| The two-dimensional, hydrodynamic model HYDRUS-2D is used to simulate irrigation schedules for an alfalfa crop over the length of a growing season. The objective is to evaluate current practices in order to produce management alternatives that reduce irrigation drainage. HYDRUS-2D uses a finite element technique that numerically solves the Richards equation for water movement in variably saturated media. The model is calibrated using field data collected from an instrumented plot at the Newlands Agricultural Research Center in Fallon, Nevada. The following ratio is used to determine what portion of the water leaving the soil profile is consumed by evapotranspiration, Det/Det+Dd where Det is the depth of water used by evapotranspiration and Dd is the depth of drainage water. Optimal results are achieved as the ratio approaches one. Using 24-hour intervals the ratio provides insight into ways to modify standard irrigation practices to create a more efficient management alternative. |
