Department of Horticultural Engineering Systems and Natural Environment, University of Sousse, High Institute of Agronomy of Chott Meriem, Chott Meriem, 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.
The watershed Sidi Salah, located in the north of Sfax (Tunisia), Knew an important water and soil conservation installations. These installations present certain operating anomalies that make them unable to well manage the hydric erosion phenomenon. This work aims to identify those anomalies and to characterize the responsible factors in order to promote the sustainable management of water and soil at the level of the watershed. The study was based on the photo-interpretation of the satellite images with high resolution, the field observation and the chemical analyses of the soil samples taken in various sites of the watershed. The results allowed us to reveal some anomalies as the loss of embankments and the destruction of the masonry installations. The responsible factors are mainly naturals, related to the turbulent water flows and the soft lithology of the soil rich in gypsum and limestone.
The present work aims to study the importance of the hydrological Meskat system and its landscape insertion through the olive groves of Sousse region. The inventory of the anti-erosion works reveals that the management of watersheds by the Meskat system was performed on approximately 44 000 ha, so, 40.5% of the supported area of the region by the erosion control structures (108 500 ha). This is an architectural and hydraulic heritage with a good quality rural landscape. This work aims to minimize the soil losses, to capture the surface runoff, to increase the soil fertility and to improve the crop yields. The current landscape of Meskats is an old as well as a current farmer's work. There is a richness conceded by the ancestors to their descendants. But this heritage is, in some cases, badly preserved. It should be noted that if, in the past, olive-tree left to the reconquest of the lowest parts of the hills to take advantage of the runoff, in the present, the urban population is looking for a natural landscape, is leaving to the reconquest of the hills (impluviums) to enjoy a world of pleasant views over the surrounding agricultural landscape, which risk the peril. However, the Meskat system remains the essential component of the territory organization, of the olive oil production and of the suburban and rural landscapes in Tunisian Sahel.