TITLE:
The Mapping of the Soils’ Degradation State by Adaptation the PAP/RAC Guidelines in the Watershed of Wadi Arbaa Ayacha, Western Rif, Morocco
AUTHORS:
Abdessalam Ouallali, Mohamed Moukhchane, Habiba Aassoumi, Farida Berrad, Ibrahim Dakir
KEYWORDS:
Water Erosion, PAP/RAC, Arbaa Ayacha, Western Rif, Morocco
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.4 No.7,
July
25,
2016
ABSTRACT: The
watershed of the Arbaa Ayacha River is an environment favorable to the
development of the phenomena of water erosion as a result of its topographic
features, lithological and climate. Therefore it has been the subject of
evaluation of states erosive and of different causal factors of the risk of
erosion by adaptation of cross-matrices based on directives PAP/RAC (Priority
Actions Programme/Regional Activity Centre) [1]. This method is based on three
approaches. The predictive approach provides a synthetic map of the
distribution of the erosive states, with 51% of the basin subjected to high
risks. The descriptive mapping of the various forms of erosion shows an
enormous extension of stripping and sheet erosion (91%), superficial gullies
and moderately deep gullies are growing in view of the gathering of runoffs
from upstream to the downstream. The superposition of the results of both
predictive and descriptive approaches gives a consolidated map PAP/RAC whose
analysis shows that soils’ loss throughout the basin is proportional to the
increase of the major factors of water erosion according to the level of
importance: The topographical factor—soil types—slope-lithology following a
positive linear relationship, while the order of the parameters that are
negative linear relationship is density of vegetation cover-land cover [2].
This same map gives maximal losses corresponding mainly to friable lithologic
natural areas of badlands at the center of the basin which correspond to
Tensift’s terraces [3]. In the downstream basin, the combined effect of deep
ravines and banks sapements promotes high risk while in the upstream, the
localized solifluxions and gravity screens participate in serious losses.