The impact of dams on floodplain geomorphology: are there any, should we care, and what should we do about it?

Hdl Handle:
http://hdl.handle.net/10034/603480
Title:
The impact of dams on floodplain geomorphology: are there any, should we care, and what should we do about it?
Authors:
Marren, Philip M.; Grove, James R.; Webb, J. Angus; Stewardson, Michael J.
Abstract:
We undertook a review of the potential for dams to impact floodplain geomorphology, using both a conventional literature review and a systematic review using ‘causal criteria’ analysis. The literature review identified potential impacts on overbank flooding, scour and sedimentation, within-channel bank erosion, meander migration and cutoff frequency, and avulsion characteristics and frequency. The temporal scale of impacts ranged from years and decades, through to millennia. The causal criteria analysis indicated that with the exception of reduced meander migration rates, most impacts had been too poorly documented to be confident of their impact at present. We identify a distinction between ‘passive impacts’ (floodplain disconnection) and ‘active impacts’ (changes in geomorphological processes and functioning). Dams do impact floodplain geomorphology: many of the impacts will be subtle, and over very long timescales (1000s of years), but altered overbank sediment loads have the potential to change patterns of scour and deposition across floodplains. Further research is needed that specifically seeks to identify the impacts of dams on floodplain geomorphology, hydrology-geomorphology-vegetation interactions, and floodplain ecological response. Given the practical constraints on overbank environmental flow releases, there is relatively little that can be done to mitigate dam impacts on floodplain geomorphology. The main options include using within-channel flows to maintain meander migration and partial floodplain connectivity. We suggest that the major action should be that once dams come online, efforts should be made to prevent channel enlargement through scour, channel widening and wood removal, so that geomorphological processes can fully reestablish immediately once the dam ceases to operate.
Affiliation:
University of Melbourne
Citation:
Marren, P.M., Grove, J.R., Webb, J.A., Stewardson, M.J. (2014). The impact of dams on floodplain geomorphology: are there any, should we care, and what should we do about it? In: I.D. Rutherfurd, G.J. Vietz (eds.), Proceedings of the 7th Australian Stream Management Conference: Catchment to Coast. Townsville, Queensland, 74-80.
Publisher:
7th Australian Stream Management Conference / asn events
Publication Date:
2014
URI:
http://hdl.handle.net/10034/603480
Type:
Meetings and Proceedings
Language:
en
Appears in Collections:
Geography and Development Studies

Full metadata record

DC FieldValue Language
dc.contributor.authorMarren, Philip M.en
dc.contributor.authorGrove, James R.en
dc.contributor.authorWebb, J. Angusen
dc.contributor.authorStewardson, Michael J.en
dc.date.accessioned2016-03-22T08:38:43Zen
dc.date.available2016-03-22T08:38:43Zen
dc.date.issued2014en
dc.identifier.citationMarren, P.M., Grove, J.R., Webb, J.A., Stewardson, M.J. (2014). The impact of dams on floodplain geomorphology: are there any, should we care, and what should we do about it? In: I.D. Rutherfurd, G.J. Vietz (eds.), Proceedings of the 7th Australian Stream Management Conference: Catchment to Coast. Townsville, Queensland, 74-80.en
dc.identifier.urihttp://hdl.handle.net/10034/603480en
dc.description.abstractWe undertook a review of the potential for dams to impact floodplain geomorphology, using both a conventional literature review and a systematic review using ‘causal criteria’ analysis. The literature review identified potential impacts on overbank flooding, scour and sedimentation, within-channel bank erosion, meander migration and cutoff frequency, and avulsion characteristics and frequency. The temporal scale of impacts ranged from years and decades, through to millennia. The causal criteria analysis indicated that with the exception of reduced meander migration rates, most impacts had been too poorly documented to be confident of their impact at present. We identify a distinction between ‘passive impacts’ (floodplain disconnection) and ‘active impacts’ (changes in geomorphological processes and functioning). Dams do impact floodplain geomorphology: many of the impacts will be subtle, and over very long timescales (1000s of years), but altered overbank sediment loads have the potential to change patterns of scour and deposition across floodplains. Further research is needed that specifically seeks to identify the impacts of dams on floodplain geomorphology, hydrology-geomorphology-vegetation interactions, and floodplain ecological response. Given the practical constraints on overbank environmental flow releases, there is relatively little that can be done to mitigate dam impacts on floodplain geomorphology. The main options include using within-channel flows to maintain meander migration and partial floodplain connectivity. We suggest that the major action should be that once dams come online, efforts should be made to prevent channel enlargement through scour, channel widening and wood removal, so that geomorphological processes can fully reestablish immediately once the dam ceases to operate.en
dc.language.isoenen
dc.publisher7th Australian Stream Management Conference / asn eventsen
dc.subjectDamen
dc.subjectFloodplainsen
dc.subjecteco evidenceen
dc.subjectenvironmental flowen
dc.subjectflow regulationen
dc.subjectFluvial geomorphologyen
dc.titleThe impact of dams on floodplain geomorphology: are there any, should we care, and what should we do about it?en
dc.typeMeetings and Proceedingsen
dc.contributor.departmentUniversity of Melbourneen
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