Stochastic Simulation

REBEKA II calculates the frequency distribution of model outputs (i.e. number of critical events for ammonia toxicity, riverbed erosion and turbidity, TSS load and time of critical TSS immission) by means of a Monte Carlo simulation. The number of runs can be chosen by the user.
For each run a deterministic simulation over 10 years is performed. In each run, the program determines for each rain event if it is critical or not with regard to the different criteria (erosion, ammonia toxicity, turbidity) and calculates the fraction of time while critical densities of TSS accumulation on the riverbed are exceeded. At the end of each run average numbers of critical events per year are calculated.

Monte-Carlo simulation

After proceeding of all runs frequency distributions of the number of critical events are plotted as results. The parameters are randomly varied between consecutive runs according to the chosen upper and lower limits and the probability distribution.

Examples of Results

The results are divided into three charts: