Water and Land Security in Drylands

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, Medenine) using hydrological modeling (HidroMORE model). Data on rainfall and temperature were collected from available stations, while those for future scenarios (Horizons 2030 and 2090) were obtained using the Coupled Model Intercomparison Project Phase 5 CMIP5 (GFDL HIRAM C360). In comparison with the reference period (1996–2005) and projecting increases in temperature of 1 and 5 °C, as well as rainfall decreases of 5.4 and 20%, reference evapotranspiration (ETo) was simulated to increase by 3–9% and evapotranspiration under non-standard conditions (ETCad_j) was reduced by 13% and 30%, respectively, for the 2030 and 2090 horizons. Thus, it is expected that the land suitable for olive cultivation will experience shrinkage and this cropping system would become increasingly problematic.

The fifth report of the Intergovernmental Panel on Climate Change reiterates that the Maghreb region is severely threatened by climate change and seems to be one of the most vulnerable regions in the world regarding its water resources responses to the changing climate conditions. The effects of climate change could significantly increase the relevance of water development policies, given that economic growth of the majority of Maghreb countries is closely related to water resources and contributes strongly to the socioeconomic balance and gross domestic product. In the Maghreb region, the need to mainstream climate change into development plans is already recognized and highlighted; the new constitutions have already adopted the sustainable development concept, which opens opportunities for improvement and protection of natural resources. Over the last decades, countries have tried to overcome water stress and scarcity by improving water policy and strategy, infrastructure development, economy of water use, wastewater, and desalinization, among others. However, the great challenge within the Maghreb region is mainstreaming climate change issues into development planning in the contextual framework of the water–energy–food security nexus, whose components are strongly interdependent. The aim of this paper is to analyze the impact of climate change on the water sector in the Maghreb region (Algeria, Morocco, and Tunisia) by means of a SWOT analysis (SWOT standing for Strengths, Weaknesses, Opportunities, and Threats) and to make recommendations on how to improve climate change mainstreaming into water development plans within the region.

Increasing temperatures due to global warming have raised concerns about food security in the southern Mediterranean region. This work attempts to study the limitation to cereal production in Tunisia. Data from six governorates were used to develop relationships between cereal yields and the sum (STx) of maximum temperatures over the threshold of 15 °C. The data envelopment analysis method was used to identify the attainable regional production among seasons having a total rainfall over 350 mm. Results showed that yields of bread wheat, durum wheat and barley decreased, respectively, by 0.4, 0.26, and 0.32 t ha⁻¹ for each 100 °C-day increase in STx, over the 1973–2013 period. An increasing trend in STx was observed for the major synoptic stations of the studied areas over the last 40 years but with different speeds. Future projections to 2050 showed a 15% rise for STx with a low radiative forcing scenario resulting in cereal yield gaps up to 0.26 t ha⁻¹.

The impact of climate change on groundwater resources can be significant in arid regions. This is due to the increase in temperature and the decrease in precipitations in such areas. This work studies the effect of Managed Aquifer Recharge (MAR) on the groundwater in the Figuig aquifer (392 km²), which is located in the Eastern High Atlas of Morocco. A numerical model was implemented to evaluate the effect of climate change and MAR up to 2099. Two areas with a surface of 1 and 32 km², respectively, are favored for the construction of dams to serve the purpose of MAR. The extreme A1F1 scenario derived from the Intergovernmental Panel on Climate Change (IPCC) was chosen for the simulation of the recharge. The simulation results show that the scenarios are feasible, and that MAR can contribute to an efficient recovery of the groundwater in the Figuig aquifer.

In the arid environment of southern Tunisia, FAO’s AquaCrop model version 4.0 has been calibrated to evaluate the effect of irrigation strategies with saline water on barley yield. Data sets during barley cropping seasons 2012 and 2013 in Médenine, southern Tunisia, were used to calibrate and evaluate this model. Barley canopy cover, grain yield, biomass production, and soil salinity and water content were simulated under three irrigation regimes. The RMSE, Willmott index of agreement (d), and r² analysis showed good agreement between the simulated and observed data, especially for the biomass production and grain yield. The difference between observed and simulated grain yield under full irrigation was only 1% for the first and second seasons. The difference for biomass was around 2%. The trend of canopy cover was well simulated with slight over estimation in the beginning of the season for both seasons. Salinity stress parameters were adjusted to simulate the combined effect of drought and salinity stress where the electrical conductivity of water (ECw) was used as the indicator threshold of salinity instead of the saturated soil-paste extract (ECe) in this case. The model tended to overestimate the soil water content and the ECe but with reasonable statistical indices for total root zone soil water content (RMSE: 8.6–11 mm, d: 0.78–0.98) and for ECe (RMSE: 1.35–0.94 dS/m, d: 0.63–0.88).

