In a large saucepan combine rhubarb, ginger, and 1 cup water. Bring to boiling; reduce heat. Simmer, covered, for 5 minutes. Remove from heat and cool slightly. Pour mixture into a fine mesh sieve set over a bowl. Strain rhubarb mixture, pressing rhubarb gently to get out as much liquid as you can. Discard pulp. Return the strained liquid to saucepan; add sugar. Cook and stir until sugar is dissolved. Cover and chill, if desired.
Just before serving, stir the orange juice and lemonade concentrates into rhubarb liquid. Transfer to a large punch bowl. Add 4 cups water. Gradually pour ginger ale down sides of punch bowl. Serve over ice. Makes 14 (6-ounce) servings.