Adopting Meteorological Approaches in Irrigation Scheduling for High Rainfall Areas

Heermann, Dale F. and Jensen, Marvin E. (1970) Adopting Meteorological Approaches in Irrigation Scheduling for High Rainfall Areas. pp. 00.1-00.10. In: Proc. ASAE Natl. Irrig. Symp. USA-NE-Lincoln, 1970/11/10-13.

PDF 216.pdf Download (366kB)

Abstract

The irrigation scheduling program developed by Jensen, et al. and
used by the Bureau of Reclamation, irrigation districts, and several private
consultants has been widely accepted by the irrigators subscribing to the
scheduling service. The program, summarized in the previous paper, forecasts
the next date of irrigation by maintaining a water budget and estimating the
number of days until the soil water depletion approaches an optimum value.
The depletion or evapotranspiration rate used for estimating the next
irrigation is a 6-day average occurring at the time of forecasting. The
irrigation-scheduling program accounts for the precipitation that occurs
before the date of forecast but assumes no additional rainfall before the
date of irrigation.

Most of the areas in which the irrigation-scheduling program has been
used are located in the arid and semiarid Western United States. In these
areas, limited rainfall has little effect on the predicted date of irrigation.
Also, 6-day average evapotranspiration is more uniform from week to week than
in sub-humid regions. Most of the variability in consecutive estimates of the
date of irrigation is caused by the differences between the estimated evapotranspiration
and that actually occurring in the forecast period. Adapting
the irrigation-scheduling program to sub-humid and humid regions may require
a more stable forecast of evapotranspiration and the inclusion of rainfall
probability. This paper describes procedures for including the precipitation
probability in the program for scheduling irrigations, and the effects of
using long-time average evapotranspiration rates for the forecasts.

Item Type:	Conference or Workshop Item (Paper)
NWISRL Publication Number:	0216
Subjects:	Irrigation > Irrigation scheduling Mass Import - autoclassified (may be erroneous)
Depositing User:	Dan Stieneke
Date Deposited:	20 Nov 2010 21:56
Last Modified:	17 Feb 2017 20:21
Item ID:	984
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/984