Groundwater is a key component for the development of semi-arid areas where surface water resources are scarce. Water managers need knowledge about water reserves to cope with their multiple constraints. In the Merguellil basin (Central Tunisia), the Kairouan plain aquifer supplies water for a rapidly growing irrigated agriculture economy but recharge processes are still poorly known. The present paper investigates groundwater transfers from upstream aquifers to the Kairouan plain through the hydraulic threshold of El Haouareb. A conceptual geological 3D model based on lithologs analyses was built. Two steady state groundwater models were run using Feflow code in high and low flow conditions. Results suggest that the limestone aquifer that ensures hydraulic connectivity between the upstream and downstream aquifers behaves like a dual-porosity medium with highly significant preferential groundwater flow paths and cannot be simulated as an equivalent porous media.

Several methods allow the determination of evapotranspiration (ET), either by direct measurement or by estimation from weather data. The most used estimation method is the FAO56 (FAO-PM), based on the concept of reference evapotranspiration (ETo) and crop coefficient (Kc). The eddy covariance technique (EC) developed for measurement of convective fluxes between land surface and the atmosphere is commonly used to estimate ET. However, these methods were established under standard conditions in flat terrain, and their use in hilly areas is questionable. In this work, the variability of ETo and ET measured by EC and energy balance (EB) in a hilly area of northern Tunisia is studied for different relief configurations. The experiment was conducted using a meteorological (M), and three EC-EB measurement stations in three wheat fields. Two stations were installed on opposite slopes of a ridge with apposing aspects and moderate slopes (A, B), and one station was installed in a flat site (C). Results of monitoring during the mid-season of wheat growth showed similar ETo levels in all sites for hourly and daily time steps with relative RMSE in the range 0.03–0.08 compared to M. Average ET values in sloping fields (A, B) were, respectively, 15% and 10% lower than in (C). However, hourly values of ET/ETo obtained from EC measurements were smaller than FAO-Kc, contrarily to those based on the EB method.

Appropriate land use and management requires a good knowledge about the main hydraulic properties of the soil, in particular soil moisture at field capacity (FC), permanent wilting point (PWP), and water holding capacity (HC). In the absence of direct measurements, these characteristics could be estimated from data on texture and organic matter content, using pedotransfer functions (PTFs). In this study, FC, PWP, and HC of predominant soil types in Cap Bon (Vertisols, Cambisols, and Calcisols), are estimated using Saxton and Rawls (Soil Sci Soc Am J 70:1569–1578, 2006) PTFs and complete sets of soil analysis data. Results show that when all soil samples (61) are taken together, obtained estimations were well correlated with measured values for FC (R² = 0.72) and PWP (R² = 0.72). Similar correlations were observed for Cambisols and Calcisols taken separately (R² = 0.65–0.70.); but there was an overestimation of FC and PWP for Vertisols (percentage of clay > 50%). However, relatively weak relationships were observed between estimated and measured values for HC in all cases (R² = 0.15). PTFs seem appropriate to be used in combination with remote sensing methods for generation of soil FC and PWP maps needed in irrigation and agriculture efficient management.

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 content in this water harvesting technique, TDR measurements were carried out for four consecutive years at three sites in the watershed of wadi Jir (Matmata, southeast Tunisia). The obtained results show that

In Tunisia, agricultural soils are subjected to progressive degradation. Application of sewage sludge is an important way to recycle nutrient elements and improve soil fertility and physical properties, causing an increase in crop yield. A field experiment was carried out, using ¹⁵N isotope techniques, to investigate the effects of labeled sewage sludge (3.7% N, 2.3 atom%) application on sudangrass and its residual effects on barley crops. Sewage sludge was applied at rates equivalent to 113, 226, and 338 kg N ha⁻¹. In addition, one control (no treatment) was also included in the experiment. Sewage sludge application increased the sudangrass yield and total nitrogen uptake as compared to the control treatment. A positive residual effect of sewage sludge application was also observed on yield and N uptake of the subsequent barley crop.

