I was thinking the same thing about ponding and even some mud erosion using a gun. I don't think big impacts would be much of a problem but I grew up on a farm using lots of big guns and we use a couple of smaller 100gpm guns now. Guns don't spinkle, they slam the ground with big, fast, heavy slugs of water.
And guns don't water evenly in the first few passes. They skip big areas on each rotation. Each tick-tick-tick of the gun can send out a 5 gallon slug of water that's 10 feet from the last 5 gallon slug. Eventually the whole area will be evenly watered but that may not be until you've made a lot of mud.
And guns don't usually do a good job of even watering at low pressures. At low pressures, guns tend to water only the outside edge of the circle. That's fine on a traveling reel where the gun moves. Since the watering circle moves, eventually everything is on the outside edge of the circle and gets watered. Stationary guns need high pressure to break up the water stream to water evenly. Ag guns usually run over 100psi and 150psi isn't that unusual.