Background Information:

Managed rivers are those streams where the natural flow regime is substantially altered by human structures. These impacts can often have deleterious effects on aquatic habitat availability for fish species and lifestages of interest or importance to humans.

Today - Microhabitat Quantification:

The Instream Flow Incremental Methodology (IFIM) involves 3 steps

• Characterize the channel and its flow by quantifying some combination of velocity, volumetric flowrate, area, or channel indices such as substrate type.
• For the species and lifestage of interest select a set of curves known as suitability curves which describe the preference of the fish for each of the channel/flow characteristic collected.
• Using a 1-dimensional cross-section based backstep flow model (such as those in PHABSIM) determine the availability of habitat, usually by area, for each species/lifestage combination.

  For more information on IFIM see USGS Instream Incremental Methodology

Tomorrow - Microhabitat Quantification:

As the cost of computer power continues to decrease more sophisticated and accurate modeling techniques become available. These techniques require the collection of both more accurate and greater quantity of data.

• Hydraulic modeling - 2-D/3-D models, Computational Fluid Dynamics
• Habitat suitability - Bioenergetics approaches to measure energy availability (food) and expenditure (metabolic and swimming cost

In order to meet the need for data of sufficient accuracy and amount the Institute of Natural Systems Engineering at Utah State University has developed an integrated GPS/Sonar system to collect bathymetry in mid and large size rivers.