Aflaj in Oman are sustainable ancient techniques of irrigation based on open channels draining water from wadis, springs or aquifers to communities of users. Omani authorities reported the existence of 4112 aflaj of which 3017 are live systems; about 1000 have underground qanats (dawoodi aflaj). Agriculture in Oman relays mainly on irrigation by means of aflaj. They currently provide 680 million cubic meters yearly and irrigate around 26,500 ha of farmlands. Their water is being managed by an administration headed by a wakil. Falaj Al-Khatmeen is a dawoodi falaj among the five Omani aflaj inscribed in the World Heritage List since July 2006. It irrigates the lands of Birkat Al-Mouz in Wilayat Nizwa. This paper provides an overview about aflaj in Oman and, through the case study of falaj Al-Khatmeen, highlights the main concepts of this traditional knowledge and water management system besides the rights and equity in access to water for stakeholders. Water is shared by athar (30 min) according to a very precise irrigation scheduling and rotation (dawaran) that can be updated depending on seasons and changes in falaj ownership and water flow. The survival of falaj Al-Khatmeen relays mainly on the efficiency of its management.

Field studies were conducted to examine the response of potato, carrot, fava bean, and pepper to irrigation regimes using saline water in a commercial farm. The irrigation regimes were full (FI100) and deficit (DI70) irrigated with levels of 100 and 70% of crop evapotranspiration (ETc) when the readily available water, 40% of total available water (TAW), in the FI100 treatment was depleted, and traditional farmer practice (FM). For all experiments, the largest soil salinity values were observed under the farmer treatment compared to the FI100 and DI70 treatments. The highest mean yields of potato (24.4–27.5 t/ha), carrot (28.4–30.3 t/ha), fava bean (19–21.3 t/ha), and pepper (10.9–12.5 t/ha) were recorded for the FI100 treatment. Compared with FI100, significant reductions in potato, carrot, fava bean, and pepper yields were observed under the DI70 treatment, with only a few exceptions, resulting from a reduction in yield components. The farmer’s method not only caused significant reductions in yields but also resulted in an increase of water usage of 14–22%, 18–21%, 12.5–19%, and 13.9–15.5% for potato, carrot, fava bean, and pepper, respectively, and increased soil salinity. Water productivity (WP) values reflected the differences in yields and varied between 4.3 (farmer) and 13.7 kg/m³ (DI70) for potato, 4.4 and 11.7 kg/m³ for carrot, 4.8 and 13.7 kg/m³ for fava beans, and 0.8 and 2.6 kg/m³ for pepper across different years and treatments. The FI100 scheduling technique with variable water amounts was more efficient and provided significant advantage in yield, water productivity and net income, compared to the FM treatment in potato, carrot, fava beans, and pepper yields under arid environment. FI100 scheduling technique is suggested for vegetable crops in the arid environment. Under water restriction conditions, adoption of the DI70 strategy allows 30% water saving compared with FI100 with relatively small impact on soil salinity and some reductions in yield and net income.

The Atacama drylands are characterized by a high level of aridity and water scarcity, abandonment of rural areas by the population and loss of biodiversity, where some areas never get any rainfall. The advection fog is a daily phenomenon and a local resource that can be used by means of a simple low-technology called “Atrapaniebla” (Fog Collector), providing water for human consumption and irrigation. Some case studies offer different scenarios in terms of this technology’s purpose: The effectiveness of these projects depends on important factors that are not to be taken for granted, like the communities involvement, the presence in the territory of an active institution and the role of the planned management. This paper analyses different case studies in the Atacama drylands, showing the need of stakeholder involvement and participatory approach. A participatory framework is proposed for project implementation and funding for successful and reliable fog collection and water management.

