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| Titel |
Extrapolating soil redistribution rates estimated from 137Cs to catchment scale in a complex agroforestry landscape using GIS |
| VerfasserIn |
Leticia Gaspar, Manuel López-Vicente, Leticia Palazón, Laura Quijano, Ana Navas |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250109479
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| Publikation (Nr.) |
 EGU/EGU2015-9383.pdf |
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| Zusammenfassung |
| The use of fallout radionuclides, particularly 137Cs, in soil erosion investigations has been
successfully used over a range of different landscapes. This technique provides mean annual
values of spatially distributed soil erosion and deposition rates for the last 40-50 years.
However, upscaling the data provided by fallout radionuclides to catchment level is required
to understand soil redistribution processes, to support catchment management strategies, and
to assess the main soil erosion factors like vegetation cover or topography. In recent years,
extrapolating field scale soil erosion rates estimated from 137Cs data to catchment scale has
been addressed using geostatistical interpolation and Geographical Information Systems
(GIS).
This study aims to assess soil redistribution in an agroforestry catchment characterized by
abrupt topography and an intricate mosaic of land uses using 137Cs data and GIS. A new
methodological approach using GIS is presented as an alternative of interpolation tools to
extrapolating soil redistribution rates in complex landscapes. This approach divides the
catchment into Homogeneous Physiographic Units (HPUs) based on unique land use,
hydrological network and slope value. A total of 54 HPUs presenting specific land use,
strahler order and slope combinations, were identified within the study area (2.5 km2) located
in the north of Spain. Using 58 soil erosion and deposition rates estimated from
137Cs data, we were able to characterize the predominant redistribution processes in
16 HPUs, which represent the 78% of the study area surface. Erosion processes
predominated in 6 HPUs (23%) which correspond with cultivated units in which slope
and strahler order is moderate or high, and with scrubland units with high slope.
Deposition was predominant in 3 HPUs (6%), mainly in riparian areas, and to a
lesser extent in forest and scrubland units with low slope and low and moderate
strahler order. Redistribution processes, both erosion and deposition processes, were
recorded in 7 HPUs (49%). The units of forest with high slope but low strahler
order showed low redistribution rates because the soil surface was well protected
by vegetation, while cultivated units with moderate slope and low strahler order
showed high erosion and deposition rates due to the tillage practices. This new
approach provides the basis for extrapolating field-scale soil redistribution rates at
catchment scale in complex landscapes. Additional 137Cs data in strategic locations
would improve the results with a better characterization of some of the HPU’s. |
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