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tion, option 1 including point and distributed inflows provided slightly better400values for the three criteria. At the Siloam Springs station, the same optionwas better on NSE and E T but worse on E P . At the Kansas station, it wassignificantly better for NSE and E T but worse for E P . Therefore, option 1is better but does not outperform option 2. This result was quite a surprise:lower performance was expected for the point inflow options. Indeed, there are405important differences between the two injection strategies and option 1 didtel-00392240, version 1 - 5 Jun 2009410415420appear much more realistic. Even when six tributaries were introduced in themodelling scheme, the intermediate area covered 682 km 2 out of the 2025 km 2drained by the river reach (see Figure 1.b). This intermediate area was nottaken into account in option 2, which could have caused significant differencesin performance with option 1, but the results did not confirm this possibility.Simulations at the Kansas station are of poorer quality than at the SiloamSprings and Tahlequah stations: the figures given in Table 2 reveal that NSEis lower by 0.1 points and E P is greater by 10%. This clearly indicate thatsimulating flow on tributaries is more difficult than on the river reach itself.We should not forget that along the main river channel, we combined twodata: propagated observed upstream flows and lateral inflows calculated bythe RR models. On tributaries, simulations made by the RR models only relyon rainfall data. This result may indicate that simulating flow on ungaugedcatchments may be significantly improved when both observed upstream dischargesand rainfall are available rather than only rainfall.A detailed analysis of simulated hydrographs confirms the previous statements.An example is given in Figure 5 with the observed and simulatedhydrographs in validation mode at the Tahlequah, Siloam Springs and Kansasstations for the 3 events having the largest peakflows in Tahlequah (events20