Irrigation capacity for extreme drought
Example: To determine how many acres can be irrigated for a target IC of 0.35 in/day, with a system flow rate of 600 GPM and an irrigation system efficiency of 90 percent:
Irrigated acres = 600 GPM/450 x 24 hrs/day = 102 acres
0.35 in/day x 0.9
Approximately 102 acres of a crop currently experiencing water stress might be able to be salvaged in this scenario.
Three software tools may also be of help to decide the best course of action. These include:
- KanSched: an ET-based irrigation scheduling tool
(see download link at http://www.ksre.ksu.edu/mil)
- Crop Yield Prediction (http://www.ksre.ksu.edu/mil/YieldEstimator.htm)
- Crop Water Allocator (http://www.ksre.ksu.edu/mil/cwa)
These tools were not designed specifically to look at the question of diverting water from one portion of the field to another, but could provide some insight about different scenarios by examining output for multiple runs with different assumptions. However, selecting the number of acres to water in salvage should be based on estimated crop water use and irrigation capacity as described above.
Before making any decisions about changing irrigation practices, please read the following article (No. 5) on crop insurance-related concerns.