Troy's Poster at the Symposium

For details on the poster, please follow this link. The symposium was quite interesting, and filled beyond capacity. The best part was the free snacklicious snickers.

Demonstration Flume

The North Carolina State University American Water Resources Association (AWRA) chapter would like to create a small teaching flume. Here is a demonstration flume that looks like it would be a lot of fun to operate. Newbury Hydraulics put this information together, including a construction blueprint at the end of the packet.

Clean Water Act - NY Times

Here's a New York Times editorial regarding the Clean Water Act. There is also a link to these investigative articles.

Hydrometry - Pressure Transducers

Quite a few days have passed since my last post about water level instrumentation, so I should probably mention my source again. Hyrdrometry, 3rd Edition, by Wubbo Boiten. (You can go read the archives if you want an official MLA style citation.) All of the pressure transducer material is based on pages 8-9.

Pressure Transducers:

Three other names commonly used for pressure transducers:
- Pressure Sensors
- Pressure Probes
- Pressure Transmitters

Function:
The basic function of a pressure transducer is to take pressure and turn it into an electric signal. The electric signal is processed, combined with known information about the water density, and converted to a height measurement. The height measurement is typically recorded on a data logger.

Here's a schematic:
Error:
There are a couple sources of error associated with pressure transducers:
1.) Air pressure above the water must be accounted for
2.) Since the pressure transducer is measuring pressure and converting it to water depth, the density of the water is a critical parameter. For instance, salt water has a different density than fresh water. Cold water has a different density than warm water.

Other Concerns:
Pressure transducers may be damaged if exposed to extreme pressures.

Characteristics:
Range: 0-40 feet
Accuracy: 0.1% of the full range

Vacation Stream Gauge

In our travels through VA, WV, PA, OH, & IL, I have been seeing stream gauges all over the place!

Here's one on the Potomac River in Paw Paw, WV:

Hydrometry - Float Operated Gauges

Float gauges provide a mechanical means to measure water height.

Here are the basic components:

Float
Line (Tape, or Wire)
Pulley (Float wheel)
Counterweight

Recorder

The line is attached to the float on one end and a counterweight on the other. It hangs on a pulley. The recorder keeps record of the pulley shaft rotation, which can be translated into water height. Recorders have traditionally been paper on a drum, but more are being converted to digital recorders that keep track of the pulley shaft rotation.

Typically, float gauges are installed in stilling wells, which help to produce stable measuring conditions.

There are several sources of error that must be considered when using the float operated gauges.

Systematic Effects:
1.) Float lag: The float tends to lag behind the true water level as the float rises and falls. This can be minimized by selecting an appropriate diameter float and sufficiently large float wheel.

2.) Intake pipe effects: The intake pipe (horizontal pipe in figure to the right) diameter can also introduce measurement error. A diameter that is too large can reduce the effectiveness of the stilling effect of the well by allowing water to surge in and out of the well. However, a too small diameter can introduce measurement lag because of head loss in the intake pipe.

3.) Chimney Effect: How far the intake pipe extends into the river cross section also impacts measurement due to chimney effect. This can produce a systematic underestimation of the water height.

Other Concerns:
4.) Counterweight: The counterweight location must be configured so the counterweight does not hit the float as it drops. Ideally, the counterweight is never submerged, as the effect of bouyancy on the counterweight will affect measurement.

5.) Tape/Wire: Kinks or twists in the line can cause measurement error. In addition, surges of water can potentially unseat the wire from the pulley.

Float Gauges in Stilling Wells
(Source: USGS)

Hydrometry Introduction

I found this book at the NC State Library:

Hydrometry, 3rd edition: A comprehensive introduction to the measurement of flow in open channels
UNESCO-IHE Lecture Note Series
Wubbo Boiten, Wageningen University, Delft, The Netherlands

Here's the publisher's description.

Based on this book and other sources I may find along the way, I hope to post a few times about the basic measurements taken along streams and rivers.

Initially, water resource measurements can be broken into two categories; quantity and quality. On the quantity side, we want answers to questions such as: do we have enough to drink, is there a risk of flooding in a certain location, are impermeable surfaces such as parking lots creating too much increase in stream flows, etc. The quality side seems obvious because we all want clean drinking water, but there are also less obvious concerns such as sediment transport, nutrient levels, wildlife impacts, and so on.


First let's look at quantity measurement.
When news about a flood hits the airwaves, we're always given stats like flood stage and water height. So water height is necessarily of interest. How do we measure it?
In talking to Dr. Birgand and in reading this book, I find five basic measuring techiques for water height.
1.) Staff Gauge
2.) Float/Counterweight Systems
3.) Pressure Transducers
4.) Bubble Gauges
5.) Ultrasonic sensors

The image on the left is a USGS Stream Gauge Station near Pullen Park in Raleigh, NC. In the background, you can see a white "stick" in the water. That is a staff gauge, which looks a lot like a measuring stick.


In addition to height, we also like to know how much water is flowing in a stream or contained in a reservoir. In streams this is measured as volumetric discharge, in units such as cubic meters per second or gallons per minute. Here are some classic methods for calulating discharge:
1.) Velocity Area method
2.) Slope Area method
3.) Stage Discharge method
4.) Acoustic Methods
5.) Electromagnetic Methods

I've used the Velocity Area method for calculations in class. The remaining four methods I hope to learn more about.

There's plenty to read about quantity measurements, so I think I'll leave the discussion of quality for another time.

