Measuring the flow of water-bodies

Here in the freshwater team at Thomson Environmental Consultants, we’ve been up to our waders in water-bodies! Over the past month we have been conducting spot flow gauging surveys on behalf of several our clients. But what is spot flow gauging, why is it important, and why are we doing it?

What is spot flow gauging?

Spot flow gauging is the measurement of discharge (i.e. the volume of water) flowing past a specific point in a water-body (usually streams and rivers), at a given time. Our data comes from using a current meter to collect accurate flow velocity measurements and combining this with channel depth and width data to obtain the discharge volume.

Thomson freshwater team spot flow gauging on the River Taff in June © Tansy Knight
Thomson freshwater team spot flow gauging on the River Taff in June © Tansy Knight

Why is spot flow gauging important?

It’s important to assess the discharge of water-bodies as this provides a piece to the wider puzzle of their complex ecological form, function and health. However, accurate measurement and evaluation of water-bodies is also critical in assessing the impact of human uses of rivers and streams such as abstraction (i.e. removal of water) for drinking water and irrigation.

During drought conditions, water companies may be permitted to abstract more water than they would normally, but only once they have demonstrated that it wouldn’t result in a negative impact on the ecology of the stream or river. The discharge data collected in these surveys, combined with water quality sampling and ecological data for river invertebrates and water plants, allows the team to accurately assess the health of a water-body.

These surveys are usually undertaken proactively during all seasons of the year so that an accurate picture can be established of the health of the water-body before any additional abstraction under drought conditions is required.

Thomson Assistant Biologist, Dale, conducting water quality sampling of a water-body © Thomson Environmental Consultants
Thomson Assistant Biologist, Dale, conducting water quality sampling of a water-body © Thomson Environmental Consultants

Why is Thomson conducting spot flow gauging?

At Thomson, the freshwater team support our clients in devising survey and assessment programmes which are proportionate to proposed development schemes, while ensuring regulatory compliance. Recently, our successful work has included spot flow gauging and ecological surveys across a range of water-bodies in the Midlands, to inform water resource management plans; surveys to support the restoration works of grade II listed weirs; and calculations to mitigate nutrient loading arising from residential developments.

Despite the variable weather we’ve been having, we’ve been lucky enough to sample a wide range of water-bodies in varying locations. Whatever the weather, you’ll be able to rely on the dedicated freshwater team at Thomson to measure and quantify water-body flow rate and provide a detailed report.

Our other services include

  • eDNA and Habitat Suitability Index assessment for great crested newts
  • Water-body sampling
  • Macroinvertebrate kick
  • PSYM and rapid surveying, identification and analysis
  • Phase 1 Habitat Assessment
  • Nutrient Budget reports with appropriate calculations
  • Otter and water vole field signs surveys
  • Preliminary Ecological Appraisals
  • Fisheries management
  • Freshwater Impact Assessments and much, much more.

Contact us today