., Redlands, CA, under direction of the NJDEP BGIS. The NHD is a dataset meant for analysis rather than policy making. It is compliant with Local resolution data under the development of USGS which is a stewardship partner with NJDEP/BGIS. More information can be found on their website.
Find this Map Online
Madison Environmental Resource Inventory
Author
Shelby Swensen, Drew University
ENV/BIOL 302 – Geographic Information Systems
Fall 2023
