Assuming that the top of the bridge is the origin, the equation is y = a * x 2.

X = the square root of 6, y=-3.

-3 = a * 6-& gt； a= 1/2

So after the water level rises by one meter, Y =-2, -2 =- 1/2 * x 2-> X= plus or minus 2.

So the water is 4 meters wide.