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<br />32.1 <br /> <br />001580 <br /> <br />WATER INFORMATION MANAGEMENT SYSTEM HANOBOOK <br /> <br />Exhibit 1 presents in the three parts of the procedure: selecting an <br />analysis method; the specific steps required in each method; and the set of <br />steps that are common to all the analysis methods described. <br /> <br />32.1 - Method Selection. Use one of the five analysis methods described <br />here. They differ in the level of detail they require. Before choosing a <br />method to use, determine the purpose of the quantification, the resources <br />(time, workforce, and funds) available for its accomplishment, and the <br />degree to which extrapolation must be used. For example, the <br />quantification of a single channel can be accomplished using a data <br />intensive approach which may be impractical for use on the thousands of <br />acres and within the limited time frame commonly associated with basin-wide <br />water rights adjudications. <br /> <br />Also consider the nature of the channel. If a channel is incapable of <br />adjusting its bed and/or banks in response to frequent flows, use method <br />E. However, the determination of channel adjustability must include the <br />consideration of other affected channel reaches. Method selection must, <br />therefore, be appropriate for the protection of the reach potentially most <br />susceptible to adverse impact from a loss of flow. Exhibit 1 represents <br />the process for method selection. <br /> <br />32.1l - Method Descriptions <br /> <br />32.11a - Method A. Method A requires the collection of field data and use <br />of existing gaglng station data. Visit all sites (stations and points of <br />quantification) and measure channel cross sectional area and water surface <br />slope. Method A requires substantial time and effort. <br /> <br />32.11b - Method B. Method B also requires field visits to all points of <br />quantification, but it entails somewhat less time and effort than Method A. <br />Measure only channel top width at bankfull stage in the field. <br /> <br />32.11c - Method C. Method C requires the use of data that exists or can be <br />developed from gaging station records, maps, photos and similar sources and <br />some visits to gaging stations for limited data collection. This method <br />utilizes a relationship of basin characteristics to bankfull discharge. <br />The relationship(s) is either developed locally or taken from USDI <br />Geological Surveyor State reports. Examples of basin characteristics <br />include area. precipitation, and mean or area-weighted elevation. <br /> <br />32.11d - Method D. Method D requires the use of data that exists or can be <br />developed from gaging station records, maps, photos, and similar sources. <br />Method D does not require field visits although some field verification is <br />desireab1e. This method utilizes a relationship between the log-Pearson <br />type III peak flow, for the return interval most nearly equal to the return <br />interval for the selected gage station bankfull discharge, and the <br />