On modeling the mechanisms that control in-stream phosphorus, macrophyte, and epiphyte dynamics: An assessment of a new model using general sensitivity analysis

The "Kennet model" is a new model of in-stream phosphorus (P) and macrophyt e dynamics. Based on mass balance equations, the model represents the inter actions between P and the suspended and bed sediments, the uptake of P by e piphytes and macrophytes, and the exchange of P between the water column an d the pore water. The model simulates the total phosphorus (TP) and the sol uble reactive phosphorus (SRP) concentrations observed in a reach of the Ri ver Kennet. Furthermore, the model simulates the generalized macrophyte gro wth patterns and total biomass observed in rivers throughout southern Engla nd. A general sensitivity analysis, based on Monte Carlo simulations and pa rameter values derived from the literature, identifies the key parameters c ontrolling the model behavior when simulating macrophyte growth. The most i mportant parameters are those that directly control macrophyte growth, thos e that define the epiphyte growth, and those that relate to the storage of P in the streambed.