Real-Time Remote Monitoring of Water Levels and Atmospheric Variables Using OnSet MicroRX Water Level Stations Quad Cities Conservation Alliance Wetland Complex

To help us understand the movement of water through the QCCA wetland complex, we're installing three OnSet MicroRX Water Level Stations (RX2401). We will measure the water levels in streams entering and leaving the property as well as the level in the lake. The station in the lake is equipped with additional instrumentation to measure atmospheric variables.

Pre-deployment Testing

Before deploying sensors in the field, "bucket tests" were conducted to ensure the sensors were operating correctly. In our case, we placed three sensors on a container that was filled with water to a known level. The data loggers were started and water level data were collected. The water level was altered multiple times to test the response of the sensors to changes in water level.

One of our stations was equipped to measure atmospheric data including air temperature, dew point, relative humidity, photosynthetically active radiation, and rainfall.

This system as also tested before deploying the station in the field.

In the field, each water level sensor was housed in a stilling well. We use stilling wells made from 2" schedule 40 PVC. A 10 ft length of this pipe cost less than $5. Holes were drilled along the length of the PVC pipe to ensure the water level in the stilling well and the level in the stream or lake were equal. A cap with a purge hole was used to keep debris from gathering in the stilling wells.

Installing Water Level Stations in the Field

We have two different types of installations - one in a stream and one in a lake. The same general approach is taken in both cases: the RX2401 data logger and communications hub is mounted to a pole or tripod on land adjacent to the location of the water level sensor which is mounted in a stilling well in the water.

Stream Water Level Measurement

Our first installation was in the stream that feeds the lake. This unit was equipped measure barometric pressure, water temperature, water pressure, and water level.

The ground was so soft that we were able to drive the mounting pole almost 2 ft deep without using any tools. We followed this up with a few taps from a weighted post driver for good measure.

We used a standard 1-5/8" diameter 16 gauge galvanized chain link fence post. It was installed approximately 6 ft from the stream where the water level sensor was installed. Our system was equipped with a 10 meter (~33 ft) long cord to connect the sensor and the data logger which allowed us a degree of flexibility in where and how we mount the components.

A second set of hands is helpful when mounting the data station - especially in cold, wet, and muddy conditions! We were lucky to have ample help from members of the Moline Conservation Club - the group responsible for purchasing these systems.

Each data station is equipped with a solar panel that provides power for the data logger, the sensor(s), and the 4G cellular data connection.

Installing the stilling well and sensor in the stream is a little more involved. I suspect this process is more enjoyable when the water temperature is more than 40 degrees F!

We mounted the stilling well alongside a t-post that was driven into the stream bed and plumbed using a 2 ft level. This stilling well was 28" tall.

We took measurements of stream dimensions and water level. This stream was 6 ft wide with water depth ranging from 1.4 to 1.6 ft. We located the stilling well 2.6 ft from the right bank. These dimensions were representative of those measured up- and down- stream from the stilling well.

Before placing the sensor, we secured the stilling well to the plumbed t-post using heavy duty zip ties.

Finally, the water level sensor was placed in the stilling well and secured with an additional zip tie.

Water Level and Atmospheric Telemetry in the Lake

The second unit was installed in a lake that's fed by the stream and drains into the wetland.

This station was equipped with atmospheric data collection capabilities as well as a water level sensor. To accommodate the additional telemetry, we used a 2 meter high tripod.

After leveling the tripod and mounting the sensors, the station was further secured using three stainless steel guy wires.

As in the previous case, the water level sensor was placed in a stilling well located in the water while everything else was mounted on land. Since the sensor was placed at a water depth of 3.2 ft, the installation was a little more involved (that is, cold and wet).

We have one more unit to install at the outlet of a wetland which drains the property. We'll install the third station after COVID-19 social distancing restrictions are lifted.

Photos credits: Many thanks to my 11 year old son, Spike, who took the field-based photos using his Samsung Galaxy S9 phone.


Photos by Roger Viadero, Jr., and Roger "Spike" Viadero, III.