Flow and Rainfall Monitoring – Available Technology and How to Effectively Operate and Maintain It (Part 1)

Rainfall monitoring is the measurement of rainwater (and potentially snow) accumulation over time. Rainfall monitoring helps municipalities and engineers better understand how much precipitation falls in an area and how it affects water supplies, land use, flooding, and other elements of the environment. Knowing the amount of rainfall enables municipalities to make decisions on topics such as asset management and flood prevention.

Civca’s first Flow Monitoring Webinar Series aimed to provide a greater understanding of natural phenomena (e.g., rainfall), assess built systems (infrastructure) and how they perform against design expectations, and explain how existing systems can be made better to accommodate future growth and adapt to changes in climate.

The second webinar discusses the technology available for flow and rainfall monitoring and how to effectively operate and maintain it. An overview of the webinar will be provided in two parts.

Types of Precipitation Monitoring Technology

There are two main types of technology used for precipitation monitoring: tipping bucket rain gauges and all season weighing precipitation gauges.

Tipping Bucket Rain Gauges

Tipping bucket rain gauges operate on a tipping bucket principle, which means the bucket will tip each time 0.2 mm of precipitation is collected. Then, a reed switch detects the events and produces a momentary contact closure. The 200 mm receiver diameter collects the rainfall. Rainfall measurements are intended to be representative of the actual rain falling on a given area. 

Features:

Tipping bucket rain gauges typically have a 200 mm receiver and 0.2 mm bucket capacity, a 0 to 700 mm/hr. measuring range, +/-2% calibration accuracy for intensities from 25 to 500 mm/hr., and they can operate in temperatures ranging from -20^o C to 70^o

Installation:

When installing a tipping bucket rain gauge, place the gauge on level
ground, have adequate protection from strong winds, make sure the area is free from
large obstructions such as buildings and trees, and ensure the area has suitable ground
surface to avoid splashing into the gauge.

Maintenance:

Tipping bucket rain gauges require minimal maintenance aside from regular cleaning. It is worth noting that surface tension changes can occur if proper routine maintenance is not conducted. To avoid this, it is recommended to use Isopropyl Alcohol for surface cleaning. It is also advised to clean the syphon periodically.

Calibration:

Most tipping bucket rain gauges are calibrated at the factory prior to shipment and should hold their calibration for thousands of events before a calibration is needed. If a calibration is required, ensure the rain gauge is thoroughly cleaned first. Most often, a cleaning should correct the measurement accuracy without having to do a calibration.

All Season Weighing Precipitation Gauges

All season weighing precipitation gauges use the weighing principle for liquid, solid, and mixed precipitation. They use advanced data acquisition and processing with signal analysis, filtering, and noise reduction for highly accurate results. In addition, algorithms are used for compensation of temperature and wind influences.

Features:

All season weighing precipitation gauges have a lifetime calibration, which means they do not need to be continuously calibrated. They are also ice-, drift- and (almost) maintenance-free, have a low total cost of ownership, and high data availability. All season weighing precipitation gauges can operate within temperatures ranging from – 40^o C to 60^o

Installation:

A ring heating control and temperature sensor are installed in the pipe housing. After being installed, all season weighing precipitation gauges provide protection from snow caps. Only the upper metal ring is heated to avoid evaporation.

Benefits:

Many all season weighing precipitation gauges provide a fast, intensity-correct precipitation output. Others can provide output of the measurement results within five minutes after precipitation has occurred. In this case, a precise, quantitative precipitation output is provided.

Why Choose Civica?

Flow and rainfall monitoring is an incredibly useful technology that has many benefits for municipal applications. By having access to real-time data about precipitation activities, smarter decisions can be made in terms of water management, heat and energy conservation, agricultural planning, and maintenance of natural resources.

In this first blog post, an overview was provided of the technology available for flow and rainfall monitoring and how to effectively operate and maintain it. In part two, the advantages and disadvantages of the different approaches to open channel flow measurement will be discussed. The blog will also cover various tools used for flow measurement.

For more information on flow and rainfall monitoring, please contact Civica today.

Learn more at:

Flow and Rainfall Monitoring – Available Technology and How to Effectively Operate and Maintain (Part 2)

Introduction to Collection System Flow and Rainfall Monitoring

How the New Systemwide Stormwater ECA Regulations Impact Municipalities

An Overview of the New Subdivision Flow Monitoring to Assess Performance of Inflow and Infiltration (I/I) Prevention

Challenges of the New Subdivision Flow Monitoring to Assess Performance of Inflow and Infiltration (I/I) Prevention

Learn about the City of Toronto’s Sewer Infrastructure and Sewer Assessment Guidelines