Hydrologic Data Development System ( by Peter Smith) is a package of spatial data and menu-driven programs that allows user-interactive determination of hydrologic parameters and estimation of flood frequency relationships for the highway drainage structures. The program employs Arc/Info, using aml. Since I am working on the TxDOT project and familiar with HDDS, I'm going to display the results and some functions of the wonderful system on Arcview environment by learning avenue programming.