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 methodology to evaluate and optimize the performance of existing RWH techniques in (semi-)arid regions was developed and tested. Engineering, biophysical, and socioeconomic aspects were integrated by using analytical hierarchy process (AHP) supported by geographic information system (GIS). Sixteen RWH locations (subcatchments) in the Oum Zessar watershed in Tunisia were examined. Based on the criteria selected, some 88% of the sites scored between 2 and 3 (low to moderate) on a 1–5 suitability scale; 6% scored higher than 3, and 6% received suitability scores less than 2. Improving RWH design by raising spillway heights by 50% increased overall suitability, with 69% of the sites scoring between 3 and 4 after such optimization. Our highly flexible, widely applicable methodology proved effective, easy to use and low cost. Its further application is recommended to support designers and decision-makers in assessing and optimizing the performance of both existing and new RWH systems.

The aggressiveness of the climate and soil vulnerability associated with low and degraded vegetation on steep slopes make the flows concentration into violent runoff causing usually huge amounts of erosion. Furthermore, ongoing socioeconomic transformations in the rural environment have contributed into the amplification of this phenomenon. Indeed, this erosion is responsible for land fertility decrease, crops falling yields, reduction of farmers’ income and silting of dams. These hydraulic structures are built by the national community at great expense. Given the limited financial resources of Tunisia and the high cost of erosion reduction, the establishment of maps for priority intervention becomes a necessity for the planner. The objective of this study is to determine a methodology for assessing the quantitative impact of human actions on erosion behavior in Nebhana watershed, located in central part of Tunisia. This study finds its interest in the fact that the developed erosion map is a decision support tool and a basis for determining the priority intervention areas as part of the Water and Soil Conservation Management Programs. Erosion mapping was carried out using empirical model based on the Revised Universal Soil Loss Equation (RUSLE). In Nebhana watershed, the average soil loss is about 3.5 t/ha/yr from the period 1965 to 2010. Between 2010 and 2015, the increase in soil and water conservation area allowed to reduce the average soil water erosion rate to around 3.2 t/ha/yr, that is a reduction of around 10% of dam silting. This work showed that the use of GIS for the analysis and processing of digital map data has made it easy and fast development of the erosion map that provides synthetic and systematic information on the intensity and spatial distribution of the phenomenon of water erosion.

Olive mill wastewater (OMW) is occurred from the production of olive oil in olive mills. Many olive mills are scattered in most Mediterranean countries which produce it seasonally. This led to an environmental problem in these olive oil-producing countries, due to the elevated level of salinity, polyphenols, and the pollution burden. However, OMW is also characterized by richness in organic and mineral compounds. Consequently, OMW spreading can be an alternative for a low cost soil organic amendment. This work aimed to study the effect of OMW spreading on the chemical properties of soils in arid regions. Amendments with OMW were applied on two different soils in arid regions from Southern Tunisia with a quantity of 300 L per 100 m² (per plot), in a completely randomized experimental setup. The main objective of this work is to identify the short-term effect of OMW on fertility of sandy soil, for the supply of soil on organic carbon, inorganic nitrogen, available phosphorus and exchangeable potassium during 2010 as well as assessment of its effect on pH, salinity of soils in arid regions. Obtained results show that under the conditions of our experiment, applying of this organic effluent has changed significantly the content of exchangeable potassium (197% and 221%, respectively, for Dar Dhaoui (A) and El Fje (B) soil), mineral nitrogen, phosphorus (370% and 445%, respectively for (A) and (B) soil), and organic matter in soil (from 0.92% to 1.51% and from 0.87% to 1.95%, respectively, for (A) and (B) soil). Consequently, OMW is considered as a rich organic material and may constitute a potential potassic amendment for dryland soils poor in this element, which has the tendency to increase the content of major elements and the soil organic matters. OMW application did not cause a significant change in soil pH, due to the low quantity of OMW used in the soil. However, we highlighted the value of OMW as an organic amendment that requires further study on optimizing used doses to avoid the possible risks. According to the obtained results we can confirm that OMW can be very useful as an organic amendment in agriculture.

This study fits into the framework of the evaluation of the impact of atmospheric pollution on the chemical composition of soil that was carried out around Gabes cement plant situated in Southeast of Tunisia commonly characterized by a high pollutant potential due to industrial encroachment. Crossing the inventoried sector, four sites are subject of the study along a pollution gradient potential started from the cement plant. The statistical analysis ANOVA shows a highly significant variation (p < 0.001) between sites of soil contents of chemical components measurements (Total limestone CaCO₃, active limestone CaCO₃, sodium Na, potassium K) marking a pollutant effect. Electrical conductivity and pH are also influenced from sites located near the plant to further ones along distance from the cement plant.

