Abstract. Changes in water resources availability can be expected as consequences of climate change, population growth, economic development and environmental considerations. A two-stage modeling approach is used to explore the impact of these changes in the Middle East and North Africa (MENA) region. An advanced, physically based, distributed, hydrological model is applied to determine the internal and external renewable water resources for the current situation and under future changes. Subsequently, a water allocation model is used to combine the renewable water resources with sectoral water demands. Results show that total demand in the region will increase to 393 km 3 yr −1 in 2050, while total water shortage will grow to 199 km 3 yr −1 in 2050 for the average climate change projection, an increase of 157 km 3 yr −1 . This increase in shortage is the combined impact of an increase in water demand by 50 % with a decrease in water supply by 12 %. Uncertainty, based on the output of the nine GCMs applied, reveals that expected water shortage ranges from 85 km 3 yr −1 to 283 km 3 yr −1 in 2050. The analysis shows that 22 % of the water shortage can be attributed to climate change and 78 % to changes in socioeconomic factors.

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When vulnerable population groups are numerically small -as is often the case -obtaining representative welfare estimates from non-purposive sample surveys becomes an issue. Building on a method developed by Elbers et al., it is shown how, for census years, estimates of consumption poverty for small vulnerable populations can be derived by combining sample survey and population census information. The approach is illustrated for Uganda, for which poverty amongst households with disabled heads is determined.

Malnutrition is associated with an inadequate diet, poor health and sanitation services and insufficient care for young children. A combination of income growth and nutrition interventions are therefore suggested to adequately tackle this issue (Haddad et al. 2003), yet evidence to support this claim is often not available, especially for African settings. This paper evaluates the joint contribution of income growth and nutrition interventions towards the reduction of malnutrition. Using a four round panel data set from northwestern Tanzania we estimate the determinants of a child's nutritional status, including household income and the presence of nutrition interventions in the community. The results show that better nutrition is associated with higher income, and that nutrition interventions have a substantial beneficial effect. Policy simulations make clear that if one intends to halve malnutrition rates by 2015 (the MDG objective), income growth will have to be complemented by large scale program interventions.

As mobile phone ownership rates have risen in Africa, there is increased interest in using mobile telephony as a data collection platform. This paper draws on two pilot projects that use mobile phone interviews for data collection in Tanzania and South Sudan. In both cases, high frequency panel data have been collected on a wide range of topics in a manner that is cost effective, flexible and rapid. Attrition has been problematic in both surveys, but can be are explained by the resource and organisational constraints that both surveys faced. We analyse the drivers of attrition to generate ideas for how to improve performance in future mobile phone surveys. RÉSUMÉ Le taux de propriété du portable ayant augmenté en Afrique, on manifeste de plus en plus d'intérêt dans l'usage de cette technologie comme moyen de recueillir des données. Cet article présente deux projets pilotes ayant eu recours au portable pour des fins de cueillette de données par entretien, en Tanzanie et au sud de Soudan. Dans les deux cas, des données sur une grande variété de sujets ont été fréquemment collectées auprès d'un panel, de manière flexible et rapide, avec un bon rapport coût/efficacité. Le taux d'abandon a toutefois posé problème dans les deux enquêtes, mais il peut être attribué à des contraintes organisationnelles et au manque de ressources. Les facteurs qui peuvent expliquer ce haut taux d'abandon sont examinés afin de trouver des solutions pour améliorer la performance des futures enquêtes utilisant le portable.