An R-GUI for Spatial Analysis of Surface Runoff using the NRCS-CN Method R package sara4r version 0.1.0 A Graphical user interface to calculate the rainfall-runoff relation using the Natural Resources Conservation Service - Curve Number method (NRCS-CN method) but include modifications by Hawkins et al., (2002) about the Initial Abstraction. This GUI follows the programming logic of a previously published software (Hernandez-Guzman et al., 2011)<doi:10.1016/j.envsoft.2011.07.006>. It is a raster-based GIS tool that outputs runoff estimates from Land use/land cover and hydrologic soil group maps. This package has already been published in Journal of Hydroinformatics (Hernandez-Guzman et al., 2021)<doi:10.2166/hydro.2020.087> but it is under constant development at the Institute about Natural Resources Research (INIRENA) from the Universidad Michoacana de San Nicolas de Hidalgo and represents a collaborative effort between the Hydro-Geomatic Lab (INIRENA) with the Environmental Management Lab (CIAD, A.C.). Software Depends: R (>= 4.3.0), tcltk, tcltk2 Imports: terra Suggests: knitr, rmarkdown Rafael Hernandez-Guzman <rhernandez.g@gmail.com> Comprehensive R Archive Network (CRAN) Rafael Hernandez-Guzman [aut, cre] (ORCID: <https://orcid.org/0000-0002-2711-9015>), Arturo Ruiz-Luna [aut] (ORCID: <https://orcid.org/0000-0001-6878-0929>) GPL (>= 3) 2023-10-26 application/tgz https://CRAN.R-project.org/package=sara4r doi:10.32614/CRAN.package.sara4r