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.

Surprise Field Trip!

After my Environmental Engineering Exam today Dr. Knappe asked if I would like to join a few grad students who were headed out to see the Cary/Apex water treatment plant! It was a great trip. I wasn't prepared, so I didn't have a decent camera, but here are a few photos from my phone.

Heading up to look at the clarifiers (particles in the water settle out here) :

Clarifier

The Town of Cary uses Ozone for disinfection of the drinking water.
They have to produce the ozone onsite:

Dr. Knappe and Qianru check out the filters.
(Qainru has been an awesome TA for my hydraulics class)

Water level sensor placed over the filter. The filters are typically anthracite and sand, several feet thick. Every so often they must be backwashed, which is controlled by a computer. These sensors are part of that process.

Water samples are taken from these faucets. Each one comes from a different place in the treatment plant, so the operators can trace what is happening at each stage in the process.
The water in the far left faucet does not come from the plant. It comes from the source water, Jordan Lake, which is approximately seven miles away.

Here's a view of the lab.
(Erin, who I study with, is talking in the foreground)

Nobody mentioned this during the tour, but I notice they must test for these toxic substances - look closely and see botulism, ricin, cyanide, anthrax, etc. They're keeping us safe!

Neuse River, Riverkeepers

Including a video with special guest, Lora R. Oh, wait, is that really Lora?

Other people who are concerned about water quality in the Neuse River are found here.

Durham Water Supply

Youngin found this article today:

Durham Water Supply
The article mentions aluminum sulfate. See below for more detail on that.

Whether treating drinking water or wastewater, there are two main goals. One is to remove particles that are suspended in the water. The other is to remove pathogens and other contaminants that pose health risk or taste and odor problems. These goals can overlap, as the particles being removed are also contaminants. Certain pathogens or micro-organisms are removed using disinfection.

The basic process of drinking water treatment when using surface water is:
1. Screening - basically this separates the really big debris out of the raw water
2. Coagulation - chemicals are added to change the surface characteristics of particles. The particles are then more inclined to clump together. Aluminum sulfate is commonly used for this purpose, though Durham has switched to ferric sulfate.
3. Flocculation - this is more of a mixing, or mechanical, step that further encourages particles to clump together
4. Sedimentation - this step slows down the flow of water and allows time for the particles, or clumps of particles to settle out of the water. They form a sludge in the bottom of a basin, and are disposed of from there.
5. Filtration - water is filtered
6. Disinfection - the addition of chlorine or other disinfectant to kill pathogens

Intro to Environmental Engineering

My next Environmental Engineering exam includes Drinking Water and Wastewater Treatment topics.

*Totally new idea...*
- Did you ever think about sludge being generated by the treatment of Drinking Water? I hadn't. Plants that treat surface water (from reservoirs or streams) have to use sedimentation tanks, etc, to get rid of solids suspended in the water. This produces sludge, which is something I associated with waste water only. (Sludge example: that thick black junk in the bottom of your septic tank)

Side note: My last post talked about USGS evaluating surface water quality. One reason it's so important to monitor/improve surface water quality is because it's more and more costly to treat that water for our use. If we have fewer suspended solids (that's the stuff that gets settled out and we call sludge eventually), and fewer contaminants that we have to remove before we use the water, it will cost us a lot less to treat the water.

*Kind of knew something like this was happening...but now I get some detail...*
- Why is chlorine the disinfectant of choice for drinking water? One reason is that it's relatively cheap. Another reason is that chlorine (in a certain form) can remain active as a disinfectant (residual time) even while the water travels out of the plant and through pipes, etc.
Here's and article: Chlorination: The Love/Hate Relationship
(Wow - all we need is a little violence/action and this topic would have all the intrigue of Shakespeare!)

--- AND ---
Notice the new link I added on the right hand side:
Water & Wastes Digest

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.

Economic Stimulus in NC

You can find information on how the Economic Stimulus might affect North Carolina here.

And if you click on the little link at the bottom, it will take you to this document, where you can read the breakdown of where stimulus money is headed. If you go to page 12 of the document, you will find, among other water related items, this information:
_____________________________________________________

Department of the Interior
U.S. Geological Survey (USGS): $140 million to repair and modernize USGS science facilities and equipment, including stream gages.
_____________________________________________________
Interesting.

Fire Water

Here's a crazy article Dr. Knappe forwarded to our class today!

Article & Link to Video:
Fire Water