Proposition d’un schéma chronostratigraphique des héritages quaternaires continentaux de la Jeffara septentrionale et de la partie nord-orientale du plateau de Dahar-Matmata (sud-est tunisien)

Entre quatre et cinq terrasses, une série de cônes de déjection coalescents, deux glacis d’érosion et un glacis de substitution constituent la gamme des formes quaternaires dans la Jeffara septentrionale et la partie nord-orientale du plateau du Dahar- Matmata. Compte tenu des données géomorphologiques, préhistoriques et chronologiques, tous les dépôts datent du Pléistocène supérieur et de l’Holocène, exceptés la croûte calcaire attribuée au Pléistocène inférieur qui scelle le premier glacis d’érosion, et le dépôt conglomératique à poudingue pouvant appartenir à la fois au Pléistocène moyen et supérieur. Les croûtes calcaires, les changements de faciès et l’agencement des formes témoignent du rôle déterminant des changements climatiques dans l’évolution géomorphologique quaternaire de ce domaine aujourd’hui aride.Four to five terraces, a series of coalescent alluvial fans, two glacis of erosion and a glacis of substitution constitute the range of the Quaternary shapes in northern Jeffara. Given the geomorphologic, prehistoric and chronologic data, all deposits are dated from Upper Pleistocene and Holocene, except the calcareous crust attributed to the Lower Pleistocene and that seals the first erosion glacis, and the conglomeratic deposit with pudding, which can belong at the same time to Middle and Upper Pleistocene. Calcareous crusts, facies changes and arrangement of forms reflect the role of climate change in the Quaternary geomorphologic evolution of this nowadays arid area

Upstream-Downstream Influence of Water Harvesting Techniques (Jessour) on Soil Water Retention in Southeast Tunisia

Weather parameters and soil moisture profiles were measured at an hourly time step during four agricultural years (September to October, from 2018–19 to 2021–22) in two Jessour (water harvesting cultivated terraces) of the same valley in Zmerten (southeastern Tunisia), characterized by an arid climate. One instrumented Jesr (singular of Jessour) was located upstream and the other one downstream. During each dry season, when crops experience water stress, the downstream Jesr had a higher available water content than the upstream one; in the downstream Jesr the soil profile moisture remained above the wilting point, whereas in the upstream soil surface, moisture levels decreased to below the wilting point. High accumulation/low intensity rains (causing saturation/excess runoff) flooded both upstream and downstream Jessour from 50 mm of cumulative rainfall, whereas high intensity/low accumulation rains (causing infiltration/excess runoff) activated the downstream Jesr from an intensity of 15.2 mm/h, and a combination of moderate intensity and moderate accumulation rains activated both Jessour from an intensity of 8 mm/h and a cumulative rainfall of 33 mm. We propose to set 50 mm of cumulative rainfall and/or 6.4 mm/h of intensity as threshold values for the activation of the Jessour system in Zmerten. However, significant soil moisture recharges can occur even without activation of the Jessour system.EEA BarilocheFil: Calianno, Martin. University of Lausanne. Institute of Geography and Sustainability and Interdisciplinary Centre for Mountain Research; SuizaFil: Calianno, Martin. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; ArgentinaFil: Ben Fraj, Tarek. University of Tunis. CGMED Laboratory; TúnezFil: Ben Fraj, Tarek. University of Sousse. Faculty of Arts and Human Sciences; TúnezFil: Fallot, Jean-Michel. University of Lausanne. Institute of Geography and Sustainability and Interdisciplinary Centre for Mountain Research; SuizaFil: Abbassi, Mohamed. University of Tunis. CGMED Laboratory; TúnezFil: Abbassi, Mohamed. University of Sousse. Faculty of Arts and Human Sciences; TúnezFil: Ghram Messedi, Aziza. University of Tunis. CGMED Laboratory; TúnezFil: Ghram Messedi, Aziza. University of Sousse. Faculty of Arts and Human Sciences; TúnezFil: Ben Ouezdou, Hédi. University of Tunis. CGMED Laboratory; TúnezFil: Ben Ouezdou, Hédi. University of Sousse. Faculty of Arts and Human Sciences; TúnezFil: Reynard, Emmanuel. University of Lausanne. Institute of Geography and Sustainability and Interdisciplinary Centre for Mountain Research; Suiz

