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This paper analyzes the complex relationships of factors influencing residue biomass management in cereal–sheep production systems in semi-arid areas of Tunisia. The Bayesian belief network (BBN) methodology was applied to identify factors enabling the better management of crop residue (CR) at the farm level. Data were collected from 152 farms located in the governorate of Siliana in north-west Tunisia. After designing the complex interactions between different variables that have an influence on the allocation of CR, BBN was also applied as a predictive model by inserting evidence conditional probabilities on the quantity of CR left on the soil and simulating the incurrent changes in the probability state of the remaining network variables. The results show that around 70% of farmers in our sample retain an overall quantity of CR lower than 200 kg/ha. The share of livestock income, livestock herds, cost of livestock feed, and off-farm income are all factors that have a strong influence on residue biomass management.

People living in arid and semi-arid areas with highly variable rainfall and unforeseeable periods of droughts or floods are severely affected by water shortages and often have insecure livelihoods. The construction of dams in wadies to harvest rainwater from small watersheds and to induce artificial groundwater recharge is one of the solutions available to overcome water shortages in the Western Desert of Iraq. The success of rainwater harvesting (RWH) systems depends heavily on their technical design and on the identification of suitable sites. Our main goal was to identify suitable sites for dams using a suitability model created with ModelBuilder in ArcGIS 10.2. The model combined various biophysical factors: slope, runoff depth, land use, soil texture, and stream order. The suitability map should be useful to hydrologists, decision-makers, and planners for quickly identifying areas with the highest potential for harvesting rainwater. The implementation of this method should also support any policy shifts towards the widespread adoption of RWH. Keywords: GIS, Rainwater harvesting, Iraq's western desert, Suitability map

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.