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<br />(1997) concluded that a universal t* 50 for gravel-bedded rivers does not exist. In this <br /> <br />study we used 0.034 and 0.06 as the values for t* 50 for consistency with similar analysis <br /> <br />(Smelser, '1997; Andrews 1983; and Wilcock et al. 1996). When to is greater than or <br /> <br />equal to tcr , the discharge is sufficient to entrain the particle. <br /> <br />RESULTS <br /> <br />Flood Frequency Analysis <br /> <br />The magnitude of flooding on the White River has decreased significantly since <br /> <br />the mid-1960s (Fig. 7). The average peak flood at the Watson gage between 1923 and <br /> <br />1965 was 122 m3/s (4300 Wls). The average peak flood magnitude between 1965 and the <br /> <br />I <br /> <br />construction of Taylor Draw Dam in 1984 was 98 m3/s (3470 ft3/s). After the completion <br /> <br />of the dam peak floods have changed little. The average peak flood for the period <br /> <br />between completion of dam in 1984 and 1997 was 97 m3/s (3437 ft3/s). Peak floods from <br /> <br />these three time periods were compared using a series oft-tests. Test resul~s (Table 1) <br /> <br />show that at a 95% confidence interval, the peak flows between 1923 and 1964 are <br /> <br />significantly different from peaks both before Taylor Draw Dam (1965 and 1983) and <br /> <br />after the completion of the dam (1984 and 1997). The average floods for the two time <br /> <br />periods since 1965 are not significantly different. Thus, the decreased flood magnitudes <br /> <br />which have occurred since the mid-1960s were not due to the construction of Taylor <br /> <br />Draw Dam because the decrease occurred before the dam was built. Regional climate <br /> <br />changes may be responsible for this shift. <br /> <br />18 <br />