|Ayars, James - Jim|
Submitted to: Journal of Irrigation and Drainage Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2000
Publication Date: N/A
Citation: Interpretive Summary: Managing irrigation in the presence of shallow saline groundwater is difficult because the relative contributions to crop water use from soil water and ground water are unknown. There are too many alternatives of cropping pattern, soils, irrigation management, and water quality to determine these interactions through field experimentation. The alternative is to develop models which can be used in qualitative studies of the variable interactions to determine irrigation strategies for field application. This project evaluated the one-dimensional water and salt transport model LEACHC using both lysimeter and field data. The results demonstrate that the LEACHC model responded in a qualitative manner which is useful for comparative assessment of irrigation management practices in the presence of saline shallow ground water.
Technical Abstract: Soil salinity is a common problem in irrigated agriculture. High salinity levels adversely impact crop yields and reduce overall soil quality. The presence of saline shallow water table can be a major contributor to this problem. The LEACHC version of LEACHM is one of the few numerical models which considers independent movement of individual ions along with their detailed chemistry. This model has not previously been tested under saline water table conditions. LEACHC was evaluated using both lysimeter and field data from the literature. The model performed well in simulation of solute transport above a saline shallow water table. For both data sets used in the model validation, less reactive ions (sodium and chloride) were predicted well while calcium concentrations were under-predicted. For the field data, the model predicted soil electrical conductivity (EC) profiles better than most of the individual ions. The water content profiles associated with the field data were also predicted quite well. Based on these results, LEACHC was selected as a simulation tool for evaluating the effects of management practices on salinity transport in crop root zones above a saline shallow water table.