Analysis of precipitation and drought trends by a modified Mann-Kendall method: a case study of Lorestan province, Iran

In this study, to evaluate the trend of precipitation change, the Mann-Kendall method has been used. The studied area is Lorestan province located in the western part of Iran. To achieve this goal, time series of annual and monthly rainfall data were collected for different statistical periods. Moreover, in order to analyze the drought, the standard precipitation index and the non-parametric Mann-Kendall test were used. To predict the meteorological drought in this province, the monthly time series of the precipitation parameter was incorporated. The results showed that most parts of Lorestan province are facing an extreme drought and such conditions will happen again in the future. Furthermore, the amount of precipitation was predicted until 2032, and the trend of predicted precipitation data in the entire Lorestan province showed that there is a significant trend in most months. The results of the research on an annual scale showed that all stations have a significant negative trend at the level of 5%, which indicates the existence of a negative trend, or in other words, a decrease in irrigation in the studied stations. Therefore, according to the obtained results, it is necessary to plan the water consumption in Lorestan province toward sustainable management.