Spatial distribution of rock fragments in dolines: A case study in a semiarid Mediterranean mountain-range (Sierra de Gádor, SE Spain)

Rock fragments (RFs) at the soil surface have great effects on the intensity of various hydrologic and geomorphic processes. However, little information is available on the spatial distribution of rock fragments (RF) in the dolines, which may be of importance in understanding overland flow and subsequent recharge in limestone karst landscapes. This study analysed spatial variability of RF cover and size in different topographic positions (top, upper, middle and lower position) in three dolines in Sierra de Gádor (Almería province, south-east Spain). The results indicated that cover percentage of small RFs (5–20 mm) increased but large RF cover (250–600 mm and > 600 mm) decreased from the upper position to the lower position of the dolines. Small RFs were usually resting on the soil surface while most large RFs tended to be partly embedded in the soil surface. Total RF cover and D50 (median diameter) of the surface RFs greater than 5 mm tended to increase with slope gradient.