WASHINGTON (WUSA) — After more than a week of consecutive days with measurable rain, major river levels rose this weekend. The excess water has been flowing through the smaller tributaries and is finally arriving in the larger rivers this weekend, leading to a rise in river levels.
The Potomac River is 383 miles long and its watershed encompasses 14,60 square miles and 12 different tributaries. 90% of D.C. metro's drinking water comes from the Potomac, which equates to 486 million gallons withdrawn per day for higher population areas.
The Potomac in D.C. near the Georgetown Waterfront reached Moderate flood stage at high tide Saturday night and Sunday afternoon and will remain in minor flood stage into Monday morning.
This was the highest crest of the Potomac River at Georgetown in more than 4 years. Below is where the Potomac river water will cover. The Flood Gates in Georgetown were raised Friday ahead of this anticipated rise. If they had not been raised, part of the Georgetown Waterfront would be underwater.
This crest was nowhere near the top 5 in history
Top 5 Historic Crests:
(1) 17.72 ft on 10/17/1942
(2) 17.30 ft on 03/19/1936
(3) 15.45 ft on 06/24/1972
(4) 14.30 ft on 04/28/1937
(5) 14.05 ft on 11/26/1877
A crest of these top-5 magnitudes would not just cover part of the Georgetown Waterfront, but would also cover part of the Kennedy Center parking lot! Take a look at the progression of inundation versus crest height. Remember: we will not crest that high this weekend. This is a comparison to some historic crests.
Why does the Potomac crest days after heavy rain? Because of how a Watershed works:
A Watershed is a region bounded by a divide that drains into a particular body of water. Watersheds are like a series of bowls. The smallest bowl holds a small amount of water and would be a creek or stream. The small bowl drains into a medium bowl, then a large bowl, then an extra-large bowl. The larger the bowl -- the larger the body of water.
The Potomac River Watershed encompasses 4 states, including Virginia, West Virginia, Maryland, Pennsylvania and the District of Columbia. This watershed flows into the Chesapeake Bay Watershed, which is 64,000 square miles.
During heavy rain events, small creeks and streams crest quickly. All of the excess water that first causes creek and stream flooding eventually travels from the smaller tributaries into the larger rivers. Our creeks and streams have been running high or in flood stage this week, and finally this weekend the Potomac is cresting.
GALLERY: IMAGES OF FLOODING THIS WEEK
