Incorporation and Testing of Revised Algorithms for the Aquatic Plant Growth Model, ECOL

Abstract

Aquatic plant growth in river systems provides a link between phosphorus enrichment and fluctuations in dissolved oxygen. Most aquatic plant models simulate the growîh of a single generalized species and therefore cannot account for the wide variability in growth patterns shown by differing species. ECOL, an aquatic plant growth model developed in the late 1970s, was incorporated into the Grand River Simulation Model (GRSM) to model the growth of the three main plant species found in the Grand River watershed: CladophDra glornerata, Potamogeton peclinam and Myriophylfzim spicatum. ECO L calculates plant uptake of phosphorus, biomass production and Ioss, and the resulting production and consumption of dissolved oxygen (DO), using a Zhour time step, New algorithms to improve the sub-models in ECOL for light, temperature and phosphorus are developed and tested in this study. The present work evaluates and corrects sources of error in GRSM96, recalibrates the improved model and identifies and quantifies remaining weaknesses.The resulting modef, GRSM98AH, has an average error between computed and observed DO of 19.6%, which is regarded as satisfactory.