Implementing Landscape Connectivity with a Topographic Filtering Model
Abstract
The widespread availability of high-fidelity topography, combined with advances in geospatial analysis, offer the opportunity to reimagine approaches to the difficult problem of predicting sediment delivery from watersheds. Here we present a model, Topofilter, that uses high-resolution topography to link sediment sources to sediment delivery to the watershed outlet. It is a reduced-complexity, top-down model that defines transfer functionsa topographic filterbetween spatially distributed sediment sources and spatially integrated sediment delivery. The goal of the model is to forecast changes in watershed sediment delivery in response to spatially distributed changes in sediment source magnitude or delivery, whether a result of watershed drivers or intentional management actions. Such an application requires the context of a watershed model that accounts for all sediment sources; enforces sediment mass balance throughout the spatial domain; and accommodates sediment storage and delivery over time. Study watershed (HUC-8) is characterized by flat upland terrain dominated by corn-soybean agriculture, contrasted by deeply incising river system near the watershed outlet with an outsized sediment contribution from near-channel sources. Topofilter computes delivery and storage of field-derived sediment according to its spatial and structural connectivity to the stream channel network; subsequently, delivery of both field- and near-channel-derived sediment, along with floodplain storage, are computed in the stream channel network to the watershed outlet. The model outputs provide spatially rich representation of sediment delivery and storage on field and along stream channel network that is consistent with available independent information on sediment accumulations and fluxes in the study watershed. Topofilter does not find a single best-calibrated solution, instead the Generalized Likelihood Uncertainty Estimate (GLUE) method was adopted to develop many possible solutions with sediment delivery rates expressed as frequency density functions across the watershed. The ensemble of simulation outputs provides a useful basis for estimating uncertainty in sediment delivery and the effectiveness of different landscape management allocation across a watershed.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.H12D..06C