This is the appearance of the Periphyton tab of the System Coefficients dialog:
Periphyton is defined as the community of organisms that is attached to or live upon submerged surfaces. Following is a description of the parameters associated with Periphyton. Refer to the main System Coefficients page for information on other categories of coefficients. To save the changes made when closing this dialog, click OK. To ignore changes, click Cancel.
Endogenous Respiration Coefficient is a coefficient used to calculate the endogenous respiration (usually 0.267, unitless)
Endogenous Respiration Exponential Coefficient is a coefficient used to calculate the endogenous respiration (usually 0.0776, unitless)
Photorespiration Fraction is the fraction of photosynthetic productivity that is oxidized by photorespiration (usually 0.05 to 0.15, i.e. 5 to 15%)
Fraction Recycled of Grazed and Scoured Periphyton is the fraction of nutrients returning to the water column from grazed and scoured periphyton (1 = closed looped system, all nutrients are cycled, 0 = all nutrients in grazed and scoured periphyton are removed from mass balance).
Spatial Limit Half Sat. is the half saturation coefficient for reduced growth rate due to crowding. (10 – 20 g/m2)
Spatial Limitation, Intercept is the intercept coefficient for reduced growth rate due to crowding (usually 0.1)
Scour Regression Coefficient is a coefficient used to calculate the periphyton removal by scour (usually 0.0007 / day)
Scour Regression Exponent is a coefficient used to calculate the periphyton removal by scour (usually 2.0 / m)
Ammonia Preference Coefficient is a coefficient used to calculate the periphyton preference of ammonia over nitrate (usually 20)
Chl-a/Carbon Ratio is the mass ratio of chlorophyll-a to carbon in the periphyton. (0.01 – 0.03, unitless)
Nitrogen Half Saturation is the growth rate half-saturation constant for nitrogen for the periphyton. (0.01 – 0.03 mg/l)
Phosphorus Half Saturation is the growth rate half-saturation constant for phosphorus for the periphyton. (0.001 – 0.005 mg/l)
Velocity Half Saturation is the growth rate half-saturation constant for periphyton with respect to current velocity. (0.2 – 0.30 m/s)
Light Saturation is the saturating light intensity for the periphyton. (50 – 200 W / m2)
Growth and mortality rates are set in the River Reaction Coefficients dialog.