Un trasvase cuestionado: El Tajo-Segura. Repercusiones socio-económicas en el sureste español e incertidumbre ante el cambio climático

Resumen:Este trabajo tiene el objetivo de analizar las repercusiones socio-económicas del Trasvase Tajo-Segura en el sureste español y las incertidumbres sobre su funcionamiento futuro debido a la reducción de recursos hídricos y una mayor frecuentación de sequías. Para ello, se han analizado estudios previos de planes hidrológicos, normativas y estudios sobre cambio climático para poder valorar los posibles efectos en el normal funcionamiento del Trasvase Tajo-Segura. También se tendrá en cuenta las nuevas normas de explotación y la apuesta por otros recursos hídricos como medidas para incrementar la resiliencia ante escenarios futuros de cambio climático.Abstract: Introduction Given the strong global socio-economic growth that have experienced developed countries during the second half of the last century, there have been numerous hydraulic actions aimed at increasing water supply to ensure the strong expansion of urban, agricultural and hydroelectric production (Tortajada, 2016). The availability of water in sufficient quantity and quality has acquired a first-rate interest in meeting urban, tourist and rural demands in territories with a natural shortage of water resources (Rico et al., 2013). In this sense, the hydraulic planning of developed countries was based initially on the so-called “old hydraulic policy” based on the construction of canals, transfers and reservoirs and, since the last decades of the 20th century, with the so-called “non-conventional sources” or “alternatives” such as the use of purified and desalinated water (Fragkou and McEvoy, 2016). In Spain, investments in hydraulic infrastructure (public and private) in the last hundred years have resulted in the construction of more than 1,200 large reservoirs, more than 20 large desalination plants and various transfers of different capacity ( Hernández-Mora et al., 2014). For example, the main water transfers in Spain (around forty) add up to a capacity of about 1,300 hm 3 /year, which represents less than 3% of the guaranteed resources, which amount to 46,000 hm 3 . Objectives and Methodology This research poses two main objectives. The first one is to analyze the socio-economic repercussions derived from the implementation of the Tagus-Segura Aqueduct (ATS) (1979) in the southeast of Spain. The second one, to analyze the future changes in the normal functioning of this hydraulic infrastructure in the future scenarios of climate change and the corrective measures and strategies carried out to mitigate their effects (proposals and alternatives). It has also been consulted on the different regulations that have a direct influence on the functioning of the ATS: Water Framework Directive (Directive 2000/60/EC); Law 10/2001, of July 5, of the National Hydrological Plan (NHP); Royal Decree-Law 2/2004, of June 18, amending the Law 10/2001, of July 5, of the National Hydrological Plan; A.G.U.A. Program (2004) (Actions for the Management and Use of Water Royal Decree Law 2/2004); Law 21/2013 of December 9, on Environmental Assessment; Royal Decree 773/2014 of 12 September (Memorandum); Law 21/2015, of July 20, of Montes; And the Tagus Hydrological Plan (Royal Decree 1/2016, of 8 January). Likewise, the estimated rainfall effects in the area of ​​study in the different reports on climate change have been analyzed (AEMET, 2017, CEDEX, 2011, IPCC, 2014). Results The participation of the ATS in the systems of supply of drinking water in high of the basin of the Segura is decisive. This work is carried out by the Commonwealth of Canals del Taibilla (MCT), which has become a key public agency for the management of water resources for urban uses in the southeast of Spain (Rico, 2016). At present, MCT has an approximate area of 12 thousand square kilometers and supplies potable water in primary network up to 79 municipalities, belonging to the provinces of Murcia, Alicante and Albacete, with a population estimated at 2.5 million inhabitants that can grow in another million more during the summer if the tourist contingent is considered. This population has had regular supply of drinking water in their homes, even during periods of intense drought, thanks to the existence of the ATS, the diversification of sources of supply, with the increasing participation of non-conventional resources and the temporary assignment of rights of water use; and to the good management carried out by the MCT and the companies in charge of the down management, have significantly increased the performance of the network. The process of the global warming that is evident in the last decades could have three direct effects on the water resources existing in the peninsular territory and, therefore, in the areas of hydrological planning analyzed, Tagus and Segura: 2. Changes in the seasonality of rainfall