Département du Génie des Systèmes Horticoles et du Milieu Naturel, Université de Sousse, Institut Supérieur Agronomique de Chott Mariem, Sousse, Tunisia
The arid climate characterizing the South-Eastern part of Tunisia and the alarming water consumption rate that continues to increase are the main environmental problems affecting Matmata mountain chain. To face these challenges, authorities are promoting water and soil conservation techniques that contribute tremendously in a sustainable agriculture. This study presents a technical diagnosis of the current state of Jessours, that are considered as traditional anti-erosion structures and are implemented on the Matmata mountain chain, particularly in the region of Beni Kheddache located North-West of Medenine. In this context, data collection was conducted the spring of 2008 in around 50 Jessours, situated in three ravines (Chaaba Ksar Beni Kheddache 1, Chaaba Ksar Beni Kheddache 2 and Chaaba El Mechref). This diagnosis helps in understanding more clearly the way Jessours system functions, how runoff is collected and in assessing the landscape integration of these structures. This study shows how the majorities of farmers are conscious of the benefits of Jessours and are actively following the appropriate practices of an efficient utilization. However, the collected data indicates that a good number of Jessours lack proper maintenance. In fact, investigations point out that although, 62% of visited Jessours are in a good condition, a worrying percentage of them, around 16%, are in bad condition. Whilst, 22% of visited Jessours are in average condition. Thus, to improve the capacity of rainfall collection of the Jessours system and to ensure a good degree of landscape integration, it is necessary to rehabilitate the neglected Jessours.
The elaboration of vulnerability maps remains a fundamental tool in the management and study of flood-related risks (floods and hydric erosion). This study aims to develop these maps through Geographic Information Systems (GIS), which can be used as basic documents for any action of developments in the watershed of Oued El Maleh in M'Saken region (eastern Tunisia). This region is characterized by the weakness of its topography and its slopes. Its rainfall, generally irregular and sometimes aggressive and torrential, can transform rivers which are often very little marked in nature, to real torrents with great erosive power, able to lead to flooding. This natural vulnerability is accentuated by the spreading of several urban areas in submersibles zones, in particular that of M'Saken, and by the development of the agricultural lands. In this context, the present study focused on the collection of digitized topographic maps, of Landsat images and others of Google Earth in order to create an integrated database in a Geographic Information System. The results are thematic maps which make it possible to define and analyze, by superposition of several layers of information, the natural environment; and to carry out a spatial analyzes required to characterize, map, and study the vulnerability.