Active Valley Meanders in South-Central Texas and Their Wider Implications
Active valley meanders are identified and some of their physical and hydrological characteristics described. A detailed study of a small catchment shows the channel morphology and valley floor to be in equilibrium. The implications of the active valley meanders are considered in terms of previously described fossil forms in high latitudes and in terms of the normal development of a fluvial landscape with incising streams. The appearance of a flood-plain may be independent of the hydrological regime of a basin and the cause of a reduction in flow effectiveness rather than the result of a real reduction in flow. Effective flows in valley meander formation have a recurrence interval from 10 to 50 yrs, and this constitutes a chanel-full flow that shapes the meanders. Identification of such flows with a recurrence interval from 1 to 2 yrs (as for bankfull flow in alluvial streams) may have led to overestimates of the past discharges and climatic parameters.