The Value of the Water in the Nebraska Sandhills

The Nebraska Sandhills is an incredible landscape of nearly 12 million acres of prairie.  Most of the Sandhills consists of privately-owned ranches, and the majority of that land is conservatively managed by ranchers trying to make a living on top of vegetated sand dunes.  Sandy soil, rough terrain, and drought-prone climate all present major challenges to ranchers, as well as to the plants and animals living in Sandhills prairie.  On the other hand, the Sandhills rewards all its inhabitants with one very important and abundant resource.

Groundwater.

Exposed groundwater in the valleys between sand dunes creates some of the most beautiful and valuable wetlands in North America.

Exposed groundwater in valleys between sand dunes creates some of the most beautiful and important wetlands in North America.

Very little of the rain that falls on the Sandhills runs off.  Instead, it percolates down into the sandy soil where most is taken up by roots of thirsty plants.  A significant portion of that water, however, makes it past the root zone of those plants and adds to the water table below.

Gr

A shallow water table makes it easy for windmills to pump water into tanks (and overflow ponds) for livestock and wildlife to drink from.

Large wetlands and shallow lakes are abundant across many parts of the Sandhills where the water table is higher than the surface of the ground, and those wetlands provide habitat for a broad array of wildlife and wetland plants.  Groundwater also seeps out of the ground and flows into myriad streams and rivers, which provide even more habitat.  Those streams also carry water through and out of the Sandhills and into larger rivers such as the Niobrara and the Platte.

Springs pop out of the Sandhills in numerous locations, creating small streams that supply water to fish, wildlife, and plants, as well as to larger rivers. This stream is already 5 feet wide less than 50 yards from its source in the background of this photo.

Springs pop out of the Sandhills in numerous locations, creating streams that supply water to fish, wildlife, and plants, as well as to larger rivers. This stream is already 5 feet wide less than 50 yards from its source in the background of this photo.

The Niobrara River

A long stretch of the Niobrara River has been designated as a National Scenic River and as people canoe, kayak, or otherwise float down it, they are rewarded by the sight of hundreds of small waterfalls adding water to the river from the Sandhills just to the south.

Smith Falls, perhaps Nebraska's most recognizable water fall, flows north out of the Sandhills into the Niobrara River.

Smith Falls, perhaps Nebraska’s most recognizable water fall, is a large example of the many waterfalls along streams feeding Sandhills water into the Niobrara River.

Platte

As the Platte River makes its way to the east, water from the Sandhills adds to its flows via many streams and rivers.  That water then joins the Missouri River and makes its way to the Gulf of Mexico.

Trumpeter swan

Trumpeter swans are one of many wildlife species that thrive in Sandhills lakes and wetlands.  The relatively consistent water in those wetlands is a critically important resource for migratory birds as well.

As fresh water continues to become more and more scarce and valuable to the world, pressure will increase to draw water from places of abundance, including the Nebraska Sandhills.  Already, proposals are being bandied about to capture and transport water from the Sandhills to human population centers or to help cover irrigation water shortages in far away places.  The water in the Sandhills already contributes to society by helping to grow forage for one of the most important livestock production regions in the world and supplying water to downstream sources where it is used for irrigation, drinking water, navigation, and recreation.  Also, of course, Sandhills water plays a huge role in supporting migratory waterfowl and shorebirds, along with a vast array of other wildlife species.

Unfortunately, the future of the water resources in the Sandhills will probably rely on whether or not water is viewed primarily as a resource to be mined, transported, stored and put to work.  Here in Nebraska, we are frequently told that water flowing out of our state is “wasted,” and should instead be captured and used for something productive.  A dry river bed is a sign that we’ve used our water efficiently.

There will be important and difficult conversations in the future about what counts as a productive use for water.  Does water have to float a barge, irrigate a crop, or flush a toilet in order to be useful?  Do fish and wildlife habitat, recreation, and aesthetic beauty also factor in?  More importantly, what are the ramifications of removing water from Sandhills land and rivers that people, wildlife, and natural processes already rely on?  It may be that our aspiration to engineer changes to the world exceeds our ability to predict the impacts of those changes.  Let’s hope not.

