1. Global change effects on a Mediterranean river flow in NE Spain EDUARD PLA 1, DIANA PASCUAL 1, JOAN ALBERT LÓPEZ BUSTINS 2, ROBERT SAVÉ 3, CARMEN BIEL 3, JOAN SERRA 3, ROGER MILEGO 4, KARIM TAMOH 5 1 CREAF (Centre for Ecological Research and Forestry Applications) – Autonomous University of Barcelona – 08193 Bellaterra 2 GC-UB (Group of Climatology – University of Barcelona (UB) – 08001 Barcelona 3 DHA-IRTA (Departament d’Horticultura Ambiental – Institut de Recerca i tecnologia Agroalimentàries) – Torre Marimon – 08140 Caldes de Montbui 4 ETC-LUSI (European Topic Centre – Land Use and Spatial Information) – Autonomous University of Barcelona – 08193 Bellaterra 5 GHS-UPC (Grup d’Hidrologia Subterrània – Universitat Politència de Catalunya) – 08034 Barcelona Study area Observed trendsNext steps Getting to know ACCUA project The interdisciplinary ACCUA project (2008-2011) attempts to identify the main vulnerabilities that affect these systems and propose some adaptation measures at local scale (Catalonia, NE Iberian Peninsula). The main objectives are (1) to establish land vulnerabilities according to water availability and (2) to propose adaptations addressed to overcome these vulnerabilities. And finally, to suggest recommendations on how to optimize future water uses. ACCUA project is founded by Obra Social Caixa Catalunya. For further information please do not hesitate to contact us at accua@creaf.uab.cat or visit our website www.creaf.uab.cat/accua accua@creaf.uab.catwww.creaf.uab.cat/accua Introduction Climate change is generally accepted as a factor influencing hydrological cycles worldwide. However, these cycles are also affected by other phenomena: -natural (geomorphological and ecosystem changes, natural climate variations, etc) -human-related (changes of agro-forest uses, developments and settlements, changes on social dynamics, etc). Within the ACCUA project framework, we have analyzed the historical trends in water balances in a small subbasin in a Mediterranean river (Catalonia, NE Spain). Fluvià river: Located between the Catalan regions of Garrotxa, Pla de l'Estany and Alt Empordà, the Fluvià catchment presents a high internal diversity of climatic conditions and land uses. The rainy head waters contrasts with the conditions of the coastal alluvial plain. There are protected natural areas. Population pressure is also important in the coastal strip. dry Catalonia wet Catalonia el Fluvià 977 mm 13 ºC Climatic conditions. Spatial distribution of the annual precipitation mean (1951-1999) for the Fluvià catchment according to the Digital Climatic Atlas of Catalonia (Unitat de Botànica and Departament de Geografia in the Autonomous University of Barcelona). The annual precipitation and temperature mean for the whole catchment is also shown. Vall d’en Bas subbasin is the headwater of the Fluvià River. The subbasin area is 13 428 ha, mostly forested (62%) with an important agricultural activity (27%). There is a meteorological station (AEMET) and a gauging station at the end of the subbasin (ACA). We have registered a 60%-reduction of river flow during the period 1984-2008. We have not detected a significant decrease on rainfall values (which remained relatively stable). We have measured an increase of 10% in mean annual temperature (+1.2 ºC) Consequently we have calculated a significant 9%-increment in ETP. This ETP increase could partially explain the reduction of surface water flow in the headwater of the Fluvià River. However, we conclude that there might be other reasons behind this flow decrease, such as modifications on forest and agricultural practices during the recent decades. We have detected significant land use changes for the period studied: rural abandonment and consequent natural colonization by forest species, reduction of forest management practices, increase of water demand (i.e., increase of irrigated crops, industry development and diffuse housing spreading). In further research we will analyze the contribution of each factor in water dynamics in order to define adaptive strategies. Using scenario modelling, on the one hand, we have the trends and climatic projections that help to build the climate change scenarios. On the other hand, land use changes scenarios are also created by means of observed trends and socioeconomic variables. To integrate everything we use a Basin Model, which interacts also with specific models for forest areas and agriculture. INTEGRATION MODEL CLIMATE CHANGE SCENARIOS LAND USE CHANGE SCENARIOS FOREST MODEL GOTILWA+ CROP MODEL OF WATER USE OBSERVED TRENDS + LAND CHANGE MODELLING OBSERVED TRENDS + GCMs PROJECTIONS BASIN MODELLING