Mohamed Ouessar

Institut des Régions Arides | IRA · Eremology and Combating Desertification

Flash floods are a significant threat to arid and semi-arid regions, causing considerable loss of life and damage, including roads, bridges, check dams and dikes, reservoir filling, and mudslides in populated areas as well as agricultural fields. Flood risk is a complex process linked to numerous morphological, pedological, geological, anthropic, a...

Abstract Effective land management in the Djeffara plain, southeastern Tunisia, is being constrained by increasing land degradation issues due to arid climate conditions and soil erosion. Thus, this study aims to assess the impact of the integrated control measures, namely windbreaks and controlled grazing, on the restoration of land cover dynamics...

Water scarcity is a significant issue in the southeastern region of Tunisia, where the sole source of water is from overexploited, salinized, and contaminated aquifers. Despite considerable advancements in studying groundwater hydrochemistry in the study area, Jeffara plain, further investigation is crucial to comprehensively assess groundwater qua...

This study aims to detect sediment at six gabions check-dams distributed in the upstream and downstream areas of the Koutine catchment located in an arid area in the southeast of Tunisia and characterized by an annual mean precipitation of less than 200 mm. The detection of sediment is based on the Electrical Resistivity Tomography (ERT) method ass...

This study focused on monitoring the water status of vegetation and soil by exploiting the synergy of optical and microwave satellite data with the aim of improving the knowledge of water cycle in cultivated lands in Egyptian Delta and Tunisian areas. Environmental analysis approaches based on optical and synthetic aperture radar data were carried...

Earth Observation (EO) technologies have played an increasingly important role in monitoring the Sustainable Development Goals (SDG). These technologies often combined with Machine Learning (ML) models provide efficient means for achieving the SDGs.The great progress of this combination is also demonstrated by the large number of software, web tool...

The organic amendment of degraded soil in South East of Tunisia was used to restore the chemical, and physical properties of soil quality investigated in this study. Biochar derived from pyrolyzed green waste at 360°C was used like organic amendment. Nines randomized plots with one square meter of the area of each plot in three replicates have been...

The aquifers under the Jeffara Plain in southeastern Tunisia is a complex aquifer system consisting of interconnected shallow and deep aquifers within Triassic and younger sediments. The extent of the aquifers is only roughly known, so a gravity and electrical resistivity analysis was undertaken to aid for determining the aquifers extent. The gravi...

Water harvesting techniques (WHTs) are important climate change adaptation measures to better manage rainwater for domestic and agricultural purposes, but which WHT to plan where is subject to sustainability considerations. Moreover, suitability of different WHTs varies from one location to another, depending on physical and socio-economic conditio...

The olive tree is well known for being adapted to the arid conditions of the Mediterranean basin. However, prolonged drought periods which are expected to become more frequent because of climate change could result in severe water stress. In order to map the spatial distribution of drought stress in the olive groves in the arid regions of southeast...

A two-year study was conducted to evaluate the physiological and biological effects of the introduction of an SDI system on adult olive tree in a 58-year-old olive (Olea europaea L. cv. Zarrazi) orchard located at Bir-lahmar, Tataouine, Tunisia. Irrigation was applied every three days at 3 am, by an automatic subsurface drip irrigation system with...

The storage of phosphogypsum waste has become an essential issue for the environment. The regulations require the presence of a safety barrier with an optimal seal to avoid contamination of the subsoil and the water table. Clays, having low permeability and a high capacity to retain pollutants (heavy metals), are therefore frequently used as a pass...

An accurate representation of the spatiotemporal precipitation distribution is very important, mainly because of the erosion risk and flooding. To study the spatiotemporal rainfall variability in the Wadi Koutine watershed (southern Tunisia), rainfall collected data were analyzed over a period of fifty years (1969–2018). The trend analysis and eval...

