Using Statistical Methods to Analyze 32 Years of Rainfall Data in Amman, Jordan

The construction of hydraulic structures, bridges, culverts, canals, stormwater sewers, and road drainage systems relies on rainwater. Calculated capacities and associated design of required structures based on collected data mandate that these structures can operate properly under various weather conditions and discharge the water that they will be exposed to. Hydrological studies observe flood hazards and plan water resource management using rainfall data. Four rain gauge stations near Amman-downtown (Ras Al-Ain area) were selected for statistical analysis. To comprehend normal, deficiency, excess, and seasonal rainfall of the chosen circle headquarters, 32 years of daily rainfall data are used. This analysis predicts rainfall and plans water resource management. Moreover, it helps determine return periods. This approach aids disaster and crisis management planners and decision-makers to analyze water availability and develop strategies for its storage using statistical measures to assess the variability of monthly and yearly rainfall. By analyzing rainwater for 32 years, the results revealed that Weibull method is 99% in agreement with the average rainfall for all selected stations. Expected maximum discharge for different return times (return times range from 5 to 100 years) was used to fit statistical distributions of (2156.1 mm, 2656.4 mm, 3270.9 mm, 3741.2 mm, and 4221.5 mm), which was identical to the average annual maximum precipitation amount based on positioning methods for all stations. As a result, this technique provides the best matching annual precipitation. Findings revealed that rainfall pattern exhibits irregularity and the probability distribution that provided the best match was determined by minimizing the discrepancy between the observed values and the estimated values.