Hydrology and Conservation Research Group Catholic University"Santa Teresa de Jesus"of ávila ávila 05005 Spain;
Forest Water and Soil Research Group Palencia 34004 Spain;
Forest Water and Soil Research Group Palencia 34004 Spain;
Department of Agricultural and Forestry Engineering University of Valladolid Palencia 34004 Spain;
Department of Statistics and Operations Research University of Valladolid Palencia 34004 Spain;