RGDSS_Task8-2_HistoricMonthlyModel_ReviewGroundwaterEfficiencies

• Title: RGDSS Task 8-2 - Phase 1c Historic Monthly Model - Review Efficiencies of Groundwater Systems
• Description: Memo documenting efficiencies of groundwater systems.
• Decision Support - Doc Type: Task Memorandum
• Date: 9/8/2000
• DSS Category: Surface Water
• DSS: Rio Grande
• Basin: Rio Grande
• Contract/PO #: C153863
• Grant Type: Non-Reimbursable
• Bill Number: HB98-1189, SB99-173
• Prepared By: Leonard Rice Engineering

Table 1
Suggested Range of Overall Maximum Ditch System Efficiencies
First Month After First Month
of Irrigation of Irrigation
District 20 26 - 55% 43 - 62%
District 21 24 - 53% 39 - 60%
District 22 16 - 46% 26 - 52%
District 24 16 - 46% 26 - 52%
District 25 16 - 46% 26 - 52%
District 26 16 - 46% 26 - 52%
District 27 24 - 53% 39 - 60%
District 35 20 - 49% 33 - 56%
Average 20 - 49% 33 - 56%
Efficiencies Used in Phase 1 a - 1 b SurFace Water Model
Surface Water Use
The efficiencies used in the Phase la and lb Surface Water Model were the average (or middle
point) of the ranges provided by the Consumptive Use Contractor. As with the ranges shown in
Table 1, different (lower) efficiencies were assigned for the first month of irrigation (April)
than for the remainder of the irrigation season (May -October). The efficiencies used in the
Phase la and lb surface water model are shown in Table 2. These efficiencies were applied to
all modeled structures of type "DIV" (receiving surface water).
Table 2
Irrigation Efficiencies for Phase 1 a - 1 b SurFace Water Model
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
District 20 52% 0% 0% 0% 0% 0% 40% 40% 52% 52% 52% 52%
District 21 49% 0% 0% 0% 0% 0% 38% 38% 49% 49% 49% 49%
District 22 39% 0% 0% 0% 0% 0% 31% 31% 39% 39% 39% 39%
District 24 39% 0% 0% 0% 0% 0% 31% 31% 39% 39% 39% 39%
District 25 39% 0% 0% 0% 0% 0% 31% 31% 39% 39% 39% 39%
District 26 39% 0% 0% 0% 0% 0% 31% 31% 39% 39% 39% 39%
District 27 49% 0% 0% 0% 0% 0% 38% 38% 49% 49% 49% 49%
District 35 44% 0% 0% 0% 0% 0% 34% 34% 44% 44% 44%' 44%
Groundwater Use
Initial efforts by the Consumptive Use Contractor also included estimation of a range of
efficiencies achieved when using center pivot and lateral sprinkler systems. On farm
efficiencies were estimated to range from 70% to 80% for sprinkler application. Sprinkler
systems are most commonly used in conjunction with groundwater wells, although minor
amounts of flood application may also occur with groundwater.
Efficiency information for groundwater use was not needed during development of the Phase
la and lb surface water model because well use was not represented until Phase lc.
Efficiencies Used in Phase 1c SurFace Water Model
Surface Water Use
The water use efficiency memorandum developed by the RGDSS Consumptive Use Contractor
was revised and updated on May 25, 2000. The revised memo provided additional information
C:Acdss\Task8-2.doc Efficiencies of Water Use September 8, 2000 -Page 2 of 4