Evapotranspiration and Consumptive
Irrigation Water Requirements
for Idaho
Evapotranspiration and Consumptive
Irrigation Water Requirements
for Idaho
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| Alfalfa Reference Evapotranspiration | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Growing Seasona |
Non Growing Seasonb |
Annual | |
| Meanj | mm/day | mm | |||||||||||||
| Monthlyc | 0.77 | 1.79 | 3.61 | 5.54 | 6.93 | 7.89 | 8.24 | 7.05 | 5.36 | 3.85 | 1.63 | 0.77 | -- | -- | 1629.66 |
| 15-Day Moving Averaged | 0.76 | 1.75 | 3.60 | 5.56 | 6.98 | 7.91 | 8.23 | 7.04 | 5.29 | 3.83 | 1.57 | 0.76 | |||
| 7-Day Moving Averagee | 0.76 | 1.78 | 3.60 | 5.54 | 6.94 | 7.90 | 8.24 | 7.06 | 5.34 | 3.85 | 1.59 | 0.76 | |||
| 3-Day Moving Averagef | 0.76 | 1.79 | 3.61 | 5.54 | 6.93 | 7.90 | 8.24 | 7.06 | 5.36 | 3.84 | 1.62 | 0.77 | |||
| Standard Deviationk | mm/day | mm | |||||||||||||
| Monthlyc | 0.13 | 0.42 | 0.48 | 0.79 | 0.51 | 0.69 | 0.50 | 0.51 | 0.53 | 0.42 | 0.26 | 0.19 | -- | -- | 78.49 |
| 15-Day Moving Averaged | 0.15 | 0.42 | 0.50 | 0.79 | 0.64 | 0.82 | 0.52 | 0.59 | 0.62 | 0.43 | 0.28 | 0.20 | |||
| 7-Day Moving Averagee | 0.14 | 0.43 | 0.49 | 0.79 | 0.60 | 0.76 | 0.50 | 0.53 | 0.57 | 0.43 | 0.28 | 0.20 | |||
| 3-Day Moving Averagef | 0.13 | 0.42 | 0.48 | 0.79 | 0.55 | 0.72 | 0.49 | 0.51 | 0.53 | 0.43 | 0.27 | 0.19 | |||
| 20% Exceedancel | mm/day | mm | |||||||||||||
| Monthlyc | 0.83 | 2.18 | 4.12 | 5.93 | 7.31 | 8.61 | 8.40 | 7.52 | 5.85 | 4.11 | 1.82 | 0.86 | -- | -- | 1676.48 |
| 15-Day Moving Averaged | 0.86 | 2.14 | 3.98 | 6.06 | 7.56 | 8.62 | 8.43 | 7.60 | 5.91 | 4.17 | 1.76 | 0.85 | |||
| 7-Day Moving Averagee | 0.84 | 2.27 | 4.02 | 5.98 | 7.54 | 8.60 | 8.41 | 7.54 | 5.83 | 4.21 | 1.77 | 0.86 | |||
| 3-Day Moving Averagef | 0.83 | 2.18 | 4.09 | 5.94 | 7.42 | 8.64 | 8.40 | 7.53 | 5.84 | 4.13 | 1.80 | 0.87 | |||
| 80% Exceedancem | mm/day | mm | |||||||||||||
| Monthlyc | 0.70 | 1.36 | 3.17 | 4.83 | 6.51 | 7.35 | 7.92 | 6.64 | 4.94 | 3.53 | 1.41 | 0.64 | -- | -- | 1574.37 |
| 15-Day Moving Averaged | 0.67 | 1.33 | 3.09 | 4.94 | 6.33 | 7.29 | 7.87 | 6.75 | 4.81 | 3.52 | 1.36 | 0.63 | |||
| 7-Day Moving Averagee | 0.67 | 1.35 | 3.17 | 4.81 | 6.49 | 7.25 | 7.89 | 6.78 | 4.89 | 3.54 | 1.36 | 0.64 | |||
| 3-Day Moving Averagef | 0.69 | 1.36 | 3.19 | 4.80 | 6.48 | 7.31 | 7.92 | 6.72 | 4.99 | 3.53 | 1.40 | 0.63 | |||
| Ave Highest ETr | mm/day | -- | |||||||||||||
| 15-Day Moving Averageg | 0.92 | 2.13 | 4.19 | 6.11 | 7.71 | 8.69 | 8.59 | 7.59 | 5.91 | 4.46 | 1.99 | 0.91 | |||
| 7-Day Moving Averageh | 1.09 | 2.59 | 4.72 | 6.87 | 8.53 | 9.49 | 9.03 | 8.06 | 6.47 | 5.04 | 2.41 | 1.10 | |||
| 3-Day Moving Averagei | 1.31 | 2.99 | 5.49 | 7.70 | 9.41 | 10.22 | 9.53 | 8.47 | 6.97 | 5.54 | 2.87 | 1.35 | |||
| Ave Lowest ETr | mm/day | -- | |||||||||||||
| 15-Day Moving Averageg | 0.60 | 1.43 | 3.06 | 4.98 | 6.26 | 7.06 | 7.82 | 6.46 | 4.70 | 3.23 | 1.26 | 0.61 | |||
| 7-Day Moving Averageh | 0.47 | 1.11 | 2.61 | 4.40 | 5.29 | 6.14 | 7.36 | 5.97 | 4.17 | 2.81 | 1.03 | 0.48 | |||
| 3-Day Moving Averagei | 0.33 | 0.84 | 2.19 | 3.72 | 4.52 | 5.19 | 6.59 | 5.30 | 3.60 | 2.44 | 0.80 | 0.33 | |||
| Special normal distribution parameters for monthly, seasonal, and annual intervals | |||||||||||||||
| Skewm | -0.18 | -0.19 | -0.23 | 0.97 | -0.03 | 0.35 | 1.34 | -0.32 | 0.54 | 0.99 | 0.25 | 1.40 | -- | -- | 0.66 |
| Kurtosiso | -0.25 | -1.11 | -0.64 | 0.89 | -0.75 | -0.73 | 3.38 | -0.28 | -0.12 | 0.97 | 0.26 | 3.40 | -- | -- | 0.45 |
