Water quality in river systems: Monte‐Carlo Analysis

Water quality models are described for a 55-km stretch of the Bedford Ouse River in central eastern England. The dynamic models relate time-varying upstream influents to downstream water quality and are stochastic to account for the uncertainty in the system. A stochastic simulation provides forecasts of water quality at a downstream abstraction point in terms of probability distributions, and these are compared with water quality standards, also defined in probabilistic terms. Effluent from the new city of Milton Keynes enters the river at an upstream point, and the impact of the effluent on the aquatic environment is assessed together with the sensitivity of the water quality model to parametric uncertainty.