Present tense vs. present progressive tense

Are either of the two following sentences more grammatically correct than the other?

Non-point source pollution is caused by rainfall moving over and through the ground. Non-point source pollution is caused by rainfall that moves over and through the ground.

The second sentence sounds more correct to me, but I know that the way a sentence sounds is not the best way to judge its grammatical correctness. For all I know, both could be correct. If so, is one more preferred than the other?

Thanks in advance.