Analysis of the Spatiotemporal Annual Rainfall Variability in the Wadi Cheliff Basin (Algeria) over the Period 1970 to 2018

Tarek Hartani,Tommaso Caloiero,Mohammed Achite,Andrzej Wałęga,Nir Krakauer

doi:10.3390/w13111477

Abstract

In the context of climate variability and hydrological extremes, especially in arid and semi-arid zones, the issue of natural risks and more particularly the risks related to rainfall is a topical subject in Algeria and worldwide. In this direction, the spatiotemporal variability of precipitation in the Wadi Cheliff basin (Algeria) has been evaluated by means of annual time series of precipitation observed on 150 rain gauges in the period 1970–2018. First, in order to identify the natural year-to-year variability of precipitation, for each series, the coefficient of variation (CV) has been evaluated and spatially distributed. Then, the precipitation trend at annual scale has been analyzed using two nonparametric tests. Finally, the presence of possible change points in the data has been investigated. The results showed an inverse spatial pattern between CV and the annual rainfall, with a spatial gradient between the southern and the northern sides of the basin. Results of the trend analysis evidenced a marked negative trend of the annual rainfall (22% of the rain gauges for a significant level equal to 95%) involving mainly the northern and the western-central area of the basin. Finally, possible change points have been identified between 1980 and 1985.

Highlights

The Mediterranean basin is climatically affected by the interaction between midlatitude and tropical processes, being located in a transition zone between the arid climate of North Africa and the temperate and rainy climate of Europe
It is considered a major hotspot of climate change, subject to strong warming and drying, with increasing consequences on spatial and temporal precipitation distribution [1]
The coefficient of variation (CV) ranges between about 16.0% and 56.5%, evidencing high variability that is typical of the Mediterranean basin [33]

Summary

Introduction

The Mediterranean basin is climatically affected by the interaction between midlatitude and tropical processes, being located in a transition zone between the arid climate of North Africa and the temperate and rainy climate of Europe For this reason, it is considered a major hotspot of climate change, subject to strong warming and drying, with increasing consequences on spatial and temporal precipitation distribution [1]. It is considered a major hotspot of climate change, subject to strong warming and drying, with increasing consequences on spatial and temporal precipitation distribution [1] Within this context, spatial and temporal precipitation analyses with different methodologies has been recently performed in the Mediterranean basin [2] and, especially, in Northern Africa [3]. In the Middle East and North Africa (MENA) region, which includes North Africa, Donat et al [10] detected an opposite behavior in the period

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