Interactions between currents and the spatial structure of aquatic vegetation

Vegetation is present in nearly all aquatic environments, ranging from meandering streams to constructed channels and rivers, as well as in lakes and coastal zones. This vegetation grows in a wide range of flow environments as well, from stagnant water to highly turbulent flows dominated by waves and currents. Feedbacks between the dominant currents and the vegetation not only significantly alter the velocity structure of the flow, but play a large role in determining the spatial structure of the vegetation as well. This thesis examines these interactions through field experiments, review of existing literature and theoretical and analytical models. The first study describes a set of experiments in which vegetation was added to the point bar of a stream meander during base flow. During the next flood event, this vegetation proved to be destabilizing as a portion of the vegetation scoured away and the cross section of the open channel showed clear patterns of erosion. The secondary circulation present in the meander was significantly altered as well. In the second study, the relationship between tidal currents and the spatial distribution of seagrass meadows is examined. Seagrass beds range in their coverage from continuous meadows, to spotty swaths dominated by discrete patches. The relationship between this area coverage and tidal currents, explained by the principles of percolation theory, helps describe why certain distributions of seagrass within a meadow are more stable than others.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Civil and Environmental Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2009

Author dc:creator

• Rominger, Jeffrey T. (Jeffrey Tsaros)

Advisor dc:contributor.advisor

• Heidi M. Nepf.

• Civil and Environmental Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/53090

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/53090