CRDSS_Task1_15-17_AnalysisOfIrrigationandMunicipleReturnFlows

• Title: CRDSS Task 1.15-17 - Water Rights Planning Model - Ana;ysis of Irrigation and Municipal Return Flows
• Description: This memorandum generally describes procedures ‎(the Glover solution)‎ to estimate the timing of irrigation return flows and summarizes the results of a theoretical return flow analysis.
• Decision Support - Doc Type: Task Memorandum
• Date: 1/9/1995
• DSS Category: Surface Water
• DSS: Colorado River
• Basin: Colorado Mainstem
• Contract/PO #: C153658, C153727, C153752
• Grant Type: Non-Reimbursable
• Bill Number: SB92-87, HB93-1273, SB94-029, HB95-1155, SB96-153, HB97-008
• Prepared By: Riverside Technology inc.

CRDSS
TASK MEMORANDUM 1.15-17
Water Rights Planning Model
Analysis of Irrigation and Municipal Return Flows
1.0 ISSUE
This memorandum generally describes procedures (the Glover solution) to estimate the timing of
irrigation return flows and summarizes the results of a theoretical return flow analysis. The objective of
the analysis is to develop procedures that can be used to estimate the timing of irrigation and municipal
return flows for use in the CRDSS water rights planning model. For the CRDSS prototype model, the
irrigation and municipal return flow timing patterns, as represented in the existing Gunnison River
planning model (GUNMOD), were adopted. Results from this analysis are proposed for application of
the water rights planning model for future CRDSS river basins.
2.0 DISCUSSION/ANALYSIS
Glover's Analytical Method
Glover's solution for estimating the pattern of irrigation return flows is based on highly idealized
geometric and hydrogeologic properties. The method was developed for a parallel drain system, and can
be applied to a stream-aquifer system as well (see Figure 1). Considering an idealized stream-aquifer
system, the stream is assumed to be located at the center of the valley, which allows the parallel drain
and stream-aquifer analogy to be applicable since the middle section of the parallel drain is a no-flow
boundary and is similar to the left or right boundary of the stream-aquifer system. The solution for the
fractional portion of the original drainable volume remaining is given by the relationship (Glover 1978):
n
8
1 t )
=
p
2 2
exp(-n
2
2
=
nn 135. ,,..
where:p = fractional part of the original drainable volume remaining at time t,
t = time (consistent units),
w = L / 2 distance from stream along the path of flow (consistent units), and
KD
=----
V
where:K = hydraulic conductivity (units of L/t),
D = saturated thickness of alluvial material, and
V = voids ratio.
1
A275 01.09.95 1.15-17 Hyre, Fosha