The agricultural irrigation water demand projections for 2011 through 2050 used data computed from the above sources. Irrigated areas for each crop were projected from the baseline of year 2008 acres using the economic models. Irrigation withdrawals that make up future agricultural demand were computed as the product of the future irrigated area for the crop (Table 4 for each county in AWD Reports above) and the predicted irrigation amounts for that crop for wet, average, and dry years (Table 5 for each county in AWD Reports above). Projected withdrawals were summed over crops within each county. Finally, the withdrawal amounts were divided into surface and groundwater sources. A county's ratio of mapped sources (Table 3 for each county in AWD Reports above) was assumed to apply for the aggregate withdrawals from that county. Thus, the proportion of a county's water source taken from groundwater was multiplied by the summed county withdrawal to obtain expected withdrawals from this source. Likewise the proportion of a county's water source taken from streams and ponds was multiplied by the summed county withdrawal to obtain the proportion expected from surface sources, but that number was reduced to 70% of the computed amount. Final values were placed in the Table 1 for each county in Ag Water Demand Reports provided above.
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