a Growing Season: This is usually the time from green up or planting in the spring to a killing frost or harvest in the fall. It is not applicable for entries without a growing season and will be blank.
b Nongrowing Season: This is usually the time from a killing frost or harvest in the fall to the of green up in the spring. It is not applicable for entries without a growing season.
c Mean of the average daily value for month
d Mean of the fourteen 15-day period averages contained in the month
e Mean of the twenty three 7-day period averages contained in the month
f Mean of the twenty seven 3-day period averages contained in the month
g Mean of the highest/lowest 15-day period average in month
h Mean of the highest/lowest 7-day period average in month
i Mean of the highest/lowest 3-day period average in month
j This value represents the mean value for the parameter for the month over the 'normal' period of record. Generally, the 'normal' period is the last thirty years with data.
k This value represents the standard deviation for the parameter for the month over the 'normal' period.
l This value represents the value for the parameter that has a 20% chance of being exceeded that month durning any particular year. Conversely, there is an 80% chance that the parameter value will be less than the value shown.
m This value represents the value for the parameter that has a 80% chance of being exceeded that month durning any particular year. Conversely, there is an 20% chance that the parameter value will be less than the value shown.
n This value represents the skewness (asymmetry) of the distribution of the parameter values for the month (year) over the 'normal' period. A value near zero indicates that the distribution approximates a normal (Gaussian) and symmetrical distribution. A negative skew indicates that the parameter distribution has relatively few low values compared to high values. A positive skew indicates that the distribution has relatively few high values compared to the number of low values. A skew value near 1 indicates that the underlying distribution approximates a lognormal distribution.
o This value represents the kurtosis of the parameter value distribution for the month (year) over the 'normal' period. Kurtosis is a measurement of the height to width ratio of the probability distribution, or the peakedness (slenderness). A normal (Gaussian) distribution has a kurtosis of 3. A high kurtosis distribution has a sharper peak and longer tails, while a low kurtosis distribution has a more rounded peak and shorter tails.
Use Constraints: The Idaho Department of Water Resources is making this data available as a public service. The Idaho Department of Water Resources strives to ensure that all technical data and other information made available to the public is accurate, complete and in conformance with the Idaho Public Records Act. Neither the Department of Water Resources nor the State of Idaho, however, assumes any legal responsibility for the accuracy or completeness of the information contained on this site. Persons using information from this site for official purposes, or other purposes, for which accuracy and completeness are required, are hereby notified that they should first verify the information with the public records or other primary sources from which the information was obtained.
Questions regarding the data should be addressed to the IDWR Geospatial Technology Section Idaho Department of Water Resources, Idaho Water Center, 322 E Front Street STE 648, Boise, ID 83702-7371. Telephone (208)-287-4800