Mounting and Installing

Considerations

During our build, we significantly underestimated the difficulty that mounting and installing the sensor would be. Here are a few areas you need to consider with your solution.

Stage Range

You will need to consider the range of water levels your sensor will likely see. You’ll want to mount your sensor such that it covers the greatest range of water levels. Keep in mind that the JSN-SR04 typically has a stable range from 10 cm to 1500 cm. In a major flood event, your sensor may very well become submerged for some period of time. At this point, you’ll need to hope that your enclosure will hold up.

Debris

Your mounting solution will likely build up large amounts of debris during its lifetime. Leaves, sticks and mud will accumulate around any and all edges that are in the water. To some extent, this is unavoidable, so they key is to make sure your sensor will continue to take accurate measurements despite debris. For water level measurement, this may mean offsetting the ultrasonic sensor from the main mounting pole to prevent built up debris from skewing sensor data.

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Ice

If the device will experience freezing temperatures, consider how ice may affect your device. Ice can freeze onto a mounting pole having a similar effect as debris buildup. When temperatures start to rise again, ice can break into massive sheets that can bend or topple your mounting solution.

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This may be an extreme case, but you get the idea.

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Our mounting pole after an ice sheet made its way through.

Soil Type

In our experience, stream and river beds are not very friendly to stake pounding. Before you choose a solution, check to see what the ground is like where you plan to install. While we use an aluminum rod to mount our device, we use a 1/2 in. steel rod with a sharpened end to make an initial hole into the ground.

Vandalization

Unfortunately, this is also a major consideration in an installation. You will likely want to choose an area with limited foot traffic. If that is unavoidable, consider a shrouded mounting solution where the device is completely enclosed. Using standard materials like PVC may help avoid attention. Be sure to communicate its purpose and the permission its received clearly. We use a small printed card for this.

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What was left of our device after it was vandalized in May.

Selecting an Option

No mounting solution is going to be the best choice for all locations, that’s why there isn’t a one-size-fits-all option (at least for now). We recommend taking two trips to the stream or river you want to install in. Take note of the stream bed hardness, tree and branch locations, and any other structures that you could potentially mount your sensor to. Take lots of photos while you’re there (if you have a ruler in the shot, you can even use it as a crude scale reference).

Now you can weigh the different options for mounting that you have. Here are some of the ones we have used or planned out.

Option

Description

Pros

Cons

Metal pole

A single metal rod, aluminum in our case, hammered into the stream bed. The sensor is fixed to the top of this pole with an options extension.

  • Simple and inconspicuous

  • A particularly rocky or sandy stream bed will not be able support a pole

  • Prone to eroding and failing

  • Debris is likely to accumulate around the pole

Metal pole with stabilization

Similar to the first option, however a metal plate is fixed normal to the pole. This plate is covered with large rocks to prevent movement.

  • Relatively simple

  • Relatively secure in fast-moving streams or rivers

  • Less prone to failure by erosion

  • May require drilling/assembly in the field

  • More conspicuous than a pole

  • Debris is likely to accumulate around the pole

Tree/branch mounted

Fix the sensor directly to a fallen tree or branch that goes over the water. You may need to correct for the angle of the tree in the mounting design.

  • Very simple construction

  • Since nothing is mounted directly in the water, debris is unlikely to accumulate

  • Requires a tree/branch at in the exact right position

  • Requires a custom solution which is highly dependent on the specifics of the situation.