COMPUTER-SIMULATION OF THE DYNAMICS OF A DUNE SYSTEM

The mobile dune system of the Donana National Park (southwest Spain) covers an area of 100 km(2). It is formed by several transverse dune fronts 5-20 m high, lying parallel to the beach, and separated by flat slacks covered by scrub vegetation. Dunes move from the beach inland at a rate of 2.5 m per year, burying the slack vegetation as they progress. The vegetation is well adapted to the dune dynamics, colonizing the slacks in the wake of a dune at the same rate the next front covers the old part of the slacks. A computer model simulating the dune dynamics is presented. The model parameter values were estimated in accordance with the sensitivity test, thus suggesting the key points of the dune dynamics. Only certain sets of values for the parameters of the model produce a topography fitting the actual one. The erosion rate, and the growth of vegetation are the parameters which most deeply affect the appearance of the simulated dunes. Under the assumptions of the model, a simulated descent of the groundwater table may produce the disappearance of the slack vegetation for more than 200 years.