Use of Hydrologic Forecasts in Reservoir and Water Supply Management: Formulation, Testing and Implementation

Over the last four decades, improvements in hydrologic forecasting have been very slow to make their way into actual reservoir operations except on an ad-hoc basis or for flood control. As a result, it has been difficult to achieve the wide range of benefits that such forecasts can provide in terms of capital cost savings, water supply reliability, and environmental and recreational benefits. In the author's experience, resistance to using forecasts has centered on the perception that they are not reliable (“always wrong”). This perception is fostered by the lack of generally available examples of how such forecasts can be effectively used in practice (formulation), and how the effectiveness of operating policies which use forecasts can be tested prior to implementation.

Based on the author's experience, this paper presents a number of forms of forecast based operating policies and details they have been used to achieve. It also shows how hindcasts were used to test the effectiveness of the policies prior to implementation and describes the tools and technologies needed for utilizing forecasts in real-time operations. Examples include actual operating policies used by or in the Potomac Basin, New York City, and South Florida. The paper will also detail national, state and local policy changes needed to reap the benefits of hydrologic forecasts for reservoir and river basin management.