An Optimization Approach for Balancing Human and Ecological Flow Needs

Balancing human and environmental water resource needs is critical to environmental sustainability. In this paper two concepts are advanced. First, a methodology is introduced to evaluate water management policies and their impacts on the characteristics of both instream flow and water supply reliability. The concept of an “ecodeficit” is introduced to quantify the impact of changes to the natural flow regime resulting from human withdrawals. This metric provides a numerical and graphical representation of the tradeoff between human and ecological needs for available water. Second, we evaluate an approach that involves both simulation and optimization of alternative reservoir release policies. We demonstrate that by refining the quantity and timing of reservoir releases the reliability of a water supply yield can be substantially maintained while improving the satisfaction of ecological flows requirements. These two concepts are early applications of a more comprehensive ecological water supply management approach currently under development.