Search

Over the next few years, Tunisia will face a growing scarcity of water. The concept of a food consumption water footprint has been recently applied to expand knowledge about water management and to respond to problems of food insecurity. In this study, following the Water Footprint Network (WFN) method, we assessed and analysed the food consumption water footprint of Tunisian households by geographical location and by group of food products. We used results from national food surveys to collect the quantities of food consumed and the WFN database containing water footprints of food products specific to Tunisia. We found that the average water footprint for the main consumed food groups has increased by 31% during recent decades, from 1208 m3/capita/year in 1985 to 1586 m3/capita/year in 2010. Despite the decline in cereal consumption in Tunisia, the food water footprint has continued to rise as a result of increased consumption of animal source products. This increase is associated with regional variations in food choices that imply large differences in water footprints. Urban diets present higher water footprints than rural diets proportionally to higher standards of living. This study provides a new perspective on the water footprint of food consumption in Tunisia by using dietary data at the household level and demonstrated significant variability in water footprints due to different food consumption modes, and socio-economic and geographic characteristics. Future food consumption trends will likely create more pressure on water resources, especially in Tunis city and coastal areas of Tunisia. Special measures related to price policies, sensitization of consumers, and changes in production systems may have to be taken by policy makers to reduce the water footprint in order to improve food security strategies and water management in Tunisia.

Water scarcity and water quality degradation are important problems that can affect human well-being. Population growth, unplanned urbanization, land-cover change, and the intensification of agricultural and industrial activities are the main reasons for water resource issues. The main aim of this work was to evaluate the effect of land-cover change on groundwater quality in the Chiba watershed, Nabeul, Tunisia. A remote-sensing technique was used to identify the principal transitions in land cover between 1998 and 2018. Additionally, four water quality indicators (electrical conductivity, chloride concentration, nitrate concentration, and sodium absorption ratio) were utilized to investigate variations in water quality in the study area. It was found that most of the watershed was covered with agricultural land in 1998 (87.5%) and 2018 (88.6%). Based on a comparison of these two periods, various types of land-cover transitions were observed. Moreover, the water quality indicators revealed that the salinity hazard and nitrate contamination in the watershed were high. The spatial relationship between water contamination level and land-cover transition category indicated that barren land to built-up land transitions had the strongest negative effect on water quality among all of the main land-cover transitions. Demonstrating the impact of land-cover change on water quality should encourage local decision makers and water managers to implement strategies for sustainable urban planning and periurban agriculture.

The main objective of this study is to estimate the total economic loss due to inefficient use of irrigation water in Tunisia. Several approaches have been used for this purpose. The optimal level of water application for different crops is calculated using the actual crop evapotranspiration which is based on FAO-56 method. The residual imputation and yield comparison methods have been used to estimate the economic value of irrigation water for different irrigated crops in different bioclimatic areas. For the empirical analysis, primary data were obtained from a series of surveys that covered 78% of the total irrigated areas and were collected within the framework of the “Virtual Water and Food Security in Tunisia project” (2013–2015). Secondary data about land distribution of crops in Tunisia were taken from the Ministry of Agriculture (2016). Around 724 farms were randomly sampled considering their bioclimatic area, farm type, and production system. The survey included the main 20 crops produced in Tunisia. Results show that most of farmers are either under or over utilizing irrigation water. The value of total direct economic losses, at the country level, of both types of water inefficiencies, was estimated to around 470 million Tunisian Dinars. Therefore, an improvement of water use efficiency at field level through dissemination of information/knowledge on irrigation scheduling and crop water requirements by extension services to farmers is needed to reduce this huge economic loss, reach higher sustainability in water use and improve food security.

