Extended streamflow prediction during the California drought

The California drought, which entered its second season during water year 1977, afforded an excellent opportunity to test and evalutate the Sacramento River Forecast Center (RFC) version of Extended Streamflow Prediction (ESP) during extreme hydrologic conditions. Because of the severity of the drought and its possible consequences, a wide variety of water users and managers had high interest in reliable long-range predictions during the year. The Sacramento RFC utilized a combination of a traditional regression-type water supply forecast approach, the more recently developed ESP model, and the rational analysis of hydrologic records from previous drought periods to produce such predictions. This paper presents a brief description of the development and operation of the Sacramento ESP model and discusses the resultant forecasts from these combined approaches.