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2017 | Buch

Water and Land Security in Drylands

Response to Climate Change

herausgegeben von: Mohamed Ouessar, Donald Gabriels, Atsushi Tsunekawa, Steven Evett

Verlag: Springer International Publishing


Über dieses Buch

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 climate change. As water and land are the essential bases of food production, the management of these natural resources is becoming a cornerstone for the development of dryland populations. The book gathers the peer-reviewed, revised versions of the most outstanding papers on these topics presented at the ILDAC2015 Conference in Djerba, Tunisia.


Chapter 1. A Study of Water Stress on Olive Growing Under the Effect of Climate Change in South East of Tunisia
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 (ETCadj) 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.
A. Hachani, Mohamed Ouessar, A. Zerrim
Chapter 2. Climate Change Impacts in the Maghreb Region: Status and Prospects of the Water Resources
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.
L. Oualkacha, L. Stour, A. Agoumi, A. Kettab
Chapter 3. Effect of High Temperature Stress on Wheat and Barley Production in Northern Tunisia
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.
Asma Lasram, Mohamed Moncef Masmoudi, Netij Ben Mechlia
Chapter 4. Study of Managed Aquifer Recharge and Climate Change, Using a Numerical Model: The Figuig Aquifer (Eastern High Atlas, Morocco)
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.
Abdelhakim Jilali, Abderrahmane El Harradji
Chapter 5. Calibration of AquaCrop Salinity Stress Parameters for Barley Under Different Irrigation Regimes in a Dry Environment
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).
F. El Mokh, Vila-Garcia, K. Nagaz, Mohamed Moncef Masmoudi, N. Ben Mechlia, E. Fereres
Chapter 6. Groundwater Recharge of the Kairouan Plain Aquifer: Evidence of Preferential Flow Paths Through the El Haouareb Limestones?
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.
Amal Sebai, Sylvain Massuel, Jamila Tarhouni, Hamza Jerbi
Chapter 7. Evapotranspiration of Wheat in a Hilly Topography: Results from Measurements Using a Set of Eddy Covariance Stations
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.
N. Boudhina, Mohamed Moncef Masmoudi, N. Ben Mechlia, R. Zitouna, I. Mekki, L. Prévot, F. Jacob
Chapter 8. Performance of Saxton and Rawls Pedotransfer Functions for Estimating Soil Water Properties in the Cap Bon Region-Northern Tunisia
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.
I. Alaya, Mohamed Moncef Masmoudi, Ph. Lagacherie, G. Coulouma, F. Jacob, N. Ben Mechlia
Chapter 9. Assessing the Groundwater Pollution Problem by Nitrate and Faecal Bacteria: Case of Djerba Unconfined Aquifer (Southeast Tunisia)
Djerba unconfined sandy aquifer (Southeast of Tunisia) is affected by several contamination phenomenon such as seawater intrusion and anthropogenic activities. This study aims to assess nitrate and faecal pollution in groundwater. More than 70 wells were sampled and analyzed. Geochemical assessment was used to understand the pollution origin and factors controlling this process in Djerba aquifer. Chemical and bacteriological analysis confirms that the sampled wells were seriously affected by both nitrate and faecal pollution problem. Chemical analysis shows that 51% of sampled wells have a nitrate levels more than 50 mg/l. The bacteriological results demonstrated that 95% of wells showed total coliforms densities higher than 10 CFU/100 ml. Thermotolerants coliforms and Escherichia coli were detected in all groundwater sampled (96% of wells). These results confirm the impact of anthropogenic activities on groundwater quality. It seems that this contamination is directly related to septic tanks, which are not waterproof; allow the infiltration of the major part of the liquid phase.
Faiza Souid, Belgacem Agoubi, Adel Kharroubi
Chapter 10. Monitoring Soil Moisture Content of Jessour in the Watershed of Wadi Jir (Matmata, Southeast Tunisia)
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
