Mud Island
2011 WAS ONE OF THE best years for extremely bad weather in the USA. Heat in Texas, tornados in Alabama and Missouri, and floods all over, from North Dakota to the Atchafalaya, to Vermont. Most of the high waters converged on the Mississippi River since it drains two thirds of the continental USA, prompting the government to open the Morganza Floodway gates in Louisiana for the first time in 38 years, intentionally flooding one area to save some others.
The transformation of the Mississippi into an engineered continental plumbing mechanism, leveed for thousands of miles, and with valves that can be a mile long, turning on and off rivers, is one of the largest single systemic constructions in the world. While it’s hard to get one’s mind around something so vast, there are two places in the country where this has physically been attempted.
One is the Mississippi Model, a 200 acre 1:2,000 scale functional model of the river made over a thirty year period by the Army Corps of Engineers, now rotting in a field outside of their headquarters in Vicksburg, Mississippi (and the subject of an exhibition by the CLUI in 1995).
The other site is the Mississippi Riverwalk, a half-mile long contour map of the river, located on the shore of the Mississippi itself, in Memphis, Tennessee. This model of the river allows people to walk the length of the river at a very “human” scale, where one step equals about a mile. The journey along the meandering miniature channel, from Illinois to New Orleans, is punctuated by interpretive plaques noting regions and features, and ends up in the gulf of Mexico, represented by a one-acre wading pool where paddle boats can be rented.
The Mississippi Riverwalk was built as part of a larger park design for Mud Island, an old sandbar on the river, next to downtown Memphis. Mud Island first appears on maps in the late 1800s, and for much of its life was notable mostly as a hazard to navigation on the river. The development of the island was conceived in the 1970s as part of the nation’s bicentennial fervor, but wasn’t completed until 1982. The park, which includes an amphitheater, museum, and restaurant structures, as well as the Riverwalk, was designed by Memphis architect Roy Harrover, whose other civic accomplishments include the Memphis international airport.
Though Mud Island is actually a peninsula now, connected to the land at its northern end, Harrover’s design called for a futuristic approach to the park, in the form of a hanging monorail over the water. The trip takes just a couple of minutes, and ends at the top of a building that provides an aerial view of the Missississippi River model and the full sized analog that surrounds it. 
Visitors to Mud Island arrive via a tall bridge, along which runs a dangling monorail. Once on the island and descending to ground level, visitors have the option of entering a museum that focuses on regional history and the river, and includes a towboat pilothouse display, full-size talking mannequins of Mark Twain and other historical figures, a “Theater of Disasters” showing a film about accidents along the river, a full-size replica of Old Ironsides, and a display about the musical history of Memphis. The museum recently got a few small updates from the company that designed it originally, Barry Howard Limited, of Santa Monica, California. Barry Howard is an interpretive center, trade show, and museum display company that has designed dozens of visitor centers, including at some of the nation’s most notable landscape attractions, such as at Mount St. Helens, the Hoover Dam, and the Bay Model, in Sausalito.
Once outside the museum and its gift shop, visitors land on the surface of the model, at a point just upstream of Memphis. The model contains gently flowing water, 1.2 million gallons of it, re-circulated every 12 hours through nearly two miles of underground piping. It slopes down from upstream to downstream, proportionately to the real river, though the designers had to cheat a little bit with the grades so that they could keep a more even slope. Other distortions include the exaggeration of the vertical scale by more than 20 times, in order to display more physical relief (horizontally the scale is 1 inch equals 175 feet, while vertically 1 inch is equivalent to 8 feet.) If it were proportionally as flat as the real river that it flows next to, water would be stagnant in it, and the sides would barely appear to rise at all.
The model is made of 1,746 precast concrete panels, each weighing 5 tons. The relief on the panels is not continuous, but is stepped, like contour lines, giving the effect of being on a map as well as a model. Each contour level step is just over an inch, equivalent to a five foot change in elevation.
Rather than display the entire Mississippi River and its extensive watershed, the Riverwalk Mississippi represents the 950 miles of the lower river, from Cairo, Illinois to the Gulf of Mexico, beginning just above the confluence of the Ohio River with the main river channel. The four principal tributaries–the Arkansas River, the Missouri River, the Ohio River, and the upper Mississippi–which extend the watershed north to Canada, west through Montana, and east to Pennsylvania, are represented with “watershed walls,” each emitting a roughly proportional amount of water over a small spillway into the model channel.
Walking the 2,200 feet/950 miles of the model river, one passes dozens of descriptive plaques and markers on the ground. The cities are represented as light relief maps, made in stone and concrete, with roads and other features in inlaid metal. AHP numbers embedded in the concrete refer to the distance upstream “above the head of passes,” the navigational beginning of the river in the birdfoot of Louisiana. After that, the concrete slabs of the river submerge into the one acre Gulf of Mexico pool, which is sometimes stocked with catfish.
At the end of the actual Mississippi River, in the full-sized Gulf of Mexico, there is a dead “hypoxic zone,” a product of all the organic nutrients and pollution that flows out of the river. In an apparent coincidence, on the Riverwalk, the Gulf of Mexico was originally intended to be a swimming pool, but the health department forbids swimming there, due to water quality problems. ♦