USGS National Water Quality Assessment

According to the USGS website, "The National Water-Quality Assessment Program (NAWQA) provides an understanding of water-quality conditions and how those conditions may vary locally, regionally, and nationally; whether conditions are getting better or worse over time; and how natural features and human activities affect those conditions."

There is a ton of information here about NAWQA, including some links to research about chemicals found in source water. USGS calls this program SWQA, for Source Water Quality Assessment. The source water program is interesting because they are looking at the water that's flowing IN the water treatment plants, as well as the water that is leaving the plants. So far they have found a lot of chemicals surviving the treatment process. However, they stress that many of the chemicals they are looking for are unregulated, and often found in very low doses that don't have known consequences to the end user. They also delve into the various ways the study could have been flawed (ex. how can you be sure you are testing the same water at both ends of the treatment plant?).

From my limited conversations with people who look at stream water quality and people who look at water treatment processes, it sounds like there isn't a lot of communication between the two groups. It would seem logical that the two groups would have a lot of information to share, or at least compare. This gets into one of my pet peeves, actually. We seem to exert a lot of energy chasing after answers that someone else has already caught. That said, I know how easy it is to be busy trying to be productive and not have the leisure time to go listen to someone else talk about what they've been up to. And, I suppose there are times when we want the same information, but in a different context.

Fire Water

Here's a crazy article Dr. Knappe (Civil Engineering) forwarded today!

Article & Link to Video:
Fire Water

Water Wiki, NC

Here's information on some of the latest water legislation in North Carolina.

...And here's a link to the main page of the Water Wiki, where you will find the following introduction:

FROM WATER WIKI______________________________________

This website is a place where you can contribute.

How should water be managed in the southeastern United States? This wiki is devoted to discussion and debate of the many facts, issues, opinions and points of view this question raises. Please add your thoughts by registering (it's simple) and writing or editing articles, or by commenting on any of the discussion pages.
~Richard Whisnant, UNC-Chapel Hill; Bill Holman, Duke University

"You cannot step twice into the same river, for fresh waters are flowing in upon you." ~Heraclitus, 500 B.C.
"You cannot click twice into the same water wiki, for fresh data are flowing in upon you." ~An Editor of the Water Wiki, 2007 "
___________________________________________________

BAE Faculty, NCSU

Here are four faculty members working in areas I am interested in:

Stream Restoration -
Dr. Greg Jennings

Urban Stormwater Management -
Dr. Bill Hunt

Wetlands -
Dr. Mike Burchell

Nutrient Retention in Surface Waters &
Improving Sampling Techniques -
Dr. Francois Birgand

As you can see from their web sites, they all have interests beyond the short heading I give...

Graduate School Rankings

NC State compares favorably to other Biological and Agricultural Engineering Graduate Programs.

For this ranking, I eliminated all the factors except:
1. Time to degree
2. Cost
3. Placement Rate (further research or a job)

Click here.

Water Research Institutes

Each state in the US has a Water Resources Institute. Federal legislation directing water resource research was passed in 1964. Amendments were made in 1978 and then the legislation took its current form, The Water Research and Development Act of 1984. Among other things, the 1984 legislation authorized the creation of Water Resource Research Institutes for each state. The program, commonly referred to as WRRI, is currently administered by the United States Geological Survey (USGS).

In North Carolina, the Water Resources Institute is headquartered at the University of North Carolina. Here's a link.

Institutes for each state are located here.

Bowling Green, Purdue, Algae/Cyanobacteria

Bowling Green University and Purdue University have some interesting image libraries for algae and cyanobacteria. The Bowling Green site also has a link to a program that was written to aid in counting specimens in images.

Here they are!

Bowling Green (Image Library and other algal links)

Purdue (Cyanobacteria)

Also, I found this book, written in part by an NC State professor, is availabe at NCSU library. Hopefully I'll be able to check it out the next time I go in.

Algae, Cyanobacteria, and FlowCAM

I found two great books at NCSU library last night.

Detection methods for algae, protozoa and helminths in fresh and drinking water. Chichester, West Sussex, England: John Wiley, 2002.

Cyanobacterial harmful algal blooms state of the science and research needs. Vol. 619. New York: Springer, 2008.

Cyanobacteria is really not a true algae, but acts like one and is commonly referred to as blue-green algae. There are surveys suggesting that half of the Cyanobacteria blooms are toxic. This creates a lot of concern should blooms form in reservoirs that are used for drinking water. Cyanobacteria also can have a negative impact on odor and taste in drinking water. Musty, earthy and stale are common descriptions of these odors and tastes. Efforts are being made to reliably detect the presence of Cyanobacteria as well as associated toxins.

One of the books also refers to this flowcam, for remote analysis of water particles:








There is a bench model and a portable model.

Sample Images

Liquid Assets II

We watched Liquid Assets on DVD tonight. It is geared more toward Civil Engineering aspects of water supply, but these definitely tie into our interests. Think about sanitary sewer overflows, which often flow directly into natural streams.

Overall, this video is very interesting and educational. It gives a nice overview of how water systems work, as well as a lot of specific stories about the challenges that everyone faces, from small towns to large cities.

A couple tidbits:
- New York City's water supply, for the most part, is gravity fed from distant lakes through two huge tunnels.
- Las Vegas actually claims they are using less water despite rapid population increases in recent years.
- Lots of camera technology is being used to inspect pipes. Atlanta has video of thousands and thousands of feet of pipe. They can use it to compare current conditions to past conditions, etc.

Check out the Trailer.

Liquid Assets

Here's the trailer to a documentary I would like to see.

Liquid Assets

The DVD