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| Titel |
Determining the sources of suspended sediment in a Mediterranean groundwater-dominated river: the Na Borges basin (Mallorca, Spain). |
| VerfasserIn |
Joan Estrany, Núria Martínez-Carreras |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250084035
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| Zusammenfassung |
| Tracers have been acknowledged as a useful tool to identify sediment sources, based upon a
variety of techniques and chemical and physical sediment properties. Sediment
fingerprinting supports the notion that changes in sedimentation rates are not just related to
increased/reduced erosion and transport in the same areas, but also to the establishment of
different pathways increasing sediment connectivity. The Na Borges is a Mediterranean
lowland agricultural river basin (319 km2) where traditional soil and water conservation
practices have been applied over millennia to provide effective protection of cultivated land.
During the twentieth century, industrialisation and pressure from tourism activities have
increased urbanised surfaces, which have impacts on the processes that control streamflow.
Within this context, source material sampling was focused in Na Borges on obtaining
representative samples from potential sediment sources (comprised topsoil; i.e.,
0–2 cm) susceptible to mobilisation by water and subsequent routing to the river
channel network, while those representing channel bank sources were collected
from actively eroding channel margins and ditches. Samples of road dust and of
solids from sewage treatment plants were also collected. During two hydrological
years (2004-2006), representative suspended sediment samples for use in source
fingerprinting studies were collected at four flow gauging stations and at eight secondary
sampling points using time-integrating sampling samplers. Likewise, representative
bed-channel sediment samples were obtained using the resuspension approach at eight
sampling points in the main stem of the Na Borges River. These deposits represent the
fine sediment temporarily stored in the bed-channel and were also used for tracing
source contributions. A total of 102 individual time-integrated sediment samples,
40 bulk samples and 48 bed-sediment samples were collected. Upon return to the
laboratory, source material samples were oven-dried at 40Ë C, disaggregated using a
pestle and mortar, and dry sieved to |
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