The model consists of 3 components which are based on the three most important criteria resulted from the habitat suitability analysis for otters (see previous post): land use, distance to human disturbance and distance to water bodies. In terms of GIS the model consisted of three raster layers of 10 x 10 m pixel size:
Matrix permeability = ƒ (Land use + distance to disturbances + distance to water)
The three layers were created using a 6-parameter model where pixels were assigned a value from 1-less favorable to 6-most favorable for otter movement and presence. Land use layer categories were: water bodies (6), forest (5), pasture (4), recreational (3), agricultural (2), and urban (1) (Fig. 1). For distance to disturbances and distance to water maps, categories were based on euclidian distances to infrastructures (roads and buildings) and water bodies (Fig. 2 and 3)
The result of the final model was a matrix permeability map where one can easily evaluate the permeability of the matrix and the best habitats for otters and plan action accordingly, to improve connectivity between those optimum habitats (Fig. 4). For the specific case of Áridos Sanz gravel quarry the map shows that the permeability of the matrix is highest to the south and once in the Duero River, the best habitats for otters are located to the east. Therefore, restoration actions with the highest potential to enhance connectivity are to be implemented in this direction.