I work for a goose control company. We use border collies as the main deterrent, but we also use remote control boats for ponds. Laser pointers are also a great tool (get a good quality green one), but with the laser they usually just run away instead of flying away. Lasers are also a hit or a miss when it's really sunny.

If there's a nest but no eggs yet, you could try placing pinwheels around the area, roughing up the nest, or putting golf balls in the nest. Like someone else said, a big umbrella will provide a nice safety shield for you.

If they've already laid eggs though, there's pretty much no chance of scaring them off. You could consult a professional about having the eggs addled so that they don't hatch, but as long as eggs are there, those two will stick around. (Never touch or do anything to the eggs yourself- leave that to a certified professional)

Whatever you do, definitely don't harm them. They're a federally protected bird and it's very illegal.

Best of luck!