Reconstruction and homogenization of some water ...Reconstruction and homogenization of some water...
Transcript of Reconstruction and homogenization of some water ...Reconstruction and homogenization of some water...
Reconstruction and homogenization of some water temperature series in the Ebro River basin
Jordi Prats ([email protected]), Rafael Val,Marina Arbat-Bofill, Josep Dolz
Why water temperature?
An increase in water temperature can affect river biota in different ways:
● Species distribution: local extinctions, colonization by exogenous species...
● Life cycles: acceleration of life cycles, change in the number of life cycles per year...
● Metabolism: more intense metabolism, shorter life expectancy...
● Behaviour: more aggressive behaviour in some species of fish...
The study
Objectives:– To obtain long term annual water temperature
series at different points of the Ebro basin
– To analyse the river water temperature trends
Study cases– Case I: Ebro at Escatrón, (Sástago); 1949 – 2000
→ Prats et al. (2007)
– Case II: Ebro at Mequinenza, Cinca at Fraga; 1980 – 2010.
Case I: data usedOrigin of the data Period Type of
measurementEstimator of mean annual temperature
Thermal power plant of Escatrón (Arrúe & Alberto, 1986)
1949-1977 Daily Max & Min
Annual average of (Max+Min)/2
Thermal power plant of Escatrón
1996-2000 Daily temp. at 9 a.m.
Average
Confederación Hidrográfica del Ebro (Sástago)
1975-2003 Monthly (variable hour, variable day of month)
Average
Val (2003) 1998-1999 Continuous(10 min)
Average
Case I: bias analysis
Analysis of bias for each type of estimator of annual water temperature through a resampling method:
– Av. of max/min → no bias
– Daily, 9h → -0.3 ºC
– Monthly → bias depending on average hour of measurement
Case I: water temperature trend
0.05 ºC/yr (1955 - 2000)
Case II: data usedOrigin of the data Period Type of
measurementEstimator of mean annual temperature
Confederación Hidrográfica del Ebro (Mequinenza, Fraga)
1980-2010 Monthly (variable hour, variable day of month)
Average
Val (2003) (Mequinenza, Fraga)
1998-1999 Continuous(10 min)
Average
Case II: bias correction
Correction in function of the day of the month and hour of measurement
Case II: water temperature trends
● Bias correction can make a difference● In 1981 – 1995 water temperature at Fraga was measured around 10 – 11 a.m. → bias of -0.8 ºC
● In 1996 – 2010 water temperature at Fraga was measured between noon and 3 p.m. → bias of 0.1 ºC
Temperature trends in world rivers
River (country)
Period Trend (ºC/yr)
Loire (France) 1881 - 2003 0.0008
Danube (Austria)
1901 - 2000 0.0014-0.0017
Danube (Croatia)
1948 - 2005 0.0-0.06
Danube (Austria)
1951 - 2003 0.001
Loire (France) 1976 - 2003 0.06-0.07
Saône (France)
1977 - 2002 0.02-0.07
Rhône (France)
1979 - 1999 0.05
Ebro (Spain) 1954 - 2000 0.05
Ebro (Spain) 1980 - 2010 0.06
Cinca (Spain) 1980 - 2010 0.04
Possible causes:– Climate change
– Thermal discharges
– Reduction in discharge
Sou
rce:
mod
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fro
m W
WF
(20
09)
Thanks for your attention!