Those of you with good memories might recall I am diverting the rainwater off the roof of my workshop into the pond, which dries up in the summer. I diverted the guttering downspouts into a 200 litre barrel, which then drains into a 38mm pipe, which runs under the lawn into the pond. So far, the barrel hasn't filled, fortunately, since I didn't bother with an overflow arrangement.
All working an absolute treat. The pond, which was more-or-less dry on Monday now has about 3" of water in it. I just need about another fortnight like this. (Sorry).
Hopefully, it will fill up completely over the winter and so be less of a problem next year. It started off this year with only a few inches of water in it. Potentially, it's about 3 ft deep, although I may raise the level of the overflow if this all works as intended.
I'm also considering duplicating the arrangement with one of the house downspouts, running it into a water butt (for my wife's plants) and then running the overflow from that into the pond.