Benefits of Water-Harvesting Systems (Jessour) on Soil Water Retention in Southeast Tunisia

In this paper, we quantify the water balance of Jessour at the scale of agricultural plots. Jessour (plural of Jesr) are ancestral hydro-agricultural systems in the Dahar plateau (southeastern Tunisia). They consist of small dams built across wadis and gullies, which retain rainwater and sediments, hence enabling cropping. Despite arid climate conditions, Jessour allow the culture of the olive tree beyond its ecological limits. Weather monitoring stations were set up and soil moisture sensors installed down to a depth of 1.25 m in the soil in two neighboring gullies in the village of Zammour: one with a Jesr and one without. Laser granulometry and organic matter analyses were carried out on samples collected near the soil moisture sensors. Measurements were recorded from 28 September 2017 to 21 September 2018. From 10 to 12 November 2017, the region received 123.3 mm rainfall. The Jesr retained the equivalent of 410.3 mm of soil moisture to a depth of 1.25 m whereas the value in the gully was 224.6 mm. Throughout the summer of 2018, the soil available water capacity (AWC) remained above 55 mm in the Jesr, while it dropped to zero in the gully. Jessour are thus very suitable hydro-agricultural systems to face the climate changes concerning this fragile region, located in the transition zone between the semi-arid to arid Mediterranean region and the Sahara

Impacts des aménagements hydro-agricoles en jessour sur le bilan hydrique dans le sud-est tunisien

Des mesures météorologiques et de la teneur en eau dans le sol à 8 profondeurs différentes ont été réalisées pendant une année dans 2 parcelles situées au fond de 2 ravins à 130 m de distance, l’un est aménagé en Jessour et l’autre est sans Jessour, en vue de quantifier les impacts de ces aménagements hydro-agricoles sur le bilan hydrique. Ces mesures ont montré que seuls 3 épisodes pluvieux majeurs (> 20 mm) ont entraîné une hausse significative de la teneur en eau dans le sol jusqu’à au moins 125 cm de profondeur. Pour ces 3 épisodes, cette hausse a été rapide et importante jusqu’à 125 cm dans la parcelle aménagée en Jesr, alors qu’une hausse semblable n’a été mesurée que pour un bref épisode pluvieux en août 2018 dans la parcelle sans Jesr. Pour les deux autres épisodes pluvieux plus longs survenus en novembre et décembre 2017, la hausse de la teneur en eau dans le sol a été nettement plus lente et modeste dans la parcelle sans Jesr au-delà d’une profondeur de 35 cm. Les Jessour semblent avoir des effets différents sur le bilan hydrique dans les sols selon les saisons

Climat, environnement et sociétés de la Préhistoire du sud tunisien: résultats préliminaires et perspectives de la recherche

