2–D SATURATED–UNSATURATED ZONE IRRIGATION AND DRAINAGE MODEL: PART II. SENSITIVITY ANALYSIS

Abstract

The modified SWMS_2D model described in the previous article was used to study sensitivity of model output tocritical head, sorption distribution coefficient, initial solute concentration, distal boundaries, plant water uptake parameters,irrigation schedules, and soil type considering a 100 m 9 m transect in the western San Joaquin Valley. Output was foundinsensitive to reductions in minimum soil water suction head (hd) and distal boundaries located 1000 m away from the domainof interest, and was found to be sensitive to values of sorption coefficient (Kd), plant water uptake parameters, irrigationschedules, and soil type. Finally, application of a method to separate evapotranspiration into evaporation and transpirationby deriving the ground shading parameters from crop coefficients was demonstrated. The results suggest that the modifiedSWMS_2D model can be used for irrigation and drainage management.