Bulletin 166-4, Urban Water Use in California, August 1994 Appendix E. Precipitation and Urban Landscaping Variance in per capita water use is affected by a number of factors, as discussed in Chapter 3 . Figure E-2 shows per capita use relative to July temperatures.
Most plants extract the stored soil moisture in the spring and early summer.
The concepts of effective precipitation and soil-moisture deficit have been used effectively in agriculture but are more difficult to apply to urban landscaping. Irrigation management on a farm is optimized because the fields are normally large, planted to one variety of crop, and evenly spaced in rows. A similar situation exists in landscapes only on large playing fields. While individual homeowners cannot be expected to apply such concepts, urban water managers can use them to analyze and project monthly and yearly demands. See also Chapter 3.