Examining safe yield and sustainable yield for groundwater supplies and moving to managed yield as water resource limits become a reality

When determining how much water can safely be withdrawn from an aquifer system, the concept of \“safe yield” has been used. This term has come to mean if annual withdrawals do not exceed the annual rate of recharge, then the withdrawals are within a safe level of extraction. However, this approach has been shown to be an oversimplification of aquifer dynamics. It is flawed for it fails to incorporate other processes occurring in an aquifer as water is pumped from the system. A new approach is suggested that adds a safety margin to the assessment of the production capacity of an aquifer. This approach is defined as \“managed yield” and it is recommended as a replacement for safe yield when developing management strategies for groundwater systems.