Overview

Earthwatch have deployed four RS Hydro Proteus Sondes in the Evenlode Catchment, in rivers upstream and downstream of two Sewage Treatment Works. These are automated, real-time water quality sensors. Ten water quality parameters are being measured at 15 minute intervals. Three of these parameters will be presented in this page.

The high frequency data produced by the Sondes is being used to compare the water quality upstream and downstream of Sewage Treatment Works to investigate chronic pollution. This site-specific work is supporting the Citizen Science and Environment Agency monitoring that is being undertaken at a wider scale across the catchment.

Please be aware that we are currently in the process of updating the Sondes Data on this page. If you have any questions in the meantime, don’t hesitate to reach out to us on ECP@wildoxfordshire.org.uk

Understanding the Data – Water Quality Parameters

Temperature

Temperature affects biological and physical processes, so it provides important context for the other measurements. For example, warmer water can hold a greater amount of dissolved oxygen than colder water, and conductance also increases with temperature. Water temperature would be expected to be warmer in the daytime than at night, and warmer in the summer than in the winter. Temperature of wastewater effluent is often warmer than water in rivers.

Dissolved Oxygen

Dissolved oxygen is the amount of oxygen present in the water that is available to support aquatic life. Photosynthesis creates oxygen, as carbon dioxide is converted into sugars using sunlight, so dissolved oxygen will be higher during the daytime, especially in the summer months when plants and algae are most active. Dissolved oxygen is reduced when plant and organic matter is being decomposed by bacteria.

Specific Conductivity

This is the ability of the water to pass an electrical current. Salts, minerals, and inorganic substances help water to conduct electricity, while organic substances reduce conductivity. Conductance is usually defined by geology. Since the Evenlode rises from underlying limestone, a relatively high conductance is expected because limestone is easily dissolved in water. Large, sudden changes in conductivity usually indicate some kind of disturbance, such as sudden soil erosion or a pollution event.