Zallerbach seems to me an alternate spelling of the name Zellerbach.
This is a German river in Bavaria, Germany Zeller Bach (Memminger Ach). It means: Zeller Creek. More info in German language about the name Zeller you find here: http://wiki-de.genealogy.net/Zeller
There's also a German river in Lower Saxony, Germany: Zellbach (which probably took its name from a monastery named Cella, which was situated at this river in the Middle Ages).