Analysis of rainfall records (1923–2004) in Atar-Mauritania

Abstract

The shortage of water resources in Adrar region, especially in Atar (Capital city of Adrar prefecture) and the surrounding villages along Seguelli watershed has been taken the concern of the policy maker and populations of this region since long time. This area had been suffering from recurrent droughts and faced water crises many times. Several attempts have been made to overcome these problems. Meanwhile the risk is still endangering the life and agricultural activities in one of the most important oasis areas. This study analyzed Atar rainfall time series periodicity, trends, and its relationship with Sea Surface Temperature (SST). The nonparametric Spearman test was used for trend analysis and the serial autocorrelation for persistency. Also, power spectrum and Fourier fit were deployed for analysis of frequency and periodicity. The tendency of Atar rainfall time series shows rainy periods in 1920’s and 1950’s and decreased rainfall since the late of 1950s. On the other hand, the prolonged drought periods appeared during 1970’s in contemporaneous with the Sahelian drought. The persistency analysis indicated the presence of biennial components in the annual and bimonthly rainfall in last three decades. SSTs of Atlantic, Indian and Pacific Ocean were modulating Atar rainfall during 1923–1992 period.