Wavelet Analysis of Rainfall and Runoff Multidecadal Time Series on Large River Basins in Western North Africa

Zineb Zamrane,Nour-Eddine Laftouhi,Gil Mahé

doi:10.3390/w13223243

Abstract

This work is dedicated to the study of the spatio-temporal variability of climate in Morocco by the analysis of rainfall (gridded and gauged data) and runoff. The wavelet analysis method has been used in this study to compare the rainfall and runoff series and to show the major discontinuities identified in 1970, 1980, and 2000. Several modes of variability have been detected; this approach has been applied to show annual (1 year) and inter-annual modes (2–4 years, 4–8 years, 8–12/8–16 years, and 16–30 years), and some modes are specific to some stations. This analysis will be complemented by the gridded data covering the period from 1940 to 1999, which will allow for a better understanding of the spatial variability of the highlighted signals set, which identified frequencies at 1 year and 8–16 years, distinguished different time periods at each basin and identified three main discontinuities in 1970, 1980, and 2000. The contribution of climatic indices is important as it is between 55% and 80%.

Highlights

The impacts of climate change and variability have received a great deal of attention from researchers in a variety of fields
The wavelet analysis method is rarely used to study the hydrological variability in Morocco
To analyze the relationship between the variability of the rainfall and the streamflow with the fluctuations of the climate indices in the three study basins in Morocco, we referred to two types of rainfall data: SIEREM rainfall and gauged rainfall and streamflow data

Summary

Introduction

The impacts of climate change and variability have received a great deal of attention from researchers in a variety of fields. Recent studies have made tremendous progress regarding the investigation of the time variation of water resources and hydrological processes [2,3,4,5,6,7] in response to climate change. Improving knowledge on the factors controlling the variability of water resources on inter-annual to multidecadal time scales is of major importance in the context of global climate and environmental change, exceptional storms, and sustained droughts [8]. It is important to document how the global fluctuations of climate change can affect the local hydrological cycles in the watershed. This may help explain the hydro-meteorological observations [9]

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