Multi-site Modeling and Simulation of the Standardized Precipitation Index (SPI) in Jordan

Abstract

Study region: Five rainfall stations located in the north west mountain region in Jordan. Study focus: In this study, monthly precipitation data is analyzed using the Standardized Precipitation Index (SPI) at time scale of 12 months (SPI-12). The multi-site Contemporaneous Autoregressive Moving Average (CARMA) model was used to model the SPI-12 data. New hydrological insight for the region: Simulation experiments with the CARMA (1,1) model reveal that the model performed well in fitting the SPI-12 data. The model was also capable of preserving the cross correlation structure of the observed SPI-12 between the studied sites. Shorter time scale SPI’s (such as the 1 and 3 months) were not used due to the fact that Jordan is an arid country and the reliability of SPI’s is questionable at the shorter time scales. These results would be important and beneficial in regional studies of water resources in Jordan such as investigating droughts on a regional level rather than on a single site. Also, the results of this study would be important and beneficial for rural areas where no observed data exists. Keywords: SPI, Drought analysis, Stochastic modeling and simulation, CARMA