Impact of historic land-use change on sediment delivery to a Chesapeake Bay subestuarine delta

• Published in: Earth surface processes and landforms Vol. 26; no. 4; pp. 409 - 427
• Main Authors: Pasternack, Gregory B., Brush, Grace S., Hilgartner, William B.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.04.2001; Wiley
• Subjects: Bgi / Prodig; Catchments. Hydrological cycle; Chesapeake Bay; diffusion model; Earth sciences; Earth, ocean, space; Exact sciences and technology; Geomorphology, landform evolution; human impacts; Hydrometeorology; landscape model; Physical geography; sediment delivery; Surficial geology; USA, Chesapeake Bay; Harford County Maryland; United States; Maryland; Chesapeake Bay; United States of America; ANW, USA, Chesapeake Bay; land use; deltaic sedimentation; history; North America; deltas; progradation; influence; Human impact; Sedimentation rate; Delta; Palaeo-ecology; Watershed; Model; Habitat; Land use; Sediment transport
• ISSN: 0197-9337; 1096-9837
• DOI: 10.1002/esp.189

Historic land use in the Chesapeake Bay drainage basin induced large fluxes of fluvial sediment to subestuarine tributaries. Stratigraphic and palaeoecologic analyses of deltaic deposits may be used to infer changes on the landscape, but are not sufficient to quantify past sediment supply. When viewed as an inverse boundary‐value problem, reconstruction of the sediment supply function may be achieved by combining deltaic sedimentation chronologies with an equation governing delta progradation. We propose that the diffusion equation is appropriate for simulating delta progradation and obtaining the sediment supply function provided a suitable diffusion constant (D) can be determined. Three new methods for estimating D are presented for the case of estuarine deltas. When the inverse boundary‐value technique was applied to Otter Point Creek, a tidal freshwater delta at the head of Bush River in upper Chesapeake Bay, D values ranged from 3763 to 6199 m2 a−1. Delta growth simulations showed a 1740–1760 initial pulse, a 1760–1780 erosive/redistributive interval, a 1780–1920 growth period, and a 1920‐present erosive/redistributive era. Coupling of simulated delta elevations with an empirical plant habitat predictive equation allowed for comparison of predicted versus actual relative habitat areas. Also, the model yielded reconstructed watershed erosion rates and stream suspended sediment concentrations that could be useful for development of water quality regulations. Copyright © 2001 John Wiley & Sons, Ltd.