Examines the processes operating in the headwaters and main channels of ephemeral rivers in semi-arid environments and includes coverage of current fieldwork investigations, modeling approaches, and management issues. focuses on dryland channel networks and processespresents a historical framework for researchdiscusses examples of current studies and evaluates contemporary modelling approachesEmphasis is on the Mediterranean region, with comparisons to other dryland regimes eg California, Australia, Chile.