Ecohydrological Variables Underlie Local Moisture Recycling in Mediterranean-Type Climates

Abstract

Mediterranean areas are projected to face increased water scarcity due to global changes. Because a relatively large fraction of the precipitation in Mediterranean areas originates locally, changes at the land surface may further dampen local precipitation. Here, we study the contribution of evaporation to local precipitation for the first time on a scale of approximately 50 km using local evaporation recycling (ELMR) and local precipitation recycling (PLMR), and make a comparison among five Mediterranean climate regions: South West Australia, South West US, central Chile, the Mediterranean Basin, and the Cape region of South Africa. Specifically, this study aims to understand the effects of ecohydrological (dependent on vegetation or the hydrological cycle) and non-ecohydrological variables on ELMR and PLMR. We find that (a) on average, ecohydrological variables correlate more frequently and more strongly to ELMR and PLMR than non-ecohydrological variables; (b) ELMR is large over wet areas and PLMR is large over dry areas; and (c) there are differences in underlying factors of ELMR and PLMR among the regions due to differences in wetness, topography, and land cover. The results suggest that in Mediterranean regions, changes in vegetation cover or the hydrological cycle may strengthen the local water cycle through enhancing ELMR. Finally, ELMR and PLMR help to identify where in Mediterranean regions we might enhance the local water cycle through land cover changes.