Process, form and change in dryland rivers: a review of recent research

Urban transformation of river landscapes in a global context

Soil erosion by water is one of the most important land degradation processes in Mediterranean environments. This process is strongly linked to problems of flooding and channel management. This art...

Erosion, flooding and channel management in Mediterranean environments of southern Europe:

Hyperconcentrated flow — transitional process between water flow and debris flow

Discontinuous ephemeral streams

GEOMORPHOLOGISTS have thought for some time that rates of sediment transfer might differ markedly in ephemeral and perennial rivers, and have used this idea to explain both the changing character of sedimentary successions and the morphology of rivers in sub-humid or semi-arid areas that have experienced significant shifts in climate during the Quaternary period1−5 But until now there has been a lack of suitable field data to confirm this suggestion, mainly because floods in arid zones are infrequent and unpredictable Here we present bedload sediment transport data for an ephemeral river in Israel, which show it to be, on average, as much as 400 times more efficient at transporting coarse material than its perennial counterparts in humid zones This suggests that existing predictive sediment transport equations24, developed and calibrated exclusively with data obtained in perennial rivers, are inadequate for application to rivers in arid environments It also suggests that areas that are at risk of shifting from sub-humid to semi-arid conditions as a result of prospective global changes in climate may suffer severe sedimentation problems

lan Reid

Papers

Very high rates of bedload sediment transport by ephemeral desert rivers