Riesch, who leads the overall World Cup standings, tacked another 60 points onto her total with a combined time of 1 minute, 59.60 seconds in the super-G and slalom runs.
Tina Maze of Slovenia was second at 2:00.00 and Austria's Elisabeth Goergl placed third.
American Lindsey Vonn won the opening super-G segment but finished the event in sixth place with a combined time of 2:00.76. Teammate Julia Mancuso finished eighth.
"My super-G was really encouraging, but I'm pretty frustrated with my slalom," said Vonn, who trails Riesch in the overall standings by 216 points with four weeks remaining in the World Cup season. "I had a hard time with the groove and lost my balance on a rut about 10 gates in and never really got my rhythm back."