Degradation in arid zone is reflected on the ground by the modification of the soil surface components. Several studies have investigated the mapping of the soil surface and components in drylands. A few studies are the outcome of ground-based observations, while others widely use multispectral remote sensing and calculating indices that are limited to samples of electromagnetic spectrum. This paper proposes an innovative method that is applied to geomorphology and environmental research. It seeks to develop a new methodology for mapping soil surface and components, based on hyperspectral remote sensing with a wide range of electromagnetic spectrum. Our case of study is Beni Zalten watershed, which is situated in the natural region of Matmata (Southeast of Tunisia). The region is characterised by limited natural resources, complex physical conditions and irrational human use. This led to the fragility of the environment and the proliferation of water-erosion problems. Therefore, mapping the soil surface and components of Beni Zalten watershed is highly useful to evaluate soil erosion sensitivity and eventual study on erodibility. The methodological approach of our research is essentially based on a Hyperion satellite image dating from December 2009, spectrophotometry measurements and spectroscopy data. This approach depends on a series of pre-treatments (radiometric and atmospheric corrections and reflectance passage), adding to a series of treatments (spectral similarity method: the spectral angle mapper SAM and a method to extract endmembers from the image: Spectral HourglassWizard). This paper is organised around three main parts: First, we will present the physical and human context. Then, we will describe the data and methodology. Finally, we will present our results and discuss the hyperspectral remote sensing and spectroscopy contribution to the cartography of soil surface and components in an arid zone.

El-Fayoum Oasis is a depression or basin in the western desert that is adjacent to the Nile, Egypt. It locates about 130 km southwest of Cairo. Qarun Lake is the only natural contemporary lake in Middle Egypt. The lake is saline with an elevation about 44 m below sea level. It receives drainage water from El-Fayoum Depression but has no surface outflow. Wadi El-Rayan Lakes have been receiving drainage water since April 1973. El-Fayoum is now an intensively agricultural region supported by abundant freshwater from the Nile River via the Bahr Yusef Canal. The main objective of this study is to use Landsat multitemporal images to detect and monitor the changes of Qarun Lake coastal area. To fulfill this objective, Landsat data (path 177/row 40) are as follows: Landsat MSS 1973, Landsat TM 1988, Landsat ETM + 2003 and Landsat-8 2015, and topographic maps (1992) scale 1:50,000 were used. Geometric correction, Image enhancement, and visual interpretation were carried out on the images and maps. Digital elevation model (DEM) and the vector contour lines of the study area were used. ArcGIS 9.2 software had been applied for mapping environmental changes around Qarun Lake in the investigated area. ENVI 4.2 software was also used to produce the physiographic map of the study area. The obtained results from the digitized topographic map (1942) showed that the surface area of Qarun Lake was about 21 km². From that time, the surface area of the Lake was more or less stable and it was in a balance with land use in El-Fayoum Depression base on the interpretation of the remotely sensed data. In 1973 the surface area of Qarun Lake reached the maximum (240 km²) due to receiving the excessive drainage water from El-Fayoum Depression. The surface area of Qarun Lake decreased to about 230 km² by 1988. Since that time until 2013 the surface area of the lake was almost stable.

Land cover, land use, soil salinisation and sand encroachment, which are desertification-indicating features, were integrated into 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 development requires the understanding of these dynamics as it withstands the monitoring of desertification processes. Two different classification methods of salt and sand features have been set up, using historical and present Landsat imagery. Mapping of features of interest was achieved using both visual interpretation and automated classification approaches. The automated one implies a decision tree (DT) classifier and an unsupervised classification applied to the principal components (PC) extracted from Knepper ratios composite. Integrating results with ancillary spatial data, we could identify driving forces and estimate the metrics of desertification processes. In the Biskra area (Algeria), it emerged that the expansion of irrigated farmland in the past three decades has been contributing to an ongoing secondary salinisation of soils, with an increase of over 75%. In the Oum Zessar area (Tunisia), there has been a substantial change in several landscape components in the last decades, related to increased anthropic pressure and settlement, agricultural policies and national development strategies. One of the concerning aspects is the expansion of sand encroached areas over the last three decades of around 27%. This work is partly supported and developed within the WADIS-MAR Demonstration Project, funded by the EU Commission through the SWIM Programme (www.​wadismar.​eu).

