SPDSS_Task53-3_Assign Key Climate Information to Irrigated Acreage and Reservoirs

• Title: SPDSS Task 53.3 - Assign Key Climate Information to Irrifated Acreage and Reservoirs
• Description: This memorandum presents the general approach for the following Task 53 subtasks: 1. Assign key climate stations to geographic areas for the SPDSS modeling efforts. 2. Estimate average monthly reservoir evaporation rates for geographic areas.
• Decision Support - Doc Type: Task Memorandum
• Date: 2/1/2006
• DSS Category: Consumptive Use
• DSS: South Platte
• Basin: South Platte
• Contract/PO #: C153954
• Grant Type: Non-Reimbursable
• Bill Number: SB01-157, HB02-1152, SB03-110, HB04-1221, SB05-084, HB06-1313, SB07-122
• Prepared By: Leonard Rice Engineering

Table 6
Estimated Average Monthly Net Reservoir Evaporation
(Inches)
Water District Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total
1-Upper 0.07 0.93 1.52 225 3.17 4.81 4.46 3.11 3.59 2.40 1.09 0.26 27.67
1-Lower 1.18 1.47 1.86 3.12 3.56 4.73 4.75 4.54 3.48 2.61 1.50 1.17 33.96
2 0.90 1.19 1.44 2.37 2.81 4.57 5.12 4.73 323 2.19 1.07 0.94 30.55
3-Upper -0.31 0.30 0.44 1.00 1.95 3.68 3.35 2.69 2.44 1.65 0.36 -0.10 17.46
3-Lower 0.75 1.04 1.16 1.92 2.18 3.89 4.44 4.12 2.76 1.86 0.87 0.79 25.78
4-U er -0.19 0.33 0.64 1.09 1.30 3.01 2.38 1.66 2.03 1.46 0.46 -0.15 14.02
4-Lower 0.73 0.93 0.90 1.62 2.00 3.83 4.61 3.85 2.50 1.80 0.79 0.66 2422
5-Upper -0.96 -0.18 -025 0.34 125 3.28 2.97 1.99 1.95 1.31 -0.18 -0.70 10.79
5-Lower 0.72 0.92 0.87 1.58 1.94 3.79 4.58 3.82 2.47 1.78 0.77 0.65 23.89
6-U er -0.54 0.11 0.16 0.65 1.71 3.39 2.54 1.12 1.89 125 0.16 -0.59 11.85
6-Lower 0.60 0.68 0.59 1.39 1.94 3.85 422 3.77 2.44 1.63 0.50 0.56 22.17
7-Upper -0.48 0.18 0.31 0.85 1.92 3.57 2.79 1.39 2.06 1.37 0.25 -0.50 13.72
7-Lower 0.70 0.84 0.86 1.71 2.20 3.88 425 3.78 2.66 1.83 0.67 0.68 24.06
8-Upper -0.02 0.57 1.03 1.90 2.87 4.35 3.71 2.49 3.06 1.88 0.78 0.03 22.63
8-Lower 0.75 0.86 0.93 2.14 2.75 428 4.15 3.73 3.02 1.96 0.87 0.69 26.13
9-U er -0.23 0.19 0.35 0.89 1.52 3.35 3.33 2.19 2.40 1.40 0.39 -0.20 15.57
9-Lower 0.71 0.85 0.86 1.72 2.21 3.91 429 3.82 2.68 1.85 0.68 0.69 2427
23 0.11 0.77 1.55 2.46 3.32 4.33 322 1.67 2.80 1.90 1.04 0.16 23.33
47 -0.64 0.17 1.06 1.80 2.41 3.95 3.69 2.67 2.13 1.37 021 -0.47 18.35
48 -0.41 0.18 0.17 0.65 1.54 3.38 2.97 2.37 2.19 1.49 0.19 -020 14.51
64 1.16 1.43 1.88 3.17 3.14 4.50 4.82 4.87 3.79 2.54 1.47 1.17 33.93
76 -024 0.43 0.70 1.37 2.42 4.19 3.91 3.14 2.81 1.91 0.53 -0.02 21.15
80 -0.09 0.42 0.68 1.11 1.99 3.61 2.66 1.63 2.35 1.37 0.55 -0.09 16.19
Comments and Concerns
Recommended average monthly evaporation rates vary from the rates used by Denver Water and
NCWCD in their surface water modeling efforts. A comparison between SPDSS recommended
average monthly evaporation rates and Denver Water rates for the same regions show they vary
between 1 percent and 35 percent. The largest variations are for upper reservoirs where Denver
Water sets winter evaporation rates to zero, whereas our analysis shows that reservoirs in these
areas should experience winter evaporation.
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