Fuensanta Reservoir
Background
The first viability studies of a reservoir at this location date from the end of the 19th century. After a series of projects, the work was assigned to the building company Patarrieta Arellano y Compañía, S.A., who carried it out between 1929 and 1933.
The historical background of the Fuensanta reservoir goes back to the end of the 19th century. In the 1870’s there was a series of important floods, especially that of 15th October, 1879, classed as “highly catastrophic”. After these events, in March, 1885, the Congress against Floods in the Eastern Coastal region was held, from which the Segura Valley Flood Defence Plan, was produced in 1886. Within this plan was the Vizcaínos Reservoir, located in the upper basin of the Segura, which would hold about 25 hm³ with a dam about 40 m high.
On 25th April, 1902, the National Hydrological Works Plan was passed by Royal Decree, and was in force until 1926, when the Confederaciones Sindicales Hidrográficas were created. Among these confederations was the Confederación Sindical Hidrográfica del Segura. With the new Plan there started a series of new studies which showed the need to unite the planned reservoirs in the Upper Segura and the River Tus. This combined reservoir would later be named the Fuensanta, after the patron saint of Murcia. The site chosen for the future reservoir was the Infierno gorge, a true abyss over 100 m deep which makes it easy to foresee the quality of cement needed due to the morphological attributes of the location, a need which was later reinforced by the soundings taken. The Carrizosa gorge, slightly further upstream, was initially discarded because it is wider and has a lower intake flow, being upstream of the Peralta wadi.
In 1915 a plan of the closure was produced showing equidistant 1-metre level curves. In the following years mechanical calculations were made for the dam, the reservoir plan was developed, the work was planned in detail and service roads and infrastructures were posited. All this work was supervised by the engineers Francisco Benavides and José María Mena.
Various problems delayed the carrying out of the first project of the dam, which was not finalised until 1925, when the engineer of the hydraulic Division of the Segura, Ramón Martínez de Campos y Colmenares published the Fuensanta Dam Project in the Rivers Segura and Tus (Province of Albacete). Here a curved dam was proposed, 75 m high, 199 m long and with a radius for the curve of 120 m. Four intakes were planned at different levels, to be made from 2 800 mm sheet iron tubes. The base spillway was to be in a gallery on the left-hand side, with two floodgates measuring 1.00 x 1.80 m ².
This Project was well received by the Public Works Council, but was not passed because the work on the dam and reservoir had already been given to the Central Authority for the Segura river with aid from the State by Royal Decree on 20th July, 1926. In this decree a new project was demanded which should include the urgent carrying out of studies and soundings in order to establish definitively the exact placement of both the dam and the reservoir.
The work of soundings and pressurised water testing was given to a specialist Swedish company with experience in Spain. The first soundings were taken in the Infierno Gorge, the first location chosen, and showed a high level of permeability in the first layers of cement with the impermeability level at about 40 m under the ground. Therefore new locations were tested upstream, between the Carrizosa and Macalón gorges. Soundings in the Carrizosa began in December, 1926, giving excellent results in terms of impermeability and cement resistance, and so this was chosen as the definitive location for the Fuensanta Reservoir.
In June, 1927, the civil engineer of the Segura river Central Authority, Isidoro Fontana Elvira, produced the Fuensanta Reservoir Project on the Rivers Segura and Tus, which referred only to the dam itself. The additional installations and the spillway mechanisms were defined separately in various partial Projects, all produced in 1927 by the same author as the original mother document.
The planned dam was a gravity-type construction, triangular in profile, 85 m high and curved with a radius of 200 m. It was expected that the reservoir would be used to produce hydro-electricity, with a gallery intake 3 m in diameter, faced with concrete, followed by three sheet iron circular Ø 1.400 mm conduits, each equipped with a floodgate. Base spillway was situated on the left-hand buttress, and consisted of a gallery 459.5 m long, with a section of double sheet iron tubing (1800 mm diameter) connected by specially designed elements to a rectangular section measuring 1.20 x 1.85 m² with two floodgate valves per conduit.
In December, 1928, the project was given technical approval with certain reservations such as, for example, the upstream setting back of the mechanical room with the spillway beneath. The alterations were published in a Modified Project, produced by the civil engineer José Brugarolas Albadalejo in January, 1929, and passed by Order on 4th March of the same year.
Months beforehand, in November, 1928, the Central Authority had renounced its brief to carry out the work in favour of the Confederation, dissolving itself and becoming united with the Confederation as reflected in the Royal Order of 21st December, 1928, which at the same time authorised the Confederation to carry out the work on the Fuensanta Reservoir.
Alter being opened to public tender, with a base contract price of 17,417,657.70 pesetas, the contract was awarded in June, 1929, to the company Patarrieta Arellano y Compañía S.A. for the sum of 16.250.672,75 pesetas, beating the budget by 6.7 %.
