COLLECTION AND STORAGE OF RUNOFF FROM HILLSLOPES IN A SEMIARID ENVIRONMENT - GEOMORPHIC AND HYDROLOGIC ASPECTS OF THE ALJIBE SYSTEM IN ALMERIA PROVINCE, SPAIN

Water harvesting systems in south-east Spain collect runoff from hills lopes in underground cisterns (aljibes). The characteristics of 51 alj ibes were recorded. Aljibe volume increases non-linearly with catchmen t area (r(2) = 0.29; N = 51). This relationship becomes even stronger for the water harvesting systems on rocky slopes (r(2) = 0.56; N = 34) . An empirical rainfall/runoff model indicates that the surface charac teristics of the catchments are critical in producing sufficient runof f during years with low annual rainfall. The aljibe system is still vi able provided the runoff coefficient of the catchments is high (curve number > 90) and the volume of the aljibes is large enough to prevent overflow (volume to catchment area ratio > 60 m(3) ha(-1)). (C) 1998 A cademic Press.