Many of the world’s extensive warm dryland regions support numerous river systems.  Some of these rivers may remain dry for long periods of time (intermittent or ephemeral rivers) but nonetheless many play a central role in landscape change, provide a wide range of ecosystems services, and exert a strong influence on human use of these marginal environments.  In 2000, I published a global overview of dryland fluvial geomorphological research and highlighted how findings emerging from places like central Australia were demonstrating much greater diversity in dryland river process, form and change than hitherto had been appreciated (Tooth, 2000, Earth-Science Reviews, v.51).  My review pinpointed areas of deficiency in dryland fluvial geomorphological research, including: 1) limited study of some aspects of modern dryland rivers (floodplain characteristics, influence of vegetation, downstream changes, importance of scale); 2) limited understanding of dryland river behaviour over longer (Cenozoic) timescales; and 3) lack of integration between the results from short-term, process-form studies and studies of the longer term histories of river behaviour.  In addition, I suggested that linking knowledge of past hydrological and channel changes to present-day dryland river changes should be a key research priority.  I argued that such research was a way to provide a sound theoretical basis for the assessment of future developments in dryland rivers, thereby contributing both to improved scientific understanding and to environmentally sensitive management,

25 years later, where is the field of dryland fluvial geomorphology?  To what extent has research in central Australia and other drylands helped expand our understanding of river process, form and change?  How has research progressed in relation to the identified areas of deficiency?  What new research themes and priorities have arisen?  Can we make sound projections of future developments in dryland rivers, and to what extent are such projections accounted for in river management policy and practice?

Drawing on field experiences in Australia, Africa, southern Europe, Asia, and North and South America, and with reference to a rapidly expanding corpus of literature, in this presentation I will address these and other questions.  I will conclude by illustrating how dryland fluvial geomorphological research can dovetail productively with other aspects of dryland (desert) science and its application, including aeolian and extraterrestrial geomorphology, pedology, ecology, archaeology, and land and water management.