Background on the change in the origins of the transfer (TTS)

Many initiatives, projects and works have occurred throughout history in order to transfer water to the driest region, the Iberian Peninsula, in southeast Spain. Water scarcity forces its residents to bring water to these lands from those places where there is a surplus of water flows. Since ancient times, the people of Vinalopó have turned to the waters of Segura and Júcar. Water from the Guadalentín and Almanzora basins were initially diverted to the Caravaca springs (Segura River Basin), and then to other rivers such as Castril and Guardal (tributaries of the Guadiana Menor in the Guadalquivir Basin). Kings and governments of all times have worried about these water transfers, to which they have dedicated money and the energies of their best trained men (^{ACHS, 1942}).

In the modern era, in the time of Charles V and Philip II, wars did not allow the development of projects to bring water from Castril and Guardal, as part of the large projects of hydraulic interconnection of the rivers of the Iberian Peninsula. Works were started, but they were interrupted, such as in 1540 because of the wars with the Protestants, in 1566 due to the Moorish Rebellion, and in 1573 with the expedition to England (the Invincible Armada).

In 1568, Hernán Pérez de Herrera sent a letter to Felipe II in which he pointed out that the solution to the water shortage would be to bring water to Lorca from Archivel, Venablón, Singla, Barranda, Caneja, Naviales and the Eyes of Archivel, places near Caravaca. In 1574, Álvaro Rodríguez de Maderuela proposed to the king a more ambitious project, the transfer from the Castril and Guardal, tributaries of the Guadiana Menor (^{Mula, Hernández, & Gris, 1986}:35).

The Royal Certificate by Felipe IV on October 15, 1733 put Don Gregorio Lopez Madera in charge of the management of the infrastructure to bring water to the area. Technical errors and a shortage of flows forced the suspension of the works as they reached Sierra de Almorox. In the times of Felipe V, the Document of January 15, 1742 gave the responsibility for the study of the conduction to Lorca from the Castril and Guardal rivers to Lieutenant Colonel Don Sebastián Ferignan y Cortés. He took the first measurements of the Castril and Guardal in June 1742, finding a flow of 2.2 m³/s and 1.4 m³/s, respectively. He levelled over 400 km and explained the project "in more than one ‘arroba’ of paper." Many years later, in 1928, geological studies, measurement campaigns, etc. were carried out to beat Ferignán's study (^{Bautista & Muñoz, 1986}:48).

Figure 1 Old Murcia Channel excavation (1776-1785). 

The attempted works on the channel to Lorca and the financial failure of the Prádez and Company led to Carlos III cancelling the concession to Prádez on September4 September, 1776 (Royal Document decreed in San Idelfonso). By means of that Royal Certificate, another company was formed under royal auspices, the Royal Murcia Channel Company. The new company kept Boizot as the director of the works, the cost of which was borne by post office rents and also by the prices of alcohol, and barrel taxes, soda and esparto. The works were finally started and, until 1780, a lot of activity was accomplished, with the opening of roughly 27 km of the channel, with some interruptions (Figure 1). High costs led to the Royal Order of March 24, 1778, which eliminated navigation and restricted the channel to irrigation uses. The Royal Decree of February, 11 1785 dissolved the Royal Murcia Channel Company and ordered the construction of the Puentes and Valdeinfierno dams (^{Gil, 2017}:53).

