Gage, Stage, Discharge

Gage, Stage, Discharge

Or…. What’s a good paddling level?

a Carolina Paddler Article

Text and photography by Alton Chewning

Editor’s note: This article is based on a talk given on a field trip to the Bynum gage on the Haw River. While it contains much specific information on this gage and the surrounding area, the discussion of how river gages are used is applicable to most of the United States Geological Survey gages as well as many in other parts of the world.

The Next Stage at Bynum Gage

It’s been perched on a high bank over the Haw River for fifty years, quietly doing its job. Challenges like cold weather and high water sometimes stalled its performance but the work has been mostly consistent for twenty-four hours a day all these years. Now, advanced in years, teetering a bit, not as slick or as quick as the young replacements, the time has come. Sometime soon, in the next few years, the Bynum Stilling Well will be retired, “decommissioned” they call it. Taken down and hauled off. Unless some savior comes along. Maybe the new neighbor, Chatham Park, will buy it and give it another life as a scenic landmark. The stilling well must be moved in any case. The eroding bank is slowly tipping it over; no longer is it safe for workers to climb to the crown. The days are short. Time to pass the job onto newer technology. This will still be the “Bynum” gage, in roughly the same location but the look will be very different.

The Walk and Talk

Gretchen Smith, President of the Friends of Lower Haw River State Natural Area FLOHA, had no idea how a river gage worked. She knew they were important to paddlers but also to swimmers, tubers and fisherman. Anyone using the river. So, Gretchen called an expert. Luckily, Lara Chapman, a hydrologic technician with the United States Geological Survey answered the call. Lara works out of the Raleigh office but lives in Bynum, so she was happy to lead a group of interested hikers on a tour of the Bynum Gage.

Gage or Gauge?

Here are some ground rules (or water rules?) for talking about river gages. There are many terms that mean similar things. Lots of specialized nomenclature. Some things are said differently than in ordinary English usage. Let’s start with the basic word, “gage.” You may think it should be spelled “gauge” but not if you are the USGS. The reason the USGS uses “gage” dates back a hundred years to its early days under John Wesley Powell, the leader of the first Grand Canyon descent. See gage versus gauge.

The word, stage, is used interchangeably with height or gage height. Lara mentioned, “I monitor Lake Johnson in Raleigh. That is also “stage”, but we call it lake elevation. Because it’s a lake we use elevation instead of stage.” Lara later elaborated, “Gage height is the height of the water in a stream above a reference point. It refers to the elevation of the water surface in the specific pool at the streamgaging station, not along the whole stream. Stage is the level of the water surface of a river or stream above an established gage datum at a given location.” Stage heights are always positive numbers, never going below zero. (Later we will discuss paddler gages which do go below zero.)

The word, discharge, means the same as flow or streamflow or cfs. Both stage and discharge can indicate certain things about the amount of water in a river, but they are distinct from each other and are measured in different ways. Discharge is shown in data as CFS, cubic feet per second. As in, “The Haw is running at 2200 cfs today. Let’s paddle.”

On a sunny Saturday, Gretchen and Lara met the hydrology fans near the Bynum pedestrian bridge. The Bynum gage is a short hike from there, on property owned by State Parks and Chatham Park but easier to access from Chatham Park. Gretchen had arranged permission and the gate was unlocked so Lara could bring her truck loaded with testing gear close to the gage site. Various parties were represented in the twenty-one hikers: FLOHA, Haw River Assembly’s Rufus King and several people from the Carolina Canoe Club. Our stalwart conservationist, Bob Brueckner, was there as well as Greg Moon, me and a couple new to the group, Don and Gerrie Beland.

The excursion took us over the historic pedestrian bridge. The bridge was built in 1922 and closed to vehicular traffic in 1999, due to safety concerns. The Bynum community persuaded the owner, NCDOT, to leave the bridge to connect the community and serve as a pleasant place to watch birds, wildlife and paddlers.

As we hiked, Gretchen filled us in on the land designated as the Lower Haw River State Natural Area and owned by NC State Parks. It is now also part of the newly authorized Haw River State Trail. She shared maps and other literature and explained we were walking on Chatham Park property, normally posted, to get to the gage since the state natural area is narrow along here. (FLOHA wants the public to enjoy the state natural area, but please do not trespass on private property.)

