Climate change impacts on water availability in three Mediterranean watersheds of Catalonia (NE Spain) Diana Pascual, Eduard Pla (CREAF) 2011 International SWAT Conference
INDEX 1.The project 2.Background 3.Data and methods 4.Results 5.Discussion and conclusions
The project MAIN AIMS: Assess territorial vulnerability of three diverse Mediterranean watersheds in Catalonia with regard to the main effects of global change on water availability Define possible adaptive options based on the assessment of territorial and social vulnerability The project has been developed during three years by four different research institutions with an interdisciplinary approach.
Study areas Siurana Fluvià Tordera Barcelona Study areas are three medium size watersheds: Fluvià (977 mm, 13 ºC) Tordera (819 mm, 14 ºC) Siurana (589 mm, 13 ºC)
INDEX 1.The project 2.Background 3.Data and methods 4.Results 5.Discussion and conclusions
Background Mediterranean basin might become one of the most vulnerable areas in Europe regarding climate change at the end of the Century Winter Summer Mediterranean basin might suffer a significant decrease in runoff at the end of the Century. Source: IPCC, Christensen et al. and Alcamo et al. 2007
1914 1919 1924 1929 1934 1939 1944 1949 1954 1959 1964 1969 1974 1979 1984 1989 1994 1999 2004 2009 Annual mean temperature (ºC) Background CLIMATE: OBSERVED TEMPERATURE TRENDS (1914-2008) 18.0 17.0 16.0 15.0 14.0 13.0 Siurana Fluvià Barcelona Tordera A 1.9 ºC temperature increase since 1979 has been monitored at the three watersheds 12.0
1915 1920 1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 Annual precipitation (mm) 1915 1920 1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 Annual precipitation (mm) Background CLIMATE: OBSERVED PRECIPITATION TRENDS 1200 1200 1000 800 1000 600 800 400 FLUVIÀ Castelló d'empúries 0,67 mm/ year FLUVIÀ Castelló d'empúries 0,67 mm/year No significant changes in annual precipitation... 200 600 0 400 200 0 Precipitation changes in March Precipitation trends in March (mm/year) from 1951-2000 Precipitation changes in March (mm/year)...but significant changes in certain months Significant area at 95% confidence level
INDEX 1.The project 2.Background 3.Data and methods 4.Results 5.Discussion and conclusions
INDEX 1.The project 2.Background 3.Data and methods 3.1. SWAT Calibration and Validation 3.2. Climate projections 4.Results 5.Discussion and conclusions
SWAT calibration and validation Model calibration: Based on stream flow series from 12 gauging stations and climatic series from 23 meteorological stations Available data: 1984-2008 (25 years) Calibration and validation: Daily time step, 3-4 years periods Objectives: simulated hydrograph similar to observed one, mean flow values and total contributions similar between simulated and measured data, Adequate values of statistics (Nash and Sutcliffe efficiency coefficient (NSE) and RMSE-observations standard deviation ratio (RSR))
SWAT calibration and validation Daily stream flow (m3/s) 300 Fluvià 200 100 0 1987 1988 1989 Daily stream flow (m3/s) 200 150 100 50 0 Tordera 1996 1997 1998 1999 Daily stream flow (m3/s) 3 Siurana 2 1 0 1991 1992 1993 Observed data SWAT simulated data Daily data
SWAT calibration and validation Monthly stream flow (m 3 /s) 70 60 50 40 30 20 10 0 Fluvià Measured data SWAT simulated data 1986 1989 1992 1995 1998 2001 2004 2007 Monthly data
INDEX 1.The project 2.Background 3.Data and methods 3.1. SWAT Calibration and Validation 3.2. Climate projections 4.Results 5.Discussion and conclusions
CO 2 atmospheric (ppm) Climate projections at global scale CO 2 emissions global scenarios (IPCC): B1, A2 1000 800 600 400 A1fi A2 B1 B2 Observed A2 B1 200 0 1900 1920 1940 1960 1980 2000 2020 2040 2060 2080 2100 Years Atmospheric and Oceanic General Circulation Model (AOGCM): ECHAM5 Dynamic downscaling (SMC): high temporal and spatial resolution (6 h and 15 km), period 2001-2100 and reference period 1971-2000 Source: IPCC (Intergovernmental Panel on Climate Change), SMC (Meteorological Service of Catalonia)
