 |
| Titel |
Controls on ecohydrological dynamics of riparian zones in Alpine catchments: A comparison study of two rivers in the Eastern Italian Alps |
| VerfasserIn |
Michael Engel, Daniele Penna, Jay Frentress, Andrea Andreoli, Peter Hecher, Ilja van Meerveld, Francesco Comiti |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250143921
|
| Publikation (Nr.) |
 EGU/EGU2017-7690.pdf |
|
|
|
|
|
| Zusammenfassung |
| In recent decades, restauration actions have been implemented in mountain rivers to face
widespread morphological changes. Such natural and anthropogenic modifications can have
relevant impacts on the ecological and ecohydrological functioning of riparian vegetation.
Understanding the water sources used by riparian vegetation is important for the
implementation of effective river restoration initiatives. Therefore, more ecohydrological
research is needed to quantify the complex interactions between hydrology and vegetation in
different alpine river systems.
In this study we used water stable isotopes and electrical conductivity (EC) as tracers to
better understand the hydrological and ecohydrological relationship between the riparian
vegetation and the river bed of alpine river systems. We choose two catchments, Ahr/Aurino
River and Mareit/Ridanna River catchments (South Tyrol, Italy) as study sites. In both
catchments, we selected two sites comprising a younger (< 5 years) and an older (> 10
years) alder (Alnus incana) stand.
At each site, soil moisture at different depths and groundwater levels were monitored.
Suction lysimeters were installed at the same depths than the soil moisture sensors. Samples
for tracer analysis were collected since June 2016 on a bi-weekly or monthly basis from
precipitation, soil water, groundwater and stream water. EC was continuously measured in a
piezometer at the Mareit River. In addition, we extracted sap water for isotopic analysis from
alder trees. First results show that all water types sampled in both catchments fell along
the global meteoric water line showing no evaporative enrichments. Sap samples
are expected to deviate from the meteoric line but they have not been analysed
yet. At both sites in the Ahr catchment, soil water seemed to be more variable and
isotopically more enriched at 10 cm depth (δ2H: - 34 to -69 ‰) than at 50 cm (δ2H:
-45 to -71 ‰), indicating a decreasing influence of precipitation with increasing
soil depth. In contrast, soil water at Mareit River seemed to depend stronger on
the topographical location of the site than on the soil depth. Groundwater in the
Ahr catchment at the end of July 2016 showed isotopic depletion (δ2H: -89 ‰),
which occurred about one month later than the isotopic depletion observed in the
stream (δ2H: -96 ‰). This may indicate a stream-groundwater connectivity with
a specific time lag. These observations may provide a first insight into the main
controls on the complex interactions between stream and vegetation in the riparian
zone.
Keywords: stable isotopes of water; sap; alpine rivers; riparian zone connectivity;
ecohydrology |
|
|
|
|
|
|