The Illustrated Field Deployment Guide for Rivers and Streams

3. Installations

The components of deployed sensors include the platform design, installation, and maintenance.

3.1 Access and Safety:

  • Safety should always be the first priority! Always use personal flotation devices (PFDs) when in contact or near a water body. Plan trips with frequent check-ins via cell phone or other means. All field work personnel should have first-aid kits and emergency training. During inclement weather or at complicated sites, crews should should include more than one person with all the appropriate safety equipment. In extreme conditions, when safety cannot be guaranteed despite taking all precautions, it is better to have missing data than to risk personal safety.
  • Vehicle Access: Ensure that your field vehicle can handle the likely range of conditions at your site(s). Consider worst-case scenarios such as flooding, ice, snow, shallow flowing water, mud, and steep inclines with loose gravel. Extreme conditions may require a 4-wheel-drive field vehicle. Wagner et al (2006)
  • Vandalism: Aside from attended monitoring, always consider vandalism. Always make the site as inconspicuous as possible. Keep site locked and ensure that structures are sturdy enough to prevent or discourage vandalism.
    Photo of gage structure at Passaic River
    Equipment housed in a structure obscured from view can decrease the chance of vandalism.

3.2 Equipment location:

  • Place structures at an elevation above the expected high-water mark. Here is an extreme example:
  • Where possible, shield sondes and intakes in partially sheltered flow to minimize damage from high flow, and attach securely to bridge piers or other sturdy locations.
    Sonde tube on armoured riverbank
    Above photo: Sonde tube anchored to riprapped bank of a stream. At this site, debris is minimal and there is little risk of the tube being dislodged. However, at sites with more debris or seasonal ice flows, positioning the sonde tube behind bridge pier or out of the main current might be necessary. (Photo: USGS)
    Sensor attached to cinder block
    The schematic above shows a simple sensor deployment. The sonde is inside a protective casing attached to a cinder block secured to the streambed with rebar. This type of deployment os sufficient at many sites and for short-term deployments. (Source: ORSANCO)
  • Structures must be sufficiently robust to handle the impact of large, fast-moving debris flowing with the water.
    Photo of debris damage to Rio Grande gagehouse
    (Photo of debris-damaged site on Rio Grande in TX: TX CEQ, USGS)

3.3 Available Infrastructure

At many sites, sufficient power can be provided by a combination of batteries and solar panels.
Photo of structure with solar panels
If a flow-through system is required, 11-volt AC power will need to be run to the site.

3.4 Extreme conditions

  • Drying - During extreme drought conditions or events that cause channels to shift, probes can be exposed to air and susceptible to dessication.

    Example of a water-quality sonde placed directly in a waterbody where uncharacteristically low water levels have left the probes nearly out of the water: if installed correctly, the tube should be easily repositioned to re-submerge the sonde (in this case that was not possible and the equipment had to be relocated to another spot with deeper water). In areas where large debris flows or ice sheets are not a problem, and for short-term deployments, this is a very economical approach. (USGS - Manitowoc River near Manitowoc, WI)

  • Freezing - Freezing temperatures and ice formation are major issues in parts of the country. In addition, sites that rely on battery power may need more frequent charging.
    Close up of end of sonde tube and autosampler intake
    Stainless steel pipes protect sondes from ice at a site in New York state. Inside the tubes, heat tape wrapped around the sonde prevents the water around the sonde from freezing while the steel pipe protects against impacts from ice jams and debris. (Photo: USGS)

    In flow-through systems, consider ice formation at the orifice intake, as well as freezing inside the pipes that deliver the water to the monitoring equipment. In extreme climates, operators may need to shut down flow-through systems during the coldest months.

    Photo: Inside a heated structure housing a flow-through chamber with three intake lines.

3.5 Service Intervals

  • All monitoring locations should be free of vegetation in order to maintain consistent and high-quality data. Areas around sensors and orifice intakes should be inspected during growing season and vegetation removed as needed.
    Macrophytes on sonde tube
    Photo above shows a mat of macrophytes on the sonde tube at a site in Texas. This site needs to be visited more often and vegetation removed in order to ensure accurate water-quality data. (Photo: TCEQ)

  • Terrestrial vegetation can inhibit site access and damage intake and communication lines; trim and remove overgrowth as necessary. A thick canopy of overhanging trees can inhibit telemetry; consider shelter location relative to large trees and other vegetation, or trim if necessary.
  • Fouling rate
    • Fouling rate is highly site dependent and should be taken into consideration when developing maintenance plans. Typically warm salt water is the most productive, requiring a higher frequency of visits to collect quality data.
    • Biofouling effects can be supressed with various anti-fouling hardware. Wipers keep optical sensors clean and free of debris,and brushes clean pH and temperature sensors while removing debris and fouling from wipers. Copper tape and copper alloys also successfully discourage biological growth on sensor bodies and sonde guards.
      Copper probe cover from Hach Hydrolab
      Copper housing over sensor probes discourages biofouling (Photo: Hach, Inc.)

  • Power requirements - If on-site DC current is available, duty-cycle determination can be disregarded. However, maintain regular maintenance intervals based on biofouling and sensor calibration recommendations.
    For sites powered by AC current (batteries and/or battery + solar power), determine a duty cycle/site visit interval and compare it to maintenance intervals for biofouling and sensor calibration to determine the most effective interval. Use the most frequent interval to maintain the site.

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