  • The jesr ensures water storage in soil, which varies on average between 100 m and 200 mm. However, in wet periods, this storage jesr can exceed 300 mm but can drop as low as 50 mm in dry periods (as recorded in the jesr of Téchine).
  • Only one effective rainfall annually can ensure adequate water supply for the rest of the hydrological year. During wet periods, olive trees extract water from upper soil horizons whereas they exploit the deeper horizons during summer and drought periods.
  • The use of the theoretical potential at permanent wilting point of pF = 4.2 seems to be inadequately adapted to olive extraction capabilities and tends to underestimate the amount of water that the adult olive trees can extract.
  • Thus, jessour can adequately ensure water supply of olive trees while ensuring effective erosion control in the mountains of Matmata and landscape ecology enhancement.
Fethi Abdelli, Mohamed Ouessar, Salah M’Hemdi, Messaoud Guied, Houcine Khatteli
Chapter 11. Direct and Residual Effect of Sewage Sludge in a Sudangrass-Barley Cropping System
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.
Rajia Kchaou, Mohamed Naceur Khelil, Saloua Rejeb, Belgacem Henchi, Jean Pierre Destain
Chapter 12. Aflaj’ Water Management in Oman: The Case of Falaj Al-Khatmeen in Birkat Al-Mouz, Wilayat Nizwa
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.
Fairouz Megdiche-Kharrat, Mohamed Moussa, Hichem Rejeb
Chapter 13. Response of Vegetable Crops to Irrigation Regimes Using Saline Waters
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.
K. Nagaz, F. El Mokh, Mohamed Moncef Masmoudi, N. Ben Mechlia, O. Belkheiri, G. Ghiglieri
Chapter 14. Fog Collection and Participatory Approach for Water Management and Local Development: Practical Reflections from Case Studies in the Atacama Drylands
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:
  • to fulfil the water needs of small isolated communities;
  • allows activities like proximity agriculture and reforestation for the rural population;
  • to support biodiversity’s preservation and scientific research.
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.
Martino Correggiari, Giulio Castelli, Elena Bresci, Fabio Salbitano
Chapter 15. Salt and Water Dynamic of Potato Crop Under Irrigation with Low Quality Waters
In Tunisia, the scarcity of water for irrigation and the quality of available resources make it necessary to adopt strategies of water management aimed to increase water use efficiency. If from one side, choosing an appropriate irrigation system, like a well-designed subsurface drip system can ensure high values of water distribution uniformity, increasing water use efficiency requires that irrigation scheduling account for actual crop water requirement, depending on soil, plant, climate, and other local conditions. During the growing season (2014) to investigate the effects of low water quality and scheduling on water’s dynamic in soil (soil water content moisture distribution, water’s stock variation) and water use efficiency (WUE) to produce potato (Solanum tuberosum L.). Subsurface drip irrigation was used for two treatments T1 and T2; T2 was irrigated 50% of T1. During the crop season soil water During the crop season soil water content variation was more important at the end due to root uptake and hard climatic condition, treatment T2 had less water stock and best water use efficiency with 10.83 kg/ha than 5.85 kg/ha for T1.
Mguidiche Belhaj Amel, Gazouani Hiba, M’hamdi Douh Boutheina, Boujelben Abdehamid
Chapter 16. Development of Methodology for Existing Rainwater Harvesting Assessment in (semi-)Arid Regions
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.
Ammar Adham, Michel Riksen, Mohamed Ouessar, Rasha Abed, Coen Ritsema
Chapter 17. Impact of Anthropogenic Activities on Erosive Behavior of Nebhana Watershed Tunisia
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.
Taoufik Hermassi, Hacib El Ammami, Walid Ben Khelifa
Chapter 18. Short-Term Effects of Olive Mill Wastewater Spreading on Chemical Properties of Soils in Arid Lands, Study Case from Southern Tunisia