Tunisia is a small North-African country with a dry Mediterranean climate. It is among the poorest countries in terms of water availability (450 m³/capita/year). With 516,000 farms, the agricultural sector occupies 65% of the country’s land, contributes with 12.6% to the GDP, and employs 15% of the labor force. The agricultural production represent...

Soil erosion remains one of the principal environmental problems in arid regions. This study aims to assess and quantify the variability of soil erosion in the Koutine catchment using the RUSLE (Revised Universal Soil Loss Equation) model. The Koutine catchment is located in an arid area in southeastern Tunisia and is characterized by an annual mea...

Soil erosion processes remain the principal environmental issue in the arid regions, such as the southern part of Tunisia. Erosion is a real threat not only for soil conservation but also for the sustainability of water harvesting techniques (cisterns, check dams). The quantification of soil loss in Koutine watershed depends on many factors such as...

Land Degradation Neutrality (LDN) is a new approach, which is receiving considerable interest worldwide, in assessing current land condition. An LDN assessment was undertaken for the Dhahar-Jeffara transect in southeastern Tunisia. The assessment was performed following the United Nations Convention to Combat Desertification (UNCCD) method in terms...

Groundwater is the main source of water in arid regions. In the Southeast of Tunisia, Zeuss-Koutine and Mio-Plio-Quaternary underflow aquifers of Jeffara plain are considered the main source of water supply for drinking, agriculture, and industry. The study area is characterized with several known groundwater pollution sources (industrial and waste...

The impact of Land use/land cover (LULC) change was assessed through monitoring the distribution of ecological indicators and tracking the aeolian deposits, which provides valuable information on desertification and climate change in Tunisian arid regions. This study was conducted in Oum Zessar area, in southeastern Tunisia. Both visual interpretat...

Understanding land users’ livelihoods and their strategies is essential in order to adapt prevention and adaptation policies and to ensure sustainable land management (SLM) planning. Considering the global call for SLM, and due to a lack of studies on land degradation (LD) in Tunisia, we aimed to explore the livelihoods of farmers, their livelihood...

En Tunisie, la ressource hydrique est le premier facteur limitant le développement du secteur oléicole. L'amélioration de son efficience d'utilisation est donc nécessaire et peut passer par des stratégies d'irrigation déficitaire. La capacité d'adaptation au déficit hydrique de la variété d'olivier 'Koroneiki', a été étudiée à travers l'analyse des...

A field experiment was carried out to investigate the effect of tree irrigation frequency on the vegetative growth and yield of two introduced olive cultivars (Olea europaea L. cvs. Koroneiki and Picholine). The trials took place in 2014. There were four different irrigation treatments, which were irrigating every other day (T0), every 4 days (T1),...

Abstract Predicting photosynthetic production in olive trees is a key feature in managing the effect of climate change on arid areas. Functional-structural plant modelling is a promising tool for achieving this goal. We used a photosynthetic sub-model that accounted for water and temperature stress and implemented it into LIGNUM model. We then cond...

A field experiment was carried out to investigate the effect of tree irrigation frequency on the vegetative growth and yield of two introduced olive cultivars (Olea europaea L. cvs. Koroneiki and Picholine). The trials took place in 2014. There were four different irrigation treatments, which were irrigating every other day (T0), every 4 days (T1),...

The present study aims to locate and rank suitable sites for Soil Aquifer Treatment (SAT) in Jerba Island (South Tunisia) by integrating a single-objective AHP method into a GIS model. The methodology represents a first step in SAT basin construction projects before field investigations. It considers several criteria related to technical, environme...

In the arid regions of south eastern Tunisia, the land use is predominated by olive trees cropping, where two main cultivation strategies can be found: using of water harvesting techniques to overcome the scarcity and variability of rainfall (in the Matmata mountains) and dryland farming (in the Jeffara plain). In these arid areas, soil moisture is...

In this paper, an approach for estimating the soil moisture content (SMC) in arid environment in Tunisia is presented. In countries characterized by arid and semi-arid climate, it is very important to obtain reliable estimates of soil moisture evolution for water management purposes, in order to reduce water wastes and properly schedule agricultura...

