Up and Downwelling Facility

The River Laboratory boasts a number of unique experimental systems for research on freshwater biology. One of these is the ‘Up and Downwelling Facility’.

Everyone is familiar with the longitudinal movement of water along the course of a river, but water can also flow vertically upwards and downwards through the streambed (the ‘hyporheic zone’). These vertical movements of water are thought to be important for the plants and animals that live in streams. For example, up and downwelling zones are thought to influence:

• Microbial bio-films
• Meiofauna and macroinvertebrates community structure
• Aquatic phytobenthos and macrophytes
• Salmonid fish egg survival 

Studying hyporheic up and downwelling zones in streams is difficult. Vertical water movements can be small and measuring them typically disrupts the patterns we wish to study. It is also very difficult to couple accurate measurements of the vertical movement of water to samples of plants and animals because most of the methods for measuring vertical water flow compromise normal biological sampling methods.

The Up and Downwelling Facility, situated on the Mill Stream (part of the River Frome), makes artificial up and downwelling zones. The intensity of the up and downwelling flows can be controlled and the water movements can be directed through various biological sampling devices

Schematic diagram of the Up and Downwelling Facility

The facility works as follows.
Upwellings of interstitial water are created by:

• Collection from within the streambed (A)
• Storage (B)
• Movement to a header tank (C)
• Release through flow control columns (C) to upwelling treatments (D)

Downwellings of stream water are created by:

• Allowing water to fall through treatments (E)
• Release through flow control valves (F) and pumping away

Collection of interstitial water from the streambed (A)	Water storage (B)
Header tank (C)	Flow control columns (D)

Recent work on the Up and Downwelling Facility has focussed on testing the performance of seepage meters - devices that hydrologists use to measure vertical water flow. The Up and Downwelling Facility provided an excellent test bed to examine the performance of these devices (photos below).

Seepage meter test bed (prior to installation)	Installing the seepage meter test bed
Testing a ‘Lee-type’ seepage meter	Adding dye to the header tank reveals upwellings

For further details of the Up and Downwelling Facility download the Up and Downwelling Facility Poster.

If you are a student or researcher wishing to collaborate with the Freshwater Biological Association on hyporheic zone research, please contact FBA Head of Science, John Davy-Bowker (jdb@fba.org.uk).