During this time Don and Gerrie Beland spoke of their hopes for the talk. They are new to whitewater, Gerrie having paddled the Middle Haw once and Don several times. In addition to learning about river gages they hoped to learn about good water levels for them to paddle the Haw. We’ll refer to that question, “What’s a good paddling level?” later in this article.

When we reached the Bynum stilling well, Lara was waiting for us, unmistakable in a dayglow orange safety coat. She began pointing out the sites and dispensing information. First, what is a stilling well?

Stage Height Measurements

The stilling well structure is reminiscent of the training towers used by fire departments to practice climbing in and out of burning buildings. Tall, with an approximate footprint of 12×12 feet, it has an exterior ladder and some gadgets on top. We were not permitted to climb the ladder; in fact, no one climbs it now. The Bynum stilling well was built in 1973 and just turned fifty years old. Over the years, the bank has crept closer to the tower and now the tower has a perceptible lean. It is no longer considered safe to enter and soon will be taken down and replaced by a much smaller structure.

The stilling well is hollow inside. Lara explains, “There are intakes in the river that bring water into the stilling well. There is a float on the inside and that float connects to a piece of equipment called a shaft encoder. It’s a newer electronic one.”

When the stilling well was first built a cable went down to a float, came up through a pulley and a counterweight was mounted on the other end. A mounted ink pen would record a graph on paper of the river stage as it changed. This data was read by a person. Over time, various analog and analog/digital devices were used to record stage height. Whether digital or pen-based, the measurements indicate stage, or gage height. The water intakes are at the bottom of the stilling well and are always under water.

This stilling well rises to about 25 ft. above the surrounding land. Lara says, “It I went up that ladder [on the side of the well] and looked down, I would see the surface of the water, exactly where it is on the outside of the well on the river. The float always rests on the water surface. The stilling well structure continues down about 15 feet underground and beneath the lowest surface level of the river.

This type of shaft encoder mounted in a stilling well is outmoded now. A newer device called a bubbler is now more commonly used. The bubbler works on pressure measurements. Pressurized air is forced down a line to an outlet at the lowest gage height of the river, a point arbitrarily chosen. This lowest point represents zero on measurements and thus no gage readings are below zero. All measurements are positive numbers. The pressurized air at this predetermined low point is “bubbled out.” With one foot of water above it, a certain amount of air pressure is required to force out a bubble of air. With two feet of water above, more pressure is required and so on. This required pressure is correlated to the height of the water column. Lara notes, “It’s a pressure transducer detecting the pressure from the water. We know the density and weight of water so the correlation can be made in feet.” This is the number paddlers read in feet when we check the river level online. We’re seeing what river level “bubbled up.”

-In the past how did you know the river level?  Jimm East, owner of the Haw River Paddle Shop in Carrboro, would call Bo Strain, who lived in the small house just across the Bynum Bridge (the pedestrian bridge now).  He would go out of his house and look down at the river and come back with a report.  Bo worked at the hospital and was a photographer and a nice fellow.  Not a paddler.

There are many advantages to the bubbler over the shaft encoder system. The intakes for the stilling well must be kept clear of debris or measurements will be off. This clearing maintenance is physical and tedious. On the other hand, the bubbler can be “auto-purged” with blasts of air every day.

Lara: “We use radar too. Usually from bridges because the radar must be over the water. But for here at Bynum, we would have to put some structure over the river to use radar, so we use the bubbler instead. These days it’s either a bubbler or radar. The USGS is slowly retiring these stilling wells.”

The shaft encoder inside the stilling well is no longer used, even as a back-up. The stilling well still serves as a housing for equipment leading to the bubbler and to communication equipment. Since the Bynum stilling well is aging and unsafe, it will be decommissioned, and a much smaller enclosure will take its place. The new enclosure will also need to be protected from flooding, so an appropriate site is still being considered.

In the past, how did you know the river level? Howard DuBose gave a live report on river levels on WDNC radio at 3pm Fridays. “The River Runners Report.”

There is another simple device at Bynum that serves as a back-up to the bubbler and a stability check on the structure. This staff plate is called the outside reference gage. It ensures the physical position of the stilling well has not shifted. The outside reference gage at Bynum is a series of staff plates. Other sites use Wire Weight Gages (WWGs) suspended from bridges. The outside reference gages are tied into NAVD88 and are calibrated to the “inside gages”, the bubblers, radars, and shaft encoders. NAVD88 refers to North American Vertical Datum of 1988. NAVD 88 consists of a leveling network on the North American Continent, ranging from Alaska, through Canada, across the United States, affixed to a single origin point on the continent. Those Carolina Paddler readers with navigational skills will be familiar with datum.

