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31.32 WATER INFORMATION MANAGEMENT SYSTEM HANDBOOK 1. Log-Pearson type III flood frequency analysis for the period of record. 2. Log-Pearson type III low flow frequency analyses for 1-, 3-, 7-, 14-, 30-, and 90-day low flows. 3. Selected basin characteristics such as mean basin elevation and drainage area. 4. Flow duration data of daily mean discharges for period of record. 5. Mean annual discharge. 6. Daily mean hydrograph for the period of record. 7. Stage-discharge relationship. 8. Hydraulic geometry of the station cross section including bankfull width and water surface slope at bankfull discharge. 9. Field measured bankfull discharge. 10. Velocity as a function of discharge. Most of the data and analyses listed above are available from the USDI Geological Survey WATSTORE assistance centers or local state offices (Section 30.72). Some data and analyses can also be obtained directly using the Flow Data file of the Environ- mental Protection Agency (EPA) STORET system. ,1.,2 - C~~~l Geometrv and ~~sin Characteristics. Data for channel geometry and basin characteristics are not generally available and must be measured in the field or interpreted from maps. Section 36.3 describes the measurement of bankfull channel top width. Items such as weighted mean basin elevation are well described in hydrologic literature and are not repeated here. Caution must be exercised if the USDI Geological Survey basin-characteristics method is being used rather than a locally developed relationship. Any basin characteristic used must be quantified according to the procedures described in the parent USDI Geological Survey document. ,1." - ~~d Measurements. The importance of field data to support the calculation of required maintenance flows is especially important in cases where legal challenge or *-FSH 4/89 AMEND 3-*