Hydrogeomorphological differentiation between floodplains and terraces

Abstract

Floodplains and terraces in river valleys play important roles in the transport dynamics of water and sediment. While flat areas in river valleys can be identified from LiDAR data, directly characterizing them as either floodplain or terraces is not yet possible. To address this challenge, we hypothesize that, since geomorphic features are strongly coupled to hydrological and hydraulic dynamics and their associated variability, there exists a return frequency, or possibly a narrow band of return frequencies, of flow that is associated with floodplain formation; and this association can provide a distinctive signature for distinguishing them from terraces. Based on this hypothesis we develop a novel approach for distinguishing between floodplains and terraces that involves transforming the transverse cross-sectional geometry of a river valley into a curve, named a river valley hypsometric (RVH) curve, and linking hydraulic inundation frequency with the features of this curve. Our approach establishes that the demarcation between floodplains and terraces can be established from the structure of steps and risers in the RVH curves which can be obtained from the DEM data. Further, it shows that these transitions may themselves be shaped by floods with 10-to 100-year recurrence. We additionally show that, when floodplain width and height (above channel bottom) are normalized by bankfull width and depth, the ratio lies in a narrow range independent of the scale of the river valley.

A web application for hydrogeomorphic flood hazard mapping

“…• establishing of statistical relations among the morphological descriptor, climatic and catchment factors (e.g., Jafarzadegan and Merwade, 2017); • seasonal variability, spatial dependence and spatial heterogeneity of extreme flood events (e.g., Castellarin et al, 2007;Neal et al, 2013); • estimation of channel and floodplain hydraulic geometries (e.g., Nardi et al, 2006;Andreadis et al, 2013;Zheng et al, 2018) and hydrogeomorphology (Yan et al, 2018);…”

Three‐Dimensional Modeling of the Coevolution of Landscape and Soil Organic Carbon

“…Even though the six sample cores are close to the Clear Creek, the main sediment deposition source is assessed to come from upland not flood deposition. The influence of sediment deposition from flood can be excluded because the six sampling cores are in a terrace zone (Yan et al, ), and all of them are outside of the flood area from the Federal Emergency Management Agency flood map (http://msc.fema.gov/portal).…”

Designing a network of critical zone observatories to explore the living skin of the terrestrial Earth

“…In other words, observatories induce scientists from different disciplines to make measurements using different disciplinary approaches at the same location instead of making them at disparate sites, driving cross-disciplinary understanding in describing CZ function (Hynek et al, 2017;Sullivan et al, 2016;Yan et al, 2017;Chen et al, 2017, in press). At first, much of the synthesis crossed only two disciplines at a time: for example, several papers emphasized how geomorphological concepts related to erosion must be incorporated to understand chemical weathering, and vice versa (Rempe and Dietrich, 2014;Riebe et al, 2016).…”

“…A full elucidation of hypotheses is beyond the scope of this paper and only a subset is shown in Table 4. Many have been published in collaborative papers (Rempe and Dietrich, 2014;Riebe et al, 2016;Li et al, 2017;Pelletier et al, 2017;Yan et al, 2017;Brantley et al, 2017a). Here we summarize three multidisciplinary discoveries that have large implications for the prediction of flow paths relevant to the largest supply of accessible and drinkable water available to humans -water contained in rock and regolith (Fetter, 2001;Banks et al, 2009).…”