Behind the stilling well is another low-tech device used for peak verifications, a crest stage gage. It’s a metal pipe that extends several feet into the bank. Inside is a wooden rod with markings in feet and inches. A technician puts some ground cork in a cup at the bottom of the rod. During a major rain event both the river water and the water in the pipe rise, floating the cork pieces. When the water stops and falls, the cork sticks to the rod at the water’s highest point. This gives a peak-stage measurement of a rain event. Such as “Flood waters on the Haw reached over 17 feet today.”

Lara shared, “We tie a point on the CSG into NAVD88, just like the rest of our gage equipment. Then we can take a ruler and measure from our survey point to our cork line to get a peak stage reading.  So, imagine the CSG at Bynum was found to be at 15.632 ft. If we were to measure a cork line at 1.45 feet, we would have a recorded peak of (15.632 ft. + 1.45 ft.) = 17.082 ft.”

-In the past how did you know the river level? Paddlers would call the USGS Office in Raleigh and ask what the Haw level was. If they talked nice, a person there would call the Bynum gage and hear a pattern of beeps, which could be translated to river level. Unfortunately, the Bynum gage phone number got out and paddlers ran down the phone’s batteries. The number was changed.

The Location

Let’s step away from devices and calculations for a moment. How did the USGS pick this site to situate a stilling well and cableway? This site was chosen at the request of the Army Corps of Engineers who fund it. Lara explained, ““You guys noticed at the pedestrian bridge how the river splits around the islands and rocks. That arrangement makes it difficult to get discharge measurements. I think there are three channels by the bridge. We picked this spot because they converge very neatly in one spot, and you have a convenient cableway location so you can get highwater measurements as well.” With the steep banks and a wide flood plain for water to spread out, the stilling well has never completely flooded.

Discharge Measurements

At this stage of the talk, Lara turned to instruments used to measure discharge or streamflow. Near the stilling well is a tall metal tower, with a cable suspended from it, crossing the river to a similar tower on the east bank. This is the cableway.

Lara: “We use Acoustic Doppler Current Profilers, ADCP for short, to measure discharge. A technician like myself would sit in a cable car and bring the car out over the river. We have a rope attached to a small boat which holds our ADCP transducer. We take the boat back and forth across the river to measure the discharge in various places.”

Lara: “The only way we can get discharge data is if we go out and measure it. If I make a measurement with an ADCP or a Flowtracker or another piece of equipment, that’s what gives our cfs cubic feet per second, that we publish online. Since we can’t be out here twenty-four hours a day taking discharge measurements, we developed what are called rating curves. We go through a lot of measurements, through a lot of math, through a lot of calculus, and develop a rating curve so that when a stage reaches a certain height, we know that according to this equation, how much the discharge will be. For example, if a hypothetical river is three feet, that equals … forty cfs. The Haw at three feet would be way more than forty cfs.

An Aside

Have you ever noticed when you go online to a USGS river gage, a graph comes up labeled “Gage Height, Feet”. If you prefer to see the river level in cfs, you go to a lower column, labeled “Select data to graph”. Here you can change the graph data to reflect “Discharge, cubic feet per second.” Even though the cfs data is more specific in a theoretical way, the Gage Height data is timely, updating frequently. Is that why it comes up first?

Lara: “We publish both because you can have a really steep rating curve or really shallow. We publish both so you can get the full picture. Because you can look at something and say, oh, three feet. That’s moving kind of slow, but if this changes for any reason, say the river bottom changes, the stage might give a different CFS. You might have been here five years ago and thought, three feet, that’s manageable for me. But we’ve changed this ratings curve in the five years since you were here and now suddenly it’s not manageable and you’re being swept downstream. So that one of the reasons we publish both on-line.”

“We take discharge measurement here every eight weeks. We only run level surveys once a year.. If the once-yearly levels are stable for three years in a row, we consider moving the frequency to every three years or then later every five years. We come and check that nothing has moved physically on the Earth, so our stage data is consistent and accurate.

Equipment used to measure Discharge

Lara displays a small boat with attachment points and holding a blocky device. Lara: “This is a type of Acoustic Doppler Current Profilers or ADCP that we use. A sensor on the bottom is the transducer.”

