Momentum of Surface Water Runoff vs. a Golf Ball

[David Schofield]

I've always wondered why more greenside bunkers aren't consructed in a manner that would allow the internal green contours from feeding balls into them.  A previous thread opined that this is for several reasons, not the least of which is maintenance.  The maintenance concerns mostly focused upon turning mowers around on the collar and the concentrated surface water drainage eroding the bunker face.  Being an engineer by trade, I started wondering if it was possible to grade a shallow swale around a bunker that would collect and redirect surface water drainage but not a golf ball.  In other words, does a golf ball have more momentum than surface water runoff?  I've fashioned a crude diagram below:

(bunker)
^^^^^^
vvvvvvvvv
--swale-->
^^^^^^
^^^^^^
(green)

[Jeff_Brauer]

I am sure every shot is different, especially around greens where the approach might be a 2 iron or a 9 iron, with the lofted irons typically stopping quicker.

It only takes a few inches of lip above a bunker to keep all but Katrina sized rainstorms out of a bunker.  I would actually think that mowing the collar all the way to the bunker lip would have a greater effect on directing balls into  bunker than rough and could be used, if mowing right up to the bunker edge isn't a problem.

Depending on height of cut, balls tend to keep rolling at anywhere from 5-10% so you could slope a green down to a bunker, and then provided a 2-3" deep swale, and perhaps a ball hit hot enough would roll down the slope and hop the little swale, if that is what you were looking for.

[Tim Nugent]

Jeff, the ball would have to be  running "hot" enough AND be perpendicular.  Otherwise the change in slope would change the direction of the ball, just like a putt down a tier.