Analysis of Historical Precipitation in Semi-Arid Areas - Case Study of the Amman Zarqa Basin

Climate change is determined as a severe threat to water resource availability in Semi-Arid Areas. Therefore, it is crucial to examine the drought trends to develop and sustain water resources. This study evaluates the effects of climate change in Jordan by investigating the long-term precipitation trends in the Amman Zarqa Basin over the water from 1971 to 2016. Daily precipitation data were gathered to analyze different rainfall stations over and around the basin.. The standardized precipitation index (SPI) variations were investigated at monthly intervals. Control charts, hypothesis testing, T-test. differences of variances, and trend analysis were used to determine climatic trends. The analysis results showed that 2003 marks an acceleration point in the precipitation decrease rate; therefore, the SPI showed a decrease and a high DI for the area in the tested year 2005 and 2010 to be a mild drought in the following years. Additionally, a change in the precipitation pattern was observed as seasonal precipitation contribution varied for the pre-2003 period compared to the post-2003 period. The SPI results show that 1995 reflects the higher drought periods, and the following years showed mild drought events; nevertheless. the year 2016 displayed lower drought events, reflecting wet events.