A transducer is a device that converts energy from one form to another. Usually, a transducer converts a signal in one form of energy to a signal in another. A Doppler shift is applied to adjust for the difference in movement of the boat-mounted sensor and the water discharge being measured.

The small boat equipped with the ACDP is lowered by rope from the cableway by a technician in a cable car. The Bynum cableway is the last one in operation in the Raleigh district. In many places hydrologic technicians use kayaks to position the small boat and ACDP. In other areas drones are used. Remote controlled boats can be used to position the sensors but in high flows the radio-controlled boat motors are not powerful enough to stay in place.

In the past… If you wanted to know if New Hope Creek had enough water to paddle, you called the Hollow Rock Store on Erwin Road and asked John Brown to step out and take a look.

Before the advent of transducers, aerometers were employed. These would be placed in the water and the propeller cups would move and make a clicking sound. Lara recalls, “You count the clicks. You would have a clipboard, stopwatch, and a head set and for forty seconds you’d have to count the number of clicks. There is a table that associates the velocity to the discharge. Now everything is done on a computer. Much easier.”

For lower flow streams, handheld devices are used, like Flowtracker, a type of ADV (acoustic Doppler velocimeter). Lara said, “This is for wading measurements. I would stand in the stream and measure the flow going by. For lower flows you have to use these because they can go to a very low depth. 90% of my measurements on Walnut Creek are with a Flowtracker.”

Water quality and turbidity can affect the readings of the various devices. ACDP’s don’t work well in very muddy water. Too much sediment can make it difficult to punch through a signal to the bottom. On the other hand, very clear water doesn’t work either. We can’t use these in most of our mountain rivers because the water is too clear to bounce back a good signal. Another condition that can throw off readings is a moving bottom, a river where the bed of rock or gravel is moving. Software can be used to compensate for a moving bottom if detected.

QUESTIONS

Bob Brueckner asks how much a gage site costs. Lara explains, “Depends on many parameters. We also do continuous water quality measurements. There are the installations, calibration, measurements and sometimes specialized equipment. State and local governments are the ones who usually pay to have these operational.” The Army Corps of Engineers funds the Bynum gage, using it for flood control purposes. The North Carolina Department of Environmental Quality funds the majority of gages in North Carolina.

*See below the Addendum:  The Costs for a USGS Gage

In the past…. A friend’s grandmother did work for the USGS in 1960’s and 70’s. She would walk to a gaging station nearby on Brown Creek in Anson Co., NC. and check the reading. She would call this information in to the USGS office.

Greg Moon mentioned the posted USGS readings for Bynum sometimes seem to lag behind real time observations of water. Lara explained the reason, “Yeah, you can see there is an antenna up there [on the stilling well]. We use the GOES satellite system to transmit information.

We must reserve blocks to transmit data, so we have a ten second window every hour for most of our sites. The site will collect data for an hour and then we hit that window, ten seconds to send it, then it lands on-line. Bynum transmits 57 minutes and 20 seconds after the hour until 57 minutes and 30 seconds after the hour. The data logger there actually records in 15-minute intervals: For example, the data logger would record the 9:00 AM, 9:15 AM, 9:30 AM, and 9:45 AM stage values which would all be transmitted together at 9:57:20 AM.
Most sites using the GOES system have different transmission windows to keep too much data from going out at once and accidentally getting “stepped on” or lost. Some sites use cell towers or radio-based transmission. The Raleigh system is called Alert Two which goes over radio. We have a repeater up on the Wells Fargo tower in downtown Raleigh, so it repeats the radio to our office. With new technology like that we can send info every fifteen minutes or every five minutes. In Raleigh we do transmit every five minutes. It’s important for our Flood Early Warning system. Because if you lived there, you know Crabtree or Walnut Creeks can flood quickly and we want to send alerts quickly. For most other sites it’s every hour when data is transmitted.”

Someone asked about the hydrological predictions that can also be found on the web. How high the Haw will be in two days. Lara responded conclusively, “We don’t do that. The National Weather Service will predict river levels. We don’t do predictions at the USGS, at least not in my sphere. Other organizations like the NWS will do that based on our data and their own data. We just publish what we see.”

I asked if other countries use similar technology and methods. Lara said they did and later sent some photos taken by USGS staff on vacation in other countries.

