QUality Evaluation and Simulation TOol for River systems (QUESTOR)
QUESTOR simulates water quality in rivers to understand changing water quality and ecosystem health under past and present conditions. It is used: (1) to predict how river water quality will respond to climate change; and (2) to predict how river water quality will respond to changing water management (eg increased abstraction or discharge; planting river-bank trees; or building a flood relief channel).
QUESTOR is a process model that is practical to run using widely available data sets as inputs. It simulates time series (daily or hourly) of river flow, temperature, nutrient and sediment concentrations, chlorophyll (algal biomass) and dissolved oxygen. When run in hourly mode it can also be used to estimate ecosystem metabolism which represents the balance between photosynthesis and respiration. In this way it provides an integrated measure of the health of the river ecosystem, as well as information about pollutant concentrations which can be related directly to regulatory standards. The model represents the branching in river networks, and directly includes the influences of tributaries, abstractions, effluents and weirs.
The QUESTOR model framework originated in the 1980s and was more fully developed in the 1990s under the NERC Land-Ocean Interaction Study (LOIS). Since then, QUESTOR has been extensively used and tested in the UK and Europe, and improved to include representation of algal biomass, dissolved oxygen (including artificial aeration), light inputs, water temperature and energy balance.
QUESTOR has a mix of unique capabilities, including: (1) its treatment of chemical and bio-physical factors controlling dissolved oxygen; (2) its representation of processes on a hourly time-step; (3) its power in directly representing the impact of river channel and riparian modifications on water quality; (4) its capability to relate (the sensitivity of) eutrophication to the environmental requirements of different phytoplankton groups; and (5) its capability to incorporate the effects of macrophytes and benthic algae.
QUESTOR was developed by UKCEH as a river network model. With collaborators it can be linked with rainfall-runoff models to fully represent catchment processes.
QUESTOR is an expert system requiring specialist knowledge. UKCEH may support the use of QUESTOR as a paid service, subject to conditions. Contact the model owner.
Development of QUESTOR was funded by: UKRI-NERC National Capability; NERC research programmes (LOIS, RELU, Pollcurb); River Thames flood relief scheme modelling (Binnies/EA); and China wetland diversion (Chinese private sector).
QUESTOR is used by UKCEH researchers, and with other users for collaborative projects.