Care and Use of Emriver Models

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  • Never use lithic materials (i.e., sand) in the Emriver tables or the Emflume1.
  • Use care when cleaning the Emriver tables with bleach. Use only a small amount as specified in the manual (6 mL for the Em2; 12 mL for the Em3; 21 mL for the Em4), and be sure the model is circulating water to keep the bleach moving through the system. Adding too much bleach or chlorine can damage the aluminum parts.
  • To keep the model sanitary, change out the water every day or two and drain the table between uses by lowering the standpipe all the way. If you won’t be using the model daily, drain the water from the table and allow the media to dry by piling it upstream and turning it occasionally.
  • Never use solvents to clean plastic parts; use only mild detergents.
  • Never use alcohol-based cleaners or Windex to clean the Emflume1; use only mild detergents.
  • Power down the pump and controller after each use by disconnecting the pump from the controller, and disconnecting the controller from the power supply.

Please read the manuals for additional information.


  • If the pump is reluctant to prime when started, reorient or shake it a bit (while underwater) to remove air trapped in its intake.  If necessary, clean any debris from the filter by unscrewing it from the pump and flushing it with water.
  • If you are having problems with either the pump or the flow controller, connect the pump directly to the power supply (bypassing the controller) and see if it works. This will help to narrow down the possible problem.
  • If your flow controller stops working, please contact us. Until it is repaired or replaced, you can simply plug the power cord into the pump connector (bypassing the controller) and get full flow from the pump. A little c-clamp or pair of vice grips on the tubing can control flow rate.
  • Be sure the AC power cord is fully inserted into the brick power supply and that the green LED is lit.


  • Little River warrants all parts for manufacturer defects. If you have a problem with a part, please contact us with a description of the problem and a photo, if possible, so we can determine how to proceed.
  • In the spring of 2016, we started using the Shurflo Bait Sentry pumps. They have a 3-year manufacturer warranty.
  • If you’ve lost or damaged a part, please contact us for a quote on the replacement cost plus shipping.




(for models shipped before October 2010)

  • Pump, tubing and valve assembly
  • Level rod bracket assembly; Beginning in June 2008, we redesigned the level rod and support so assembly is self-evident.
  • Head scale inserts; use these files to print paper inserts for your head scale in millimeters.
  • An AutoCAD drawing file can be modified to produce a scale calibrated in ml/sec. The AutoCAD file must be modified based on the particular calibration data for your headscale-notch gage pair. Please contact us for a copy of the document.


What are our prices?

We provide customized quotes based on your needs. Please use the contact form or email us to request a quote.

  • Model prices start at US $5,000 plus shipping.
  • The color-coded media (Memphis and Carbondale Mixes) starts at US $26.67 per pound (0.45 kg).
  • The non-coded media (Alpha Mix) costs less than $6 per pound (0.45 kg). We will sell up to 60 pounds (27 kg); for larger orders please contact us for more information.
  • We can help you determine how much of our media you would need to fill your own stream table. Please contact us with the dimensions of your table.

Can I put my own modeling media in the Emriver model? Can I mix sand or organic material with your model sediment? Why do you use plastic?

The Emriver box is strong and durable but isn’t approved for use with sand (lithic material) because those materials are much heavier than Emriver modelling sediment, and the box or supports could collapse under the increased weight. Sand also can clog our pumps and filters and damage other parts of the model. Because it is lighter, our plastic material moves more quickly and demonstrates processes more accurately at this compressed scale.

Can I mix non-coded (Alpha) Emriver media with color-coded (Carbondale, Memphis) media?

If you do, you lose the effective purpose of the color-coded media, which was has a specific D50 (median in a range of) particle size. If you do mix the two, the sediment is no longer color-coded-by-size.

How does the media directly relate to the real world of sand, gravel and cobbles?

Particle sizes are meant to act like sand, silt, and clay. The exact ratios of the sizes in the mix aren’t matched to a particular stream or river, but the behavior of the sediment sizes is comparable and can demonstrate similar changes. However, all the sediment has the same density, so it is size only that can be examined.

Direct scaling of all the variables in river morphology and processes isn’t possible, so the relationships are approximate. Simulating specific situations, such as modeling and predicting whether a certain section of river will be stable or not, is difficult or impossible in any physical model; but Emriver models do a great job of showing processes and morphological changes in rivers.

Why do particles in the color-coded media move at different rates?

In the real world and in the model, it’s not as simple as “smaller particles are easier to move.” The red particles and, to some degree, the black ones are small enough that they stick together somewhat, just like clay. The white and yellow particles stick together a bit when wet but not nearly as much as the red and black. They have electromechanical attraction. All particles experience this attraction, but only in the smallest ones does it overcome the other forces (gravity, flowing water) and keep the particles together. That’s why you sometimes see the small areas of pure red. In the real world, a clay riverbank or bed can be as difficult to erode as solid rock.

