PRECIPITATION CHANGING AND WETLANDS IN THE MIDDLE-ATLAS, MOROCCO

Lebaut Sébastien, Lorraine University, France
Labhar Mohamed, Sidi Mohamed Ben Abdellah University, Morocco

Abstract

The Middle Atlas mountain range of Morocco, lying 350 km from NE to SW, is one of the better-watered mountain ranges of northern Africa. This, coupled with essentially calcareous bedrock made this area of great hydrogeological interest that contains twenty major natural lakes or ponds of karstic origin, half natural lakes permanent or semi-permanent in Morocco. Area between 6 and 400 ha, they are diverse and precious ecosystems and also provide significant socio-economic benefits. There are also many non-permanent wetlands not connected to the lakes (grasslands and others).
These fragile environments, under the influence of rainfall fluctuations in particular, have seen their surface and their number largely decrease. Actually, fluctuations of rainfall in Morocco and the Middle Atlas are very pronounced as many studies have shown. And even if it is located in a sub-humid climate, these changes have affected the water level in lakes but also wetlands bordering. In this context of high stakes and growing interest numerous studies have been undertaken but often limited to a unique wetland and based on recent years. It therefore lacks a comprehensive study on a common period of time.
The aim of this work is to examine the impact of rainfall fluctuations on the extension of wetlands over the last thirty years from the twenty major lakes and ponds and their adjacent wetlands spread over 7000 square kilometers. For this satellite imagery by the homogeneous, synoptic and repetitive character allows to infer the dynamics of these geographical objects spread over large areas. In this respect the Landsat TM images, available since the early 1980s, are a remarkable source of data. To characterize these water bodies and adjacent wetlands for the past thirty years, image hybrid processing techniques are mobilized to account for the phenology of these complex ecosystems.
The results are analyzed and discussed in relation to rainfall fluctuations characterized by methods including segmentation in the rainfall data sets.

Keywords: wetland, Morocco, Middle-Atlas, remote sensing, precipitation, climate change