Global change effects on a Mediterranean river flow in NE Spain

1. Global change effects on a Mediterranean river flow in NE Spain EDUARD PLA1, DIANA PASCUAL1, JOAN A. LOPEZ-BUSTINS2, ROBERT SAVÉ3, CARMEN BIEL3, JOAN SERRA3, ROGER MILEGO4, KARIM TAMOH5 1CREAF (Centre for Ecological Research and Forestry Applications) – Autonomous University of Barcelona – 08193 Bellaterra 2GC-UB (Group of Climatology – University of Barcelona) – 08001 Barcelona 3DHA-IRTA (Departament d’Horticultura Ambiental – Institut de Recerca i tecnologia Agroalimentàries) – Torre Marimon – 08140 Caldes de Montbui 4ETC-LUSI (European Topic Centre – Land Use and Spatial Information) – Autonomous University of Barcelona – 08193 Bellaterra 5GHS-UPC (Grup d’Hidrologia Subterrània – Universitat Politència de Catalunya) – 08034 Barcelona Study area Introduction el Fluvià 977 mm • 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). 13 ºC Climatic conditions. Spatial distribution of the mean annual precipitation (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. Fluvià catchment: Located in NE Spain, the Fluvià catchment presents a high internal diversity of climatic conditions and land uses. The rainy headwater contrasts with the less humid conditions of the coastal alluvial plain. There are protected natural areas. Population pressure is also important in the coastline. Vall d’en Bas subbasin is the Fluvià catchment headwater. 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). Observed trends Next steps OBSERVED TRENDS + GCMs PROJECTIONS OBSERVED TRENDS + LAND CHANGE MODELLING CLIMATE CHANGE SCENARIOS LAND USE CHANGE SCENARIOS In further research we will analyze the contribution of each factor in water dynamics in order to define adaptive strategies. Firstly, we will generate climate change scenarios based on climatic trends and projections. Secondly, we will create land use change scenarios by means of observed trends and socioeconomic variables. Finally, both scenarios will be integrated in a Basin Model, which interacts also with specific models for forest areas and agriculture. BASIN MODELLING INTEGRATION MODEL FOREST MODEL GOTILWA+ CROP MODEL OF WATER USE We have not detected a significant decrease on rainfall values (which remained relatively stable). We have registered a 60%-reduction of river flow during the period 1984-2008. 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. 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.cator visit our website www.creaf.uab.cat/accua We have detected significant land use changes for the studied period: 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).