Figure 6. Quantifying the number of temperature classes within the stream networks

In natural freshwater systems, the floodplain is periodically inundated with water, resulting in the exchange of nutrients, sediments, and organisms necessary for long-term ecosystem health. Periodic floods maintain the physical stream channel, facilitate interactions between terrestrial and freshwater realms, and create habitat for aquatic organisms that feed or spawn in the floodplain. These processes are necessary to support a fully functional freshwater ecosystem. Sustaining the processes requires connectivity between the channel and floodplain, termed “lateral connectivity” (Noe and Hupp, 2005). Naturally vegetated and connected floodplains store flood waters and sediment, reducing channel scour and bank erosion. In addition, maintaining and restoring the floodplains and riparian wetlands to a more natural condition can foster infiltration that serves to recharge groundwater aquifers, helping mitigate extreme low flows associated with more frequent drought conditions. Due to land use change, channelization, and altered flow regimes, the historical extent of flooding has been much diminished in Northeast and Mid-Atlantic streams. We assumed that areas with more intact floodplains have the potential for increased lateral connectivity and thus resilience to climate change and other disturbances.