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0;, ~ "81': V,.L.U ....... 32.7 WATER INFORMATION MANAGEMENT SYSTEM HANDBOOK C. SteD ~. Calculate drainage area, area-weighted mean elevation, or other appropriate watershed characteristics for ungaged points of quantification. For ungaged points of quantification develop the same data as was regressed against the log-Pearson 1.5 years return interval flow in Step 2. D. ~-!. Calculate bankfull discharge (Q ) for ungaged points of quantification using the relation Heveloped in Step 2 and the data in Step 3. E. lIteD 'i. Proceed to Section 32:8, A. Common Step 1. 3Z~I - Method E. Use this method in essentially non-erodible/ bedrock stream channels. It differs from other methods in that the maintenance flows needed are those which provide only for the transport of tributary and/or introduced sediment. Further, since ~he width of non-erodible/bedrock channels does not adjust to frequent discharges, bankfull width cannot be used as an indicator of bankfull or other discharges. The maintenance flow requirement for non-erodible/bedrock stream channels does not include rise-recession, baseflow or vegetation encroachment prevention flows because bank erosion and vegeta- tion encroachment potentials are considered to be negligible. Consequently, only the magnitude and duration of bankfull discharge are considered as needed for channel maintenance. A. SJc..~. 1. Secure the following data for the representative and all suitable gage stations. a. Channel width vs. discharge or water stage vs. discharge relations. b. Drainage area of watershed above gage. c. Area-weighted mean elevation of watershed above gage. d. Other watershed characteristics if appropriate. 2. Secure the following data for the representative gage station. a. Duration table of daily values summary. b. Mean annual discharge. c. Daily mean hydrograph data for the period of record. *-FSH 4/89 AMEND 3-*