Flood Early Warning System Based on Water Level and Accumulated Precipitation Thresholds Under Hydro-Meteorological Data Scarcity. Case: Cañar River Basin- Ecuador

Sebastian Paez-Bimos, Santiago Llerena

Thursday 2 july 2015

12:36 - 12:39h at Europe 2 (level 0)

Themes: (T) Flood risk management and adaptation, (ST) Early warning systems, Poster pitches

Parallel session: Poster pitches: 11K. FloodRisk - Early Warning

Puerto Inca City and its area of influence are affected every rainy season by flash floods caused by Cañar River. Cañar River Basin extends over an area of 2.356 km2 and it is located in the western foothills of the Andes in southern Ecuador. The aim was to develop a methodology for a qualitative flood forecast as a tool for early warning systems. The method uses historical precipitation data series to establish thresholds for hourly accumulated precipitation and observations on field in order to define thresholds for water levels. These historical based thresholds have been applied to precipitation and water level data collected by automatic hydro-meteorological stations in real time. The flood forecast method considers that the water level indicate the base flow; while rainfall shows the conditions of the basin to generate runoff that can produce a peak flow. Qualitative flood forecast has been estimated based on interaction of precipitation and water level thresholds exceedance. The simultaneous exceedance of water level thresholds in the river and accumulated precipitation thresholds predicts the occurrence of flooding. The method was validated with a flood event occurred in March 30th 2014. The results show that qualitative flood forecast method is able to predict the occurrence of a flood event with a minimum of three hours in advance. Nevertheless, there is a limitation since the method has been validated using a single flood event, therefore it is planned to be further validated with hydro-meteorological data from upcoming rainy seasons.