Table 1. Main state variables, scales, and computational methods for the GCM ecosystem model for the Grand Canyon.

Submodel       State      
       variables      
    Spatial    
    resolution    
    Temporal    
    resolution    
    Dynamic approach    
Hydrology flows, stages reach (15 miles); depth slice (2 feet) hour (diurnal flows); month (GCD release volumes) historical input data; user "shapes" Glen Canyon outflow policy
Sediment transport suspended sediment concentrations, sand mass storage morphology types (channel margins, eddies, main-channel pools); depth slices within reaches hour (effect of diurnal flow on maximum stage, storage potential); month (mass balance, storage) historical/modeled sediment inputs, tributary rating curves, mass balance monthly change
Aquatic primary production benthic algal biomass depth slices within reaches hour (primary production, mortality); month (mean biomass) average biomass predicted from equilibrium of biomass rate equations
Riparian plant communities relative biomass/area by vegetation type substrate types (e.g., sand, rock); depth slices within reaches month (flooding event impacts); year (biomass production, competition) flood duration/mortality curves, logistic growth and competition equations
Aquatic and terrestrial insect production grazer and filter feeder biomass/area, drift biomass concentration reach (slices within reach for mortality estimates) month numerical integration of biomass dynamics equations
Vertebrate indicator species juvenile age structure, adult numbers, and biomass reach, tributary and backwater area per reach month (juvenile predation, habitat effects); year (adult growth, survival) monthly juvenile survival as solution to ordinary differential equation; annual adult change by delay-difference model