Abstract
Standard Precipitation Index (SPI) is a beneficial climatic drought indicator for the estimation of drought in terms of severity, size, and frequency. SPI also helps in the analysis of both temporal and spatial drought variability. In this study, data series of one climatic variable (precipitation) has been used to calculate SPI for 12 meteorological stations distributed in the Northern part of Libya covering 31 years from 1979 to 2009, in this study, the standard precipitation index was calculated with a scale or time scale of one month (monthly) and a time range of three months (seasonal), and to calculate this index, the rainfall data is reconciled using The gamma distribution and then converting the resulting distribution to the standard normal distribution, and these steps were applied to all stations, after that, and to analyze the results, three different categories were developed to determine the dry and wet conditions (moderate, severe, extreme), based on the values of the standard index of precipitation. Drought characteristics were classified into three sections, namely intensity S, duration D, and size M. After this, the Mann-Kendall test was applied to discover trends in the standard precipitation index data series on a monthly and seasonal scale in the study area. prevailing compared to extreme and severe cases, whether for the monthly or seasonal time scale, and it is also clear that the regions that witnessed more sustainability are the highest severity, that is, the longer the duration of sustainability, the higher the intensity of drought, also the spatial analysis showed that severe and medium droughts occurred in different years, and the results showed The Mann Kendall test showed that most of the stations that have a general increasing trend of drought with respect to the monthly and seasonal range occur in the northwestern region, and the study concluded that it is possible that the study area will be exposed to longer and more severe droughts in the future, and therefore, obtaining detailed information on the duration and size of The frequency of drought provides an adequate early warning as well as drought monitoring, especially with precautionary plans in place to avoid dangerous drought risks.