Wetland

A pool of wasted water stagnates uselessly in a Sandhills wetland…

Watching a Wetland Breathe

It’s amazing what you can see when you compress time.

Back in October, I posted some early results from a timelapse photography project at our Niobrara Valley Preserve.  That project is helping document the recovery of the property from a wildfire and to see other changes that our eyes would otherwise miss.  We’re hoping to learn just as much from a similar, though smaller, timelapse project along a restored wetland/stream complex in the Platte River Prairies. Last week, I got my hands on the images from that project and have been looking through them to see what we can learn.

So far, one of the most fascinating things I’ve seen comes from a series of images from July 2012 – right after the camera was installed.  As I scanned through the photos, I realized that one little wetland pool kept changing size.  Its water level (exposed groundwater) was going up and down, making the pool bigger and smaller.  Looking more closely, I realized that it was happening in a regular daily pattern.  I’ve put a selection of images from a three day timeframe into a slideshow below.  If you let your cursor hover over the slideshow window, you can click the arrows to move through the images more quickly.  Watch the water level in the pool in the center of the photo – it starts out full in the morning, empties as the day goes along, and then is full again the next morning.  This same pattern repeated itself over and over throughout the summer.

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I shared what I was seeing with John Heaston, The Nature Conservancy’s Platte River Program Director (in Cozad, Nebraska), who said the pattern is a great illustration of the effects of evapotranspiration – the process through which water moves from the surface of the earth to the atmosphere.  Evapotranspiration is a combination of direct evaporation of exposed water and plant transpiration – the movement of water out of a plant’s stomata (pores in their leaves).

Plants try to regulate how much water they lose through their stomata by opening and closing those pores, but transpiration is also strongly affected by light, heat, humidity, and wind.  During hot, dry and windy days, plants pull a lot of water in through their roots and then lose it into the atmosphere as they try to cool themselves.  In dry soils,  plants may shut their stomata altogether during the hottest part of the day in order to conserve moisture.  In wetlands, however, plants have abundant water, so they can continue transpiration through the heat of the afternoon.  Add that high rate of transpiration to the evaporation of standing water during those same sunny afternoons, and you have evapotranspiration in high gear.

What’s exciting to me about these timelapse images is the opportunity to watch evapotranspiration happen.  The plants in the wetland are pulling so much water from the ground during the day, the local level of groundwater drops by at least a few inches.  During the night, transpiration slows dramatically, and that groundwater level recovers.  Interestingly, the stream to the left of the little pool doesn’t appear to change during the day.  While it doesn’t appear to have a strong flow, there is presumably enough water coming from upstream to negate any losses from plant transpiration, so the level of water stays stable through the day.

Watching the repeating pattern of dropping and rising water levels in a wetland is fascinating.  It’s as if we’re watching the earth breathe – which, in some ways, we are.  It’s also a great example of the power of timelapse photography.  By condensing time, we can see patterns we would otherwise miss.

To see more examples of timelapse photography, check out the Platte Basin Timelapse Project’s website.  They have one of their cameras on this same wetland (separate from the one that produced the images shown above) and you can see a couple years’ worth of images in a few minutes.

The other interesting aspect of both sets of timelapse imagery from this wetland is that 2012 was the driest year on record for this area.  Most streams, rivers, and wetlands went dry last summer, including most of the stream that runs through our property.  However, throughout the entire summer, the wetlands and stream in the stretch shown by these cameras maintained a fairly steady water level.  It’s one of the reasons we’ve spent so much effort trying to restore the site – we feel like we need to take full advantage of the unique resource there.  We’re not sure why the groundwater is so strong in that particular place, but in dry years, the fish, birds, invertebrates, and plants sure appreciate it.  So do we.

Thanks to John Heaston and Tala Awada for technical help with this post.  Any errors are mine, not theirs.  In addition, thanks to Michael Forsberg and Jeff Dale of Moonshell Media for partnering with us on the set-up of the timelapse project(s), and to Steven Speicher for his help and advice.