Resumo

PIGHINI, Ramiro J. et al. CARTOGRAPHIC RELATIONSHIP BETWEEN HYDROLOGICAL VARIABLES AND DEGRADATION TO SURFACE SOIL LOSS: PILOT SITE A° ESTACAS, ENTRE RÍOS. Cienc. suelo [online]. 2022, vol.40, n.2, pp.167-184.  Epub 21-Abr-2023. ISSN 1850-2067.

Expansion of agricultural land use in the north of Entre Ríos province diminishes land occupied by native forests. At watershed scale, this change in land use impacts the provision of ecosystem services and in-creases soil´s degradation and water erosion. Current limit of soil loss for design of terraces is 15 Mg.ha-1. yr-1, three times larger than FAO threshold for sustainable agricultural production. In this work the mapping of hydrological variables and soil loss is combined to determine and characterize vulnerable areas to soil water erosion, as tools for watershed land use planning. The parameters of curve number (CN), topographic index (TCI) and the USLE equation were used. Work was carried out in a GIS environment in the A° Estacas watershed, with a spatial resolution of 30 meters. The images were referenced to the POSGAR 2007 - FAJA 5 system. The input data used were: ALOS PALSAR DEM, soil map of the province at a scale of 1:100,000, average annual precipitation, and Landsat 8 images. Statistical methods included univariate analyses, Kernel density distribution, and máximum likelihood. Soil loss increased directly with runoff generation (CN), and inversely with the probability of waterlogging (TCI). The generated mapping verified that regardless of land use, it is feasible to reduce the soil loss threshold for sustainable production in the basin to 3 Mg.ha-1. yr-1. The proposed mapping defined areas requiring rapid corrective actions, where estimated soil losses exceeded 15 Mg.ha-1.yr-1. In addition, the mapping allowed to localize vulnerable areas within the watershed, with soil loss between 5 and 15 Mg.ha-1.yr-1, under agricultural and livestock use, where their intervention should be reviewed.

Palavras-chave : hydrology; water erosion; topographic index; curve number.

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