New piecewise-continuous hydraulic functions for modeling preferential flow in an intermittent-flood-irrigated field
Academic Article
Overview
Research
Identity
Additional Document Info
View All
Overview
abstract
Modeling water flow in macroporous field soils near saturation has been a major challenge in vadose zone hydrology. Using in situ and laboratory measurements, we developed new piecewisecontinuous soil water retention and hydraulic conductivity functions to describe preferential flow in tile drains under a floodirrigated agricultural field in Las Nutrias, New Mexico. After incorporation into a twodimensional numerical flow code, CHAIN_2D, the performance of the new piecewisecontinuous hydraulic functions was compared with that of the unimodal van GenuchtenMualem model and with measured tileflow data at the field site during a number of irrigation events. Model parameters were collected/estimated by site characterization (e.g., soil texture, surface/subsurface saturated/unsaturated soil hydraulic property measurements), as well as by local and regionalscale hydrologic monitoring (including the use of groundwater monitoring wells, piezometers, and different surfaceirrigation and subsurfacedrainage measurement systems). Comparison of numerical simulation results with the observed tile flow indicated that the new piecewisecontinuous hydraulic functions generally predicted preferential flow in the tile drain reasonably well following all irrigation events at the field site. Also, the new bimodal soil water retention and hydraulic conductivity functions performed better than the unimodal van GenuchtenMualem functions in terms of describing the observed flow regime at the field site.