The work awarded included the reservoir, flow directors, administration and staff buildings, houses for the workmen, cement storage, a hospital, chapel, school, access road to the base gallery, telephone lines, water supply and infrastructure replacement.
Work started in June, 1929, and by Order of 24th June, 1930, the First Revised Project was passed, which varied the conditions governing the access road to the base gallery and the water supply. Later a Second Revised Project was passed by Order of 3rd August, 1933.
The supply and assembly of the spillway floodgates was awarded after public tender in 1931 to Maquinista y Fundiciones del Ebro, S.A.
The civil engineering of the tunnel was diverted and its base spillway was begun by the company Hidráulica La Fuensanta, SA, but when the ownership of the reservoir passed to the Confederación Hidrográfica del Segura, authorisation was given for the work to be continued by the Administration, and finally it was released to the same company that had been awarded the work on the reservoir. The use of the tunnel to build another spillway outlet gave rise to the First Revised Base Spillway Project, published in June, 1932. The First Revised Base Spillway Project, was passed on 2nd August, 1933.
But the need for the tunnel work to coincide with the installation of the spillway closure mechanisms, which was carried out by a different sub-contractor, caused some delays and even temporary halts in the work. The provisional handover of this work took place on 10th February, 1934, and Final Reception was on 22nd July, 1935.
On 31st January, 1936, the final Revised plan and Handover of the Fuensanta Reservoir Works was published. This was passed by Ministerial Order on 17th November, 1939, at the same time as the Provisional and Final Handover Deeds of the work.
The Fuensanta dam was finished in 1932, the same year as the reservoir was put into use. However there was still complementary work to be completed, such as the finishing of drainage channels, galleries, accesses, etc. This work was interrupted by the outbreak of Civil War in 1936. Once it was finished, in November, 1940, the Regional Public Works Inspector visited the reservoir and saw the results of the neglect of the previous years. Numerous tasks had not been completed and leakages and other defects in the spillway mechanisms made it difficult to use the dam effectively. Three types of additional work were necessary:
- The finishing of certain elements of the crest and its accesses, galleries and spillway elements, services to the local population, etc.
- Correction of leaks on the left-hand side.
- Reconstruction of walls and other elements destroyed due to neglect of the dam or to spillway defects.
This work was outlined in various independent projects. The first was the Accessory Finishing Work Project for the Fuensanta Reseroir, published by Rafael Cochoud Sebastiá in 1941, which tackled the following; the widening of the crest road, finishing of the control cabin in the access well to the base spillway, strengthening the crest of the dam, and the demolition of various buildings used during construction. The documentation available reveals no certificate of adequate reception of this work, from which it can be deduced that it was probably never carried out.
In addition, the network of galleries in the dam installations was maze-like, communication between levels was difficult and there was only one exit point. To amend this, the Reservoir Control Section produced a report on 7th May, 1963, after a visit to the facilities on 26th April the same year. In this report it was recommended that the gallery network should be improved urgently in order that it be possible for the maintenance personnel to move freely and comfortably when checking the seals, spillway network and the whole of the inside of the structure. In reply to this recommendation, in 1964 the engineer then in charge of the reservoir, Alfonso Botía Pantoja, published the Complementary Work Project Nº 4 of the Fuensanta Reservoir. Updating of Current Galleries and New Dam Inspection Galleries. The project defined the following actions:
- Cleaning of inter-gallery communication wells, with a square cross-section of about 1 m2, and drilling of 600 mm diameter drains.
- Extension of intermediate and lower galleries up to the buttress rock and widening of communication well nº 20 to allow communication between the three gallery levels
- Installation of ladders in chambers and wells
- Lighting to be installed in the gallery network and the wall of the dam.
The work was finished in 1968.
Access
Access from Murcia or Madrid is through Hellín, a town located on the A-31 motorway. From here take the regional CM-412, towards Elche de la Sierra. About 6 km after this town, turn left on the CM-3206. 15 km from this junction there is a left turn which is the service road to the reservoir.
