A pilot operational flood warning system in Andalusia (Spain): presentation and first results

Abstract : The Guadalhorce Basin is located in Andalusia (South of Spain). Its floods have historically represented a major hazard for the city of Málaga. In 2008 it has been decided to implement a pilot operational flood warning system (GFWS) with the aim of analyzing the capability to minimize the risk to people, and economic activity, as well as for guiding water resources management. The system is oriented to provide distributed warnings based on rainfall accumulations and discharge forecasts. Rainfall accumulation maps are generated according to the interpolation of rain gauge measurements and weather radar rainfall maps whereas discharge forecasts are computed using a distributed rainfall-runoff model. Due to the lack of flow measurements, the model was calibrated a priori in most of the basin area. The performance of the system has been tested on two recent rainfall events which caused many inundations. First results show how the GFWS performed well and was able to forecast the location and timing of flooding. It demonstrates that a simple model and a rough calibration could be enough to issue valuable warnings. Moreover, the European Flood Alert System (EFAS) forecasts have been used to prevent from the flood several days in advance. With low resolution and long anticipation, EFAS appears as a good complement tool to improve flood forecasting and compensate for the short lead times of the GFWS.