Abstract
The Soil Conservation Service Curve Number Model is a conceptual model intended for estimating effective rainfall (ER). This model is grounded in a parameter - referred to as Curve Number (CN), which is determined from information on the characteristics of the watershed. The Standard Method (M1) for determining the CN is based on soil and land-use tables; however, some authors have proposed alternative methodologies for defining the CN value from monitored rainfall-runoff events, such as those described by Hawkins (1993)HAWKINS, R. H. Asymptotic determination of runoff curve numbers from data. Journal of Irrigation and Drainage Engineering, v. 119, p. 334-345, 1993. https://doi.org/10.1061/(ASCE)0733-9437(1993)119:2(334)
https://doi.org/10.1061/(ASCE)0733-9437(...
(M2), Soulis and Valiantzas (2012)SOULIS, K. X.; VALIANTZAS, J. D. Variation of runoff curve number with rainfall in heterogeneous watersheds. The Two-CN system approach. Hydrology and Earth System Sciences, v. 16, n. 3, p. 1001-1015, 2012. (M3), and Soulis and Valiantzas (2013)SOULIS, K. X.; VALIANTZAS, J. D. Identification of the SCS-CN Parameter Spatial Distribution Using Rainfall-Runoff Data in Heterogeneous Watersheds. Water Resources Management, v. 27, n. 6, p. 1737-1749, 2013. https://doi.org/10.1007/s11269-012-0082-5
https://doi.org/10.1007/s11269-012-0082-...
(M4). The objective of this study was to evaluate the impact of using these methods for determination of the CN parameter on the estimation of ER, taking as reference forty rainfall-runoff events monitored between 2015 and 2018 in the Cadeia River Watershed, which has characteristics of the Pampa biome. The different methods assessed for definition of the CN parameter resulted in contrasting performances with respect to the estimation of ER for CRW, as the following findings: i) M1 gave ER values with little reliability, mainly due to the classification of antecedent moisture content classes; ii) M3 provided the best results in determining ER, followed by M2; and iii) the ER values estimated according to M4 differed from those observed, mainly for events with lower rainfall depths.
Keywords:
effective rainfall; extreme events; hydrological modeling