Dynamic reservoir operations using seasonal hydrologic forecasts: managing water resources for ecological integrity

Past reservoir operations have reduced the natural hydrologic variability in river flows throughout the US, causing significant degradation in aquatic ecological health. This study illustrates how seasonal hydrologic forecasts can improve reservoir operator's ability to restore ecological functions to rivers while maintaining or enhancing their ability to achieve traditional purposes. The Connecticut River basin is used to illustrate this opportunity. Achieving ecological base flows that provide for the migration of juvenile diadromous fish is the operational objective that is explored, in addition to traditional objectives. Previously identified teleconnections between summertime streamflow in the Connecticut River Basin and both the wintertime North Atlantic Oscillation (NAO) and springtime North Atlantic Horseshoe (NAH) sea surface temperature phenomenon are used to forecast hydroclimate in the summer season. Individual summertime base flow targets for each reservoir are conditioned on these forecasts and implemented in a reservoir optimization model to identify the tradeoffs between individual dam objectives and ecological flow targets. A main objective of this study is to examine the use of “season-ahead” forecasts in reservoir operations as a method to cope with non-stationary future climate in a multi-objective system.