Evaluation of the scs-curve number distribution in southern portuguese watersheds

Abstract

Basedin anaggregated large-scale vectorized soil and land cover datasetsa new map was generatedwith the spatial distribution of the Soil Conservation Service Curve Number in the southernregion of Portugal. The methodology and data showedthat the most dominant HydrologicalSoil Group in the studyregion is D (72% of the total area) –low permeability soil–followed by B (12%)and C (9%).The spatial averaged SCS-CN in the study region is 77, varying from 63 in Ribeiras do Algarve to 81 in Arade, Guadiana and Mira watersheds.In 94.4% of the area the SCS-CN is above 60andin 45.8%, comprehendedbetween 80 and 100,suggesting a high capacity for generating surface runoff.Significant differencesare observable between existing SCS-CN maps and the new one, whichmayeasethe implementation of models based in this parameter at regional to local scales.