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<br />OD1357 <br /> <br />28 <br /> <br />1) One basin test - This test compares the predictive <br />capabilities of the two model categories in a particular basin. The <br />writers use the published results of the authors who evaluated both <br />a conceptual model and a physically-based model in the same basin. <br />The results for the six subtests are listed in Table 11-4. Examina- <br />tion of the table reveals the following about the subtests: <br />a) The physically-based models generally overestimate the <br />peak runoff rate, while the conceptual models equally over- and <br />under-estimate the peak runoff rate. <br />b) The physically-based models are slightly more accurate <br />(the mean peak discharge ratio is closer to 1.00) than the conceptual <br />models in most of the subtests. <br />c) The modified correlation coefficient (RMOD) for the <br />physically-based models ranges from poor to fair for the subtests, and <br />for the conceptual models it is poor for all subtests. <br />d) The special correlation coefficient (RS) for the <br />physically-based models as well as the conceptual models ranges from <br />poor to good for the subtests. <br />e) Neither category of models predicts the runoff hydrograph <br />more accurately (RMOD, nor RS closer to 1.0) than the other. <br />f) The standard deviations of the peak discharge ratio, the <br />modified correlation coefficient, and the special correlation coeffi- <br />cient for the two model categories are similar. That is, the variance <br />about the mean values is similar for both physically-based and con- <br />ceptual models. <br />