Laserfiche WebLink
<br />Memorandum To: File <br />Page 9 <br />September 28, 2001 <br />an extended modeling period, we may be forced to select a gage for the daily pattern that is less <br />representative of baseflow conditions, and results may be less impressive. <br />Regarding the USFWS method of developing daily gage flows from monthly model results, this study <br />demonstrates that the USFWS method is subject to significant errors. Either the Daily Pattern or Daily <br />Input model can provide more detailed and reliable results. Assuming representative patterns and/or <br />daily data are available, either of these two methods should be used in preference to the USFWS <br />method. <br />Comments and concerns <br />1. The pilot study identified the need for a method to automatically distribute monthly Calculated <br />demand to daily values. As a result, the State added a new type of disaggregation flag to Statemod's <br />capabilities. Under the new flag value of `4', a daily time series is generated from a monthly time <br />series by estimating that the average monthly value represents conditions on the 15`h of the month. <br />These monthly midpoints are interpolated to develop the parameter values throughout the month. <br />The interpolated values are adjusted as required to preserve monthly volume in the daily time series. <br />The method has been implemented for baseflow, demand, and reservoir targets. <br />2. As described in the section entitled "Conclusions", the excellent calibration of the Daily Pattern <br />model was partly due to favorable circumstances related to the Elk River at Clark gage, rather than <br />power inherent in the disaggregation approach used. In other words, in applications in which the <br />available gage does not represent baseflow conditions very well, calibration will not be as tight as in <br />the pilot project. <br />TaskMem2Final.doc /3OYL 6 <br />