The precipitation-runoff relationship has been approximated using simplified schemes like the numerical curve (NC) method of the USDA Soil Conservation Service. Nevertheless, the theoretical basis of this approximation has been recently questioned. Thus, under the paradigm of develop a simple and operative model, the expo-model has been proposed that can be parameterized using one parameter in a similar way as NC method. This model was applied to data from an experiment using soil-grass mixes in a Morin type rain simulator and the results found were satisfactory in the experimental fits. Furthermore, in order to estimate the parameter of the expo-linear model the use of remote sensing technology has been proposed. Thus, using reflectance data measured in the before mentioned experiment the feasibility of the characterization of the expo-linear model was analyzed. The results, restricted, show that this approximation is feasible, but it requires data without the problems associated to the experimental design used in the rain simulator.