Estimación del Impacto del Cambio Global sobre el Riesgo de Sequía en el Sureste de Españaevaluación y Pronóstico sobre los Recursos Hídricos y el Uso del Agua

Resumen

Segura Hydrographic Demarcation and Commonwealth of Taibilla Channels, located in the southeast of the Iberian Peninsula, are characterized by irregular and scarce rainfall, being the only European hydrographic demarcation with an average rainfall of less than 450 mm. Therefore, this territory has a structural rainfall shortage, which results in an almost permanent water deficit. In addition to the climatic conditions, the high population density of this geographical area means that meteorological and hydrological droughts are a serious socio-economic problem. There are signs of adaptation to droughts by all the civilizations that have occupied the geographical space of south-eastern Spain. At present, the Commonwealth of Taibilla Channels, created in 1927, allows the supply of drinking water to a total of 80 municipalities distributed between the provinces of Murcia, Alicante and Albacete. Throughout its history, this body has suffered two major periods of shortage of water resources, which triggered the implementation of other major water supply infrastructures in south-eastern Spain. The first took place in the 1960s and led to the approval of the Tagus-Segura Transfer, which finally came into operation in 1979. The arrival of exogenous resources from the Tagus headwaters led to an exponential growth in the irrigated area, which caused a notable increase in the average water deficit of the Segura Hydrographic Demarcation. Subsequently, at the end of the 20th century, the second major deficit period occurred, which triggered the drive for desalination through the construction of a series of desalination plants along the entire Spanish Mediterranean coast. In recent years, desalination is becoming an ordinary source and a substitute for transfers from the Tagus-Segura Transfer. Given the decrease in rainfall expected in the different climate change scenarios, this non-conventional resource must become a strategic resource in the area of study, especially during drought situations. The main objective of this research is to evaluate the impact of the global on the risk of drought in the Segura Hydrographic Demarcation and in the Commonwealth of Taibilla Channels. To this end, apart from analyzing current water management policies and practices, an exhaustive evaluation has been carried out of the trends and changes observed in rainfall and dry rainfall sequences, both for the longest local series of rainfall and for the regionalized series. The territorial regionalization has been carried out with the principal component analysis method, and both in the regionalization of rainfall on a monthly scale and in the regionalization of droughts, a total of four homogeneous regions have been obtained. The results obtained reflect that the regions of the headwaters of the Segura and Mundo, and the coastal strip and pre-coastal valleys, are the ones that present the most marked changes, with a significant decrease in rainfall and an intensification of drought periods since the second half of the S.XX. In addition, it has been shown that the increase in temperatures has a notable influence on the increase in the intensity of droughts and that the coastal strip and pre-coastal valleys are the areas that present the greatest vulnerability to drought. In short, this thesis proposes a series of methodologies and tools aimed at reducing vulnerability and exposure to droughts. The measures implemented should always be articulated within the framework of Land Management, as this is the most effective tool for mitigating the socio-economic and territorial consequences and repercussions of droughts.