September 9-15, 2013. What happened? Over a 7 day period, a record amount of rain fell over the Front Range region of Northern Colorado As a result, rivers.

September 9-15, 2013

Colorado Flood

Colorado FloodWhat happened?

Over a 7 day period, a record amount of rain fell over the Front Range region of Northern Colorado

As a result, rivers and streams overflowed their banks causing widespread flooding across Northern and Northeastern Colorado

How much rain fell?According to different weather stations,

various amounts of precipitation were recorded during the storm

Colorado Flood

How much rain fell? (cont.)Locally, various amounts of rain were reported

Boulder = 17.15”Estes Park = 10.77”Drake (on Hwy 34 between Loveland and Estes

Park)= 10.68”West Loveland = 5.19”East Loveland = 4.69”Johnstown = 3.63”Milliken = 4.51”West Greeley = 2.9”

Colorado Flood

How much water is that?Calculate how many gallons of water fell in Estes Park.

10.77” of rain fell in Estes ParkSurface area of Estes Park = 5.9 mi2

12 in x 12 in x 10.77 in = 1550.88 in3 of water/ft2

1 gallon = 231 in3 so…. 1550.88 in3 x 1 gallon = 6.71 gal of water/ft2

ft2 231 in3

1 mi2 = 27,878,400 ft2 so….. 5.9 mi2 x 27,878,400 ft2 = 164,482,560 ft2 in Estes Park mi2

Therefore……. 6.71 gallons x 164,482,560 ft2 = 1,103,677,978

gallons!!! ft2

Colorado Flood

So really, how much water is that?Water capacity is measured in acre feet

Acre foot – equals one acre of ground covered in 1 foot of water1 acre is roughly equal to the size of a football field

Colorado Flood

So really, how much water is that????? (cont)So, if 1,103,677,978 gallons of water fell on

Estes Park, how many acre feet is that?

1,103,677,978 gallons x 1 acre foot = 3387 acre feet!

325,851 gallons

That’s 3387 football fields covered with 1 foot of water!

Colorado Flood

So where did that water go?Water that falls either is absorbed into the

ground or becomes run-off that filters into streams and riversWhat do you think happened to the water in Estes

Park?

Colorado Flood

Colorado FloodBig Thompson Watershed

The Big Thompson Watershed is the area that drains into the Big Thompson RiverThis region extends from up in the mountains

west of Estes Park down to where the Big Thompson merges with the South Platte River east of MillikenCovers 900 square miles (576, 000 acres!)Contains 173 lakes and 975 miles of river

Big Thompson Watershed (cont.)All the rain that fell in Estes Park and the

surrounding areas funneled into the Big Thompson Watershed

Colorado Flood

So why did it flood?There are several reservoirs built along the front range for controlling flood waters

Ex: Lake Estes, Carter Lake Reservoir, & Horsetooth Reservoir

Lake Estes has a water capacity of 3068 acre feet

3387 acre feet of precipitation fell in Estes Park (which doesn’t include everything that fell outside Estes Park and made its way into the reservoir from other feeder streams and rivers!)

Can you see a problem developing here?

Colorado Flood

So why did it flood? (cont.)The amount of rain that fell in and around

Estes Park was too much for Lake Estes to contain so water was released downstream to keep the dam from giving way!

Colorado Flood

So why did it flood? (cont.)As the rains kept falling, rivers collected run

off and water went downstreamTo save dams, water was being released from

reservoirs

All that combined = LOOK OUT BELOW!

Colorado Flood

“1000” Year Event – What does that mean?Natural disasters are categorized on the

likeliness that they will occurA “1000” year event means that there is a 0.1%

chance of that happening during that yearA “100” year event means that there is a 1.0%

chance of that happening during that yearThe flooding that was experienced in Northern

Colorado was categorized anywhere from a “1000” year event to a “100” year event depending on location

Colorado Flood

Where did flooding occur?Several regions were affected by the flooding

Boulder – Boulder CreekLyons/Longmont – St. Vrain RiverLoveland – Big Thompson RiverGreeley/Evans – Cache la Poudre & South Platte

Rivers

Locally, Johnstown and Milliken were affected by the Big Thompson, Little Thompson, and the South Platte rivers

Colorado Flood

Colorado Floods

Johnstown/Milliken

As the waters continued to go downstream, more communities were affected by themFort Morgan, CO

Sterling, CO

And farther east along the Platte River

Colorado Flood

So what does this mean for our future?

You have been hired as an environmental consultant to assess the damages caused by the Colorado Flood of 2013 and report on the long term effects that the floods will potentially have on this ecosystem

Are you ready for the challenge?

Colorado Flood