Seasonal changes in the hydrological and erosional response of a hillslope under dry-Mediterranean climatic conditions (Montes de Mلlaga, South of Spain)

The Mediterranean eco-geomorphological system was analysed at one representative hillslope of the geological unit of Montes de Mلlaga (Province of Mلlaga, Spain) under dry-Mediterranean climatic conditions. The research was divided into two stages. First, the eco-geomorphological pattern of the slope and some physical properties of the soil were analysed. Second, the hydrological and erosional response of the eco-geomorphological system was analysed by applying simulated rainfall to the main elements of the system and using closed plots with different lengths. This hydrodynamic analysis was carried out during two periods crucial for the Mediterranean environment in hydrological terms: the end of the dry season (or the beginning of the active hydrodynamic season) and the middle of the wet season. The results show that i) the hydrophobic behaviour of soil is the predominant runoff generation mechanism that accounts for sediment movement, ii) once soil was moistened in the wet season, it lost its hydrophobicity and the saturation of soil became a predominant runoff generation mechanism, and iii) there was high variability in hillslope runoff with evident hydrological disconnections, which made the hydrodynamic response of the eco-geomorphological system complex due to the absence of a clear predominance of abiotic or biotic factors.