Trends of Change in Rainfall Amounts in Northeastern Libya during the Period 1961-2010

Abstract

This research aims to identify trends of change in annual rainfall rates, whether increasing or decreasing, and to determine the deviations from the general trend line in the northeastern region of Libya during the period from 1961 to 2010. The research relies on two methods: the general trend line method and the triple moving averages method. It was found that the trends of change in annual rainfall rates during the study period tended towards a decrease in the stations of Tobruk, Shahhat, and Benghazi, while they tended towards an increase in the stations of Derna and Ajdabiya. This indicates a decrease in rainfall amounts in most parts of the study area with varying degrees of change between them. Analysis of the triple moving averages revealed random fluctuations in the annual rainfall rate between periods of increase and decrease compared to the overall average. This variation showed intermittent dry and wet periods of varying duration and magnitude in relation to the general trend line.