In crystalline semi-arid areas, small alluvial aquifers are important hydrological resources for rural population. But the dynamics of these restricted resources remains highly influenced by anthropogenic actions. Sustainability of their availability lies on the development of water management strategies well-adapted to the physical and socioeconomic local constraints. In crystalline areas of semi-arid Brazilian north-east, the exploitation of alluvial aquifers for irrigation and domestic supply by rural communities has been developed over the last 10 years. This study has been carried out based on two approaches 1) a physical one, to characterize and suggest a hydrological and salt-mass functioning model of these poorly studied resources and 2) a socio-economical one, to characterize users and strategies and water resources use and management. The study is based on six-year data (physical and socioeconomic issues) and on the construction of monthly time-step hydrological and mass balance models that allowed to quantify the terms of alluvial aquifer balances and to discuss interactions with other water resources (hard-rock basement aquifer, reservoirs). Hydrological functioning hypotheses have been also tested with a spatial physical-based model. Models were used to simulate hydrological and salinity responses of the alluvial aquifer under different water management scenarios. Several possible prospective scenarios of water management have been built based on the main internal (physical and anthropogenic) and external (public policy) constraints. The impact of these scenarios on the short- and long-run water availability (quantity and quality) has been simulated. It underlined the importance of integrated management of up- and downstream water resources. Finally, a regional, remote-sensing based method to map alluvial aquifer has been developed and tested. It was used to estimate the mean annual water volume available in large watershed.