Temporal and spatial variation in quality of hyporheic water in one unregulated and two regulated boreal rivers

• This study describes the temporal and spatial variations in hyporheic water quality in three boreal rivers, the River Tobyälven, an unregulated river, the river Mangälven, a regulated river with a minimum discharge requirement and the river Järperudsälven, aregulated river without any minimum discharge requirements. A total of 43 permanent piezometers were used to measure dissolved oxygen (DO), temperature, electrical conductivity, pH, NO3 and NH4 in the hyporheic water at 150mm and 300mm depth, at monthly intervals from October 2001 to October 2002. Another seven piezometers were installed in brown trout redds and monitored during the incubation period, from December 2001 to April 2002. In the river Tobyälven, temporal patterns in hyporheic water chemistry correlated to variations in surface water chemistry and discharge. In the river Jäperudsälven, the hyporheic water chemistry did not correlate to discharge or surface water chemistry. In the river Mangälven, the water chemistry was dominated by releases from a large upstream lake, and there were weak correlations between surface water chemistry andhyporheic water chemistry at some sites. The incubation conditions for brown trout eggs were most favourable in the unregulated river, characterized by high DO levels that remained high throughout the incubation period. In the river Järperudsälven the DOlevels were variable during spawning, and then gradually declined to critically low levels during incubation, whereas in the river Mangälven the DO conditions were intermediate and stable. Thus we observed a stronger coupling between surface waterconditions and hyporheic conditions, i.e. vertical connectivity, in the unregulated river than in the regulated river with minimum flow requirements, which in turn was stronger than in the river without minimum flow requirements. Copyright # 2007 JohnWiley & Sons, Ltd

Ämnesord

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Environmental Sciences (hsv//eng)

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)

Nyckelord

flow regulation

hyporheic water chemistry

flow requirements

incubation

vertical connectivity

Biology

Biologi

Environmental Science

Miljövetenskap

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