TITLE:
Predicting Hourly Stream Temperatures Using the Equilibrium Temperature Model
AUTHORS:
Cindie Hébert, Daniel Caissie, Mysore G. Satish, Nassir El-Jabi
KEYWORDS:
Stream Temperature, Modeling, Equilibrium Temperature
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.7 No.4,
March
13,
2015
ABSTRACT: Water
temperature is a key physical habitat determinant in lotic ecosystems as it
influences many physical, chemical and biological properties of rivers. Hence,
a good understanding of the thermal regime of rivers is essential for effective
management of water and fisheries resources. This study deals with the modeling
of hourly stream water temperature using the equilibrium temperature model.
This water temperature model was applied on two thermally different
watercourses, namely, the Little Southwest Miramichi River (LSWM) and Catamaran
Brook (CatBk; New Brunswick). The equilibrium temperature model is a simplified
version of a deterministic model. As such, in the equilibrium temperature model
the total heat flux at the surface is assumed proportional to the difference
between the water temperature and an equilibrium temperature. In the present
study, the equilibrium temperature was assumed to vary linearly with hourly air
temperature. This study showed that there was a good relationship between the
equilibrium and air temperature at the hourly time scale. The root-mean-square
error (RMSE) obtained with the hourly equilibrium temperature model was similar
to results reported in previous studies with values of 1.05°C (CatBk)
and 1.36°C (LSWM). The model’s performance was best in late summer and
autumn when water levels were low. In contrast, the presence of snowmelt in the
spring resulted in poorer performances. This study also showed good results in
estimating the daily mean (Tmean)
and maximum (Tmax) water
temperatures from the predicted hourly water temperatures, which were often required
in fishery management.