Santomera Reservoir
Background
In 1933 Plan Nacional de Obras Hidráulicas (National Hydraulic Works Plan) was drawn up, which included the projects for the preliminary plans for the base works regarding floods and reservoirs; the Rambla de Santomera Reservoir) was included therein.
The Spanish Civil War in the following years led to the works being abandoned until they were recovered in the Act passed on 11th April 1939, when the Plan Nacional de Obras Públicas was passed. And part of this included the above-mentioned Plan Nacional de Obras Hidráulicas which covered the drainage basins in the areas under the new political regime and which in 1940 was extended to cover all the areas of Spain. Among the works included for the Segura basin were the constructions of the reservoirs for correcting the Ramblas del Moro, El Judío and Santomera.
THE PROJECT FOR RETENTION AND EXPLOITATION OF FLOODWATERS IN THE RAMBLAS DE SANTOMERA AND ABANILLA, BY MEANS OF THE SANTOMERA RESERVOIR AND AS FLOOD PROTECTION FOR THE VEGA BAJA DEL SEGURA was drawn up by the Confederación Hidrográfica del Segura in August 1950 in an attempt to protect the rich fertile lands from the catastrophic floods occurring in these wadis
This project envisaged the construction of the Santomera dam (including its auxiliary dyke), the construction of a diversion dam in the Rambla de Abanilla and of a 7,850 m long canal with a flow capacity of 250 m³/s for the transfer of waters to the Santomera reservoir.
Using such a system would concentrate the Santomera wadi (Rambla Salada) floodwaters in the reservoir, as well as those coming from the River Chícamo (or Rambla de Abanilla), with a larger catchment basin than the former.
Prior to the regulation reports of the Ministry and Council of Public Works by order of the Ministry of 11th June 1954 the part referring to the Santomera dam and the regulation of its wadi was technically approved, with the exclusion of the transfer from the Rambla de Abanilla, which would require further study, and with the proviso that the Asesoría Geológica (Geological Office) and the Jefatura de Sondeos (Probings Office) were to issue a report regarding the conditions of the land. An Amended Approach Project was later drawn up which envisaged the recommended modifications following the surveys mentioned.
Once the official report was made public by Ministerial Order on 10th April 1956, it was passed, along with the project, on 6th June, 1956.
There was a public call for tender for the works on 30th April 1959 and the works were awarded on 14th January 1960 with a completion date set 32 months thereafter.
On 18th May 1960 the works were reassessed and the corresponding Report was prepared which set out, on the basis of the Dam Surveillance Report dated 15th March 1960, the need to prepare a Reform Project.
This was duly authorized on 26th July 1960 and the Reform Project was drawn up. It was technically and definitively passed on 15th December 1963, and an extension of the deadline was granted through to 18th September 1965.
The works were finished within the set time and on 23rd January 1967, they were provisionally accepted, which was certificated on 10 May of the same year.
Following the period of guarantee, the works were definitively accepted on 15th February 1968.
Access
Access to the dam is from Murcia via the Alicante motorway. After 12 km take the Fortuna exit and after two kilometres the access road is signposted on the right.
The most important city nearby is Murcia, some 12 km away. Smaller nearby towns include Molina de Segura (24 km), Fortuna (9 km), Abanilla (13 km) and Orihuela (15 km). The nearest town (not taking into account small scattered villages) is Santomera, which is 5 km away.
The nearest railway station is Murcia-El Carmen, 12 km away on the RENFE Madrid–Albacete-Murcia-Cartagena (Línea LR15) railway line. The nearest airport is Murcia-San Javier, 44 km away.
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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Province
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Murcia |
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Municipality
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Santomera |
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River
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Rambla Salada |
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Hydrographic basin
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Segura |
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DETAILS OF THE RIVER
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Length of the dammed river
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5,08 Km |
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DETAILS OF THE BASIN
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Surface area of the reservoir basin
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152,78 km² / 347,65 km² |
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Maximum altitude of the reservoir basin
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1.372 m |
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Shore length
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28,60 km |
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Reservoir surface area
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263,40 ha |
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Reservoir volume
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26,62 hm³ |
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BODY OF THE DAM
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Type
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Gravity |
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Materials
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Mass concrete |
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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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0,83/1 (h/v) |
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Height above course of river
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37,00 m |
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Level crest (axis of road)
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101,50 m. |
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Crest length
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205,79 m |
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Crest width
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4,00 m |
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Total fabric volume
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103.212,46 m³ |
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SPILLWAY
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Number of Spillways
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2 |
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Type of spillway
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Superficie |
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Location
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Centre of the dam |
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Position relevant to flow direction
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Frontal |
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Situation
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On dam |
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Closure type
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Floodgate |
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Number of openings
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3 |
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Free length of each opening
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7 |
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Total free length
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22,60 m |
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Floodgate type
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Taintor |
Purpose
The Santomera dam was designed and built with the main purpose of its serving as a defence for the Vega Baja del Segura against the disastrous floodings of the Santomera and Abanilla wadis.
The Project for the dam formed part of the “Project for the retention and exploitation of floodwaters of the Ramblas de Santomera and Abanilla, by means of the Santomera reservoir and as flood protection of the Vega Baja del Segura”, which was drawn up by the Confederación Hidrográfica del Segura in August 1950.
General view of Santomera reservoir
Due to the characteristics of the materials of the foundations and the abutments (especially the left bank abutment), important seepage occurred, although it was decided not to tackle this problem on account of the exclusive use of the reservoir for the purpose of flood abatement.
Later, in 1986, and regarding the possibility of using the reservoir to store waters from the Tagus-Segura Distribution Canals, the “Impermeabilization of the left embankment of the Santomera reservoir (05/86)” was drawn up, and injections and surface treatments were carried out from the existing inspection gallery.
