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| Titel |
Identifying erosive periods by using RUSLE factors in mountain fields of the Central Spanish Pyrenees |
| VerfasserIn |
M. López-Vicente, A. Navas, J. Machín |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 12, no. 2 ; Nr. 12, no. 2 (2008-03-06), S.523-535 |
| Datensatznummer |
250010573
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| Publikation (Nr.) |
 copernicus.org/hess-12-523-2008.pdf |
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| Zusammenfassung |
| The Mediterranean environment is characterized by strong temporal variations
in rainfall volume and intensity, soil moisture and vegetation cover along
the year. These factors play a key role on soil erosion. The aim of this
work is to identify different erosive periods in function of the temporal
changes in rainfall and runoff characteristics (erosivity, maximum intensity
and number of erosive events), soil properties (soil erodibility in relation
to freeze-thaw processes and soil moisture content) and current tillage
practices in a set of agricultural fields in a mountainous area of the
Central Pyrenees in NE Spain. To this purpose the rainfall and runoff
erosivity (R), the soil erodibility (K) and the cover-management (C) factors
of the empirical RUSLE soil loss model were used. The R, K and C factors
were calculated at monthly scale. The first erosive period extends from July
to October and presents the highest values of erosivity (87.8 MJ mm ha−1 h−1),
maximum rainfall intensity (22.3 mm h−1) and
monthly soil erosion (0.25 Mg ha−1 month−1) with the minimum
values of duration of erosive storms, freeze-thaw cycles, soil moisture
content and soil erodibility (0.007 Mg h MJ−1 mm−1). This period
includes the harvesting and the plowing tillage practices. The second
erosive period has a duration of two months, from May to June, and presents
the lowest total and monthly soil losses (0.10 Mg ha−1 month−1)
that correspond to the maximum protection of the soil by the crop-cover ($C$
factor = 0.05) due to the maximum stage of the growing season and
intermediate values of rainfall and runoff erosivity, maximum rainfall
intensity and soil erodibility. The third erosive period extends from
November to April and has the minimum values of rainfall erosivity
(17.5 MJ mm ha−1 h−1) and maximum rainfall intensity (6.0 mm h−1) with
the highest number of freeze-thaw cycles, soil moisture content and soil
erodibility (0.021 Mg h MJ−1 mm−1) that explain the high value of
monthly soil loss (0.24 Mg ha−1 month−1). The interactions between
the rainfall erosivity, soil erodibility, and cover-management factors
explain the similar predicted soil losses for the first and the third
erosive periods in spite of the strong temporal differences in the values of
the three RUSLE factors. The estimated value of annual soil loss with the
RUSLE model (3.34 Mg ha−1 yr−1) was lower than the measured value
with 137Cs (5.38 Mg ha−1 yr−1) due to the low values of
precipitation recorded during the studied period. To optimize agricultural
practices and to promote sustainable strategies for the preservation of
fragile Mediterranean agrosystems it is necessary to delay plowing till
October, especially in dryland agriculture regions. Thus, the protective
role of the crop residues will extend until September when the greatest
rainfall occurs together with the highest runoff erosivity and soil losses. |
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