Watershed models are useful tools to help understand the impact of land use on hydrology. The 2010 release of the Soil and Water Assessment Tool (SWAT) model (SWAT2009) has been provided with a Land Use Update (LUU) module that allows land use to be updated dynamically during simulation runs. In this chapter, we explain the working of the LUU module in SWAT2009 and discuss features of SWAT2009 Land-use Change (SWAT2009_LUC), an interactive tool for developing input files for use by the LUU module. The utility of LUU is demonstrated using a hands-on exercise involving the SWAT2009_LUC tool through a case study conducted in a watershed that is being urbanized in Northwest Arkansas.