2001-2002, The Dutch Delta, The Netherlands

In 1953 a large part of the Netherlands was flooded as seadikes broke as a result of a combination of leap tides and storm. The area where the flooding took place is sometimes referred to as the Dutch Delta. In order to commemorate this event after 50 years many activities will take place in 2003 in the Netherlands. The government facilitates and guides these activities in the project Delta2003.

The SimDelta model is developed as part of the Delta2003 project. The objective is to combine knowledge of geomorphological processes that shaped the Dutch Delta into a simulation model that can be used to explain the past and to explore future morphological developments of the region.

The model is a spatial model that runs on a grid consisting of cells of 250 by 250 meters and runs in time steps of a hundred years, starting in the year 6500 BC. Although the model is based upon knowledge that is readily available in literature and in the form of expert knowledge of a community of morphological experts, the model approach can be considered ambitious and refreshing because geomorphological models running on such a time and spatial scale do not exist yet. The model would form a bridge between fine spatial models simulating small areas over small periods of time and coarse models lumping large areas that run over longer periods of time.

The model combines three spatial scales. The cellular scale, the global scale and, in between, the cluster scale. It is the cluster scale, which enables an interaction between the coarse models that couple sea level development to morphological change of large morphological units such as the tidal area. On the cellular scale the spatial effects of the global processes is defined. Some key processes modeled with cellular automata type of models, such as the development of tidal channels and the development of peat.

The SimDelta model runs in two modes, being the Explorer mode and the Interpolation mode. As Explorer the model starts from the initial situation and evolves form there based upon the scenarios and measures. The Interpolation mode does the same, but additionally performs a correction based upon intermediate maps. In this mode the model, thus performs a proces based interpolation of different categorical maps in time.