Drought-induced water scarcity in water resources systems

Not all water resources systems suffer water scarcity under a given drought situation. From the management perspective, water scarcity is the shortage of water resources to serve water demands. Water scarcity is related to the absence of rainfall, but also to other non-meteorological factors, such as lack of infrastructures for water storage or transport, excess of demands or their mutual incompatibility, and constraints for water management (water rights, floods). Drought contingency planning and management decisions depend on the reliability and vulnerability of water resources systems to confront water scarcity. Four indices have been developed to evaluate water scarcity: the index of demand satisfaction, the index of demand reliability, the index of resources use and the index of reliability increase. These indices may be used to diagnose the causes of potential water shortage and to anticipate possible solutions. The Ebro river basin (Spain's biggest) has been taken as study case. The methodology has been applied to 17 systems in the Ebro basin, establishing comparisons among them and proposing solutions to avoid water scarcity.