In arid and semi-arid areas, farmers are experiencing unprecedented water scarcity, which is likely to increase by the perspective of global warming. The purpose of this study was to evaluate the effect of three irrigation frequencies on vegetative growth, leaf turgor pressure, and photosynthesis of young olive trees (Olea europaea L. cvs ‘Koroneik...

Studies in arid regions have shown that scattered trees strongly influence the environmental conditions under their canopies providing favourable conditions for the recruitment of other plants. The most critical factor controlling plant productivity in arid regions is soil–water availability. Hence, understanding the soil–water relationships below...

Groundwater is the main source of water in arid regions. Thus, groundwater pollution becomes a major issue due to the increasing contamination, which poses serious and harmful risk to the environment. Groundwater vulnerability maps can be used as a tool to help decision makers to protect groundwater resources from contamination. The vulnerability o...

Land cover, land use, soil salinization, and sand encroachment, which are desertification-indicating features, were integrated in a diachronic assessment, obtaining quantitative and qualitative information on the ecological state of the land, particularly degradation tendencies. In arid and semi-arid study areas of Algeria and Tunisia, sustainable...

Arid and semiarid regions face water scarcity and climatic uncertainty. Rainwater harvesting (RWH) has been used for generations to cope with these challenges. Numerous methods have been applied to select suitable sites for RWH. However limited attention has been given to evaluation of RWH structure performance. In this study, a comprehensive metho...

Soil moisture is an important indicator to determine the potential production of a crop, especially in recurrent drought threatened countries as Tunisia. It is also important in hydrologic modeling of watersheds. In the context of enhancing the value of jessour (plural of jesr), and providing scientific knowledge of the evolution of soil water cont...

Climate change (CC) is a main issue of interest at the international as well as the national levels. It is important at this stage to do research to analyze impacts and adaptation strategies. The objective of this study was to evaluate the water stress of olive groves within the context of CC in the South East of Tunisia (watershed of Oum Zessar, M...

Despite broad interest in use of water harvesting techniques (WHTs) to reduce pressure on natural resources in arid zones, few ex post assessments are available on how WHTs impact livelihood sustainability. This paper assesses the impact of WHTs on the livelihood conditions of inhabitants in the Oum Zessar watershed in south-east Tunisia. We used a...

Climate projections for Tunisia show a rise in temperature by 2020 of 1.1 degrees Celsius (°C) and 2.1 °C in 2050. The south of the country is much more of a concern. Rainfall is projected to decrease between 10% in the north and 30% in the south over the same period. In the province of Médenine, in Southern Tunisia, where the bio-climate is dry (r...

Groundwater vulnerability mapping is largely used as a modeling tool to delineate areas susceptible to pollution and to protect groundwater resources from this threat. The Zeuss-Koutine aquifer, which constitutes an important source of drinking water in the Southeastern Tunisia, is subjected to an intensive exploitation and threatened by pollution...

This book presents recent lessons learned in the context of research and development for various dryland ecosystems, focusing on water resources management, land and vegetation cover degradation and remediation, and socioeconomic aspects, as well as integrated approaches to ensuring water and land security in view of the current and predicted clima...

This paper presents an integrated and a trans-disciplinary analysis from a case study in Northwest of Tunisia in order to release a decision for upscaling sustainable land management practices in the national level. The integrated, trans-disciplinary approach aims at initiating a process of co-production of knowledge and joint learning between rele...

This study investigates the relationship between fine resolution, local-scale biophysical and socioeconomic contexts within which land degradation occurs, and the human responses to it. The research draws on experimental data collected under different territorial and socioeconomic conditions at 586 field sites in five Mediterranean countries (Spain...

States of ecological maturity and temporal trends of drylands in Morocco, Algeria and Tunisia north of 28 ˝ N are reported for 1998–2008. The input data were Normalized Difference Vegetation Index databases and corresponding climate fields, at a spatial resolution of 1 km and a temporal resolution of one month. States convey opposing dynamics of hu...

