DRENA: A model for the transport of nuclides in drainage slopes

This report presents documentation and a user's manual for program DRENA, a mathematical model of nuclides transfer in simple slopes and sections of a drainage catchment. Mathematical equations and physical principles utilized to develop the code are presented in section 2. The flowchart and some mathematic and numerical details are presented in Section 3. Section 4 presents an overview of how problems should be set up to properly use the code as well as the detailed input instructions and output results formats. One example problem, including sample input data sets and output data, are presented in Section 5. The complete program listings including comments are presented in the Appendices. Nuclides are assumed to enter the catchment via atmospheric deposition and then carried by the water runoff and the dragged sediments. The desorption/adsorption dynamics between water and sediments are considered to be in the equilibrium given by a Kd parameter, a distribution coefficient. Codell's and Einstein expressions for the caudal and concentration of dragged sediments are utilized. (Author) 36 refs