干旱区生态环境知识资源中心

Irrigation of arid and semi-arid agricultural regions has produced salinization and waterlogging problems. Tile drainage systems will effectively lower the water table and transport salts out of the root zone. However, the salts exiting the irrigated soils via drains cause new problems, such as reducing groundwater quality and damaging wetlands habitat. This research investigates the simulation of management alternatives that control drainage and the mass flux of salts in the drainage water and demonstrates an improvement over the use of leaching fraction and leaching requirement as conceptual models.

HYDRUS_2D, a two-dimensional Windows-based modeling environment, is used to simulate solute transport under the influence of alternative irrigation management practices for an alfalfa crop. HYDRUS_2D uses a finite element technique that numerically solves the Richards equation for saturated/unsaturated flow, and the Fickian-based advection/dispersion equation for solute transport in variably saturated porous media. The response to management alternatives (depth of irrigations, using water sources of varying quality in irrigating a soil with varying salinity) allows managers to evaluate the influences on the mass flux of salts in drainage water before they put a new approach into practice. The results include graphical displays of water and solute fluxes and the salt distribution in the upper soil profile.