Abstract
Centuries of human development have altered the connectivity of rivers,
adversely impacting ecosystems and the services provided. Significant
investments in natural resource projects are made annually with the goal
to restore function to degraded rivers and floodplains and protect
freshwater resources. Yet restoration projects often fall short of their
objectives, in part, due to the lack of systems-based, strategic
planning. To evaluate channel-floodplain (dis)connectivity and
erosion/incision hazard at the regional scale, we calculate Specific
Stream Power (SSP), an estimate of the energy of a river, using a
topographically-based, low-complexity hydraulic model. Other basin-wide
SSP modeling approaches neglect reach-specific geometric information
embedded in Digital Elevation Models. Our approach leverages this
information to generate reach-specific SSP-flow curves. We extract
measures from these curves that describe (dis)connected floodwater
storage capacity and erosion hazard at individual design storm flood
stages and demonstrate how these measures may be used to identify
watershed-scale patterns in connectivity. We show proof-of-concept using
25 reaches in the Mad River watershed in central Vermont and demonstrate
that the SSP results have acceptable agreement with a well-calibrated
process-based model (2D Hydraulic Engineering Center’s River Analysis
System) across a broad range of design events. While systems-based
planning of regional restoration and conservation activities has been
limited largely due to computational and human resource requirements,
measures derived from low complexity models can provide an overview of
reach-scale conditions at the regional level and aid planners in
identifying areas for further restoration and/or conservation
assessments.