River meandering, climate change and terraces

Fill-cut and strath terraces flank the margins of many river channels, and offer unique subaerial archives of river history. The information held by terraces may also aid in decoding connections between terrestrial sediment sources and marine sinks. A long-standing and widespread hypothesis is that strath terraces record changes in the ratio of lateral to vertical erosion rates of bedrock, whereby platforms eroded by lateral migration are abandoned during abrupt periods of local incision. Several mechanisms have been proposed to alter partitioning between lateral and vertical erosion, including tectonic events, intrinsic instabilities in the erosion processes, and most frequently, climate change. Conversely, terraces may also form from lateral migration and continuous incision, or from pulses of incision caused by intrinsic river dynamics (e.g., neck cutoffs). Few tools currently exist to distinguish terraces that record intrinsic stream dynamics from those that record events with significance for the depositional record. To address this knowledge gap, we have constructed a numerical model to simulate terrace formation of a meandering single-thread river under a variety vertical and lateral erosion rates. The model also includes a novel, fully automated algorithm to detect river terraces and extract their ages, dimensions, and spatial orientations. Through combined analysis of simulated landscapes and remote sensing data, we seek reliable geometric and age fingerprints for different terrace-forming mechanisms.