Water saturating driver side floorboard of 1999 Lincoln Continental

After rainfalls, I find that the driver floorboard carpeting is saturated.  On a
few occasions, stopping short whilst driving, I also noted that I could hear
water in the doors.  Turning into a parking lot, I repeatedly accelerated and
braked, listening to be certain for the swhishing sound of water and
determined that that was indeed the case.  Water doesn't accumulate in
the doors every rain but the carpet situation always does.  Could you tell
me why this could possibly be happening and how to rectify it.  Thank you
in advance.