In this paper, we present the comparison and validation of the Shuttle Radar Topography Mission Version 3.0 Global 1 Arc-Second (SRTMGL1) Digital Elevation Model (DEM) and the Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model Version 2 (ASTER GDEM2) applied to two areas of Maghreb region (Biskra, Algeria and Medenine, Tunisia). These are the two target areas assessed in the frame of WADIS-MAR project (http://​www.​wadismar.​eu), which is one of the five demonstration projects implemented within the Regional Programme SWIM (http://​www.​swim-sm.​eu) and funded by the European Commission. Newly released SRTMGL1 is available for free download since October 2014 over the African continent through United States Geological Survey (USGS) web data tools. Given the previously reported issues regarding optical sources DEMs, SRTMGL1 can provide significant advantages in elevation modelling and geoscience applications, but studies regarding its quality assessment and validation are in their early infancy. We employed the two data sets in a visual and quantitative comparison and subsequently, their validation was conducted using ground control points (GCPs) collected within the target areas. Results show that SRTMGL1 presents an overall major accuracy and higher sensitivity to small-scale features and slight variations in landforms.

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 an integrated impact assessment (IIA) framework incorporating extended cost–benefit analysis (ECBA) and the sustainable livelihoods approach (SLA). The former internalizes environmental impacts while the latter enables assessment of the contributions of WHTs to rural livelihoods in the watershed. We began by using ECBA to estimate the profitability of investments in WHTs. We then scaled up our impact perspective from the local level to the watershed level using SLA based on survey data from beneficiary households upstream, midstream and downstream. Our goal was to better understand and evaluate changes in livelihoods and associated environmental effects. We focused on the links between cost–benefit of WHTs and sustainable livelihoods, looking in particular at the capitals that connect the two. Our ECBA results suggest that WHT techniques did benefit the local population at both the private and the social level (IRR > 20%; NPV > 2000 TD/ha). Sensitivity analysis confirmed this result. SLA findings point to a central role of social capital in promoting sustainable livelihoods, followed by physical capital enhanced by WHTs construction, especially in the upstream and downstream segments of the watershed. Recommendations were derived from these outcomes for more integrated watershed management policy.

This paper applies multiple analytical and empirical methods to evaluate the sustainability impacts of climate change and prospective adaptation measures based on water harvesting techniques (WHTs) at the regional level. We developed a sustainability composite index (SCI) for an arid zone in Tunisia, specifically the south-eastern Province of Medenine. To quantify the SCI, a static computable general equilibrium model (CGE) was adapted to the region. To provide a database for the CGE model, we built a regional social accounting matrix (RSAM). A bottom-up approach was applied to build a regional supply and use matrix for the agricultural sector incorporating natural resources (land and water) as intermediate inputs. Our regional SAM included ten production factors, 18 production sectors producing 22 goods and services, two household types (urban and rural), one representative enterprise, two public sectors (central and regional administration), taxes accounts, two capital accounts (savings/investment and changes in stocks), the rest of the world and the rest of the country. We used the RSAM to calculate the regional GDP. Two simulations were run, focused on the 2030 time horizon from the baseline year of 2006: (i) declining natural capital due to the effects of climate change and (ii) implementation of a regional climate change adaptation strategy based on water harvesting technologies (WHTs). Scenario identification drew on previous research and was performed in close collaboration with regional stakeholders. Based on the outputs of the CGE model, the impacts of the two scenarios on the main regional economic indicators were analysed. Using multi-criteria analysis (MCA), we calculated an aggregated SCI for regional development. Results suggest that implementation of the regional climate change adaptation strategy would have positive impacts, but would be insufficient to maintain the SCI at its current level.

The aim of this paper is to examine the impact of research, development extension (RD&E) and climate change (measured in terms of change in rainfall) on the productivity growth of agriculture in Tunisia during the period 1970–2011, using output-based Törnqvist index combined with econometric regression. Results show that RD&E and climate change are significantly affecting the long-run productivity growth of the Tunisian agriculture. Climate change lessens the productivity of agriculture in the long run whilst RD&E boosts its productivity. Empirical findings suggest that an increase in agricultural RD&E investment is critical to improving long-run productivity growth in the face of adverse climate change.