What’s a good level for paddling?

We’re back to the question Don and Gerrie Beland asked at the start of the hike. What’s a good level for paddling the Haw? Here’s a photo of the paddling gauge painted on the base of a support on the Hwy 64 bridge over the Middle Haw.

A log and other debris hide the lower part of the gauge with the zero and below marks. In Paul Ferguson’s “Paddling Eastern North Carolina” a table shows the correlation between the paddling gauge readings the USGS gage readings in stage height and cfs.

So, between the paddling gauge and the USGS gage readings from the internet or various apps, how do we know if the water level is good for us to paddle?
Ferguson makes a point in his book, “For a gauge to be useful to paddlers. Information is needed relating the gauge readings to paddling conditions. Randy Carter was a pioneer whitewater paddler in the 1960s. He painted gauges so that the zero-foot mark was at the point he estimated was the minimum water level for solo canoeing. Not everyone painted gauges using this convention. Some gauges used six inches below the zero mark as a minimum and others have arbitrary starting points. To know the meaning of a gauge reading, one needs experience paddling the river, or information from other paddlers or guidebooks.” Ferguson would add now there are many apps likes rivers.run and on-line sources like American Whitewater that can supply information on what to do with gage or gauge readings.

As Lara pointed out a stage height reading of 5 feet can mean one thing at one time and something different later because the river has physically changed. The height versus flow correlation has changed.

Ferguson states, “Flow can also be used for comparisons of different rivers. If two river gauges each have a height of 5.0 feet, it is unlikely their flows are equal because the gauges start at different points relative to the riverbed, and the river channels have different sizes and shapes. A flow reading of 2,000 cfs at two different points is relative to the riverbed, and the river channels have different sizes and shapes. A flow reading of 2,000 cfs at two different gauges means exactly the same amount of water is flowing in each river at the gauge locations. If one knows the relative size of the river channel, previous experience can be used to estimate what the flow might mean for paddling water conditions.”

Carolina Paddler asked several local boaters the question: What’s a good paddling level for Middle Haw? Lower Haw?
Bob Brueckner: 1,500 cfs on the Middle, and 2,000 cfs on the Lower
Zach Schiada: For me, Middle Haw has to be 1000 cfs to be any fun and Lower at 1500. Above those are good and I’ve run as low as 170 cfs on both.
Steve McConnell: I will not paddle the Lower Haw below 1000 cfs.  I have paddled at 900 and have said never again in a whitewater boat. I would VASTLY prefer 1200-1500 with the best levels being between 2500 to 4000, in my humble  opinion. I am also happy to paddle up to 7000 cfs with a good group.  

For the Middle I think you can go a little lower, but I seem to recall that  minimum is still around 900 cfs with the best levels again between 1200-4000.  Above 5000 it’s a lot of water, but I don’t recall it being that interesting.

The question was deliberately vague and doesn’t account for the ability and experience of the paddler. Some people say a good range for first-timers or novices on the Lower Haw is 1200 cfs to 2000 cfs. For the Middle, 800 cfs to 2500 cfs. Each paddler finds their own “good levels” through experience.

Hydrologic Technicians

Listening to Lara Chapman talk about gages, stages, and discharge, it’s hard not to soak up her enthusiasm for the job. We asked what was her educational background? Lara: “I got my B.S. in environmental science from Appalachian State. I also have minors in geology and psychology. I always knew I wanted a job that entailed both office and fieldwork. My program required a hydrogeology course to graduate, and after taking that class I really fell in love with the field and tailored my remaining electives for a career in hydrology!”

Are there dangers associated with the job? Lara: “It’s not a safe job. There are snakes and bugs and sun, even alligators on the coast. Up north hypothermia is an issue. They have to take ice measurements, so they walk out on lakes and drill holes into ice and lower their Flowtracker down through the hole to get the flow and they are always concerned about the ice giving way. Out west, they have massive rivers, so you are not kayaking them but use cableways more often. Even they can be dangerous. See this video from a swollen river in Arizona during a flood event in 1993.

“Multiple people have died doing this job. One story happened in the seventies with this type of stilling well. To flush it out you have to pump water into it. They were pumping water in order to flush the intakes and they had a gas-powered pump on the inside of the stilling well and the person inside the well was at the bottom. Carbon monoxide built up and he went unconscious and slipped under the water. A coworker went into the well to get him out but could not lift him out. He tied the unconscious friend to the ladder and left to get help. While he was gone the pump failed allowing the well to fill with water and the coworker drowned. There are dangers. This is one reason we always wear PFDs now.”

