Here's a short walk through the (200 acre!) Mississippi River Basin Model, built by the U.S. Army Corps of Engineers: pic.twitter.com/I3ZKwAsmgW— Nate Berg (@nate_berg) November 9, 2018
From Wikipedia:
By 1952 the Missouri River segment was fully operational and used extensively to predict problems during that year's April floods, helping to avoid damage of an estimated $65 million. By 1959 the model was complete as far as Memphis and a comprehensive testing program was begun which coordinated the entire model.