Prolonged Response of River Terrace Flooding to Climate Change

Abstract

From the start of river incision onward, the abandoned terrace surface is only reached by floods during peak discharges. Two main flood facies are distinguished: a relatively high-energetic, coarse-grained facies and a relatively low-energetic, fine-grained facies. In general, the flood deposits become gradually finer-grained and the finer-grained facies relatively more prominent when the river incises progressively deeper. This signifies a delayed and prolonged effect of channel incision and flood deposition compared with the climate changes that initiated the incision. However, these long-term trends may be interrupted by shorter-term events of flooding or non-deposition. Those short events are expressed by cycles of coarse-grained deposits from small/shallow flooding channels due to short peak discharges or fine-grained suspended sediment and incipient soils during periods of low flow. These short events may be attributed to short climatic episodes or intermittent intrinsic river evolution.