Restoration Potential Model Nearc 2008 30minPresentation Transcript
Restoration Potential Model Chris Leuchtenburg Massachusetts Riverways Program A statewide GIS Model to assess potential stream restoration projects at dam sites.
Quality Issues and Control
Use of the Model
“ There’s not one thing any of us in resource management can do that will restore fish and aquatic habitat faster than removing a dam.” John Nelson, Fisheries Biologist
Dam Impoundments are not Lakes Dam Failure Risk To Habitat
More than 3,000 Dams Where to start? Which dams to visit first? How to communicate about stream restoration? How to motivate advocates? How to evaluate restoration projects? What data will support funding proposals? How to measure results?
Environmental Impacts Model
Fragmentation – upstream river length that would be opened if dam removed
Inundation – length of former river habitat currently in impoundment
Degradation – hydrologic residence time
Incomplete and inaccurate dams data
Data extent limited to Massachusetts
Routed Stream Centerline data unavailable for 5 Major Watersheds
Unsupported, old software tools (Watershed Analyst, ArcView 3.x)
Able to fully model 53% of 3,008 dams with this approach
Cumbersome, mistake prone process
Extended beyond state boundaries
Replaced Watershed Analyst with ArcHydro
Replaced incomplete Routed Centerlines data with MA and USGS (NHD) stream centerlines
Supplemented MassGIS elevation data with USGS data.
Length of stream centerline in dam subwatershed (10)
Presence of coldwater stream in dam subwatershed (5)
Number of dams downstream to the ocean (5)
Head of tide (5)
Living Waters in dam subwatershed (5)
Road Density (10)
Statewide Restoration Benefit score for 2600 dam sites.
All Major Watersheds except Cape and Islands
Attributes of Dams
Coldwater stream in subwatershed
Road density in watershed
Number of dams downstream to ocean
Head of tide
Flexible scoring tools
Dam on headwaters
Dam in highest quartile of dams per mile in watershed
Four levels of sport fish
303d impairment caused by dam
Outstanding/Exceptional resource streams
Connect score (upstream and downstream)
This pertains to all computer models of the environment. In order to model an aspect of the environment, it has to first be abstracted into values and shapes that cannot reflect the true diversity of the natural world.
The location of dams, missing or inaccurate centerlines and incorrect attributes in the dams data produce errors.
A.K.A. bugs and requirements.
The results would be altered by the inclusion of different metrics (excluding Living Waters, replacing road density with impervious surfaces or adding 303d)
Metrics are limited to the data available.
The results would also be changed by shifted the weighting of the metrics.
The modeler may make mistakes in the use of the software or in the development of the model scripts.
A model created to identify opportunities may be mistaken for a proposed list of projects. A dam with a high Restoration Potential score is a good candidate for assessment, but even a cursory assessment may deem it to be a poor candidate for a project. This is the most difficult source of error to control.
Quality Issues and Processes
Check all watersheds less than 20,000 square meters
Tag secondary structures (dikes)
Move misplaced dams
‘ Nudge’ unresponsive dams
Rerun watershed delineation
Stream surveys add small dams and verify dams
Missing or incorrect attributes
Watershed Delineation Variation
Strong statistical Pearson correlation to ranking of 35 dams by Riverways staff (Tim and Brian.)
Review of highest scoring dams with alternative metrics
Stimulated interest in new locations.
Maps are effective communication tools.
Using the Restoration Potential Model
Input to prioritization
Full presentation for restoration planners
Background or input to restoration discussion with broader audience
Dams in River Context
Source of information
Data for grant proposals
Measure and track progress
Dam Subwatersheds with Coldwater Streams
Next Steps: Model Improvement
Continually improve dam data: periodically rerun model.
Improve accuracy of ‘dams downstream’
ModelBuilder structure enables rapid change and multiple variations