Tag Archive for: acre foot

Flash Flood Watch in Effect Until 7 a.m. Monday; Luckily, Woodridge Detention Pond Nearing Completion

Tonight, the Lake Houston area is under yet another flash flood watch. Residents of North Kingwood Forest and Elm Grove are wondering whether a new detention pond in Woodridge Village will be enough to protect them.

Another 1-4 Inches of Rain Possible

We may get another chance to test the engineering on the detention ponds in that new Woodridge Village under development in Montgomery County. Our area received 1-3″ of rain today and more is on the way tonight. The area remains under a flash flood watch until 7a.m. Monday morning.

Heavy rainfall and severe thunderstorms will be possible tonight into early Monday.

Jeff Lindner, Harris County Meteorologist warned at 8:30 p.m. Sunday night that, “Numerous thunderstorms are in progress over portions of Liberty, Harris, and Montgomery Counties. Heavy rainfall is the main threat with these cells with recent HCFCD gages in SE Montgomery County recording 2.60 inches in 1 hour. Additional rainfall amounts tonight of 1-2 inches with isolated totals of up to 4 inches are possible.”

The storms appear to be fast moving so the higher totals are less likely than in early May when approximately 200 homes flooded in Elm Grove and North Kingwood Forest just south and east of the area that Woodridge contractors had clearcut.

Role of Detention Pond in Reducing Flood Potential

Had the Woodridge Village S2 Detention Pond been excavated before May 7, it might have prevented much of the flooding. But despite the land being cleared for approximately six months, the pond had not yet been built. LJA Engineers designed the pond to hold 50 acre-feet of runoff. What does that mean?

How Much is An Acre Foot?

One acre foot would cover an entire acre to a depth of one foot. An acre is about the size of a football field. That means 50 acre feet would cover:

  • One football field to a depth of 50 feet
  • 50 football fields to a depth of one foot
  • Or, in the case, of this pond, about 3.5 acres to a depth of about 15 feet.

The pictures below show what it looks like today. Very little of this area was excavated on May 7.

S2 has the shape of a hockey stick. Here’s the “face” of the stick. It took a 14mm super-wide-angle lens to get the width of this pond in the frame. This conveys its width but does not adequately convey its depth.
This panoramic image was stitched together in Photoshop from seven still images taken with a normal focal length lens. It more accurately conveys the height of the sides. But there’s still nothing in the frame to communicate scale.
Although the sides don’t look tall in the previous photo, this is what they look like when you turn and face them. This shot was taken while standing near the bottom. My eye level is more than six feet high and didn’t come halfway up the slope.
This notch in the wall of the pond allows water from the ditch behind the grass to overflow into the pond instead of flooding North Kingwood Forest (behind the tree line. That’s the theory anyway … if the calculations are correct.
The red circle shows the location of the notch between the pond and drainage ditch beyond it.

Hopefully, the amount of detention in place tonight is enough to handle the rain we get.

Posted by Bob Rehak on 6/16/2019

656 Days after Hurricane Harvey

Thoughts expressed in this post represent my opinions on matters of public policy and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP statute of the Great State of Texas.