The Power of Spatial Analysis – Wetland Prioritization

By Walt Foster

My introduction to computers was in 1968, when I was at the Navy’s Numerical Weather Center in Monterey, CA. We forecast weather for the world with 5 computers – 2 of 16KB, 2 of 32 KB and one of 65 KB – which filled an entire building. From then through the early Apple years until now, I’ve always been more interested in what a computer can do, rather than exactly how it does it. When I had the opportunity to found the Region 7 GIS group 25 years ago I jumped at the chance. In those early years, we were enamored of making pretty maps to depict conditions around the region. But, as time went on, I became more aware of, and interested in, the analytical capabilities of the technology.

One of the greatest benefits of GIS technology lies in its use in analyzing and visualizing the distribution of environmental processes that are multidimensional in space and time.  Activities of humans have had a profound effect on the environment, particularly our wetlands which have been cut in half.  The Clean Water Act requires that EPA work to maintain and restore wetlands and their attendant biodiversity and ecosystem services, a serious challenge given the scope and our resources.

EPA Region 7, along with the University of Missouri and EPA’s Office of Research and Development, developed and applied a method for prioritizing watersheds potentially critical for supporting wetland species biodiversity.  This project is called a Synoptic Wetland Assessment.

This synoptic (long-view) approach attaches variables linked with wetland function to 8-digit hydrologic units (HUCs) and then uses those variables in different combinations to rank the HUCs.  The goal was to identify 8-digit HUCs within the four-state region in which actions (restoration and protection) would likely have the most benefits for the conservation of wetland biodiversity.  Five indicators of habitat quality (agricultural density, wetland density, wetland habitat diversity, mean distance between wetland patches, and mean wetland patch size) and two indicators of species sensitivity (Natural Heritage species global rarity score and a modifier to the global rarity score including endemism) were combined in different ways to derive three indices.

Above is a map of the 241 sub-basins throughout our region, with HUCs ranked by priority from high to low according to the aforementioned indicators.  The highest priority sub-basins (those that were ranked highest in terms of restoration and protection potential) occur in clusters throughout the region, with the highest rankings occurring in the Ozark Highlands of Missouri, the Osage Plains in eastern Kansas, the Nebraska Sand Hills, and the Minnesota & Northeast Iowa Morainal, Oak Savannah.

All wetlands within our region are important to protect and restore, but the scope of this challenge is immense.  This project provides a model for helping to prioritize this challenge on a regional scale, and the tools for other scientists to apply the synoptic model at smaller scales (state or watershed scale) to effectively utilize resources.  Restoring our lost and degraded wetlands to their natural state is important to ensure the health of America’s watersheds. If you want to read more about the science of the synoptic wetland assessment model you can check it out here.  You can find out more about EPA’s role in protecting wetlands here.

Walt Foster has been with the GIS program in EPA Region 7 since its inception except for an hiatus during which he served as the NEPA section chief and worked with EPA’s Office of International Affairs on environmental projects in eastern Europe.  More recently he worked on a series of projects with a number of cooperating agencies and NGOs designed to characterize the ecological state of Region 7 and identify priority ecological resources for regional programs to use in their planning and response activities.

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