Importance of bank erosion for sediment input, storage and export at the catchment scale
The importance of bank erosion was quantified during three periods (October 2006–April 2007, May 2007–April 2008 and May 2008–April 2009) in the 486 km2 catchment area of River Odense, Denmark. A catchment sediment budget was established including other sediment sources such as tile drains and surface runoff, in-channel and overbank sinks and storage and the resulting bed load and suspended sediment load exported from the catchment.
Material and methods
Bank erosion and sedimentation were measured using ca. 3,000 erosion pins established in 180 pin plots, each consisting of three vertical lines of pins. Thirty-six representative reaches, each with a length of 100 m, were selected by a stratified random procedure in GIS. Bed load and suspended sediment export from the catchment were measured using a bed load sampler and from continuous measurements of turbidity at the outlet gauging station.
Results and discussion
The gross sediment input from bank erosion during the three study periods amounted to 21,100–25,200 t in the River Odense catchment, which is considerably higher than the estimated input of sediment from tile drains and surface runoff, which amounted to 220–500 t and 0–100 t, respectively. The measured bed load (20–490 t) was five to 60 times lower than the suspended sediment export from the catchment (1,240–2,620 t) during the three study periods, with the largest difference occurring in the driest year. Sediment sinks and storage were of high importance for the catchment sediment budget as the measured in-channel storage of sediment on stream banks was as high as 16,200–20,100 t, and the overbank sediment sink was estimated at 360–3,100 t.
Bank erosion was the dominant sediment source (90–94 %) in the River Odense catchment during the three study years. In-channel and overbank sediment sinks and storage dominated the sediment budget as 79–94 % of the sediment input from all sources was not exported from the catchment during the three study years. Such a large attenuation of sediment in river channels and on floodplains is extremely important for fluvial habitats and ecology. Moreover, it has strong implications for attempts to document changes in sediment export following implementation of mitigation measures.
KeywordsBank erosion Fluvial sediment Sediment budget Storage
The work was supported by the Neighbours and the Environment Research Programme project ’BUFFALO-P’ and the Strategic Research Foundation project MONITECH (grant no. 2104-08-0050).
- Collins AL, Walling DE (2007) Fine-grained bed sediment storage within the main channel systems of the Frome and Piddle catchments, Dorset, UK. Hydro Process 21:1448–1459Google Scholar
- Cooper DM, Naden P, Old G, Laize C (2008) Development of guideline sediment targets to support management of sediment inputs into aquatic systems. Natural England Research Report NERR008. Natural England, Sheffield, UKGoogle Scholar
- Hasholt B (1983) Dissolved and particulate load in Danish water courses. In: dissolved loads of rivers and surface water quantity/quality relationships. IAHS Publ 141:256–264Google Scholar
- Helley EJ, Smith W (1971) Development and calibration of a pressure-difference bed load sampler. U.S. Geological Survey Open File Report, Washington, USAGoogle Scholar
- Kondolf GM, Boulton A, O'Daniel S, Poole G, Rahel F, Stanley E, Wohl E, Bang A, Carlstrom J, Cristoni C, Huber H, Koljonen S, Louhi P, Nakamura K (2006) Process-based ecological river restoration: visualizing three-dimensional connectivity and dynamic vectors to recover lost linkages. Ecol Soc 11(2):5, [online] URL: http://www.ecologyandsociety.org/vol11/iss2/art5/ Google Scholar
- Kronvang B, Svendsen LM, Brookes A, Fisher K, Møller B, Ottosen O, Newson M, Sear D (1998) Restoration of the rivers Brede, Cole and Skerne: a joint Danish and British EU-LIFE project, III—channel morphology, hydrodynamics and transport of sediment and nutrients. Aquat Conserv 8:209–222CrossRefGoogle Scholar
- Kronvang B, Laubel AR, Larsen SE, Andersen HE, Djurhuus J (2003b) Buffer zones as a sink for sediment and phosphorus between the field and stream Danish field experiences. Water Sci Technol 51:55–62Google Scholar
- Owens PN, Walling DE, Leeks GJL (2000) Tracing fluvial suspended sediment sources in the catchment of the River Tweed, Scotland, using composite fingerprints and a numerical mixing model. In: Foster IDL (ed) Tracers in geomorphology. British Geomorphological Research Group, Symposia Series. Wiley, UK, pp 291–308Google Scholar
- Shapiro SS, Wilk MB (1965) An analysis of variance test for normality (complete samples). Biometrika 52:591–611Google Scholar
- Simon A, Curini A, Darby S, Langendoen EJ (1999) Stream-bank mechanics and the role of bank and near-bank processes in incised channels. In: Darby SE, Simon A (eds) Incised river channels: processes forms, engineering and management. Wiley, Chichester, pp 123–152Google Scholar
- Snedecor GW, Cochran WG (1989) Statistical methods, 8th edn. Iowa State University Press, USAGoogle Scholar
- Strahler AN (1957) Quantitative analysis of watershed geomorphology. Trans Am Geophys Union 8:913–920Google Scholar
- Zaimes GN, Schultz RC, Isenhart TM (2008) Streambank soil and phosphorus losses under different riparian land-uses in Iowa. J Am Water Res Assoc 44:935–947Google Scholar