I.S.RIVERS
LYON 2018
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Material & methods
140 stations (1obs./10min) / 2012 – 2016
Drainage area: 60% of study area
Wallonia (Southern Belgium): 16.000 km²
Non navigable rivers of Wallonia (< 1km²)
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Introduction
Context
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« Water temperature: the ecological master factor »
J.R. Brett (1971)
1•
How to effectively monitor water temperature?
- Water temperature monitoring network (e.g. water framework monitoring)
- Potential of ancillary data source like gauging network?
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How can river managers take into account water
temperature (e.g. riparian shade management)?
USING GAUGING NETWORK FOR REGIONAL MONITORING OF
STREAM WATER TEMPERATURE (WALLONIA, BELGIUM)
Utilisation d’un réseau de stations de jaugeage pour le monitoring
régional de la température des cours d’eau (Wallonie, Belgique)
Blandine Georges
1, Hervé Piégay
2, Léo Huylenbroeck
1, Philippe Lejeune
1, Yves Brostaux
1, Adrien Michez
1(1)Faculty of Gembloux Agro-bio Tech (ULiège) (TERRA research and teaching center), Passage des Déportés 2, 5030 Gembloux, Belgium (2)University of Lyon, UMR 5600 CNRS EVS, Site ENS de Lyon, 15 Parvis René Descartes, F- 69342 Lyon, France
» Hot thermal episode = percentile 95 temperature of the 7 hottest days » 4 variables most correlated with hot thermal episode
» Riparian shade explains a large part of the hot thermal variability: 21%
0,04
0,21
0,01 0,00 0,00
0,00
What about temperature for Salmo trutta fario ?
» Exceedances occur between May and September
» Max 25 days/month above thermal preferendum
» Lethal temperature only occured in 2015
Thermal preferendum : 19°C Lethal temperature : 25°C
(Only for brown trout stations)
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Results and discussion
A.
Gauging network for temperature monitoring?
C.
Which environmental parameters most influence
annual hot thermal episode?
Objectives
A.
Evaluate the potential of gauging network for stream
water temperature monitoring
B.
Characterize the thermal regime at the river network
scale, focusing on the thermal requirements of the brown
trout (Salmo trutta fario)
C.
Quantify the impact of environmental parameters on
water hot thermal episode
» Continuous temperature data from the gauging network can be used and are relevant for water temperature
monitoring
» The difference between the
measurements of the two networks is not to a temporal drift, the river size, the elevation
B.
Characterization of stream water temperature
Elevation
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Perspectives
Improve understanding of environmental parameters (land cover, shade, slope, air temperature…) that regulate stream water temperature
Use infrared thermal images acquired from drones to have spatially continuous mapping of stream water temperatures (for a hot thermal episode)
Develop decision making tools for river managers (e.g.: define target river reaches for riparian forest restoration)% of the hot thermal
variability explained by a single variable or shared by two or more variables
Fish zones Monitoring network (gauging network)
1Brett J.R., 1971. Energetic responses of salmon to temperature. A study of some thermal relations in the physiology and freshwater ecology of sockeye salmon (Oncorhynchusnerka). Amer Zool 11:99–113.
» Sinusoïdal trend
» 0.1°C (7/02/2015) to 29.9°C (4/07/2015) » Important daily variability over the network » Intra-year thermal variability
Max Median Min
Riparian shade (1km upstream the station) Agricultural area
Artificial area Forest area
