Hydrologic Forecasting and the Relative Role of its Three Pillars: Models, Observations and Parameterization

2012 CUAHSI Biennial Colloquia

Soroosh Sorooshian / University of California-Irvine

Talk Description:

To be responsive to the need for more effective management of water resources, engineers and scientists must utilize more sophisticated hydrologic prediction tools. Depending on the problems, the hydrologic information needed may range from hourly forecasts (i.e., in the case of flash floods) to seasonal to inter-annual (i.e., in the case of water resources systems such as reservoir operation), and to decadal to century (i.e., in the case of long range water supply planning and structural designs). While good progress has been reported related to both, “weather-scale” and “climate-scale” hydrologic predictions, many challenges face the research community attempting to extend the forecast lead time and accuracy.

Over the past half century and with the advent of digital computers, hydrologic models of various levels of complexity have been developed and continually refined and proposed. Progress towards development of more sophisticated and efficient parameter estimation methods have also been made and extensively reported in the literature. More recent advances we are witnessing are related to both space-based and in-situ observation tools to measure hydrologic fluxes at space-time resolutions required by the new generation of models.

However, despite of the progress in each of these three pillars of hydrologic forecasting, the improvements in the overall forecast quality is yet to reach the users expectations. Some recent results from a number of reported evaluation studies will be presented. Personal reflections based on over 3 decades of research and experience will shared with the goal of encouraging further discussion about the recent proposed strategies to advance hydrologic sciences.