Measurements and numerical simulations of 1 the activation degree and vegetation cover on 2 parabolic dunes in north - eastern Brazil

16 In this work we present measurements of vegetation cover over parabolic dunes with 17 different degree of activation along the north-eastern Brazilian coast. We extend 18 the local values of the vegetation cover density to the whole dune by correlating 19 measurements with the relative brightness index C of high resolution QuickBird 20 panchromatic satellite image of the dune field. Next, we introduce the vegetation 21 data into a continuous model for vegetated dunes, coupling sand erosion and vegeta22 tion growth, and perform simulations of parabolic dunes. Finally, from the compar23 ison of both, the measurements and the simulation results, we show that the model 24 is able to predict the dune shape and the vegetation distribution of real parabolic 25 dunes as result of the evolution of a blow-out. 26