Since 2010, a large area of Chile is in a period of severe drought, with impacts on the population and the water resource systems. Therefore, it is necessary to carry out research on drought behavior in Chile, its prediction and monitoring, should be addressed to find suitable measures to reduce its effects. A simple calculation model is presented for the SPI, PPN, DEC and EDI indexes. Based on the hypothesis that these indexes are an indicator of the drought condition in the central-southern area of Chile; the proposed model takes as the only input variable the cumulative number of raining days. The most efficient index for the model is identified, the study is regionalized and temporal and spatial analysis of the model is carried out. A modified index of drought is obtained, based on a simple rainfall day counter. The model represents an efficient method to show a drought event.

Since 2010, a large area of Chile is in a period of severe drought, with impacts on the population and the water resource systems. Therefore, it is necessary to carry out research on drought behavior in Chile, its prediction and monitoring, should be addressed to find suitable measures to reduce its effects. A simple calculation model is presented for the SPI, PPN, DEC and EDI indexes. Based on the hypothesis that these indexes are an indicator of the drought condition in the central-southern area of Chile; the proposed model takes as the only input variable the cumulative number of raining days. The most efficient index for the model is identified, the study is regionalized and temporal and spatial analysis of the model is carried out. A modified index of drought is obtained, based on a simple rainfall day counter. The model represents an efficient method to show a drought event.