The location of the reservoir can be seen in the following map:
Characteristics
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LOCATION OF THE RESERVOIR
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|---|---|
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Province
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Albacete |
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Municipality
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Yeste |
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River
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Segura |
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Hydrographic basin
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Segura |
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DETAILS OF THE RIVER SEGURA
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Length of the river
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14,6 km |
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DETAILS OF THE BASIN
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Surface area of the Fuensanta reservoir basin
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1.220,6 km² |
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Maximum altitude of the Fuensanta reservoir basin
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1.860 m |
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DETAILS OF THE FUENSANTA RESERVOIR
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|---|---|
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Shore length
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81,3 km |
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Reservoir surface area
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924 ha |
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Reservoir volume
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224,7 hm³ |
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BODY OF THE DAM
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|---|---|
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Type
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Gravity |
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Upriver slope
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0,05/1 (h/v) |
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Downriver slope
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0,81/ (h/v) |
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Height above course of river
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79,18 m |
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Level of crest (axis of road)
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601,40 |
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Crest length
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232,00 m |
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Crest width
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6,00 m |
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Total fabric volume
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255.430 m³ |
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SPILLWAYS
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Number of spillways
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1 |
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Type of spillways
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Lateral canal |
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Location
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Left-hand support |
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Position relevant to flew direction
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Lateral |
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Situation
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Left-hand support |
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Closure type
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Free |
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Number of openings
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2 |
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Free length of each opening
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75,00 m |
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Total free length
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150,00 m |
Purpose
The main uses of the reservoir are flow regulation to meet the needs of the users of the Segura (irrigation, domestic supply, etc) and the abatement of floodwater from the high plains of the Segura.
Originally the reservoir was to be used for the production of hydro-electricity, and the plant was even built, but in the end this was not brought to fruition due to work being suddenly interrupted in 1936 with the outbreak of the Spanish Civil War. Later, in 1966, Hidroeléctrica Española drilled a wide-diameter opening in the body of the dam for outlet into the plant, but this was later covered with a metal structure.
Currently this project is being looked at again, and the construction of a plant on the right-hand side of the river is under way, between the abatement basin of the spillway and the outlet of the base spillway.
The Fuensanta Reservoir is used in tandem with the Cenajo Reservoir, about 62 km downstream, the pair forming a control system for floodwaters in the Segura basin.
Territorial and Administrative Context
Physical characteristics of the basin.
The catchment area of the Fuensanta Reservoir measures 1,220.6 km². The basin has an average altitude of 1,263 m and occupies part of the provinces of Albacete, Jaén and Granada. The main tributaries of the Segura in the basin are the River Zumeta and the River Tus (which joins the Segura in the reservoir itself).
The Fuensanta Reservoir has a surface area of 890 ha at maximum normal level, all this area being in the municipality of Yeste, in the province of Albacete. The capacity of the reservoir at this level is 209.7 hm³. The reservoir is "V-shaped" due to its location at the meeting of the Segura and Tus rivers. Shore length of the reservoir is 81.3 km, while the length of the Segura’s course occupied by the reservoir is 14.6 km.
Environmental Information.
The Fuensanta reservoir and dam are included in the Area of Community Importance known as "The Sierra de Alcaraz y Segura and the canyons of the Mundo river" (Code ES4210008). ACIs are naturally unspoilt areas which arise from the European Directives on Birdlife (79/409/CEE) and Habitats (92/43/CEE), and their main characteristic is that they contribute appreciably to the maintenance or re-creation of a type of natural habitat of a protected species which is favoured by the bio-geography of the area. The ACIs are part of the network of Protected Areas of Castilla-La Mancha.
The ACI in question occupies a surface area of about 1,750 km² in the province of Albacete and is part of a group of mountain chains interspersed with stunning flood valleys, which make for a particularly beautiful landscape.
However, because the projects and the construction of the dam and the reservoir date from so long ago, it was never subject to any study concerning its environmental impact.It is worth mentioning that there have been various repopulation initiatives on the part of the Confederación Hidrográfica del Segura on the shores of the reservoir over many years. These have been carried out in areas such as Paraje de Toril, Arroyo Morote, Paraje Umbría, etc., all of them under the aegis of the CHS engineer Luís Aycart Benzo.
As for the environmental factors which condition the way in which the reservoir is used, it should be mentioned that the Hydrological Plan fro the Segura Basin establishes a minimal flow for the part of the Mundo river between the Fuensanta and Cenajo reservoirs of 2.3 hm³/month (0.90 m³/s).
Finally, it should be pointed out that in the provisional Exploitation, Conservation and Vigilance Norm there is a chapter devoted to the environmental integration of the dam and reservoir, with rules for the minimum level and emptying of the reservoir, minimum flow, rules of behaviour in environmental emergencies, etc.
Geology and Seismology.
Regional Geology.
The underlying geology of the basin of the Fuensanta reservoir is composed largely of the Aptian division of the Lower Cretaceous, but there may be deposits from the base of the Cretaceous, including Barremian deposits from the Neocomian division.
The facies is entirely coastal marine, lithologically and paleontologically localised in the Tenéncico de Benifaza layer.
The whole series of layers is best exposed in a section on the banks of the River Tus, from the Altos de las Molatas, on the road bridge, to the bed of the Arroyo Morote, in Jartos.
