Modelling in-stream temperature and dissolved oxygen at sub-daily time steps: An application to the River Kennet, UK

Abstract

The River Kennet in Southern England shows a clear diurnal signal in both temperature and dissolved oxygen concentrations through the summer months. The water quality model QUESTOR was applied in a stepwise manner (adding modelled processes or additional data) in order to simulate the flow, temperature and dissolved oxygen concentrations along a 14 km reach. The aim of the stepwise model building was to find the simplest process-based model which simulated the observed behaviour accurately. The upstream boundary used was a diurnal signal of hourly measurements of temperature and dissolved oxygen. In the initial simulations, the amplitude of the signal quickly reduced to zero as it was routed through the model; a behaviour not seen in the observed data. In order to keep the correct timing and amplitude of temperature a heating term had to be introduced into the model. For dissolved oxygen, primary production from macrophytes was introduced to better simulate the oxygen pattern. Following the modifications an excellent simulation of both temperature and dissolved oxygen was possible at an hourly resolution. It is interesting to note that it was not necessary to include nutrient limitation to the primary production model. The resulting model is not sufficiently proven to support river management but suggests that the approach has some validity and merits further development.

Time-series analyses of water temperature and dissolved oxygen concentration in Lake Valkea-Kotinen (Finland) during ice season

“…Dissolved oxygen (DO) is one of the main parameters used to assess the quality of lake water (Terzhevik et al, 2009) and it provides a useful index of the health of lakes (Correa-González et al, 2014;Williams and Boorman, 2012). In ice-covered lakes, DO is a crucial ecological parameter and a sensitive indicator of physical transport processes while the water body is isolated from the atmosphere.…”

Nocturnal river water temperatures: Spatial and temporal variations

“…Night-time water temperatures influence the behaviour, distribution, refuge use and phenology of cold-blooded organisms (Williams and Boorman, 2012), as well as the metabolism of whole rivers (Demars et al, 2011) (Table 1). For example, timing of feeding in juvenile Atlantic salmon (Salmo salar) depends on Tw, with fish feeding preferentially at night when Tw falls below 10 °C (Fraser et al 1993).…”

“…However, such statistics mask sub-daily variations in Tw that are biologically significant (see below) or misrepresent 'true' Tw through biased sampling. For instance, Everall et al (2014) show how systematic 15 minute sampling of Tw throughout day and night yields an annual mean Tw estimate for the River Dove that is ~1 °C cooler than the mean of monthly spot samples taken only during daylight hours.Night-time water temperatures influence the behaviour, distribution, refuge use and phenology of cold-blooded organisms (Williams and Boorman, 2012), as well as the metabolism of whole rivers (Demars et al, 2011) (Table 1). For example, timing of feeding in juvenile Atlantic salmon (Salmo salar) depends on Tw, with fish feeding preferentially at night when Tw falls below 10 °C (Fraser et al 1993).…”

A Time Series Model Comparison for Monitoring and Forecasting Water Quality Variables

“…Among the most important parameter is the dissolved oxygen concentration as an indicator of river health, which is used by regulators as part of the classification for good chemical status [25]. This parameter directly indicates the status of an aquatic ecosystem and its ability to sustain aquatic life.…”