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Arid and semi-arid regions around the world face water scarcity problems due to lack of precipitation and unpredictable rainfall patterns. For thousands of years, rainwater harvesting (RWH) techniques have been applied to cope with water scarcity. Researchers have used many different methodologies for determining suitable sites and techniques for R...

A simple water-balance model was developed, combined with field measurements to analyse the performance of various RWH designs and management scenarios.

Harvested rainwater is an alternative source of water in arid and semi-arid regions (ASARs) around the world. Many researchers have developed and applied various methodologies and criteria to identify suitable sites and techniques for rainwater harvesting (RWH). Determining the best method or guidelines for site selection, however, is difficult. Th...

The main objective of this study is to define a general method to select suitable RWH sites and techniques in ASAR through the inventory of the main methods and criteria developed during the last three decades.

Soil degradation and desertification processes in the Mediterranean basin reflect the interplay between environmental and socioeconomic drivers. An approach to evaluate comparatively the multiple relationships between biophysical variables and socioeconomic factors is illustrated in the present study using the data collected from 586 field sites lo...

Arid regions of Maghreb (North Africa) suffer scarce water conditions and the erratic behaviour of rainfall events over brief intervals often produce short and intense floods events which converge into ephemeral wadi beds. The watershed of wadi Oum Zessar, in South-East Tunisia, is characterized by a rainfall rate of about 200 mm/year, overexploita...

The Jeffara Plain, in Medenine region (SE Tunisia), suffers of dry climatic conditions. Lower Triassic sandstones widely outcrop within the Plain and they host a strategic aquifer exploited for drinking and irrigation purposes. An insufficient natural recharge and an increasing water demand have led to an overexploitation of such aquifer. Water har...

An approach to derive relationships for defining land degradation and desertification risk and developing appropriate tools for assessing the effectiveness of the various land management practices using indicators is presented in the present paper. In order to investigate which indicators are most effective in assessing the level of desertification...

Indicator-based approaches are often used to monitor land degradation and desertification from the global to the very local scale. However, there is still little agreement on which indicators may best reflect both status and trends of these phenomena. In this study, various processes of land degradation and desertification have been analyzed in 17...

Studies in arid regions have shown that scattered trees strongly influence the environmental conditions under their canopies providing favourable conditions for the recruitment of other plants. The most critical factor controlling plant productivity in arid regions is soil water availability. Hence, understanding the soil-water relationships below-...

In a context of climate change and fragile environmental and economic background, the arid and semi-arid land of Tunisia faces great challenges as vulnerability of productive land to degradation is accelerated by human interventions. Thus, there is a strong need of continuous temporal and spatial monitoring of land cover/land use change and the dyn...

Soil degradation and desertification processes in the Mediterranean basin reflect the interplay between environmental and socioeconomic drivers. An approach to evaluate comparatively the multiple relationships between biophysical variables and socioeconomic factors is illustrated in the present study using the data collected from 586 field sites lo...

This paper introduces and evaluates DryMOD, a dynamic water balance model of the key hydrological process in drylands that is based on free, public-domain datasets. The rainfall model of DryMOD makes optimal use of spatially disaggregated Tropical Rainfall Measuring Mission (TRMM) datasets to simulate hourly rainfall intensities at a spatial resolu...

This paper introduces and evaluates DryMOD, a dynamic water balance model of the key hydrological process in drylands that is based on free, public-domain datasets. The rainfall model of DryMOD makes optimal use of spatially disaggregated Tropical Rainfall Measuring Mission (TRMM) datasets to simulate hourly rainfall intensities at a spatial resolu...

The aim of this work is to assess the short term effect of OMWW (olive mill waste water) application on chemical and biological soil properties. A field experiment was carried out in southern Tunisia. OMWW application was done at rates equivalent to 0, 15, 30 and 45 m3/ha. Results showed that increasing rates of OMWW enhance the soil fertility due...

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