Our interested group thanked Lara for her thorough and engaging discussion of gages. She replied, “Thank you again so much for your interest in what we do! I truly love my job and it makes it that much more enjoyable when people show interest in the science we conduct! The water resources division is frequently outshined by our natural hazards division (earthquakes and volcanos), so we try to do outreach events whenever we can.”

Now the fun math stuff. Travel Distance and Time

In our last Carolina Paddler article, “The Gist of the USGS”, we posed a question. See below:

We promised you a fun question. Water coming down the Haw River originates in Forsyth, Guilford and Rockingham counties before arriving at the Bynum gage. Many whitewater paddlers concentrate on the sections known as the Middle and Lower Haw for their swift water fun. Rain falling in the immediate vicinity, Alamance and Chatham counties, has little effect on Haw streamflow. There are two gages before the Haw River empties into Jordan Lake, one at the small town of Haw River (02096500) and the other downstream near the town of Bynum (02096960). Hydrologists commonly call a burst or bubble of traveling water a “slug.” So, the question is: How long does a slug of water take to travel from the Haw River gage to the Bynum gage? Here is a hint. The travel distance between the two gages is approximately 156,527 feet.

So, what was your answer? Bob Bruckner outlined some of the difficulties in answering this question.

Bob: There are actually three dams between the Haw River and Bynum gauges:

* Puryear Mill Dam [in Swepsonville]: Converted to a hydroelectric in 1927; closed in 1970. (Unregulated, not in operation)
* Saxapahaw Dam: Converted to hydroelectric in 1938. (FERC regulated, active)
* Bynum Dam: Converted to hydroelectric in 1940. (FERC regulated but not in operation)

Even though the Saxapahaw Dam is the only one generating power, the other two are impounding some water and probably throw off flow calculations to some degree.

There are also some large tributaries such as Big Alamance Creek that could affect flow. And there’s an old dam (36.174961, -79.512056) on Reedy Fork Creek (or Reedy Creek) in Alamance County. This stream also joins the Haw.

The Calculation

Lara Chapman, always up for a puzzle, graciously provided her calculations:

“After some discussion with my coworkers, this calculation will only be a very rough estimate. It is also entirely dependent on the stage and discharge of the Haw River and can vary drastically.

For the purposes of an example calculation, I chose to use data from a site visit to Haw River at Haw River, NC made on May 25, 2023. I chose this visit because the Haw River held somewhat steady in gage height for a few days surrounding this visit.

I found the approximate distance between the gages by using Google Earth.

In order to calculate discharge, we multiply velocity (ft/s) by area (ft^2) to get ft^3/s (cfs).

So, by taking the discharge measurement made on May 25, 2023, I can use the average velocity from this measurement (1.36 ft/s), and the distance between the Haw River gage and the Bynum gage (~156,527 ft.) to get time = 115,093 seconds or approximately 32 hours.

If we assume the velocity stayed the same from Haw River to Bynum, the water passing through Haw River on May 25, 2023, at 7:30 AM, reached Bynum on May 26, 2023, at 3:30 PM.

Understand there are many factors to this calculation. For example, the Haw River itself is dammed at least twice between these gages. I believe the dams in Swepsonville and Bynum are spillways, but a regulated dam [like Saxapahaw] would render this calculation obsolete.

For fun! Let’s take the measurement made on September 13, 2023, at Haw River. We had an average velocity of 2.89 ft/s. Running our calculation again, if we assumed this velocity stayed constant (which it did not, I’ve attached a screenshot of how quickly the Haw changed that day), it would take approximately 15 hours for the water to reach Bynum.

I’ve also attached a screenshot of some graphs/tables related to the raw data collected at Haw River on May 25th. It’s a great illustration of how velocity varies drastically even within our cross sections during our measurements. This measurement was made using a FlowTracker, and each dot you see on the bottom diagram is where the FlowTracker was held in the stream as a hydrologic technician waded across.”

Conclusions

Carolina Paddler: So, from this we can gather a slug of water coming from the Haw River gage to the Bynum gage could take anywhere from 15 to 32 hours. Along with all the variables noted above, larger volumes of water will travel faster and get here sooner. Periods of drought and low river levels will slow a slug of water’s travel.

