Engineer Research and Development Center US Army Corps of Engineers Estimation of Evaporation From Reservoirs Kevin Stamm, Kellie Bergman, Tim Temeyer Water Management, Omaha District Dr. Steven F. Daly ERDC/CRREL Second Annual Missouri Basin River Forecaster’s Meeting 15-17 November 2010
Estimation of Evaporation From Reservoirs. Kevin Stamm, Kellie Bergman, Tim Temeyer Water Management, Omaha District Dr. Steven F. Daly ERDC/CRREL Second Annual Missouri Basin River Forecaster’s Meeting 15-17 November 2010. Overview. - PowerPoint PPT Presentation
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Engineer Research and Development Center
US Army Corpsof Engineers
Estimation of Evaporation From Reservoirs
Kevin Stamm, Kellie Bergman, Tim Temeyer
Water Management, Omaha DistrictDr. Steven F. Daly
ERDC/CRRELSecond Annual Missouri Basin River
Forecaster’s Meeting15-17 November 2010
Engineer Research and Development Center
US Army Corpsof Engineers
Overview
• Results from a long term, relatively low cost study to estimate evaporation from reservoirs in the Omaha District and NWD-RCC
• Requirements: - Physically based - No new instrumentation installed in field- Remove existing evaporation pans- Work within the CWMS framework
Engineer Research and Development Center
US Army Corpsof Engineers
Engineer Research and Development Center
US Army Corpsof Engineers
Evaporation EstimationTwo Processes:• Bulk flux evaporation estimation • 1-D temperature heat budget to
estimate vertical temperature profile in reservoir
Using:• Met data available through Internet
from NWS or estimated• Reservoir geometry data
Engineer Research and Development Center
US Army Corpsof Engineers
Bulk-Flux Algorithm
• Estimate reservoir surface roughness based on wind speed
• Assume neutral stratification in air• Estimate transfer coefficients• Calculate fluxes• Estimate air stratification
Engineer Research and Development Center
US Army Corpsof Engineers
Engineer Research and Development Center
US Army Corpsof Engineers
Engineer Research and Development Center
US Army Corpsof Engineers
Surface Temperature is Key
Surface temperature has a strong influence on the evaporation flux because the saturation humidity immediately above the water is a strong function of the water temperature
Engineer Research and Development Center
US Army Corpsof Engineers
1-D temperature heat budget to estimate surface temperature
• Heat transfer through surface with atmosphere
• Distribution of heat throughout depth of reservoir: 1-D
Engineer Research and Development Center
US Army Corpsof Engineers
Flow Through times
Engineer Research and Development Center
US Army Corpsof Engineers
Heat transfer through surface with atmosphere
• Sensible heat flux• Latent heat flux• Solar radiation• Long wave radiation in and out - Both solar and long wave require
information on cloud cover – NWS METAR
Engineer Research and Development Center
US Army Corpsof Engineers
Distribution of heat throughout depth of reservoir: 1-D
• Solar Radiation penetration• Thermal diffusion• Mixing due to Wind• Mixing due to Potential Energy
Engineer Research and Development Center
US Army Corpsof Engineers
Solar Radiation penetration
• Majority of solar radiation is absorbed at surface
• But the remaining solar energy can penetrate to depth and be absorbed below the surface
• The clearer the water the deeper the penetration
• Measured using Secchi disk
Engineer Research and Development Center
US Army Corpsof Engineers
Wind and Density Mixing
• Density mixing cause denser water to mix with less dense water below. (Primarily in the fall)
• Wind mixing uses the work of the wind blowing over the surface to mix denser water from below with less dense water above (Anytime the wind blows.)
Papio 11 NE KOMA 1121.00 3262.00 377.00 8.65 7.81 210.55 0.37 Papio 16 NE KOMA 1104.00 1285.00 125.00 10.28 1.87 346.32 0.14 Papio 18 NE KOMA 1110.00 3037.00 259.00 11.73 4.73 323.76 0.27 Papio 20 NE KOMA 1095.80 2682.00 239.00 11.22 1.78 760.62 0.25 Pipestem ND KJMS 1442.50 8944.00 840.00 10.65 69.91 64.50 0.64
Salt Creek 10 NE KLNK 1244.90 1627.00 211.00 7.71 6.85 119.75 0.23 Salt Creek 12 NE KLNK 1232.90 1912.00 217.00 8.81 2.14 450.76 0.23 Salt Creek 13 NE KLNK 1341.00 2161.00 236.00 9.16 2.36 461.92 0.25 Salt Creek 14 NE KLNK 1244.30 7813.00 739.00 10.57 4.75 830.11 0.59 Salt Creek 17 NE KLNK 1242.40 783.00 123.00 6.37 6.41 61.61 0.14 Salt Creek 18 NE KLNK 1284.00 5088.00 1847.00 2.75 12.84 199.83 0.89 Salt Creek 2 NE KLNK 1335.00 1100.00 162.00 6.79 2.32 238.96 0.18 Salt Creek 4 NE KLNK 1307.40 2531.00 309.00 8.19 5.79 220.25 0.31 Salt Creek 8 NE KLNK 1287.80 2053.00 277.00 7.41 4.56 226.93 0.29 Salt Creek 9 NE KLNK 1271.10 1451.00 195.00 7.44 3.99 183.34 0.21