We present the preliminary results of a Tunisian-Italian project of scientific collaboration in the field of environmental studies and prehistoric and anthropological research in southern Tunisia ruled by an interdisciplinary approach that includes geo-archeology, geochronology, geochemistry, palynology, paleoanthropology and population genetics. The research area is south of the Chott el Jerid and its surroundings, where the major physiographic feature is a large playa which contained one of the mega lakes that existed in the Sahara during wet periods in the late Quaternary. The region is a pivotal area between the Mediterranean and the Sahara, then favorable to study the cultural diffusion and humans displacements through different periods and environments.Nous présentons les résultats préliminaires d'un projet Tuniso-Italien de collaboration scientifique dans le domaine des études environnementales et de la recherche préhistorique et anthropologique en Tunisie méridionale mené selon une approche interdisciplinaire qui comprend la géo-archéologie, la géochronologie, la géochimie, la palynologie, la paléoanthropologie et la génétique. La zone de recherche se trouve au sud du Chott el Jérid  et ses environs. Il s’agit d’une zone caractérisée par la présence de l’un des méga lacs qui existaient dans le Sahara pendant les périodes humides à la fin du Quaternaire. La région est une zone charnière entre la Méditerranée et le Sahara, donc favorable à l’étude des diffusions culturelles et des déplacements humains à travers les différentes périodes et environnements. Nous présentons les résultats préliminaires d’un projet Tuniso-Italien de collaboration scientifique dans le domaine des études environnementales et de la recherche préhistorique et anthropologique en Tunisie méridionale mené selon une approche interdisciplinaire qui comprend la géo-archéologie, la géochronologie, la géochimie, la palynologie, la paléoanthropologie et la génétique. La zone de recherche se trouve au sud du Chott el Jérid et ses environs. Il s’agit d’une zone caractérisée par la présence de l’un des méga lacs qui existaient dans le Sahara pendant les périodes humides à la fin du Quaternaire. La région est une zone charnière entre la Méditerranée et le Sahara, donc favorable à l’étude des diffusions culturelles et des déplacements humains à travers les différentes périodes et environnements.We present the preliminary results of a Tunisian-Italian project of scientific collaboration in the field of environmental studies and prehistoric and anthropological research in southern Tunisia ruled by an interdisciplinary approach that includes geo-archeology, geochronology, geochemistry, palynology, paleoanthropology and population genetics. The research area is south of the Chott el Jerid and its surroundings, where the major physiographic feature is a large playa which contained one of the mega lakes that existed in the Sahara during wet periods in the late Quaternary. The region is a pivotal area between the Mediterranean and the Sahara, then favorable to study the cultural diffusion and humans displacements through different periods and environments

Temporal scale imbrication and its importance for interpretation in geocultural sites in Jebel Dahar (Southeast Tunisia)

Geocultural sites combine a high cultural and natural heritage value and are particularly suitable for the interpretation and promotion of cultural and natural heritage. Based on previous geoheritage inventories, this paper analyzes seven geocultural sites in Jebel Dahar (Southeast Tunisia) from the perspective of temporal interrelationships. Through a synthesis on the development of the natural landscape of Jebel Dahar and its occupation by human beings, the work focuses on the importance of the interweaving of temporal scales in the analysis and interpretation of geocultural sites. A specific methodology in four steps is proposed: (i) a synthesis on the components of the site in the form of a text; (ii) a summary table built according to a temporal scale composed of six periods (geological, geomorphological, prehistoric, historical, present and future); (iii) a graphical representation of the interweaving of these temporal scales; (iv) a cartographic representation of the results of the analysis. Steps (iii) and (iv) were applied only to the geocultural sites of Matmata-Beni Issa and Douiret. The paper also emphasizes the importance of the interweaving of temporal scales in the interpretation of geocultural sites. These scales could be part of the criteria for the inventory, selection, evaluation, interpretation and management of geocultural sites

De la carte géomorphologique à la carte géotouristique : Proposition et application d’une méthode de représentation cartographique par SIG

