Investigating the variation pattern and erosivity power of precipitation in the Sindh river basin of India during last 120 years

In recent years, due to global warming, precipitation fluctuations in different areas have increased and it is a burning researchable issue. Therefore, in the present study, the trend and abrupt changes of precipitation time series in Sindh river basin, India was investigated using the modified Mann–Kendall tests, Pettitt test and the precipitation concentration index (PCI) during the period 1901–2020. In addition, the erosivity power of precipitation is analyzed using the modified Fourier index. The results of the Pettitt test showed that the significant abrupt change occurred in 37 series out of 136 studied series in monthly, seasonal and annual time scales. Among these, 67% of the occurred shifts were negative and the remaining 33% were upward. Also, the highest number of failure points was detected in 1941. Therefore, the study period is divided into two sub-periods: baseline (1901–1941) and variation (1941–2020) and further analysis were performed on these two sub-periods. The results of MMK test showed that, there was no significant increasing trend in precipitation over the basic period, and a non-significant increasing trend was found in 64% of the investigated series. But on the other hand, in the variation period, the precipitation trend was decreasing at 74% of the studied series. According to the PCI index, the precipitation distribution in all studied stations on an annual scale was classified in a very irregular class and the irregularity was increased during the variation period. Due to the increase in precipitation irregularities, the values of MFI index have increased in the variation period.