What's new in CAPS 2020
Several changes have been made to the CAPS data and software since the 2011 and 2015 statewide runs. Here are highlights:
- New data. The biggest change in this version is the incorporation of new land cover and buildings data. MassGIS land cover/land use (2016) is a completely new representation of natural and developed land cover, replacing the old 2005 land use. MassGIS building structures (2019), also known as “roofprints” are a high-resolution representation of all buildings larger than 150 ft2 in Massachusetts. The incorporation of these two new layers allows us to distinguish more clearly and precisely among buildings, pavement, and developed open space (yards, parks, and other semi-natural areas), as well as distinguish among several types of building uses. We’ve also incorporated new versions of data sources that have been updated since the 2011 and 2015 runs, including MassDOT roads (2018), trains (2015), MassGIS protected open space (2020; used in road traffic processing), NRCS soils (2012), and TNC dams (2017). We have replaced MassDOT’s discontinued model of road traffic rates with our own model, based on road segments with measured traffic. Road-stream crossings (2020) have been updated to reflect the new data and additional field surveys of more than 4800 crossings by the North Atlantic Aquatic Connectivity Collaborative (NAACC). Additionally, a number of new data sources were included to support the new metrics.
- New metrics. Hydrologic alterations, nitrogen enrichment, phosphorus enrichment, and boat traffic. The hydrologic alterations metric estimates anthropogenically-induced low and high flow on streams and rivers (due to dam storage, impervious surface, and water discharges). Nitrogen and phosphorus enrichment metrics estimate anthropogenic inputs of these two nutrients into streams and rivers (from impervious surfaces, water discharges, septic systems, urban areas, croplands, and cranberry bogs). Boat traffic is a measure of the effects of commercial and recreational boat traffic on coastal shoreline ecosystems.
- Dropped metrics. Our old nutrient enrichment metric was replaced by the two new empirically-based metrics, nitrogen enrichment and phosphorus enrichment. These new nutrient metrics are based on empirical modeling. They only apply to streams, not wetlands or waterbodies. Wetland buffer insults was dropped from this version. This metric measured the percentage of the 33 m statutory buffer around wetlands that contained impervious surface. Compared to other metrics, it was obsolete in two ways: it was a patch-based metric, giving a single value to an entire wetland basin, regardless of size; and it incorporated stressors in a fixed buffer (based on regulatory, rather than ecological, considerations) as opposed to the variable-width kernel buffers we use elsewhere. Furthermore, this metric performed poorly in an empirical study.
- Changed metrics. The original tidal restrictions metric used data from field-measured restrictions to estimate the decrease in tidal inundation in meters. Many of these field surveys were made at remediation sites where culverts have since been upgraded to allow more natural tidal flow. As a result, given new land cover data, the regression model that powered this estimate no longer holds. We’ve fallen back to the approach used for the thirteen-state Designing Sustainable Landscapes project, where the tidal restrictions metric gives an index to the modeled degradation from downstream tidal restrictions, without tying it to an estimate of the change in water levels.
- New community models. Community models have been expanded to include the four new metrics, and crosswalked to new communities.
- Bug fixes and improvements. This version reflects several bug fixes and improvements in metrics and the way data were prepared.