Rainfall-runoff relationships were developed and comprehensively assessed for five basins located in semi-humid and semi-arid areas. It was shown that a common rainfall-runoff relationship can represent that of three basins far away from one another. The error was allowable and the accuracy was high. Three evaluation metrics, including the similarity index, the relative root mean square error, and the topography index, were employed to quantitatively assess the similarity of the underlying surface in selected basins. Results show that a common rainfall- runoff relationship can describe different basins with similar underlying surface conditions, even though they are far from one another. It was concluded that the relative root mean square error and the distribution curve of the topography index are more suitable for assessing the similarity of the underlying surface in semi-humid and semi-arid basins.