Trends into rainfall time series of two andes basins of Valle del Cauca (Colombia)

Abstract

With the goal of detecting changes or trends in registered data of daily rainfall in the basins of rivers Dagua and Cali, located in the south-west of Colombia, in the Valle del Cauca, nine climate extremes indices were calculated using the RClimDex software. For this, precipitation trends were analyzed in 18 rain gauges located in the study area with historical series ranging between 21 and 56 years. Homogeneity tests were made to data to ensure consistency in the information. The results show changes in rainfall, dominated by the increasing trends for almost all indices; however most of the trends do not show high statistical significance. Also, a significant increase in the average annual total rainfall of 15.2 mm (Dagua river basin) and 9.1 mm (Cali river basin) in the stations located below 1500 msnm was obtained. Moreover, in the stations located at higher elevations, decreases were observed. There is a homogeneous spatial distribution for the most of the indices and similar patterns were found located in defined areas of the study zone, which may affect the runoff production in watersheds in the coming years.