Sensitivity Analysis of the Water Quality for River-Reservoir Systems Model

Most total ecosystem models require extensive data sets for initializing and calibrating the model to the prototype system. Data collection programs, however, are expensive and time-consuming. To obviate these constraints, the data collection program should be guided by a knowledge of the model sensitivity to various initial conditions and coefficients. A software program was developed for the Honeywell 600 computer system that permitted an evaluation of sensitivity of coefficients and initial conditions in the WQRRS model. In general, the model results were more sensitive to 10% changes in coefficients at high nutrient concentrations than at low nutrient concentrations. The model results were quite sensitive to a 10% change in the evaporation and dispersion (effective diffusion) rate coefficients, biota growth, respiration, and temperature rate coefficients. The nutrient regime affected the sensitivity of the half-saturation coefficients and stoichiometric equivalences. Sensitivity analyses perform a useful function in modeling programs.