Climate change impacts on water availability in three Mediterranean watersheds of Catalonia (NE Spain) Diana Pascual, Eduard Pla (CREAF) Roger Milego (ETC-SIA) SCARCE 2nd annual 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. 27
Background CLIMATE: OBSERVED TEMPERATURE TRENDS (1914-28) 18. Annual mean temperature (ºC) 17. 16. 15. 14. 13. Siurana Fluvià A 1.9 ºC temperature increase since 1979 has been monitored at the three watersheds 12. 1914 1919 1924 1929 1934 1939 1944 1949 1954 1959 1964 1969 1974 1979 1984 1989 1994 1999 24 Barcelona Tordera 29 Background Annual precipitation (mm) Annual precipitation (mm) CLIMATE: OBSERVED PRECIPITATION TRENDS 12 1 12 8 1 6 4 8 2 6 4 2 FLUVIÀ Castelló d'empúries,67 mm/ year FLUVIÀ Castelló d'empúries,67 mm/year 1915 192 1925 193 1935 194 1945 195 1955 196 1965 197 1975 198 1985 199 1915 192 1925 193 1935 194 1945 195 1955 196 1965 197 1975 198 1985 199 No significant changes in annual precipitation... Precipitation changes in March Precipitation trends in March (mm/year) from 1951-2 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 3.3. Socioeconomics scenarios 4.Results 5.Discussion and conclusions
SWAT model Water balance model Distributed and continuous hydrological model coupled to a GIS interface SWAT estimates superficial and sub-superficial flow, aquifers recharge, erosion, sediments deposition and movement, SWAT calibration and validation Model calibration: Based on stream flow series from 12 gauging stations and climatic series from 23 meteorological stations Available data: 1984-28 (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) 3 Fluvià 2 1 1987 1988 1989 Daily stream flow (m3/s) 2 Tordera 15 1 5 1996 1997 1998 1999 Daily stream flow (m3/s) 3 Siurana 2 1 1991 1992 1993 Observed data SWAT simulated data Daily data SWAT calibration and validation Monthly stream flow (m 3 /s) 7 Fluvià 6 Measured data SWAT simulated data 5 4 3 2 1 1986 1989 1992 1995 1998 21 24 27 Monthly data
INDEX 1.The project 2.Background 3.Data and methods 3.1. SWAT Calibration and Validation 3.2. Climate projections 3.3. Socioeconomics scenarios 4.Results 5.Discussion and conclusions Climate projections at global scale CO 2 emissions global scenarios (IPCC): B1, A2 CO 2 atmospheric (ppm) 1 8 6 4 2 A1fi A2 B1 B2 Observed 19 192 194 196 198 2 22 24 26 28 21 Years A2 B1 Atmospheric and Oceanic General Circulation Model (AOGCM): ECHAM5 Dynamic downscaling (SMC): high temporal and spatial resolution (6 h and 15 km), period 21-21 and reference period 1971-2 Source: IPCC (Intergovernmental Panel on Climate Change), SMC (Meteorological Service of Catalonia)
Climate projections at regional scale FUTURE PRECIPITATION TRENDS Annual precipitation (mm) FUTURE TEMPERATURE TRENDS 2 15 1 5 Fluvià 26-23: -2.4 to -3% 276-21: -12.2 to -15.3% B1 26-23: -7.6 to -9.6% 276-21: -24 to -28.3% A2 Scenario A2 Reference Five-years running mean Reference 1984 1989 1994 1999 24 29 214 219 224 229 234 239 244 249 254 259 264 269 274 279 284 289 294 299 Scenario B1 Five-years running mean scenario B1 Five-years running mean scenario A2 Source: SMC 21 (Meteorological Service of Catalonia) Climate projections at regional scale FUTURE PRECIPITATION TRENDS FUTURE TEMPERATURE TRENDS 2 Mean temperature (ºC) 17.5 15 12.5 1 Fluvià 26-23: +.51 to +.58 ºC 276-21: +2.2 to +2.3 ºC A2 1984 1989 1994 1999 24 29 214 219 224 229 234 239 244 249 254 259 264 269 274 279 284 289 294 299 B1 26-23:+.26 to +.47ºC 276-21: +3.4 to 3.6 ºC Scenario B1 Scenario A2 Reference Five-years running mean Reference Five-years running mean scenario B1 Five-years running mean scenario A2 Source: SMC 21 (Meteorological Service of Catalonia)
Precipitation spatial distribution PRECIPITATION REDUCTION AT XXI CENTURY (mm/decade) A2 climate scenario predicts stronger and significant reductions, specially on headwaters Source: SMC 21 (Meteorological Service of Catalonia) Precipitation trends (mm/decade) -53 - -4-39 - -3-29 - -2-19 - -1 Significant area at a 95% confidence level INDEX 1.The project 2.Background 3.Data and methods 3.1. SWAT Calibration and Validation 3.2. Climate projections 3.3. Socioeconomics scenarios 4.Results 5.Discussion and conclusions
