Habitat availability models
These models combine hydrologic model output with biological variables to examine life-stage- specific habitat availability under a variety of discharge scenarios. The scale of these models can be at the individual fish level (Individual Based Model; IBM) or at the population scale for any specific life stage or combination/continuum of life stages. These models can be very useful for comparing different dam operations or configurations.
These models have been developed by PNNL for the Hanford Reach of the Columbia River to assess the influence of hydroelectric dam operations on the availability of habitat for fall Chinook salmon. PNNL has also used these models to assess the impacts of different flow scenarios on the amount of habitat that was dewatered; leading to increased risk of stranding or entrapment of early rearing juvenile fall Chinook salmon. These models can be adapted to other river basins where good bathymetric surfaces are available. Depending on the species/life- stage, local habitat use data may be required to model habitat availability/quality. If local habitat use data are not available, then use data from similar areas may be used.
A detailed bathymetric surface of the basin of interest is required. These can be available from LiDAR or CHARTS aerial surveys. Hydrologic and meteorological data are also required for the hydrodynamic models to run. The biological habitat use data typically include variables such as the depth, velocity, substrate, bed slope, and distance to shore for the life stage of interest. These may be available from local sources or may be used from similar areas or from the literature.
Output can be in the form of total areal estimates of habitat availability/suitability under each scenario. These data may be displayed in geospatial coverages or in tabular/graph formats.
Linkage to Other Models
The flow/fish habitat combination often uses 1 or 2-dimensional (rarely 3-D)1D or 2D hydrodynamic models (but rarely 3D models). Hydrodynamic models used for these types of efforts in the past at PNNL are MASS1, MASS2, and River2D (the MASS models were developed by PNNL)
Level of Effort
Depending on data availability (particularly the bathymetric surface data), the modeling effort to compare a modest range (4 to 10) of different system configurations could be completed in a 12 -month cycle. A high degree of expertise is required to set -up the models and to do the initial QA/QC quality assurance/quality control and calibration. Less skill is required to do subsequent model runs and habitat analyses.