Analysis of Long-Term Changes in Hydro-Climatic Components (Case Study: Maroun Sub-Basin)

Abstract

This research investigates the trends and changes in the statistical distribution of climatic parameters (the warm days index, TX90p, and precipitation) and hydrological parameters (river flow discharge) in the Maroun basin over a 50-year period (1971-2020). The Mann-Kendall test was employed to identify trends, and the Pettitt test was used to determine the timing of abrupt changes. The results indicated that the TX90p index exhibits a statistically significant increasing trend (p-value = 0.018), with a change point in the year 1995, following which its mean value increased by 57%. Although the decreasing trends in precipitation and discharge were not statistically significant at the 95% level, the Pettitt test identified an abrupt change in both parameters in the year 2008. A comparison of the statistical distribution of the data before and after the change points, using Kolmogorov-Smirnov, analysis of variance, and location tests, confirmed that not only the central tendency but also the shape and dispersion of these parameters have changed significantly. Specifically, the mean precipitation and discharge decreased by 28% and 46%, respectively, while their standard deviations also decreased by 38% and 52%, respectively. These findings collectively indicate a shift in the regional climate pattern towards warmer and drier conditions, which has serious implications for water resources management.