Monday October 12th, 4pm, Mann Hall 323
Abstract: A regional model to predict the frequency distribution of daily flows above the mean annual flow of high gradient channels in Colorado was developed. The model was derived based on analyses of flow records from 32 gages in Colorado with drainage areas ranging from 4 to 3700 km2. The frequency distribution of daily flows at these locations can be reproduced with a broken power law (BPL) function described by two free parameters. Both parameters are strongly correlated with drainage area, and based on these correlations a regional model capable of predicting the frequency distribution of daily flows above the mean annul flow at ungaged locations was formulated. The applicability of the model was tested using daily flow records from 32 similar-size basins in Idaho and 32 basins in Washington. The frequency distribution of daily flows of snowmelt dominated basins in Idaho was also well fitted by the BPL function. According to the model, the frequency of channel-forming (bankfull) discharges decreases downstream, meaning that the basin response to precipitation and runoff is non-linear. This multi-scaling behavior can be physically interpreted as the result of interactions between floodplain storage and spatial variations in runoff.