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Brian Yellen

Publications and source records attributed to Brian Yellen.

4 recordsLinked to original sources
USGS2025

Marine-sourced sediment supply supports salt marsh resilience to sea level rise in the Northeastern US

Salt marshes rely on sediment to maintain elevation and resist sea level rise (SLR). While riverine sediment is well studied, marine-sourced sediment remains understudied, particularly in regions with limited river input. We examined the influence of marine-sourced sediment on salt marsh stability across 103 sites in the Northeastern US, using a new satellite-derived suspended sediment concentration (SSC) product. Marsh vulnerability was assessed using the Unvegetated-to-Vegetated Ratio (UVVR) and relative marsh elevation (Z*). We identified two thresholds: SSC >20 mg/L and RSLR <5.2 mm/year. Marshes meeting either threshold tended to remain intact, while those with both low SSC and high RSLR were more vulnerable to degradation. A north–south gradient was observed, with most unstable marshes in the southern region, where SSC declined by 0.9% per decade on average, compared to 0.072% in the north. These findings highlight the need to include coastal sediment dynamics in restoration and adaptation planning.

Northeastern United States↗
USGS2025

Distribution and disturbances of ditches across salt marshes of the Northeast U.S. with implications for management and restoration

Effective management of valuable coastal systems, such as salt marshes requires an understanding of the complex stressors influencing their continued threat of drowning. However, efforts to determine the effects of one potential stressor, ditches, have produced diverging results complicating management efforts. Ditches (linear trenches dug to drain salt marshes for agriculture and mosquito control) alter salt marsh hydrology, but their effects on widescale marsh function and degradation are poorly understood. We created a dataset of visible ditches and summarized ditch densities (length of ditches over area) for salt marshes of the Northeast U.S. to evaluate ditching against vulnerability metrics, including elevation and the unvegetated to vegetated marsh ratio (UVVR). We identified a scale dependency in which the larger/coarser the spatial scale of analysis, the greater the fraction of ditched salt marshes. Scale dependence explains discrepancies between previously determined ditch indices. In terms of effects on marsh vulnerability, relative elevation was not influenced by visible ditch presence. Ditch densities affected UVVR, exhibiting a multiple threshold behavior. When present at low densities, ditches have little effect on ponding; yet as ditch densities increase, UVVR (i.e., ponding) increases. The relationship between ditching and UVVR reverses at the highest ditch densities, with ponding substantially decreasing. The multiple threshold vulnerability response of Northeast salt marshes to the hydrologic influences imposed by ditching suggests restoration strategies should consider the degree of ditching rather than simply ditching presence.

Connecticut, Delaware, Maine, Maryland, Massachuse↗
USGS2014

Source, conveyance and fate of suspended sediments following Hurricane Irene. New England, USA

Hurricane Irene passed directly over the Connecticut River valley in late August, 2011. Intense precipitation and high antecedent soil moisture resulted in record flooding, mass wasting and fluvial erosion, allowing for observations of how these rare but significant extreme events affect a landscape still responding to Pleistocene glaciation and associated sediment emplacement. Clays and silts from upland glacial deposits, once suspended in the stream network, were routed directly to the mouth of the Connecticut River, resulting in record-breaking sediment loads fifteen-times greater than predicted from the pre-existing rating curve. Denudation was particularly extensive in mountainous areas. We calculate that sediment yield during the event from the Deerfield River, a steep tributary comprising 5% of the entire Connecticut River watershed, exceeded at minimum 10–40 years of routine sediment discharge and accounted for approximately 40% of the total event sediment discharge from the Connecticut River. A series of surface sediment cores taken in floodplain ponds adjacent to the tidal section of the Connecticut River before and after the event provides insight into differences in sediment sourcing and routing for the Irene event compared to periods of more routine flooding. Relative to routine conditions, sedimentation from Irene was anomalously inorganic, fine grained, and enriched in elements commonly found in chemically immature glacial tills and glaciolacustrine material. These unique sedimentary characteristics document the crucial role played by extreme precipitation from tropical disturbances in denuding this landscape.

New England↗