Also, what you think you see moving in the model is not always accurate, because estimating the relative motion of the particles is difficult. When we shoot videos and slow them down, you can see the difference. And when we measure the output at the drain, the actual size mix is very different from what we estimate by eye. There also is a phenomenon in which the larger particles tend to bounce on the top, so you perceive them more strongly. It’s just like a can of mixed nuts; if you shake it, the big ones rise to the top. So, the yellow and white ones tend to be more visible if the whole bed is in motion.

Why can’t I see the red particles?

One reason is because of the rate at which processes are going. Moving slower with a low slope (high standpipe) and low Q (discharge) gives the media sizes time to sort. Too high a Q is probably the most common mistake we see; you get a lot of movement, but bedforms aren’t that interesting. Around 60 ml/second will do the job, but it takes time. We recommend care in adding more red; the usual mix is only 1.5 percent of the total by weight. You can remove excess by sieving, but it’s a lot easier to add than it is to remove.

How do you keep the model and its sediment clean?

1. Add the appropriate amount of bleach (see top of page) into the reservoir and run it through the model. Be careful when adding bleach as it could damage the aluminum.
2. Drain the water after each use. If the model will be used continually, change the water daily or, at the very least, every other day.
3. Allow sediment to dry when the model is not in use by piling it toward the upstream end of the box and removing the standpipe. This allows water to drain more easily. Mix and spread the sediment occasionally to allow for more drainage.

How do I disassemble and store an Em2?

1. Disassemble the tubing, pump, filter and power supply and set aside.
2. Allow sediment to dry.
3. Pile the sediment toward the upstream end of the box. Remove the standpipe to allow water to drain more easily. You can move the piles of sediment around to help get the water out. Allowing at least 24 hours is ideal, but if you don’t have that much time and the sediment isn’t completely dry, that’s OK. Just don’t store it wet in the buckets for too long, or it will start to stink and possibly develop a biofilm. You can help keep it clean by pouring a cup of bleach into the reservoir and letting it run through the system.
4. Once the sediment is reasonably dry, scoop it into the buckets the sediment originally came in.
5. Empty the water from the reservoir.
6. The tubing, pump, sediment trap, tools, etc., can be stored in the reservoir for transport.
7. The table can be transported on a car rack or in a pickup truck. If the table is being transported in the bed of a truck, the reservoir and supports can be stored inside during transport. Storing the Em2 uses only about 9 square feet of floor space, not including height.

Why should I choose an Emriver stream table over a homemade one?

Emriver models are durable and are completely portable, easy to set up and break down. We’ve been in business for more than 20 years, and our first Emriver model is still in use. Our principal designer has more than 20 years of experience working in fluvial geomorphology and has put strong science behind the models. We’ve taken into account design and portability, as well as these processes, which aren’t usually considered:

• Scaling and similitude in Emriver modeling sediment:  When you scale a life-size river down to meters, you have to account for things like friction and electrostatic forces. When you want to mimic a certain fluvial action on a small scale, sand is not the best option; it doesn’t accurately model river processes because it sticks to itself.

• Design: Em2 and Em3 models are designed to be portable and durable throughout travel. You usually don’t see that in a homemade model.

• Sand is cheaper, but the pump will break: Although you can find sand at any hardware store, and it’s much less expensive and more readily available, your pump will ultimately break down with lithic sand.

Can the models demonstrate coastal or tidal processes?

By raising and lowering the standpipe, you can simulate river mouth interactions with lakes and oceans.

Can the model demonstrate groundwater and precipitation?

See our Instruments page for information about our groundwater system for the Em3 and Em4 models. Even without the groundwater system, the models do display the results of groundwater processes. The model charges so that it includes a water table beneath the sediment outside the stream. The effects of underground directional flow can be seen in the model, including strata formations and floodplain terraces.  Patterns left behind demonstrate how groundwater once flowed in that area.

The effects of contaminants in the stream on groundwater (and vice versa) can be seen by digging a well outside the stream and using dye (outlined above). Aside from contaminants, the dye also acts as a marker to show that water flows between the stream and the water table (groundwater) outside the stream. Using dye also demonstrates how groundwater interacts with water in a channel, even when it isn’t contaminated.

We do not have a precipitation model at this time.

What is the difference between the Em3 and Em4 models?

The primary difference is surface area which allows for larger scale experiments, ability to collect more quantitative data, and room for more students to observe.

Can we build models that represent specific rivers or watersheds?

Our models are impressively accurate at demonstrating river dynamic principles and processes rather than specific river or watershed systems. Please see the How to Use section for resources and ways to use our models.

Do we offer fee-based research or modeling?

Steve consulted on river management projects for many years but decided to shift all his time to building models. We don’t conduct experiments in-house; instead, we work continually to improve our models for client use in research and teaching.

Do we build custom items?

We are a small staff and devote our time to building and improving our current product line, and, as we have time, to develop new instruments and accessories. But if you have a special need, feel free to run it by us and we’ll see what we can do.