The safety of dikes in The Netherlands, located in the delta of the rivers Rhine, Meuse and Scheldt, has been the subject of debate for more than ten years. The safety (or flood risk) of a particular area may depend on the safety of other areas. This is referred to as effects of river system behaviour on flood risk (quantified as the estimated number of casualties and economic damage). A computational framework was developed to assess these effects. It consists of several components that are loosely coupled via data files and Tcl scripts to manage the individual programs and keep track of the state of the computations. The computations involved are lengthy (days or even weeks on a Linux cluster), which makes the framework currently more suitable for planning and design than for real-time operation. While the framework was constructed ad hoc, it can also be viewed more formally as a tuplespace Realising this makes it possible to adopt the philosophy for other similar frameworks.