Half-Barrel Water Garden + Rain

Hi all,

Being new to this, I'm beginning a half whiskey barrel water garden.
While I figure out where to put it, I'm hoping that you all can
address my concern about rain flooding the barrel.

To what extent can this affect my yard? I also have some mature trees
and planted shrubs that I don't want to kill due to problems that
might result from too much water, if in fact this could happen.

But all indications from my local water garden store workers seem to
indicate that this wouldn't be a problem. And I couldn't find
anything through online searches indicating there would be a problem.
What would you say? How many feet should I place this barrel pond from
other plants, and what can I do to prevent flooding without installing
underground drains?

I was thinking of just playing it safe and placing it on the covered
porch (less sunlight, though, and I would like blooms), or filling the
bottom with rocks high enough to hold a pole w/ cement as base where I
can put an umbrella up to shield the pond from rain. What do you all
recommend if I even need to have concern?

Thanks,

Daniel Phillips

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