Analyzing irrigation, soil salinization, or crop production problems often requires simulations of root water uptake as a function of water and salinity stress.  We give an overview of macroscopic modeling approaches that are based on the Richards equation with a sink term specifying water uptake.  Various parameterizations of the sink term as functions of water and salinity stress are reviewed and example applications are presented.  We also review the incorporation of more dynamic root functions into sink terms, such compensatory uptake.  Lastly, we discuss the challenge of estimating uptake reduction parameters from crop salt tolerance databases.