Photo of the Week – February 20, 2015

Nebraska’s Central Platte River always becomes a focus of attention about this time of year as migratory ducks and geese descend upon the river by the thousands and millions, followed shortly after by a half million sandhill cranes.  This year, the river grabbed our attention a little early when ice jams shunted flowing water across several thousand acres of nearby land, including some of our prairie.  I’ll provide some more descriptions and photos of that event next week, but for today, here are two images I took yesterday as I walked around an ice field sitting on top of that prairie.

(And don’t worry, the flood shouldn’t cause any major damage to the prairies, though we’ll be watching closely for a potential influx of invasive plants brought in by the water and rebuilding a few fences.)

Ice

A crust of ice across the top of a prairie slough cracked apart as the water receded beneath it.  The Nature Conservancy’s Platte River Prairies, Nebraska.

ice

A prairie slough, normally a groundwater-fed wetland, flowed with river water for a week or so during the flood.

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Watching Wetland Water Levels – Timelapse Photography

It’s timelapse photography time again…  I downloaded more photos from the cameras at our restored wetland in the Platte River Prairies a couple weeks ago, and have been looking through the images for stories.  One theme that stood out in this batch was the variability of the water level in the wetland through time.

This wetland is directly connected to the water table, but is also supplied by a groundwater-fed stream that brings both rainwater and groundwater from about 25 miles west of us.  Platte River flows and irrigation pumping both influence the water table here in the Platte Valley, as does evapotranspiration by plants – and other factors.  It’s a complicated series of events and processes.  However, in general, we expect the water table to be relatively high in the spring and to decline as summer progresses.  I looked at photos from early June and early July (below) and that pattern of summer decline is apparent this year.

June 8, 2014

June 8, 2014.  A panoramic image created by merging photos from two adjacent timelapse cameras.

July 8, 2014

July 8, 2014.  You can click on each photo to see a larger/sharper version of it.

Seeing the pattern of water level rise and fall through weeks and months is interesting, and timelapse photography allows us to watch that pattern pretty easily.  However, it’s also interesting to look at shorter-duration patterns.  I shared one example of that back in December, with a series of images showing daily water level drops due to evapotranspiration.  Today, I’m sharing a second example of short-term water level changes – this time, it’s due to water coming downstream after a rain event.

In the early morning of June 21, 2014, a big storm system moved through our area, dumping between 2 and 4 inches of rain.  The map below shows the precipitation amounts from that storm.

This photo from http://water.weather.gov/precip/ shows rain amounts for our area on June 21.  The black arrow indicates the location of our wetland.

This image from the National Weather Service (http://water.weather.gov/precip/) shows rain amounts for our area on June 21. The black arrow indicates the location of our wetland.

Rainwater from the storm swelled the stream that flows into our wetland, but also created runoff flow throughout the watershed.  The Youtube video below shows the water level changes in our wetland through the day on June 21, 2014, starting at 7am and ending at 8pm.  The changing light conditions from image to image make it a little difficult to see, so you may have watch it several times to get the full effect.  The foreground, the green peninsula on the left, and the little island just left of center are all good landmarks to help see the water level change.

There’s nothing earth-shattering about stream or wetland water levels rising and falling after a big rain event.  On the other hand, it’s not often we get the opportunity to actually see it happen.  Timelapse photography gives us the opportunity to compress time and see natural processes from a different perspective.  For me, at least, that opportunity helps me better understand and appreciate the variability of the earth we live on.

As always, thanks to Moonshell Media for their help with this timelapse photography project.  If you’re interested in exploring timelapse photography for conservation purposes, you can contact them at 402 817 4313 or info@moonshellmedia.com.