WSPC07406

• File Number: 8062
• Description: Federal Water Rights - Colorado Litigation - National Forest ISF Claims - Technical Sutdies
• State: CO
• Basin: Statewide
• Date: 8/28/1987
• Author: Unknown
• Title: Technical Studies - Water Information Management System Handbook - Chapter 30 - Procedure for Quantifying Channel Maintenance Flows
• Water Supply Pro - Doc Type: Report/Study

001589

32.8--1

WATER INFORMATION MANAGEMENT SYSTEM HANDBDOK

Step 3 - Calcu1ate or measure bankfull discharge for all suitable gage
stations using channel width vs. discharge, water stage vs. discharge, or
field measurements.

Step 4 - Calculate drainage area, area-weighted mean elevation or other
appropriate variables for regression with bankfull discharge (QS) for the
points of quantification. Other variables such as precipitation may be more
appropriate in some areas. If such is the case, measure those variables for
both the gage station watersheds and for the watersheds above the points of
quantification.

~~e) ~ - Oevelop general relation. Regress the bankfull discharge values
B rom Steps 2 and 3 against the drainage areas (or other appropriate
variables) of representative and all suitable gage stations using watersheds
in similar area-weighted mean elevation zones to develop a relation of the
form:

where:
Qa =
f(DA) =

Qs = f(DA)

bankfull discharge
some functional relationship of drainage area

Note: This relation will be developed for as many elevation zones as the user
chooses. Alternatively, if the data are not stratified by elevation zones,
the user may develop a relationship of the form QB = f(DA,E), where
E = elevation.

Step 6 - Calculate bankfull discharge (QS) for points of quantification
using the relation developed in Step 5.

~tep 7 - Proceed to Section 32.8.
QB only), and 11 ~QB only).

32.8 - Common Steps. The following steps (ex. 1) are common to all the
methods described. These must be "completed after the results of the selected
method are in hand.

Do Common Steps 1, 2 (part 1), B, 9, 10

Common Ste~ 1 - Normalize and plot the representative gage station
flow-durat on curve (ex. 2).

1. If using the duration table of daily values summary from USDI
Geological Survey data sources, divide the cFS values 9iven in the listed
table classes by the calculated bankfull discharge (QS) to develop a ratio
for each listed flow class.

2. Construct the flow-duration curve (normalized) by plotting the
calculated ratio values versus the corresponding percent time value that a
given class CFS value is equaled or exceeded. Connect plotted points with a
smooth curve.

ID No. 3
R/28/67