CRDSS_Task1_15-17_ColoRiver_IrrigationReturnPatterns

• Title: CRDSS Task 1.15-17 Colorado River Basin Representative Irrigation Return Flow Patterns
• Description: The purpose of this task was to develop return flow patterns for both the monthly and daily CRDSS planning models using geologic parameters representative of actual locations of irrigated acreage in each of the five CRDSS basins and a methodology that is acceptable and can be reproduced.
• Decision Support - Doc Type: Task Memorandum
• Date: 1/20/2003
• DSS Category: Surface Water
• DSS: Colorado River
• Basin: Colorado Mainstem
• Contract/PO #: C153933, C154062
• Grant Type: Non-Reimbursable
• Bill Number: SB92-87, HB93-1273, SB94-029, HB95-1155, SB96-153, HB97-008
• Prepared By: Leonard Rice Engineering

Table 1
Geologic Parameters by Site
Site
# Irrigating
Structure Hydraulic
Conductivity
(feet/day) Saturated
Thickness
(feet) Specific
Yield Stream to
Barrier
(feet) Recharge
to Stream
(feet)
1 400534 150 70 0.12 30000 3400
2 410944 150 70 0.15 4000 1000
3 280674 70 70 0.12 1500 450
4 370539 150 75 0.15 3000 1500
5 370658 150 75 0.2 1500 450
6 510699 150 70 0.15 6600 600
7 580920 150 70 0.15 5300 2500
8 440517 60 30 0.1 2000 600
9 430935 60 20 0.1 8000 4200
10 310523 70 50 0.1 2600 1500
Avera e 107.5 60.0 0.134 6450.0
Median 150.0 70.0 0.135 3500.0
The Glover parameters used in the analysis to represent the CRDSS basins were as follows:
Transmissivity = 48,250 gpd/ft (Hydraulic Conductivity of 107.5 feet/day * Saturated
thickness of 60 feet * 7.48ga1/cfs)
Specific Yield = 0.13
Stream to Barrier = 3500 feet
Stream to Irrigated Acreage = 600 feet for lands relatively close to live stream
= 1500 feet for lands further from live stream
The Glover analyses were performed using the State's model, as described above.
Monthly Analysis -Lands Close to Live Stream
Figure 2 shows the monthly accretions to the river, as a percent of recharge, for lands close to a
live stream. As shown, a small percent of the water is still returning to the river 24 months after
it has been applied. Table 3 shows the procedure for including surface water returns with the
ground water accretions. Note that a practical decision was made to end the return flow pattern
when less than 0.5 percent of applied water is returning. The remaining water was distributed to
previous months based on proration, whereby early months with more return flows received
more of the distributed water.
Figure 2 also shows the total returns to the river, from both surface water and ground water.
As shown, the monthly return flow patterns for lands close to the stream return 100 percent of
non-consumed water via surface returns or ground water recharge within nine (9) months of
diversion. The values were formatted and included in the monthly delay pattern file CRDSS.dIy.
Page5of12