The Terraces of the Anti-Atlas: From Abandonment to the Risk of Degradation of a Landscape Heritage

Mohamed Sabir

doi:10.3390/w13040510

Abstract

The Anti-Atlas is subject to an intense rural exodus. The agricultural terraces built for several centuries have been abandoned. They are gradually deteriorating. The risks of runoff and erosion are becoming significant. The objective was to study the effect of the abandonment of terraces on the risks of runoff and erosion in the territory of two villages, Tizerkine and Timzemzit. After the characterization of the soil surface conditions, the extent of erosion and the risk of runoff were qualified according to the age of abandonment. Erosion was assessed by estimating the “soil surface factor” (PAP/CAR method) and infiltration by the double ring method. The abandonment of the terraces has led to a reduction in the plant cover of the soil surface and its opening and to enhancing its compaction. The risk of runoff is high. A year of abandonment reduced the infiltration from 301.8 mm/h (SD: 105.8 mm/h) to 129.6 mm/h (SD: 28.9 mm/h). Furthermore, 5 years of abandonment reduced it to 62.9 mm/h (SD: 14.9 mm/h). The walls of the terraces are gradually being destroyed with an increasing age of abandonment. More than half (57%) of the terraced slope surface has suffered moderate to high water erosion. More than 11% of the surfaces are severely degraded after 20 years of abandonment. The heritage made up of these managed slopes is being lost. Particular attention must be paid to these landscapes in order to better rehabilitate and develop them.

Highlights

The Anti-Atlas is characterized by its arid slopes managed in terraces by ancestral populations
The heterogeneity of a soil tends to hide the decrease in the final infiltration capacity that we are trying to demonstrate
The Western Anti-Atlas, subject to an intense rural exodus, has known, for several decades, a phenomenon of the abandonment of agricultural land located on slopes managed in terraces since time immemorial

Summary

Introduction

The Anti-Atlas is characterized by its arid slopes managed in terraces by ancestral populations. The abandoned plots, whose wall has collapsed, present a systematic compaction of anthropogenic and climatic origin of the superficial soil horizons [8]. This compaction is leading to a decrease in the infiltration process and, an increase in runoff [9]. These arable plots are threatened in the short term by the amplification of erosion phenomena. This state of affairs is causing the premature silting up of the dams necessary for the irrigation of intensive crops in the plains of Souss-Massa [1]

Objectives

Methods

Results

Conclusion