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.
Donia Jendoubi, Houcine Taamallah, Khadija Bouajila, Ahlem Gara, Mohamed Moussa, Mustapha Sanaa
Chapter 19. Spatio-Temporal Evolution of the Fragmentation Classes of the Mikea Dry Deciduous Forest (Southwestern Madagascar)
In southwestern Madagascar, the Mikea forest is a highly diverse ecosystem of great biodiversity, which mixes dry deciduous forest in the eastern part and xerophytic thicket in the western coastal area. However, dry forests and shrubs are rapidly destroyed due to slash-and-burn cultivation (hatsaky) and exploitation of forest resources by riparian communities and external operators. The aim of this paper is to evaluate forest fragmentation in the Mikea national park, by comparing past and recent forest maps. The analysis of forest fragmentation is based on landscape indices. The changes in forest cover have been detected from time-series SPOT satellite images registered over 15 years (1999, 2005, and 2014). Between 1999 and 2014, forest area is reduced by 39.8% which is equivalent to an annual forest loss rate of 4.6%. The forest fragmentation is associated with a significant decrease in forest patch size. The mean patch size decreases from 37,228 to 18,731 ha from 1999 to 2014. The primary direct causes are economic driven due to intense anthropogenic activities such as wood charcoal production, logging, accompanied by frequent wild land fires. The indirect cause is the absence of a sustainable environmental management and conservation strategy.
Hibraim Rijasoa Ravonjimalala, Jan Bogaert, Dominique Hervé, Samuel Razanaka, Jaona Ranaivo, Herizo Randriambanona, Solofo Rakotondraompiana
Chapter 20. The Impact of Atmospheric Pollution on the Chemical Composition of Soil Around Gabes Cement Plant Southeastern Tunisia
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.
Ines Terwayet Bayouli, Houssem Terwayet Bayouli, Mohamed Tarhouni, Mohamed Nefatti
Chapter 21. Contribution of Hyperspectral Images (Hyperion) and Spectroscopy for Mapping Soil’s Surface and Materials (Case of the Watershed of Oued Beni Zalten, the New Matmata, Tunisia)
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.
Imen Ben Haj Yahia, Aziza Ghram Messedi
Chapter 22. Use of Remote Sensing and GIS for Land Degradation Assessment of Qarun Lake Coastal Area, El-Fayoum, Egypt
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.
M. M. Kotb, R. R. Ali, M. A. El Semary
Chapter 23. Classification Methods for Detecting and Evaluating Changes in Desertification-Related Features in Arid and Semi-arid Environments
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).
Gabriela Mihaela Afrasinei, Maria Teresa Melis, Cristina Buttau, Claudio Arras, Amar Zerrim, Messaoud Guied, Mohamed Ouessar, Bouajila Essifi, Mongi Ben Zaied, Amor Jlali, Hanen Jarray, Giorgio Ghiglieri
Chapter 24. Evaluation and Validation of SRTMGL1 and ASTER GDEM2 for Two Maghreb Regions (Biskra, Algeria and Medenine, Tunisia)
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.
Claudio Arras, Maria Teresa Melis, Gabriela-Mihaela Afrasinei, Cristina Buttau, Alberto Carletti, Giorgio Ghiglieri
Chapter 25. An Integrated Cost–Benefit and Livelihood Approach for Assessing the Impact of Water Harvesting Techniques (WHTs) on Livelihoods: A Case Study in the Oum Zessar Watershed, South-East Tunisia
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.
Mohamed Arbi Abdeladhim, Mongi Sghaier, Luuk Fleskens, Mohamed Ouessar
Chapter 26. Assessing the Impacts of Climate Change on Sustainable Development at the Regional Level: A Case Study in Medenine, South-East Tunisia
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.
Mohamed Arbi Abdeladhim, Mongi Sghaier, Luuk Fleskens, Lindsay Shutes, Abdallah Akari
Chapter 27. How Investment in RD&E Offset the Negative Impact of Climate Change on the Tunisian Agricultural Productivity Sector
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.
Boubaker Dhehibi, Aymen Frija, Aden Aw-Hassan
Water and Land Security in Drylands
herausgegeben von
Mohamed Ouessar
Donald Gabriels
Atsushi Tsunekawa
Steven Evett
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