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 nonconventional 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 ( Hernandez-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, 2017, 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 (MCI), 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: Reduction of precipitation and, therefore, of available water resources, accompanied by an increase in temperatures and potential evapotranspiration Changes in the seasonality of rainfall Increase in the irregularity of the rains, which would lead to an increase in extreme events (droughts and heavy rainfall events) Besides, in relation to the new operating rules (limit of 400 hm(3)) (before were in 240 hm(3)), it can be seen that, if they had been in force since 1979, the ATS had not operated on numerous occasions (1983-84, 1992-93, 1995-96, 2005-07, 2008-09 and 2015-16). This is obviously due to the fact that the new rules of exploitation are more conservative and conform to new needs and realities that are more objective and fair than the previous ones. On the other hand, if the hypothetical reduction of 7% is taken into account (reduction of the rainfall due to climate change), it can be seen how practically, this reduction would not mean a substantial change in the normal operation of the ATS, since to handle that threshold of reduction, the transfer would be closed taking into account both the currently and the hypothetical reduction volumes of 7%. In addition, during these four decades of ATS operation, there have been several cyclical episodes of drought (1980-85, 1992-95, 2004-09 and 2014-16), that is to say, conjunctural dry periods which have affected the headwater of the Tagus river every ten years. Therefore, what can be deduced from this analysis is that the operation of the ATS will be conditioned, rather than by the effects of the reduction of precipitation, by the succession of dry episodes and, evidently, by the new rules of regulation, more conservative and in favor of the donor basin. Conclusions From what can be learned from the analyzed case is that the ATS is a hydraulic infrastructure that has allowed the socio-economic development of the southeast of Spain, although it is an infrastructure questioned since its implementation in 1979 by the tensions between the donor and receiving basins. In the southeast of Spain, the commitment to desalination (National Hydrological Plan, 2001 and AGUA Program, 2004) has become a solution to increase the supply of water resources in the southeast of Spain, although they try to make this resource the solution to the long-standing controversy surrounding the ATS. It will be expected if the forecasts of climate change and reduction of contributions that have been realized on the headwater of the Tagus, where the so-called effect 80 has become evident, and how the new operating rules can influence the operation of this infrastructure. Alongside this, a greater involvement of the State, the Autonomous Communities and the different political forces could be achieved in order to achieve a National Water Pact, with measures to adapt to climate change. Within these consensus measures, the maintenance and/ or revision of existing transfers should not be ruled out, or the possibility of carrying out others of a moderate size that could function from the normative development of articles 67 to 72 of TRLA.
Seguido, AFM; Cantos, JO; Amorós, AMR
A questioned transfer: The Tagus-Segura. Socio-economic repercussions in Spanish southeast and uncertainty regarding climate change
Revista De Estudios Regionales