1984 1989 1994 1999 2004 2009 2014 2019 2024 2029 2034 2039 2044 2049 2054 2059 2064 2069 2074 2079 2084 2089 2094 2099 Annual precipitation (mm) Climate projections at regional scale FUTURE PRECIPITATION TRENDS FUTURE TEMPERATURE TRENDS 2000 B1 1500 Fluvià 2006-2030: -2.4 to -3% 2076-2100: -12.2 to -15.3% A2 1000 2006-2030: -7.6 to -9.6% 2076-2100: -24 to -28.3% 500 Scenario B1 Scenario A2 0 Reference Five-years running mean Reference Five-years running mean scenario B1 Five-years running mean scenario A2 Source: SMC 2010 (Meteorological Service of Catalonia)
1984 1989 1994 1999 2004 2009 2014 2019 2024 2029 2034 2039 2044 2049 2054 2059 2064 2069 2074 2079 2084 2089 2094 2099 Mean temperature (ºC) Climate projections at regional scale FUTURE PRECIPITATION TRENDS FUTURE TEMPERATURE TRENDS 20 17.5 Fluvià 2006-2030: +0.51 to +0.58 ºC 2076-2100: +2.2 to +2.3 ºC B1 15 A2 2006-2030:+0.26 to +0.47ºC 2076-2100: +3.4 to 3.6 ºC 12.5 10 Scenario B1 Scenario A2 Reference Five-years running mean Reference Five-years running mean scenario B1 Five-years running mean scenario A2 Source: SMC 2010 (Meteorological Service of Catalonia)
Precipitation spatial distribution PRECIPITATION REDUCTION AT XXI CENTURY (mm/decade) B1 A2 A2 climate scenario predicts stronger and significant reductions, specially on headwaters Source: SMC 2010 (Meteorological Service of Catalonia) Precipitation trends (mm/decade) -53 - -40-39 - -30-29 - -20-19 - -10 Significant area at a 95% confidence level
INDEX 1.The project 2.Background 3.Data and methods 4.Results 5.Discussion and conclusions
Results RELATIVE STREAM FLOW CHANGES RESPECT 1984-2008 (%) Short term (2006-2030) B1 A2 Stream flow variation at headwater -20-13 -16 % Stream flow variation at headwater -48-33 -32 % Stream flow variation at river mouth -14-9 +4 % -9-9 +5 % -14-18 -16 % Fluv Tord Siu Fluv Tord Siu Long term (2076-2100) B1 A2 Stream flow variation at river mouth -31-22 -22 % -22-25 -22 % -39-37 -33 % Generalized stream flow reduction, more severe at A2 scenario (-33 to -39 % at long term, scenario A2) Stronger reductions are expected at Fluvià headwater (-20 to -48 % at A2 scenario) Scenario B1 predicts a slight stream flow increase in Siurana basin at short term Fluv Tord Siu Fluv Tord Siu
Results STREAM FLOW SEASONAL VARIATION (FLUVIÀ) Long term (2076-2100) Stream flow variation (%) 10 0-10 -20-30 -40-50 2.5% Scenario B1 Scenario B1 Winter Spring Summer Autumn -22.0% -25.5% -36.1% -34.3% Scenario A2-40.7% -40.2% -44.7% Autumn and summer will be the most affected seasons in both scenarios by the end of the Century. Seasonal changes can affect water supply for agricultural and urban uses Stream flow variation (%) 10 0-10 -20-30 -40-50 Scenario A2 Winter Spring Summer Autumn
Results REAL EVAPOTRANSPIRATION (mm) (FLUVIÀ) 2006-2030 2076-2100 Real evapotranspiration (mm) By the end of the Century, a 14 to 25 % reduction of real evapotranspiration is expected 2006-2030 2076-2100
Results ECOLOGICAL FLOW VARIATION (FLUVIÀ) 2006-2030 2076-2100 Number days Q < Q ecologic By the end of the Century, the number of days per year with stream flow lower than ecological flow will increase (more than 90 days in A2) Increase number days Q < Q ecologic < 0 0-10 11-30 2006-2030 31-60 61-90 > 90 2076-2100
INDEX 1.The project 2.Background 3.Data and methods 4.Results 5.Discussion and conclusions
Discussion and conclusions SWAT is an appropriate tool to assess climate change impacts on Mediterranean watersheds A strong alteration on water dynamics is expected during the XXI Century: 22% to 48% reduction of stream flow, more severe in the A2 scenario than in the B1 Reductions especially severe in the wetter headwaters (Fluvià and Tordera) Autumn and summer are expected to be the most affected seasons. 14% to 25% reduction of real evapotranspiration. Greater vulnerability of wet watersheds in northern Catalonia, where present ecosystems are more sensitive to changes in environmental conditions Results highlight the strong impact of climate change on regional water resources and stress the need for incorporating these analyses into adaptive management in the Mediterranean region
Thank you! www.creaf.uab.cat/accua accua@creaf.uab.cat