In October 1932, Martín Navarro Flores returned to the province of Almería and, accompanied by engineers Manuel Lorenzo Pardo and Clemente Sáenz García, moved to the Hijate slope, where they considered it feasible to transport the flows to the Almanzora basin (^{Fernández, 2006}:294). On this trip, it seems that these engineers also thought of supplying these lands with water from other basins, such as the Guadiana and Tajo (^{Flores, 2004}:191-192). The trip by Lorenzo Pardo and Clemente Saenz through southeast Spain allowed them to get in touch with the people of the Bajo Almanzora, Lorca and Cartagena fields, and to understand the urgent need to bring waters from other basins to these parched lands to avoid misery and stop emigration. "An invitation led Lorenzo, on October 24, 1932 through the lands of Cartagena and Almanzora, we accompanied him ... Three or four days later, back in Madrid on Alicante roads and inside the car, we commented on what we had contemplated with pain" (^{Sáenz, 1971}:239-247). That made Lorenzo Pardo design a new hydraulic policy that would take better care of the southeast. He criticized the Hydraulic Works Plan of 1902 and designed the Hydraulic Works Plan of 1933, which included a study of the country's hydrological imbalance and measures to correct it, such as the Plan for the Improvement and Extension of Irrigation of Levante.

The solution of a transfer to the southeast had its origins at the headwaters of the Tajo, crossing the headwaters of the Guadiana, and with the possibility of connecting with the Júcar through the Alarcón reservoir, to get the waters of these three basins to the Talave reservoir in the Segura Basin (^{Torres, 1961}: 37-38). The Plan for the Improvement and Extension of Irrigation in Levante planned to transfer water from the headwaters of the Tajo and the Guadiana, together with surpluses from Mijares, Turia, Júcar and Segura, in order to reach a total volume of 2297.160 hm³/year to irrigate the 338 000 ha in the provinces of Almeria, Murcia, Alicante, Valencia, Albacete and Cuenca (^{Flores, 2004}:192).

Another proposal came from Félix de Los Ríos in 1933, when reporting on the Hydraulic Works Plan, who had already indicated the possibility of transferring waters to Levante from the Ebro River. This proposal was made in 1937, and was composed of two separate parts: one, to transfer waters from the Ebro to the Turia and, the other one, transfer and successive compensation until reaching the fields of Cartagena and Almanzora (^{Torres, 1961}:40-41).

The General Plan of Public Works of 1940 introduced three basic concepts or guidelines for water resources planning at the national level: 1. integral regulation of own resources in the deficit basins prior to the planning of the water transfers; 2. improvement of the management of the hydraulic availabilities in the deficit areas to reduce contributions from the abundant basins as much as possible; 3. use only surplus flows from the abundant basins in deficit basins. The Plan mentions "maximum interest" in the resumption of the studies on the transfer from the Castril and Guardal rivers for the purpose of improving irrigation in Lorca and Almanzora, in order to finally decide if it is an acceptable solution or reject it.

A Ministerial Order on September 25, 1941 appointed the engineers who were to give an opinion on this work to carry out the following tasks: a) compilation of all the projects and pre-projects drafted for the aforementioned purpose, as well as measurement data of the Castril and Guardal rivers; b) study of the hydraulic needs for irrigation in the basins of the rivers mentioned, and as a consequence, the amount of water that could be transferred; c) in view of the results of the previous sections, proposal for the drafting of a suitable project.

The Study Commission for the Use of the Castril and Guardal rivers presented some solutions that were considered to be suitable for the users of the different river basins (Guadalquivir, Almanzora, Segura), including: in the Almanzora, water is a need; in Lorca, help; and in the Guadalquivir, promise of expansion. The Commission started with evidence that the transfer from Castril and Guardal was feasible, that there were winter flows without a current use concession; and that Lorca and Almanzora had reasons to be examined and perhaps served the national interest (^{ACHS, 1942}:49).

In fact, this proposal to transfer water from Castril and Guardal to the Almanzora was not a reality until 2003, through the Negratín-Almanzora Connection (^{Gómez, 2017}:159). However, part of the Bajo Almanzora, Lorca and Cartagena saw the idea of ​​transferring water renewed in the General Draft of the Joint Use of hydraulic resources for the central and southeast Spain the Tajo-Segura Complex, November 1967, by the engineers José María Martín Mendiluce and José María Pliego Gutiérrez. After the construction of the aqueduct, the waters reached the Segura basin in 1979, and through the Postravase network, they also reached the Cartagena, Lorca and Almanzora fields. The report drafted in 1967 by the Commission of Hydraulic Resources of the II Plan for Economic and Social Development (II PDES) and its proposal to initiate the correction of the national hydraulic imbalance by means of the Tajo-Segura Transfer was decisive for initiating the work. The fundamental conditions considered in the 1967 Draft to determine the volumes to be transferred meant that the Tajo-Segura Transfer proposal was supported by the criteria for the use of surplus and the economy of transfer schemes, both in its construction aspect and in the exploitation.

