HR: 16:15h
AN: NB14G-03    [Abstracts]
TI: Control of Vertical Water Exchange in Sand-bed Streams by Instream Wood - Key to Hyporheic Restoration
AU: * Mutz, M
EM: m.mutz@limno-tu-cottbus.de
AF: Brandenburg University of Technology, Seestr. 45, Bad Saarow, D-15526 Germany
AU: Kalbus, E
EM: edda.kalbus@web.de
AF: Brandenburg University of Technology, Seestr. 45, Bad Saarow, D-15526 Germany
AU: Meinecke, S
EM: stefan.meinecke@uba.de
AF: Umweltbundesamt, Schichauweg 58, Berlin, D-12307 Germany
AB: The vertical water exchange between water column and hyporheic zone is crucial for many aspects of stream ecology. In sand-bed streams this exchange is often low resulting in shallow hyporheic depth and low metabolic activity. Our objective was to assess the effect of wood addition on the vertical connectivity at base-flow. Experiments were conducted in the large dimension Artificial Stream and Pond System (FSA, German Federal Environmental Agency) with and without natural quantity of instream wood (0.53m³ wood / 100 m² stream bed). The water exchange was assessed from loss of diluted tracer (Uranine) from the water column. The water exchange comprised two superimposed processes, that differed in exchange rate. The presence of wood had no effect on the slower process, but doubled the exchange rate of the faster process. Wood caused re-deposition of 47% of the stream bed. Related to this area the exchange rate was more than threefold the rate at level sand bed. Wood also increased the overall exchange depth. The results underline the potential to restore hyporheic functions in low energy sand-bed streams by management of instream wood and wood recruitment.
DE: 1800 HYDROLOGY
DE: 1845 Limnology
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly