The impact of upstream water abstractions on reservoir yield:: the case of the Oros Reservoir in Brazil

Water abstraction for irrigation Upstream of a reservoir and its impact oil reservoir yield and reliability are studied. Water demand and availability are strongly related in semi-arid environments where the irrigation sector is responsible for a large part of consumptive water use. Variations in water abstractions for irrigation depend on irrigation requirements per hectare and the size of the irrigated area. The Oros Reservoir in semi-arid Northeast Brazil has been taken as a case Study. The results show that water abstracttion for irrigation is of significant importance for reservoir yield and reliability. Yield-reliability simulations for the study area show that taking into account upstream water abstraction fir a reservoir yield of 20.0 m(3)/s results in a water-scarcity probability of 10% on all annual basis (90% reliability). This is only 5% if upstream abstraction for irrigation is ignored. This Study shows that observed land-use Changes in the study area do have a significant impact oil reservoir yield reliability. The variability of upstream water abstraction Was found to be of low importance for reservoir yield and reliability.