The top layer is a puddingstone of thick polygenic elements, with a diameter of a few centimetres, almost in contact with each other, bound together with calcareous, slightly sandy cement. The rounded edges are eroded from previous reefs of the Jurassic and Triassic Age, but there is also a large amount of arenaceous Triassic material or Silurian quartzite, and some "Scolithus" have been found, doubtless from the vanished Triassic layers. This layer is compact and gives rise to cliffs and cornices, although they are not as dangerous as those in the calcareous banks, which are known as bands. This formation is roughly 50 m thick.
Under this is a very compact and coherent limestone, slightly sandy, which is the clearest lithological feature in the country due to its strength and resistance to erosion. It can be claimed that it is the main cause of the topography.
The palaeontological fauna in this habitat varies from one place to another. The greatest number of organic remains, indeed a real treasure trove, has been found at the River Tus bridge, above the Palomar narrows. In other places, such as the Sierra de los Paúles, hardly any fossils at all have been found.
In terms of genera and those most frequently found, the first in the list of organisms found are the "Pectens", which is the most commonly found in this calcareous layer; next are the "Ectoprocta" and some "Corals", among them the "Ciclolites" found in the Carrizosa, and the "Hippuritidae".
The aforementioned fossils are frequently mixed with “Orbitolinas”, “Lenticularis” and “Conoidea”, although these are not very visible and are scattered throughout the calcareous material without being grouped together.
In general this fossil flora and fauna is typical of coastal or estuarial facies. This is important because in this context, sand or clay banks are always interrupted in the form of round intrusions. Their depth is under 100 metres, but since they expose the underlying detrital layer, which does not always lend itself to a clear division of strata, frequently cliffs of more than 100 metres are attributed to this “Pecten” limestone. Examples of this are Los Vizcaínos, the Sierra de los Molares and even the gorges of Carrizosa and El Infierno.
Immediately under this “Pecten” layer there is a strong formation, in places up to 200 metres thick. Like the “Pecten” limestone it defines the characteristic landscape features of the cliffs of the peaks and high ground. The lower layer, softer and sandier, forms the floor of the valleys and ravines which flow steeply into the main rivers.
Lithologically, this set of conditions has a lot of variation; the first layers working from the top down, are limestones with "Toucasias" and small "monopleurids", which are easily seen in the Abuelo ravine, just downstream of the Fuensanta Reservoir, and in the descent to Jartos from the cliffs on the left bank of the River Tus.
These limestones, which are always fairly sandy, alternate on their margins with the same rock, which has been milonitised (i.e. fractured "in situ" by mass movement and then re-cemented). There are also bands of fairly loose, whitish sands which are in marked contrast to the dark brown colour of the limestones and upper puddings.
A strong limestone layer, which sits atop the Lower Cretaceous, gives rise to the narrows of the Fuensanta Reservoir, occupying the two steep banks with a slight slope towards the west.
The first sounding carried out on the Carrizosa gorge, for the studies prior to the implantation fo the Fuensanta Reservoir, detected complete impermeability when water was injected under pressure. This led to further soundings in the area, as many as eleven drillings being distributed throughout the lower part of both banks and the bed of the river, to different depths. In the bed of the river, soundings of between 2.60 m and 5.20 m were taken in the flood layers, as well as rock soundings of between 15.00 and 46.60 metres. The soundings in the banks perforated limestone rocks to a depth of between 15.35 and 40.36 metres, always with the same impermeability results with water injected at 20 atmospheres, except for sounding number 19, where a leak was detected in a crack at 28.83 m depth. This leak stopped immediately when water impregnated with clay was injected.
At the same time, three samples were taken along the left-hand buttress, to find the depth of passage, which was determined at 4 metres. The study was completed with some excavations on the right bank.
Seismology.
Construction Norm NCSR-02 (concerning seismic resistance), passed by Royal Decree 997/2002, includes in sub-section 2.1 a map of seismological danger areas. The level of danger is expressed as the basic seismic acceleration ab – a characteristic value of the horizontal acceleration of the land surface as a function of the acceleration of gravity g – and the contribution coefficient K, which takes into account the influence of different types of earthquakes expected in the level of seismic danger at any given location.
The range of ab values in the seismic danger areas of Spain is between 0.04g and 0.24g, while the value of K is between 1.0 and 1.3.
According to the map mentioned above and Annex 1 of the Norm, which includes a list of ab and K values in different municipalities of Spain, the typical seismic danger parameters in the area around the Fuensanta Reservoir are as follows: ab = 0.04g; K = 1.0.
Orthophotos
(5,5 MB)Situation
The Fuensanta reservoir is located on the Segura river in the Carrizosa gorge. Both the dam and the whole of the reservoir are in the municipality of Yeste, in the province of Albacete.
The intersection of the dam and the river-bed is at the following geographical coordinates:
U.T.M. coordinates :
Reference system ETRS89. Time zone= 30
X=569.199
Y=4.249.550
Geographical coordinates (based on the Greenwich meridian):
X 2° 12' 23,97" West
Y 38° 23' 33,26” North
