Skip to main content
ARS Home » Research » Publications at this Location » Publication #148559
Title: WATER FLOW AND SOLUTE TRANSPORT IN FURROW-IRRIGATED FIELDS

Author
item ABBASI, FARIBORZ - UNIV LEUVEN, BELGIUM
item FEYEN, JAN - UNIV LEUVEN, BELGIUM
item ROTH, ROBERT - UNIV OF ARIZONA
item SHEEDY, MIKE - UNIV OF ARIZONA
item Van Genuchten, Martinus

Submitted to: Irrigation Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/23/2003
Publication Date: 9/1/2003
Citation: Abbasi, F., Feyen, J., Roth, R.L., Sheedy, M., Van Genuchten, M.T. 2003. Water flow and solute transport in furrow-irrigated fields. Irrigation Science. 22(2):57-65.

Interpretive Summary: Water flow and solute transport processes into and through natural soils can be very complex, even in relatively uniform soils. This has been demonstrated in a number of large-scale tracer experiments during the past several decades. Difficulties in carrying out and modeling such experiments stem from the presence of considerable soil surface heterogeneity, variability in subsurface soil hydraulic and solute transport parameters, lack of expedient methods for accurately measuring soil properties at the desired scale, and the high cost and labor generally required for field experiments. While measurement techniques have considerably improved recently, they are generally still far too expensive for routine characterization of large fields at sufficient resolution. In this paper results of several field-scale furrow irrigation experiments are presented to investigate the effects of water level and solute application time on bromide distribution along and below the furrows. One experiment was conducted under free-draining conditions in which bromide was applied during the entire irrigation event, while three experiments were carried out on blocked-end furrows in which bromide was injected during either the entire irrigation event, the first half of the irrigation, or the second half of the irrigation. Results show a dependency of downward solute transport on water level and application time, and considerable non-uniformity in the solute distributions as observed at various sites along the furrows. However, it was difficult to associate the observed solute non-uniformity to only water level and/or application time because of the heterogeneous nature of the soil surface conditions and variability in the soil hydraulic and transport properties. Subsurface solute distributions below the first half-length of the furrows were much more uniform than in the second half, regardless of the irrigation regime and the solute application time. Solute distribution uniformity and application efficiency together can provide useful information about prevailing field-scale flow and solute transport processes. The effects of water level and irrigation application time on the distribution of water below the furrows were found to be negligible, likely because of rain several days after the irrigation.

Technical Abstract: Solute transport experiments under realistic conditions at the field scale are not easily implemented because of the often overwhelming problems of soil surface heterogeneity and variability in subsurface hydraulic and solute transport properties. In this paper, results of several field-scale furrow irrigation experiments are presented to investigate the effects of water level and solute application time on bromide distribution along and below the furrows. One experiment was conducted under free-draining (FD) conditions in which bromide was applied during the entire irrigation event, while three experiments were carried out on blocked-end furrows in which bromide was injected during either the entire irrigation event (100 percent), the first half of the irrigation (FH), or the second half of the irrigation (SH). Soil samples for bromide analysis were collected 5 days after the irrigation at three sites (inlet, middle, and outlet), in each case at three different locations in furrow cross-sections at depths of 0.20, 0.40, 0.60, 0.80, 1.0, 1.4, and 1.8 m. Results showed substantial solute non-uniformity along the monitored furrows, with the degree of non-uniformity depending upon water level and solute application time. Non-uniform distributions were especially observed at the outlet sites, with those at the inlet and middle sites being far more uniform. Solute application efficiencies for the FD, 100 percent, FH, and SH experiments were 50, 100, 64, and 93 percent, respectively. The effects of water level and irrigation/solute application time on subsurface distributions of the soil water content were found to be relatively minor.