INFLUENCES OF MICRORELIEF PATTERNS AND PLANT COVER ON RUNOFF RELATED PROCESSES IN BADLANDS FROM TABERNAS (SE SPAIN)

Soil surface morphology, soil thickness and their evolution strongly a ffect infiltration processes. Badland surfaces are characterised by a substantially low plant cover and a reduced soil development controlle d by high erosion rates. In the badlands of Tabernas (Almeria, SE Spai n), the soil surface morphology exhibits a marked spatial variability, caused by different processes under moisture and temperature alternat ions in different slope aspects. Previous studies on the area have rev ealed the different hydrologic behaviour of North-and South-facing sur faces. In this paper, we go into more detail trying to establish the i nfluences of both micro-relief patterns and plant cover on the hydrolo gical behaviour of sixteen representative soil surfaces from the badla nds of Tabernas. Rain simulations at a constant intensity of 55 mm/h h ave been carried out on 16 circular plots of 0.24 m(2), during 30 min, to evaluate runoff, infiltration, and sediment production parameters. Surface morphology has been evaluated by image analysis of photograph s, before and after the simulations; the following parameters have bee n considered: plant cover and type, length and width of cracks, and st oniness. Surface roughness was determined with a laser profile meter. Runoff and erosion responses have been gathered in three and four grou ps, respectively, which are related to differences in slope gradient, soil depth and surface morphology. Runoff is positively correlated wit h slope gradient and negatively correlated with plant cover and total cover. Erosion is negatively correlated with lichen cover, with non-cr yptogamic plant cover, with total cover and with surface area occupied by cracks. In some aspects, Tabernas badlands have an hydrological be haviour similar to other badlands described elsewhere (i.e., shallow m oisture penetration, short times to runoff, different responses in run off). However, they are particular in the following: (a) apparent morp hological stability after rainfall events of high magnitude and intens ity, along with high sediment production associated either from micro- rills that follow open cracks in the regolith, or from overland flow o n bare, crusted, silty surfaces; (b) runoff enhancement by surface rou ghness through the channelling effect of the sealed depressions among pedestals and mounds of crustose lichens. (C) 1997 Elsevier Science B. V.