A STOCHASTIC-MODEL FOR 2-STATION HYDRAULICS EXHIBITING TRANSIENT IMPACT

The objective of the paper is to interpret data on water level variati on in a river affected by overflow from a sewer system during rain. Th e simplest possible, hydraulic description is combined with stochastic methods for data analysis and model parameter estimation. This combin ation of deterministic and stochastic interpretation is called grey bo x modelling. As a deterministic description the linear reservoir appro ximation is used. A series of linear reservoirs in sufficient number w ill approximate a plug how reactor. The choice of number is an empiric al expression of the longitudinal dispersion in the river. This approx imation is expected to be a sufficiently good approximation as a tool for the ultimate aim: the description of pollutant transport in the ri ver. The grey box modelling involves a statistical tool for estimation of the parameters in the deterministic model. The advantage is that t he parameters have physical meaning, as opposed to many other statisti cally estimated, empirical parameters. The identifiability of each par ameter, the uncertainty of the parameter estimation and the overall un certainty of the simulation are determined. (C) 1997 IAWQ. Published b y Elsevier Science Ltd.