Thank you, Lara, and all the other people who used some of their precious time to play with these calculations. A fun exercise.

Haven’t had enough of river gages? One more article to come. Carolina Paddler visits hydrologic technicians as they take measurements on the Haw and elsewhere.

FLOHA

Lastly, Carolina Paddler would like to thank Gretchen Smith and Friends of the Lower Haw for arranging this useful event. Please check out their website. Gretchen also sent this note with more information including maps of the area we walked.

Below is a map of the entire Lower Haw River State Natural Area.  Our website also has a link to an interactive map here:  Map (lowerhaw.org).  We have several different types of maps on our Publications web page in the section “Other Documents” at this link:  Publications (lowerhaw.org).  Also below is a map I printed from the county’s GIS mapping tool of just the area we walked, but this map is not on our website.  I have put a purple pin at the gage location, lower right corner, and crudely highlighted the narrow strip of the state natural area in green highlight.  The old roadbed we walked on is marked with pink dashes.  You can use the county’s GIS mapping tool at this link

ADDENDUM (November 13, 2023) The Costs of a USGS Gage

The USGS  currently charges $16,400/year for O&M (operation and maintenance) for a stage/discharge site. Installation is about $10-12k, but if cooperators agree to a 5-year contract minimum, the USGS covers the cost of installation.

For a stage-only site, where we would not need to make measurements, we charge $7,400/year for O&M.

As for water quality, the cost for a “Big 4” (temperature, specific conductance, pH, and dissolved oxygen) continuous site is about $30k a year for O&M. A lot more time and resources go into continuous water quality maintenance than traditional surface water sites.  The NCDEQ pays for most of the USGS gages in the state. Their monitoring network is much more groundwater and water quality sampling oriented.

SOURCES:

USGS related:

-A Brief History of Geologic Mapping in the USGS
https://www.usgs.gov/programs/national-cooperative-geologic-mapping-program/brief-history-geologic-mapping-usgs#:~:text=Early%20Years—Mapping%20the%20Nation&text=Predecessors%20of%20the%20USGS%2C%20which,tracts%20in%20the%20American%20West.

Recording water levels:

-A Brief History of Steven’s 116 Year Chart Recorder Legacy
https://stevenswater.com/news-and-articles/a-brief-history-of-stevens-116-year-chart-recorder-legacy/

-Crest Stage Gages
https://www.usgs.gov/special-topics/water-science-school/science/crest-gage-a-quick-way-measure-river-stage

-Identifying and preserving high-water mark data.
https://pubs.usgs.gov/publication/tm3A24

– Lara Chapman: “My coworker in our Charlotte office, Laura Lapolice, did a great video about how we service CSGs!” https://www.facebook.com/watch/?v=13839999591706

-A and AA aerometers
https://water.usgs.gov/osw/pubs/ofr99-221/ofr99-221.pdf

-FLOHA

https://www.lowerhaw.org/documents various documents and maps

https://www.google.com/maps/d/viewer?mid=1XlSuocNkevb68Z4gHoY8vHrTaLM&ll=35.79505566074565%2C-79.16704449999997&z=11 an interactive map of the Lower Haw

Waterdata at USGS
https://waterdata.usgs.gov/blog/gage_height/

Email Correspondence
Chapman, Lara. (2023) Email to Alton Chewning, various dates, October, November.
Smith, Gretchen (2023) Email to Alton Chewning, various dates, October, November.
Brueckner, Bob (2023) Email to Alton Chewning, various dates October, November.

Why does the USGS use the spelling “gage” instead of “gauge”?

https://www.usgs.gov/faqs/why-does-usgs-use-spelling-gage-instead-gauge#:~:text=Newell%20is%20purported%20to%20be,influence%20added%20a%20%27u%27.

-Lara Chapman. This is a hydrographic imagery camera at Walnut Creek.

o USGS HIVIS (Hydrologic Imagery Visualization and Information System)

HAW RIVER NEAR BYNUM, NC – 02096960
https://waterdata.usgs.gov/monitoring-location/02096960/#parameterCode=00065&period=P7D&showMedian=true

 

Ferguson, Paul. “Paddling Eastern North Carolina” Pocosin Press, 2018, pp22-24, 105.

Copies of Ferguson’s book, “Paddling Eastern North Carolina”, are available on the CCC website. At $10. For members a real bargain.

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