This new soil water flux model is designed to improve GOSSYM's ability to simulate water transport processes in the soil profile. It addresses processes of infiltration, surface runoff, percolation losses, evapotranspiration losses, and redistribution of water in response to water potential gradients within the profile. Development of the new model involves consideration of current and future GOSSYM model structure, assumptions about the soil profile and soilwater interactions, and selection of appropriate simulation equations and solution techniques.