Long Term Probabilistic River Forecasting Applied to International Integrated Water Management Projects

Abstract

The National Oceanic and Atmospheric Administration (NOAA), National Weather Service (NWS) is transferring National Weather Service hydrometeorological forecast system technology to many countries throughout the world. The demand for NWS technology continues to increase due to an increasing stress on freshwater resources, that is caused by a continuing increase in water demand among various types of water uses and complicated by growing pollution. Conflicts in water use transcend local, regional, country and transboundry levels. The NWS is transferring the National Weather Service River Forecast System (NWSRFS) to Panama, Mexico, and South Africa. These countries have recently experienced severe droughts and floods, and are determined to manage their existing water resources more effectively. Application of long term probabilistic forecasting capability is an important step in achieving optimal management of water supplies. The NWSRFS is a computer system consisting of many software modules which perform various hydrologic, hydraulic and data management operations to forecast streamflow. NWSRFS includes the Calibration System, Operational Forecast System, Interactive Forecast Program, and the Ensemble Streamflow Prediction (ESP) component. The ESP uses conceptual hydrologic/hydraulic models to forecast future streamflow using the current snow, soil moisture, river, and reservoir conditions and historical meteorological data. The ESP system assumes that meteorological events that occurred in the past are representative of events that may occur in the future. Each year of historical meteorological data is assumed to be a possible representation of the future events and is used to simulate a streamflow trace. The simulated streamflow traces can be scanned for maximum flow, minimum flow, volume of flow, reservoir stage, etc. for any period in the future. Applications for ESP for water management have proven quite effective in improving longterm water management.