Quantifying process-based mitigation strategies in historical context: separating multiple cumulative effects on river meander migration

Alexander K Fremier; Evan H Girvetz; Steven E Greco; Eric W Larsen

doi:10.1371/journal.pone.0099736

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Quantifying process-based mitigation strategies in historical context: separating multiple cumulative effects on river meander migration

Journal article

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Quantifying process-based mitigation strategies in historical context: separating multiple cumulative effects on river meander migration

Alexander K Fremier, Evan H Girvetz, Steven E Greco and Eric W Larsen

PloS one, Vol.9(6), pp.e99736-e99736

2014

DOI: https://doi.org/10.1371/journal.pone.0099736

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https://hdl.handle.net/2376/112257

PMCID: PMC4070911

PMID: 24964145

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Abstract

Conservation of Natural Resources - trends

Models, Theoretical

Conservation of Natural Resources - methods

United States

Ecosystem

California

Rivers

Water Movements

Conservation of Natural Resources - legislation & jurisprudence

Environmental legislation in the US (i.e. NEPA) requires defining baseline conditions on current rather than historical ecosystem conditions. For ecosystems with long histories of multiple environmental impacts, this baseline method can subsequently lead to a significantly altered environment; this has been termed a 'sliding baseline'. In river systems, cumulative effects caused by flow regulation, channel revetment and riparian vegetation removal significantly impact floodplain ecosystems by altering channel dynamics and precluding subsequent ecosystem processes, such as primary succession. To quantify these impacts on floodplain development processes, we used a model of river channel meander migration to illustrate the degree to which flow regulation and riprap impact migration rates, independently and synergistically, on the Sacramento River in California, USA. From pre-dam conditions, the cumulative effect of flow regulation alone on channel migration is a reduction by 38%, and 42-44% with four proposed water diversion project scenarios. In terms of depositional area, the proposed water project would reduce channel migration 51-71 ha in 130 years without current riprap in place, and 17-25 ha with riprap. Our results illustrate the utility of a modeling approach for quantifying cumulative impacts. Model-based quantification of environmental impacts allow scientists to separate cumulative and synergistic effects to analytically define mitigation measures. Additionally, by selecting an ecosystem process that is affected by multiple impacts, it is possible to consider process-based mitigation scenarios, such as the removal of riprap, to allow meander migration and create new floodplains and allow for riparian vegetation recruitment.

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Title: Quantifying process-based mitigation strategies in historical context: separating multiple cumulative effects on river meander migration
Creators: Alexander K Fremier - School of the Environment, Washington State University, Pullman, Washington, United States of America
Evan H Girvetz - International Center for Tropical Agriculture, Nairobi, Kenya; School of Environmental and Forest Sciences, University of Washington, Seattle, Washington, United States of America
Steven E Greco - Department of Human Ecology, University of California Davis, Davis, California, United States of America
Eric W Larsen - Department of Human Ecology, University of California Davis, Davis, California, United States of America
Publication Details: PloS one, Vol.9(6), pp.e99736-e99736
Academic Unit: Environment, School of the (CAS)
Publisher: United States
Identifiers: 99900547669401842
Language: English
Resource Type: Journal article