37 Pags., 6 Figs., 3 Tabls. The definitive version is available at: http://www.sciencedirect.com/science/journal/15375110, The radial water distribution and irrigation performance of an agricultural sprinkler with plastic nozzles were analysed. Twenty-six tests with an isolated sprinkler corresponding to different combinations of three working pressure (p, 200, 300 and 400kPa) and three nozzle diameters of the main nozzle (4.0, 4.5 and 5.0mm) were performed to evaluate the radial water distribution curves, All the tests were performed under calm wind (≤1ms-1) under open air conditions. Fifty tests corresponding to six combinations of nozzle diameter and pressure with the same sprinkler model were performed under a wide range of meteorological conditions in a rectangular solid-set system at 18m×18m sprinkler spacing to evaluate the Christiansen's Uniformity Coefficient (CUC) and wind drift and evaporation losses (WDEL). The resulting radial water distribution curves were compared with those from impact sprinklers with brass nozzles. Sprinkler model had an important effect on the radial water distribution, even under similar operational conditions, and these differences were shown in the first 2.5-6m from the sprinkler. The CUC and WDEL of a solid-set sprinkler system were compared with simulated values from the >Ador-Sprinkler> model. The results of this analysis showed that the type of sprinkler had a moderate influence on sprinkler irrigation uniformity. The analysis presented in this study may serve to develop a decision tool to choose the most suitable combinations of sprinkler model, nozzle diameter and working pressure to optimise the uniformity and efficiency of sprinkler irrigation., This research was funded by the MCINN of the Government of Spain through grants AGL2007-66716-C03-01/02, AGL2010-21681-C03-01/03; the European Commission through grant QUALIWATER (INCO-CT-2005-015031) and by the FPI-MICINN PhD grants programme.

39 Pags., 6 Tabls., 4 Figs. The definitive version is available at: http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1475-2743

49 Pags., 3 Tabls., 6 Figs. The definitive version is available at: http://link.springer.com/journal/271, Gross sprinkler evaporation losses (SELg) can be large and decrease irrigation application efficiency. However, it is not universally established how much of the SELg contributes to decrease the crop evapotranspiration during the sprinkler irrigation and how much are the net sprinkler losses (SELn). The components of SEL were the wind drift and evaporation losses (WDEL) and the water intercepted by the crop (IL). The gross WDEL (WDELg) and evapotranspiration (ET) were measured simultaneously in two alfalfa (Medicago sativa L.) plots, one being irrigated (moist, MT) and the other one not being irrigated (dry, DT). Catch can measurements, mass gains and losses in the lysimeters and micrometeorological measurements were performed to establish net WDEL (WDELn) during the irrigation and net IL (ILn) after the irrigation as the difference between ETMT and ETDT. Also, equations to estimate ILn and net sprinkler evaporation losses (SELn) were developed. ILn was strongly related to vapor pressure deficit (VPD). SELn were 8.3% of the total applied water. During daytime irrigations, SELn was 9.8% of the irrigation water and slightly less than WDELg (10.9%). During nighttime irrigations SELn were slightly greater than WDELg (5.4% and 3.7%, respectively). SELn was mainly a function of wind speed., This research was funded by the MCINN of the Government of Spain through grants AGL2007-66716-C03-01/02, AGL2010-21681-C03-01/03; the European Commission through grant QUALIWATER (INCO-CT-2005-015031) and by the FPI-MINECO PhD grant program.

To confront water scarcity and support food security, the concept of virtual water is used. As defined by Allan (1997) virtual water is "the water embedded in key water-intensive commodities such as wheat" or "the water required for the production of commodities". The importance of this concept is related to its potential contribution for saving water, especially in water short regions like Tunisia. This research study tries to evaluate the strategic importance of polluted or gray water, which is a component of virtual water. Reduction of virtual water for strategic agricultural products can be obtained by the gray water reduction. The latter is defined as "water required diluting polluted water to reach the normalized quality, different with countries". Water pollution is especially related to use of chemical products (fertilizers, pesticides, etc.) for some crops like vegetables. Besides having a lower opportunity cost, the use of green water for crop production has generally less negative environmental externalities than the use of blue water (irrigation with water abstracted from ground or surface water systems). Tunisia exports some crops and gray water volumes in exports have rarely been estimated. Thus, estimation of gray water plays a role in ensuring water and water-dependent food security and avoiding further potential damage to the water environments in both importing and exporting countries. In this context, Tunisian semi-arid region is chosen because the presence of a long period of dry and shiny, occurring after a cold and rainy one, useful for vegetables crops and family food security. The aim of this study is to present: Methodologies which can be used to reduce virtual water for some strategic vegetables crops in Tunisian semi-arid region, based on irrigation techniques improvements and the control of runoff and leaching water; Resources management practices that can be used to improve family income, especially women and children and target food security.