Levee morphology and sedimentology along the lower Tuross River, south-eastern Australia

Levees on the lower Tuross River in south-eastern, Australia reflect a comp lex interplay between depositional and erosional processes. Stream power, c onditioned primarily by valley width, is the key determinant of levee morph ology and sedimentology ill this confined valley setting. Three styles of l evee are described. The Rewlee levee is functionally linked to a flood chan nel in narrow valley settings (< 250 m). These levees contain a diverse fac ies assemblage characterized by various scales of erosion surfaces. Vertica l accretion on levees has produced conditions under which stream power valu es exceed the threshold for catastrophic floodplain stripping. The levee at the Mortfield site is associated with less confined settings (valley width 500-600 m), which present lower flood stage and stream power conditions. T his levee hosts a wide range of facies, but erosion surfaces are seldom obs erved. In the more open valley setting at the Central site (valley width 70 0-1000 m), levees comprise uniform, fine-grained deposits, which grade to p ronounced distal floodplains with backswamps. As levees reflect a combinati on of within-channel and overbank processes, both depositional and erosiona l, these geomorphic features influence the character and sedimentology of a djacent landforms and the associated alluvial architecture of the basin.