The 7.5-metre-long patch has been created from a single section of hand-polished green marble, and was designed using 3D software.
The material has been carved into realistic waves that replicate water that has been "gently ruffled" by the wind.
The piece reflects on the hidden presence of the Loire river, which flows beneath the courtyard of the Domaine de Chaumont-sur-Loire Centre D'Arts et de Nature, where the installation is presented.
"I wanted to address the garden with water as my muse," said the designer. "The water whose presence we sense even before we first catch sight of it below the chateau, flowing uninterrupted to the sea."
"Petite Loire is a freeze-frame, the river's perpetual movement caught in a frozen, fossilised moment," he added. "A few dozen metres above the river's natural level, Petite Loire cuts cleanly through the garden's surface, delving into the soil to reveal a fluvial relief, both vertiginous and practicable, in green marble."
The piece is a continuation of the designer's Liquid Marble series, the first instalment of which made its debut at Milan design week in 2013 as a static pool with dark rippling waves carved from black marble. The piece was housed in a room constructed from contrasting white marble.
With his Petite Loire installation, Lehanneur hopes to create something resembling a "magic portal" that visitors will experience on entering the chateau courtyard.
"Everything is liquid in this space, evanescent, enlightened, and yet it is executed in a material that is one of the most solid imaginable," said the designer.
Lehanneur also played with perceptions for his Clover street furniture – installed in Paris last year – using digital machining to blend different types of wood into giant, spindly stems.
The Petite Loire installation is being shown in the courtyard of the Domaine de Chaumont-sur-Loire Centre D’Arts et de Nature in France, and will remain on display until 2 November 2016.
Photography is by Michel Giesbrecht.