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Semi-arid areas are found in a large number of countries and regions of Africa and South and Central Asia. They display high vulnerability to climate change with considerable adaptation needs. In this paper, we review country-level and multi-country projects supported by international agencies. We examine the priorities and goals presented in national adaptation planning documents and in sectorial planning documents. Through this analysis, we seek to compare adaptation needs with current trends in national, regional and global projects and collaborations. Our results suggest that initiatives supported by international agencies play a considerable role in achieving national adaptation priorities, especially in areas such as agriculture and water management. However, compared with specific adaptation options such as drought-resistant species and irrigation (which tend to be the scope of the projects), the analyzed documents tend to see challenges in agriculture more in the contexts of food security, livestock and rural development. They emphasize the strong connection between rural livelihoods and sustainable land and ecosystem management. Priorities listed in the national documents but not captured in current initiatives include human health, pastoralism, security and migration. Our results also show high levels of mainstreaming adaptation into sectorial planning documents, especially those on poverty reduction; however, compared with the focus on the project level, they here emphasize adaptations focused on institutional development and governance. Finally, the outcomes indicate that global, regional and national initiatives are distributed unequally and that countries in Central and West Africa and Central Asia currently exhibit low participation, especially in national projects.

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Mathematical modelling and computer simulation of grain drying are now widely used in agricultural engineering research. Several models have been proposed to describe the heat and mass transfer processes involved in the drying of agricultural products. Most of these models, however, have been derived under assumptions that are not explicitly stated and that restrict their applications from the outset. Furthermore, it is not always clear what differences, if any, exist between various models. The purpose of this paper is to provide a general framework from which mathematical models for any type of drier may be derived. We illustrate the use of this framework by deducing equations for the four basic types of convective grain drier, namely fixed bed, crossflow, concurrent flow and counterflow. Finally we discuss some of the differences between the models thus obtained and those of other workers.