J4.10 Operational Rainfall and Flow Forecasting for the Panama Canal Watershed

In 1998 and as part of a science cooperation and technology transfer effort, the Hydrologic Research Center (HRC) and collaborators designed and implemented at the Panama Canal Authority (PCA) a prototype forecasting system for the real time rainfall forecasting over a number of small sub-catchments of the 3,200-sqkm mountainous Panama Canal Watershed in Panama (Figure 1). The system (called PANMAP) uses as input ETA forecasts (on an 80-km grid) and observations from surface hydrometeorological stations, upper air radiosondes, and a 10-cm weather radar, to produce mean areal precipitation estimates and forecasts within the Watershed on scales of 150-400 km with a maximum 12-hour lead time and with hourly resolution. The system design combines embedded cloud models and state estimators for data assimilation and uncertainty estimation (Georgakakos et al. 1999). The rainfall forecasts and associated forecast variance are fed into operational hydrologic models, implemented for each Watershed sub-catchment within the framework of the U. S. National Weather Service River Forecast System (NWSRFS). The hydrologic model (SS-SAC, Sperfslage and Georgakakos, 1996) combines an adaptation of the Sacramento soil moisture accounting model with a robust state estimator design for real time updating from flow observations and forecast variance generation. The PCA is using the system operationally since October 1998 and the present paper presents results from an evaluation of system performance that is currently being performed using the operational data obtained by the system. Figure 1. Panama Canal Watershed topography (color scale in m) and sub-catchments used in PANMAP. “Sub-catchment” 11 is Lake Gatun.