Another flume!

sgfulton
Jan 20, 2018
5 min read

I finally had a chance to upload and annotate photos from a recent trip to my research site over the Christmas break. Unfortunately, temperatures were frigid. The first day it was 9 degrees when we left for the site, and temps didn't get out of the teens all day. The trip was to install a "cutthroat" flume to measure streamflow and install a couple of additional RIDGID construction boxes to protect my equipment and prevent theft. We left on the 27th of December and returned New Year's Eve. I couldn't have done it without the help of two UGA colleagues, Cj Rayfield and April Byrne, two UGA students, and one of my advisors, Dr. John Dowd. I went during this ridiculous time because it took me this long to construct additional data loggers to test the wireless sensor network in the field, plus the only time I could get help was during the holiday break.

I've never seen it this cold in the field! The sediment pond was frozen over (see photo, below), as was this small waterfall (above). The waterfall is immediately above the site where I had installed a much larger "H-flume" in the winter of 2015 with the help of my sister, Maren Fulton and my dad, Jack Fulton, and a couple of University of Kentucky colleagues (what's up with my horrible timing for these trips??? See previous blog post).

"Before photo (left)." This is the location where we installed the cutthroat flume (below; "Is 9 degrees cold enough for ya, CJ?"). It's located immediately below the rock check dam at the toe of two hollow fills. The rock check dam collects any sediment that washes off the face of the hollow fills while the site re-vegetates

following reclamation. Hollow fills are structures created to dispose of excess mining overburden ('spoil") in headwater stream valleys, or "hollows" as they're called in Appalachia.

This is the first time I've ever seen the sediment pond frozen over (above)! The sediment pond is intended to trap sediment which washes off the site before it's fully re-vegetated and stores up to 25-year storm peak flows thereby minimizing storm flood effects downstream.

Flumes are precisely engineered structures used to measure streamflow. They are tested and calibrated in the lab to correlate water depth in the flume to the volume of water leaving the flume (i.e., streamflow or "discharge"). Using a flume-specific "Discharge Table," discharge is estimated by measuring the depth of water in the flume at a certain location. This is typically done by installing a pressure transducer in a "stilling well" (the white column at the upper end of the flume in the photo below). The stilling well has a hole at the base where water is allowed to enter, and provides a calm, level water surface where water depth can be accurately measured. Pressure transducers measure the weight of water above the instrument which can then converted to water level.

To install the "cutthroat" flume, we first dug a small diversion channel through the right-hand stream bank (above). The channel is needed to divert flow past the flume so we can dig out the channel and banks to construct a level foundation on which to seat the flume. We secured the flume in-place by installing 4x4s in the channel and banks at the mouth of the flume (upper end with the two gray cross-bars) and the discharge end of flume (lower end which extends beyond the photo). (We actually had to use a 2x4 at the mouth because a 4x4 wouldn't fit between the edge of the flume and the stilling well). Once the 4x4s are installed, we poured bentonite to the area between the base of the flume and streambed. Bentonite, a "shrink-swell" clay that swells when wet, is poured in the foundation, sealing the flume and preventing water from "leaking" and flowing underneath. This ensures (hopefully) that all flow is captured, and hence measured correctly. (The photo below shows the completed stream diversion channel diverting flow around the flume. You can also see where the 4x4s anchor the flume to channel and banks.)

We had to leave the U-Haul and Jeep below and haul all the tools and supplies up through the woods to the site. Here we're measuring and cutting plywood to construct the "wingwalls" for the flume.

Measure twice, cut once!

Wingwalls divert streamflow into the flume and prevent flow from bypassing the flume (below, looking downstream). They extend from the edge of the flume to, and are anchored in, the banks. Bentonite is poured into the cavities between the flume and the banks to further seal the flume and prevent leakage.

Concrete bricks help support the wingwalls as well as fill space between the wingwalls, thereby minimizing the amount of bentonite needed (photo above, and facing upstream, below).

"After" photo of the final install (below). The rock check dam is visible in the background. Rock check dams are constructed between the sediment pond and the toe of fills to capture sediment which washes off the face of the fills during storm events. These check dams minimize the amount of sediment moving in to and filling up the pond, thereby minimizing pond maintenance and clean-out while increasing its lifespan.

We also installed two RIDGID construction boxes to house and protect the monitoring equipment. They are installed in a concrete foundation to prevent theft and tampering by animals and trespassers. In the eastern Kentucky coal fields, if it's not bolted down and camouflaged (I'll paint them later when it's warmer) folks will steal it...or at least shoot it up! The box in the photo below (looking upstream towards the two hollow fills) will contain the 12V battery and Arduino-based data logger that will collect and save data from monitoring instruments which will be installed in the stream near the flume. Each monitoring station will be equipped with an XBee radio module (900 MHz). These radios will form a "wireless sensor network" which will transmit data from one station to another until the data is received by the base station. The base station is housed in another RIDGID box (not visible in the photo below) installed on the ridge above the hollow fills. Once the data from each monitoring location is received by the base station, it will transmit and live-stream the data to the web via a cellular modem.

Nice advertisement for RIDGID (above)!

My advisor, Dr. John Dowd (left and below), "supervising" concrete mixing and ensuring the RIDGID box is firmly planted in the concrete.

The second of two RIDGID construction boxes installed this trip (above and below). This box will store the data logger for collecting water chemistry and water level data from the sediment pond. NOTE: the pond appears white because it is now also has a layer of snow on the ice.

Another look at the frozen pond (below). You can barely see the pond stilling well (where another pressure transducer will be installed to measure pond water levels) through the grass to the right of the RIDGID box. Sure hope the concrete cures some day!

Happy crew...finished and SO ready to go home!

The photo below shows the much larger 2' H-flume the I installed in the winter of 2015 with help from my dad and sister, Dr. Chris Barton from the University of Kentucky and one his colleagues. Flumes need a lot of maintenance to keep them functioning, including the removal of sediment deposited from upstream. We couldn't clean it out this trip because the saturated sediment was frozen solid!