Rating curves are robust tools for continuously evaluating streamflows by gauging water levels. This paper introduces a procedure to derive rating curves by combining a stage-discharge relationship proposed by Maghrebi et al. and the inverse-distance weighting (IDW) method. In order to determine the appropriate value of the α parameter in IDW, a trial-and-error procedure using different values of α from 0 to 5 is implemented. To this end, 2000 subsamples in different sizes selected randomly from the observed data of four cross-sections are generated, and the corresponding rating curves are delivered. The mean absolute percentage error (MAPE) and the root mean square error (RMSE) are used to evaluate the results. The results from four cross-sections demonstrated that α=0 corresponds to the least favorable results, while α=1 is the most appropriate value. The Maximum MAPE and RMSE, observed in the Trent River section, were 22.5 % and 13.1 m3/s using Maghrebi’s relation, respectively. These values decreased to 13.5 % and 8.6 m3/s when applying the proposed method using 7 points. Additional cross-sections from the Tiber River are used to validate the method and to compare it with the classical model. The results demonstrated that MAPE and RMSE values are reduced with increasing sample size, and the proposed model outperforms the classical one for small sample sizes. RMSE values declined from 62, 27.4, 46, 76.7 m3/s to 32.8, 14.4, 23.5, 33.9 m3/s using seven observed points in Ponte Nuovo, Santa Lucia, Ponte Felcino, and Ponte Rosciano cross-sections, respectively. The proposed model illustrated a notable decline in the uncertainty bands, which diminished significantly with increasing sample sizes. The proposed method is advantageous in constructing rating curves in new sites, specifically in the case of limited funding, and building more reliable rating curves in gauged sites.

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