The preliminary draft clarified that the volume of the transfers would be determined by the unmet needs in the deficit area, by the availability of surpluses in the feeder basin, or by the technical-economic characteristics of the works that enable the transfer. Large transfers had to be planned in such a way that the flow captured and transported would be as uniform as possible throughout the year, to achieve a lower cost per cubic meter transported, lower installed power per cubic meter at the pumping outlets and advantages in the scheduling of the supply.

The total surpluses calculated in the Tajo basin, measured at the border with Portugal, were 5 502 hm³/year, reflecting the full satisfaction of the Tajo's total demands in the future, and since Bolarque was the suitable point of capture for the origin of the aqueduct, the transferrable volume would be fixed by the surplus in section I in the future, estimated at 1 118 hm³/year. In terms of transfers to the southeast over time, availability would be determined by the stocks for each year. The maximum resources that could be assigned to transfer to the southeast without any damage to the Tajo were 1 000 hm³/year.

Once the preliminary draft was submitted and the information process had occurred, which received 85,000 allegations, it was finally approved by Ministerial Order of August 2, 1968, after agreement by the Council of Ministers. On February 12, 1969 Law 1/1969 was published in the Official State Gazette (BOE), which approved the II Plan for Economic and Social Development (II PDES), whose article 17 provided that "The joint use of the hydraulic system Tajo-Segura (ATS) will be regulated by means of a Law." Decree 102/1969, of May 9, approved the Consolidated Text of the Law of the II PDES, and in its Fourth Final Disposition, reiterated what was ordered in article 17 of Law 1/1969. Law 21/1971 complied with this mandate, and later, Law 52/1980, when the Tajo-Segura Aqueduct (ATS) was in operation, regulated the economic regime related to its exploitation.

Management of water transfers in the Tajo-Segura Transfer system

As a result of the elimination of the Ebro transfer, an environment unfavorable to transfers was created in Spain (when Cristina Narbona was the Ministry of Environment). Some researchers of economic history, geography, ecology, etc. associated with the New Culture of Water (Arrojo, P., Del Moral, L., Martinez, J., Esteve, M.A., etc.) published statements opposing networks for those water shipments. Other researchers have defended the contributions of surpluses to the deficit basins (Gil, Morales, Rico, Hernández, Gil, Gómez, Melgarejo, Soto, etc.) based on the analysis of the role played by the water distributed by hydraulic complexes such as the TTS or the Negratín-Almanzora Connection (CNA).

Law 52/1980, of October 16, regulating the Economic Regime of the Exploitation of the Tajo-Segura Aqueduct, in its second article stipulated: "For the purposes of this Law, works of the Tajo-Segura aqueduct will be considered those executed or financed by the State to obtain, regulate, conduct and distribute the transferred water, as well as the complementary works necessary to achieve its perfect functioning".

Figure 2 Ojós dam, start of Postrasvase in Segura River Basin 

“Pre-transfer” is defined by the set of works carried out in the Tajo Basin that enable the transfer of water from the Tajo headwaters to the Segura basin. While “transfer,” in the strict sense, is defined as the Tajo-Segura Aqueduct (from Bolarque in the Tajo Basin to the Talave in the Segura Basin). And Postrasvase (post-transfer) is the set of channels, aqueducts, siphons and reservoirs, water flow stations, etc., for distributing the water transferred once it reaches the Segura Basin (Figures 2 and 3).

