Abstract. We studied the effect of flooding frequency on the vegetation of the northern part of the Delta region in the southwestern Netherlands under different grazing and soil conditions using Detrended Correspondence Analysis. We found grazing and frequency of flooding to be the most important environmental factors that determine zonation of vegetation types in the area. We used logistic regression to describe the probability of occurrence of 25 vegetation types in relation to the frequency of flooding under grazed and ungrazed conditions. We implemented the vegetation response model in a Geographical Information System so as to calculate new vegetation maps of outer dike areas under different flooding regimes. The model will be used for evaluation of the effects of different sluice management schemes on outer dike plant zonation in the research area.