Active geomorphic features of the Connecticut River watershed, such as sandbars and islands, provide habitat for various floodplain species. Endangered and threatened riparian plant and animal species such as the Silver Maple (Acer saccharinum), the Wood Turtle (Glyptemys insculpta) and the Puritan Tiger Beetle (Cicindela puritana) depend on these features for habitat. Human development, particularly dams and channelization, have altered flow and sediment regimes, thus impairing formation of sand and gravel bars. Large scale mapping of the fluvial geomorphology in both general river ecosystems and the Connecticut River is necessary to understand the dynamics of these features and preserve habitat.
Results/Conclusions
Orthophotographs from 2012 of the entire Connecticut River watershed and ten of its major tributaries were used to develop a spatial model in ArcGIS Pro to identify geomorphic features. This multi-stage image classification model identifies and ranks pixels of proximity and similar color to identify and map sandbars and islands. Fluvial variables were calculated and results show that stream gradient, size, sinuosity and watershed area significantly determine the number of bars and islands present in the watershed. Habitat information was gathered on New England’s riparian species from the National Heritage and Endangered Species Program (NSESP), and used to identify river reaches that provide critical habitat. Results show that species such as the Cobblestone Tiger Beetle (Cicindela marginipennis) are present in river reaches with greater bars and islands. Information about species presence in these features will allow policy makers to identify locations for conservation. The spatial algorithm developed to create the model may be applied in other large river ecosystems across the region