Dynamics of agricultural groundwater extraction: Comment and correction

In a paper published in this journal, Hellegers et al. [Hellegers, P., D. Zilberman, E. van Ierland, 2001. Dynamics of agricultural groundwater extraction. Ecological Economics, 303-311] analysed a dynamic model of groundwater extraction in which they added the quality dimension of nitrate concentration to an intertemporal model of resource depletion. This contribution shows that the set-up of the model contains a serious mistake which affects the results of the paper and it corrects the results.