The waters transferred by the Tajo-Segura Aqueduct (ATS) are distributed in the Postrasvase (post-transfer) area to meet irrigation and supply needs, and benefit the provinces of Murcia, Alicante and Almeria. Most are used for irrigation (up to 400 hm³/year), but the supply to the population has priority (up to 110 hm³/year), and is managed by the Commonwealth of Canales del Taibilla (MCT).

Figure 3 Irrigation areas in the Tajo-Segura Postrasvase (post-transfer). Right and left margin channels. 

In recent years, a decrease in rainfall in the headwaters of the Segura and Tajo has required the MCT to increasingly turn to desalination flows (^{Bernabé & Gómez, 2015}:286). During this period (1979-2017), the operation of the Tajo-Segura Transfer has been irregular, which in a way jeopardizes its future. An average of 324 hm³/year has been transferred through a channel built to transport 1 000 hm³/year. During hydrological years such as 1998/99 to 2002/03, more than 500 hm³/year were transferred, while other years less than 300 hm³/year were transferred. The official explanation for this variability in transfers is that the resources at the headwaters, whose historical average is 1 311 hm³/year (1940/41-2010/11), have decreased to 776 hm³/year during the period 1980/81-2010/11 (22% less). In the basin as a whole, the average for the period 1980/81-2010/11 shows a decrease in contributions of 16%, compared to the historical series (1940/41-2010/11). This difference in reductions in the headwaters, and in the basin as a whole, suggests that parameters other than rainfall are significantly affecting the resources of Entrepeñas-Buendía. We would highlight: a poor policy for dams and water releases, excessive and illegal exploitation of aquifers in the Tajo headwaters and those close to the aqueduct path (such as no. 23, de La Mancha aquifer), and the non-completion of some of the works planned in the 1967 Draft, such as the West solution for the supply of Madrid. To this we must add that there are more and more needs to be met by the Tajo-Segura Transfer, charged to the resources of the Tagus capital. Thus, the ecological flow (Qe) in Aranjuez increased from 5 to 6 m³/sec but much more has been left, which has meant more than 50% of the contributions of the headwaters of the Tajo (AP), as observed in the data in Table 1. Also to meet the environmental needs of spaces such as Tablas de Daimiel (up to 30 hm3/year) and to supply populations in municipalities in the La Mancha plains (Guadiana and Guadalquivir basins), up to 50 hm3/year (^{Gómez et al., 2011}:70).

The Tajo-Segura Aqueduct was established as the set of "works necessary to prevent the abandonment of southeast Spain," providing resources for supplies and irrigation, and for the economic development of the southeast. It is a public work that is being amortized by users through fees that were set by Law 52/1980, of October 16, regulating the economic regime of the exploitation of the Tajo-Segura Aqueduct. With news regarding the existing fee regime, such as cost recovery (twenty years before the Water Framework Directive institutionalized this for the countries of the European Union). As of January 1, 1986, the amounts obtained by the portion of the fee corresponding to the cost of the works, that is to say component "A" of the fees, were to be directed entirely to the communities of Castilla-La Mancha, Madrid and Extremadura, in the proportion of 4/9, 3/9 and 2/9, respectively, for the execution of hydraulic works and sanitary engineering, such as those indicated in the Preliminary Draft of 1967, in these Autonomous Communities.

The Tajo-Segura Aqueduct infrastructure has become essential to water uses along its route, especially in situations of drought. Some works not only enable the distribution of transferred waters from the Tajo, Guadiana or Júcar, but also resources from the southeast. An agreement was reached for payment of a fee by the beneficiaries of the waters for the use of these hydraulic infrastructures. Along with its tracings, water treatment plants, irrigated spaces, and economic activity have been developed. The development in the southeast region has come about due to "waterways" such as the Postrasvase network, the Commonwealth of Canales del Taibilla, the Negratín-Almanzora Connection (C NA), the Rabassa-Fenollar-Amadoiro (in connection to the Júcar-Vinalopó water transfer), and water distribution networks for desalination as well as those for WWTP and STP after purification for reuse.