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| Titel |
Sediment and Phosphorus losses by Surface Runoff from a Catchment in the Humid Pampa Landscape, Argentina Republic |
| VerfasserIn |
M. A. Méndez, E. L. Díaz, M. L. Lenzi, M. Lado, Eva Vidal-Vazquez |
| 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 |
250114119
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| Publikation (Nr.) |
 EGU/EGU2015-14418.pdf |
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| Zusammenfassung |
| The estimation of sediment and phosphorus transfers from soil into watersheds as a result of
agricultural activity is a key aspect for characterizing the sustainability of current land use
systems. The objective of the present study was to quantify the temporal evolution of
suspended sediment and dissolved phosphorus losses from the upper basin of the
Gualeguaychú River. The studied catchment has an area of 483 Km2 and is located in the
Entre Ríos province, Argentina Republic. The climate is subtropical humid with
average annual rainfall of 1200 mm. Soils are characterized by very low infiltration
rates. Land use was assessed by remote sensing and GIS tools, and consists of: 31%
abandoned rice fields, 20% naturalized fields, 20% soybean (second cycle), 10% soybean
(first cycle), 7% rice, 4% Pasture, and the remaining 7% is devoted to civil and
road works, native forests and other crops. Low soil infiltration capacity, together
with landscape geomorphological traits of the studied landscape and zonal rainfall
regime, typically originates periods with high surface runoff volumes, mainly in
autumn, spring and summer months. The study was conducted during a period of
eight years. Instantaneous water flow measurements (discharge) were estimated in a
control section of Gualeguaychú River from hydrometer reading and the rating
curve of height-flow. In addition, 134 water samples of 2000 cm3 were collected
during the study period to analyze the concentration of suspended sediments and
dissolved phosphorus. The instantaneous flow was estimated with the hydrometer
reading and the application of curve of height – flow. The discharge range was from
0.14 to 128 m3/sec, indicating a high variability in the response of the catchment
to seasonal rainfall. On average suspended sediment and dissolved phosphorus
losses of the experimental catchment were 1.42 Mg and 0.335 Kg per hectare/year,
respectively. It was also shown that few events of high rainfall that generate excess
runoff were responsible for the most of recorded losses of sediment and phosphorus.
Moreover, the highest exportation of sediments and phosphorus from soil to streamflow
occurred in the spring and summer period. The daily losses of phosphorus or sediments
were mainly explained by the amount of precipitation accumulated during the five
days prior to sampling, as shown by regression analysis, and a higher coefficient of
determination was obtained for samples extracted during the summer season. This response
mainly has been demonstrated to be produced in periods with higher amounts of
precipitation equal or greater than 35 mm arising in this season, which are characteristic
for summer storms with high rain intensities, and therefore greater erosive power. |
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