WSPC04299 - Laserfiche WebLink

Home Browse Search

00" 1'7" .1 U L' 31.31b '\' WATER ;NFORMATION MANAGEMENT SYSTEM HANDBOOK 15. The discharge regime of an erodible bed/bank channel can be characterized by, at least, the channel's hydraulic geometry. 16. Channel width at bankfull stage is the best single variable, among those available through measurements of a channel's hydraulic geometry, for estimating bankfull discharge. 17. Other frequently occurring discharges can be described as percentages of bankfull discharge. ~ - Data Needs. Maintenance flow quantification requires some basic hydrologic data. These include streamflow, channel geometry, and watershed characteristics data. It is neither practicable nor reasonable, however, to presume that streamflow data is necessary on all channels administered by the Forest Service before such channels can be managed so as to secure a favorable condition of water flows. Therefore, the procedure is designed to achieve the favorable flow objective without the benefit of on-site data. ~1.~1 - Streamflow Data. Obtain data for as many streamflow gaging stations as practical within the area to be quantified. In most cases, the United States Department of the Interior (USDI) Geological Survey will be the only available source of these data. ~1.~1a - Criteria. Streamflow data used in the analysis should meet the following criteria: 1. Flow regimes described by gaging station data should be representative of areas where maintenance flows will be calculated. 2. Data should consist of at least a representative 10 years of record. 3. Gaging stations used in the analysis of unregulated watersheds should have less than 10 percent of the total annual flow volume above the gaging station diverted or regulated. 4. Data sets used should, as much as practicable, represent long term average conditions. ~1. ~1b - Gal!inl! Station Data. The obtained for each gaging station. require all the listed data' items. following data should be However, not all methods *-FSH 4/89 AMEND 3-*