FLOOD08079

• County: Statewide
• Basin: Statewide
• Title: Consumptive Use and Return Flows in Urban Water Use
• Date: 12/1/1996
• Prepared By: Colorado Water Resources Research Institute
• Floodplain - Doc Type: Educational/Technical/Reference Information

,
I I I I I r
_______I_______~-------~-------I-------~-------~-------
I 1 I I I I
_ _ _ __ _ _ _1_ _ _ _ _ _ _ --'- _ _ _ _ _ _ ~ I _ _ _ _ _ _ _1_ _"_ _ _ _ _ ,]. _ _ _ _ _ _ _ 1_ _ .
: : :-Cottonwoo~ Curve: : - - - - --
_______1_______4_______~_____ -I-------~---- ~
I I I I
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I I I I I I

- ~ ~ ~ ~ ~ ~ ~!~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ - - - ~ - - - - - -i- - - - - - - ~ -7- - ~ - - - - ~..

--______1 _____.__--'- ____ __ ___1_______1___ ___I
- : - I - :- - - Col9rado Spring~ Polynomial ~urve - - - -
________1_____ -4- _____~--_----1-------4-_-----~-_-----
I I I I I
I I I I I I
-------1-- -,-------r-------I-------,-------r--------
I I I I I I

Due to the expense involved in generating these engineering reports and the legal fees
involved in going to Water Court, many cities which filed for a water credit accepted, and continue to
accept, the 15% water credit. The money they would have spent hiring engineering consultants and in
litigation was used to acquire additional water rights.

~ 100
-
-g 90
:a 80
Co
<( 70
..
~ 60
3: 50
-
g 40
:0::;
-5 30
~ 20
Q)
Q. 10
Co
$ 0
c
o

50

100 150 200 250
Water Applied I Potential CU ("!o)

300

350

Cottonwood Curve:

Colorado Springs Polynomial Curve:

55 <WA/ClI <160 DP!WA=0.357*WA/ClI-19.6
W A/ClI >160 DP!W A=IOO*(W A/ClI-IOO)/(App/ClI)

DP!W A= -0.6993+ 1.6633(W A/ClI)-0.8847*
(W A/ClI)^2+0.2147(W A/ClI)^ 3-
0.0197(W A/ClI)^4

Fig.\. Deep Percolation as a Function of Applied Water -- Cottonwood and Gronning Curves

The City of Colorado Springs Study -- the Gronning Line

The city of Colorado Springs (approximate 1994 population: 309,000, average annual water
use: 69,200 acre-ft; Saletta and Kaufman, 1994) believed that its return flows were substantially
greater than 15% of the water application. In 1985, Colorado Springs retained consulting engineers,
Gronning Engineering Company, and began its own lysimeter project. By 1986, Colorado Springs
had installed eighty-six, 40 cm diameter, drainage type lysimeters throughout the city. Today the city
still operates and maintains more than 90 lysimeters. Unlike the hand-packed soil profile lysimeters
used in the Cottonwood study, the Colorado Springs lysimeters used an undisturbed soil core profile
obtained from in situ Iysimeter placement. The lysimeter results were presented in a different format
than the Cottonwood Curve, and a straight line relationship, the "Gronning Line," was developed
demonstrating the relationship between effective irrigation application and gross irrigation return
flows.

3