Closing the Gap Between Watershed Modeling, Sediment Budgeting, and Stream Restoration

Abstract

(2011), Closing the gap between watershed modeling, sediment budgeting, and stream restoration, in Stream Restoration in Dynamic Fluvial Systems: Scientific Approaches, Analyses, and Tools, Geophys. Monogr. Ser., vol. 194 The connection between stream restoration and sediment budgeting runs both ways: stream restoration is proposed as a means to reduce sediment yields, but an accurate understanding of sediment supply is necessary to design an effective project. Recent advances in monitoring technology, geochemical techniques, high-resolution topography data, and numerical modeling provide new opportunities to estimate sediment erosion, transport, and deposition rates; upscale them in a geomorphically relevant fashion; and synthesize sediment dynamics at watershed scales. For practical application at large scale, watershed models used to predict yield often do not resolve lower-order channels, leaving an essential "blind spot" regarding sediment processes. We illustrate the challenges and emerging approaches for estimating sediment budgets using examples from two very different physiographic settings: the Mid-Atlantic Piedmont and the agricultural plains of southern Minnesota. We highlight common challenges and themes in defining an effective watershed sediment model. In both cases, reliable estimates of sediment yield depend essentially on the accurate identification of sediment sources and sinks and, hence, require careful delineation of landscape units and identification of dominant sediment sources and sinks. The primary elements needed to bridge the gap between sediment budgeting, watershed modeling, and stream restoration are (1) specificity regarding location, mechanism, and rates of erosion, (2) accurate accounting of sediment storage, (3) appropriate methods for upscaling local observations, (4) efficient means for incorporating multiple lines of evidence to constrain budget estimates, and (5) stream restoration methods that incorporate sediment supply in assessment and design procedures.

Identifying Sediment Sources and Sinks in the Root River, Southeastern Minnesota

“…From Figure 3, plot A, 70 percent of the main stem of the Root River is lined by terraces greater than 4 m tall. Reaches of the river network characterized by significantly taller-than-average stream banks likely receive larger net sediment contributions from channel migration or widening (Lauer and Parker 2008;Smith et al 2011). b.…”

“…Considering these limitations, Smith, Belmont, and Wilcock (2011) list four elements needed to advance sediment prediction at the landscape scale:…”

Landscape-scale geomorphic change detection: Quantifying spatially variable uncertainty and circumventing legacy data issues

“…Quantifying spatial patterns of erosion and deposition at a landscape scale is vitally important for improving models of water quality and sediment routing, predicting channel dynamics at the network scale, advancing landscape evolution models, and providing constraints for watershed sediment budgets (Smith et al, 2011;Mueller and Pitlick, 2013;Passalacqua et al, 2015). The past decade has witnessed rapid advances in our ability to collect high-resolution topographic (HRT) data and concomitant improvements in computing power, which have increased our ability to acquire, store, and analyze large data sets.…”

Estimating Streambank Erosion Rates with a GPS‐Based Video Mapping System

“…For erodibility, streambank attributes such as bank angle or bank surface protection can be assessed and ranked to determine the factors with greatest influence on the erosion susceptibility of a streambank location or reach (Smith et al. ).…”