Holly`s Last Hydraulics Project

Forrest M. Holly Jr’s last hydraulics project, completed in late 2016, involved the qualities for which he was known and admired: technical ability (especially in numerical modeling of water flow), genial companionship, and an interest in various things beyond hydraulic engineering. Our paper describes Forrest Holly’s qualities, doing so in the context of his last hydraulics project, which involved understanding flow behavior in a reach of the Illinois River that extended about 10km upstream from Marseilles Lock and Dam, Illinois. We worked with him on his last project, which involved the application of his numerical code CHARIMA, a one-dimensional numerical model of unsteady flow in a river channel; CHARIMA is a French acronym for Charriage dans les Rivières Maillées (sediment transport in multiply connected river systems). His model already had been in use since the early 1990s by electric-power companies needing to simulate river flow and temperatures from downtown Chicago to Marseilles Dam.

When applied to unsteady flow, without sediment transport or concern for water temperature, CHARIMA’s computations are equivalent to those of the widely used numerical model HEC-RAS. Holly worked closely with Dr. Alexandre Preissmann at SOGREAH Consulting Engineers, Grenoble, France from 1976-1981, implementing and developing the Preissmann computational scheme, which became widely used internationally for numerical models such as HEC-RAS and CHARIMA. Holly chose to use CHARIMA because of his close familiarity with the code and his experience in using the code for modeling flow in the Illinois River. Holly’s modeling, and last hydraulics project, usefully showed how operation of Marseilles Dam’s spillway gates could influence water levels in the navigation approach to Marseilles Lock.

Computational hydraulics was a major professional interest of Holly, but it was just one of his interests. He enjoyed, for example, the books of the great Victorian novelist, Charles Dickens. Many instances during Holly’s last project were spent discussing plots and characters in one or other of Dicken’s books. Our paper briefly describes Holly’s last hydraulics project and reminisces about working with him.