On observe aujourd’hui une tendance à rapprocher les sciences de la Terre en général, comme la géomorphologie, des non spécialistes. Le géotourisme est l’un des moyens permettant d’informer sur la géomorphologie, souvent peu connue du grand public et des scientifiques d’autres disciplines. En vue de promouvoir et de valoriser la géomorphologie, il est possible de concevoir et de produire des cartes géotouristiques à partir de la cartographie géomorphologique. Les systèmes d’information géographique (SIG) constituent un outil efficace pour l’archivage, l’analyse et la diffusion de données spatiales ; à travers leur système de gestion de base de données (SGBD), ils facilitent aussi le passage de la carte géomorphologique relativement complexe à la carte géotouristique, beaucoup plus simple. Les travaux scientifiques dans le domaine de la cartographie géotouristique se limitent souvent à présenter des exemples de réalisations cartographiques sans détailler l’approche méthodologique choisie ni évaluer ces produits relativement à leur conception cartographique. Ce travail propose une méthode pour la conception et la représentation de cartes géotouristiques, basée sur des supports d’information géomorphologique. Elle découle d’une réflexion menée sur les critères de choix de données à représenter et de symbolisation à uniformiser, en s’appuyant sur des retours d’expérience cartographique et en intégrant des concepts et outils tirés du domaine des technologies de l’information géographique. L’article propose des lignes directrices pouvant servir de base pour les recherches en géotourisme. Il a pour objectifs principaux d’améliorer les produits cartographiques et d’uniformiser les systèmes de légende de cartographie géotouristique.There is now a tendency to bring the Earth sciences in general, such as the geomorphology, closer to non-specialists. Geotourism is one of the ways to inform about geomorphology, often not much known by the large public and scientists from other disciplines. To promote and valorize geomorphology, it is possible to design and produce geotourism maps based on geomorphological mapping. Geographic Information Systems (GIS) are an effective tool for the archiving, analysis and dissemination of spatial data; through their Database Management System (DBMS), they also facilitate the transition from the rather complex geomorphological map to the much simpler geotourism map. Scientific work in the geotouristic mapping field is often limited to the presentation of cartographic examples of achievements without detailing the methodological approach chosen or evaluating these products from the point of view of their cartographic conception. This work proposes a method for the design and representation of geotourism maps based on geomorphologic information data. It is based on a basic reflection on the criteria for selecting data to represent and symbolization to be standardized, by relying on cartographic feedback and integrating concepts and tools from the field of geographic information technologies.The article proposes guidelines that can serve as a basis for geotourism research. Its main objectives are to enhance cartographic products and to standardize geotourism mapping legend systems

Megalithic Structures of the northern Sahara (Chott el Jérid, Tunisia)

I monumenti megalitici sono una caratteristica archeologica distintiva del pae-saggio sahariano. Partendo da una base piuttosto limitata di lavori editi, e nell’ambito di un programma di ricerca dedicato al Sahara settentrionale, abbiamo avviato nel 2015 un’indagi-ne territoriale sui monumenti in pietra della pre-protostoria e della storia antica della Tunisia meridionale. L’area di studio selezionata è localizzata a est e a sud-est della depressione del Chott el Jérid (governatorato di Kebili). In questo lavoro viene presentata la strategia di ricerca adottata, modulata sulle specifiche caratteristiche locali, quali il pessimo stato di conservazio-ne dei monumenti e la loro incerta cronologia. I nostri risultati, basati sulla combinazione di analisi di telerilevamento, ricognizioni di superficie e scavi di alcuni monumenti, evidenziano una densa occupazione di questa regione del Sahara settentrionale, dove edifici monumentali di possibile funzione funeraria si collocano cronologicamente dalla tarda preistoria fino all’età romana. L’uso persistente dell’area in un arco di tempo molto lungo ne conferma la posizione centrale nelle antiche vie di collegamento transaharianeMegalithic monuments are a distinctive archaeological feature of Saharan land-scape, as indicated by different systematic research projects undertaken so far. Starting from a very low baseline of previous archaeological research, and as part of a comprehensive research programme focussed on northern Sahara, we launched in 2015 a territorial investigation of stone monuments of the pre-protohistory and early history of southern Tunisia. To do this, we selected a sample study area east and south-east of the Chott el Jérid depression (Kebili re-gion) where to conduct field research. In this paper we present the research strategy adopted, planned to address some issues such as the poor state of preservation of the monuments or their uncertain chronology, also known from other parts of the Sahara. Our results, based on the combination of remote sensing analysis, field survey and selected excavations, highlight a dense occupation of this area of northern Sahara, where monumental buildings of possible funerary function tentatively trace back to the late pre-protohistory up to the roman age. The persistent use of the area across a long-time span corroborates its pivotal location in ancient trans-Saharan connection route