SUSTAINABLE SCENARIO TRENDING SCENARIO Socioeconomic scenarios How will the territory be in 23...?... IF WE DEVELOP ADAPTIVE MEASURES? Socioeconomic background Moderate economic growth Moderate population growth Containment of energy consumption Population (thousands of people) Water demand (hm3/year) Population (thousands of people) P Water demand (hm3/year)... IF WE PROJECT THE TRENDS FROM THE PAST 2 YEARS? Socioeconomic background Fast economic growth Fast population growth Intensive use of fossil fuels Globalisation Source: ACCUA from ACA and IDESCAT data Socioeconomic scenarios Land cover scenarios for 23 Land Change Modeler (Idrisi) land cover change analysis and prediction software
Socioeconomic scenarios Land cover scenarios for 23 ACCUA scenarios SCENARIO CATALONIA 23: TRENDING SCENARIO SUSTAINABLE SCENARIO Land cover scenarios 23 Vulnerability of main agricultural classes Main land cover flows Land Change Modeler Extension - IDRISI Urban sprawl Analysis and prediction of changes. Analysis of change explanatory variables. sostenible Socioeconomic scenarios Land cover scenarios for 23 Trending Sustainable Fluvià Tordera Siurana
INDEX 1.The project 2.Background 3.Data and methods 4.Results 5.Discussion and conclusions Results at short term (26-23) RELATIVE STREAM FLOW CHANGES RESPECT 1984-28 (%) Stream flow variation at headwater - 8-5 + 9 % -11-5 +11 % -2-11 -11 % -2-11 -1 % Fluv Tord Siu Stream flow variation at river mouth - 5-3 - 4 % - 5-2 - 8 % -13-15 -25 % -13-14 -29 % Fluv Tord Siu Generalized stream flow reduction, more severe at A2 scenario (- 2 to -29 %) Fluvià and Tordera: Differences between socioeconomics scenarios are not relevant Strong effect of forest in water balance Siurana: The increase of the water demands (irrigation) amplify the effects of climate change. In Fluvià watershed, the highest reductions are expected in the headwater.
Results at long term (276-21) RELATIVE STREAM FLOW CHANGES RESPECT 1984-28 (%) Stream flow variation at headwater -48-33 -32 % Stream flow variation at river mouth -31-22 -22 % -22-25 -22 % -39-37 -33 % Fluv Tord Siu Fluv Tord Siu Generalized stream flow reduction, more severe at A2 scenario (-33 to -48 %) Stronger reductions are expected at Fluvià headwater (-31 to -48 %) Results ECOLOGICAL FLOW VARIATION (FLUVIÀ) 26-23 276-21 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 9 days in A2) Increase number days Q < Q ecologic < - 1 11-3 26-23 31-6 61-9 > 9 276-21
Results CHANGES IN CLIMATIC DISTRIBUTION OF FOREST SPECIES Beech at Fluvià Oak at Tordera 1984-28 26-23 276-21 Species from humid areas (beech, oak, scots pine) trend to marginal conditions. 1984-28 26-23 276-21 Holm oak at Siurana 1984-28 26-23 276-21 These same species in currently marginal areas may be compromised their viability. Sclerophylls and evergreen species (Holm oak, Aleppo pine) extend their suitability to higher areas Unsuitable Marginal Source: BIOCLIM model Suitable Results FIRE RISK (DROUGHT CODE. CANADIAN METEREOLOGIC INDEX) Number of days / year with DC > 8 (EXTREM RISK) Number of days/year DC>8 1984-28 26-23 276-21 Number of days/year DC>8 1984-28 26-23 276-21 1984-28 26-23 276-21 Number of days/year DC>8 Risk fire increase may aggravate forest vulnerability
16 14 12 1 8 6 4 2 16 14 12 1 8 6 4 2 Results IRRIGATION REQUERIMENTS FOR CORN IN FLUVIÀ LLEGENDA 28 23 Necessitatsde reg per mesos (mm) Irrigation requirements (mm/month) Juny June Juliol July Agost August Setembre September October Octubre 276 21 Irrigation requirements LLEGENDA (mm/month) Necessitatsde reg per mesos (mm) June Juny July August Juliol September Agost October Setembre Octubre Irrigation requirements in some actual crops, which are rarely or not currently irrigated, may be highly increased at the end of the XXI Century. Source: IRTA INDEX 1.The project 2.Background 3.Data and methods 4.Results 5.Discussion and conclusions
Discussion and conclusions 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) Socioeconomic scenarios for 23 did not show contrasted differences, except in Siurana watershed where the full development of the Catalan Irrigation Plan affects water availability. 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