Later, in 1986, and regarding the possibility of using the reservoir to store waters from the Tagus-Segura Distribution Canals, the “Impermeabilization of the left embankment of the Santomera reservoir (05/86)” was drawn up, and injections and surface treatments were carried out from the existing inspection gallery.
These works were carried out, although seepage continued (but to a lesser extent following the treatments carried out) until nearby quarrying was ceased, since its explosions had been causing vibrations which were incompatible with the sealing of the left bank of the massif. Once the explosions ceased, seepage gradually decreased and finally disappeared completely..
Nevertheless, today the reservoir cannot be used as a regulating reservoir of the Distribution Canals on account of the high salinity of the waters proceeding from Rambla Salada which are stored in the reservoir.
This environmental conditioning means that the reservoir cannot be used for irrigation purposes, being used exclusively for flood abatement.
Santomera dam, made of mass concrete with a straight ground plan, has only one characteristic cross section. It comprises 14 blocks separated by concertina expansion joints every 15.00 m. Its total length at the crest is 205.79 m, with a width of 4.00 m on the latter. The total height is 51.50 m above its foundations.
The total volume of cement used for the main dam was 103,212.463 m³ and 25,583.369 m³ for the stilling basin.
The crest of the dam is situated at a height of 101.50 and it has a 3.00 metre wide road which is protected by concrete paving. Two pavements 0.50 metres wide run along both sides of the road. Both upstream and downstream, the crest is protected on both sides by concrete parapet walls which are 40 cm high and 54 cm wide, on which railings have been installed, made of 100 mm diameter metal tubes.The lowest level of the foundations is 50.00 m, with the bed at this point situated at 64.50 m. The average thickness of the foundations is therefore 14.50 m.
The body of the dam houses a network of inspection and drainage galleries, on two levels, with their corresponding communicating stairways.
Territorial and Administrative Context
Physical Characteristics of the Basin.
The fundamental characteristics of the dam and reservoir of Santomera are:
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Crest level
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101,50 |
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Reservoir capacity
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26,29 hm³ |
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Reservoir surface area
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263,4 ha |
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Section of river regulated
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5,08 km |
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Length of shore
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28,6 km |
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Surface area of own basin
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152,78 km² |
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Surface area of whole basin
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500,43 km² |
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Maximum height of basin
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1 372 m |
Geology and Seismology.
Regional Geology.
The town of Santomera lies on the northern edge of the Vega Baja del Segura, about 4 km from the river. Behind the town there is a relatively flat area of an approximate surface area of 6-7 km², which is bordered by contour limit 50, a small alluvial valley in the final stretch of the course of the Rambla Salada or Santomera which is bordered on both banks by sharp topographical reliefs. On the left, the western prolongation of Sierra de Orihuela, with heights of up to 500 m; and to the right, Sierra de Los Cantalares, not so high, and which stretches to the area around the town (Punta del Bermejo).
To the west of Sierra de Orihuela there is a series of small isolated hills or hillocks, which run as far as the natural downstream boundary of the dam.
Geology and Soils of the Storage Area.
The age of the outcropping materials in the area ranges from the Triassic, the only representative of the Secondary Age, through to the Quaternary. The lithological plan for the different formations is given below.
Triassic. The area in question forms part of the inner area of the Cordilleras Béticas, and is usually referred to as the Zona Bética. Within this, the Triassic formations represented are attributed to the Ballabona-Cucharón complex. The geological report includes in the Orihuela page three tectonic units which are designated: Túnel, Bermejo and Orihuela. In the area under study all the Triassic materials belong to the Bermejo unit, in which, in turn, the Mina formation and the Cantalares formation are distinguished.
- The Mina formation, which is present along the main road between Campillo and Monteagudo, consists essentially of quartzites and slates with an estimated thickness of 300-400 m.
- The Cantalares formation, which is stratigraphically above the former, is basically composed of carbonated rocks. The lithology of this formation is very variable, with 5 series being distinguished, and all of them, with the exception of the uppermost, contain limestones, dolomitic limestones or dolomites of various colours, loamy and slatey rocks. The limestones are generally very siliceous and there are quartzite banks and abundant greywacke and gypsum, the latter in banks of several metres. Where the two formations meet there appear metabasites (E1), masses of volcanic origin concordant with the carbonatic strata which locally can be dozens of metres thick.
Miocene. Only the upper part of the Miocene appears, in marine and continental facies. The reduced outcrops of grey loams and sandy limestones on the right bank of the Santomera reservoir are attributed to the Tortonian age, and these are marine sediments which run laterally to a continental conglomerate complex. The gypsiferous loams which occupy the north-western part belong to an ample outcrop, dated as Andaluciense, and which are assigned a thickness of about 400-500 m. Locally they are topped by continental horizons of little thickness, like that which can be seen at the tail-end of the reservoir.
Geology and Soils of the Natural Downstream Boundary.
The dam rests on its right abutment on the conglomerate formation, pudding stones of great thickness, composed of not very rounded stones from the Triassic age. These conglomerates, concordant to the north with the Andaluciense loams, further south form the only Miocene representation. They lie directly on the Triassic in the area between the reservoir and Los Cantalares hill.
The left abutment of the dam lies on limestone with a certain degree of fissuring, which has been the cause of important seepage on different occasions during the life of the dam.
(1,7 MB)Fotos
Fotografías antiguas
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Cántaros | Galería fotográfica |
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Título documento num. 2 | Galería fotográfica |
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Título documento num. 3 | Galería fotográfica |
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Título documento num. 4 | Galería fotográfica |
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Título documento num. 5 | Galería fotográfica |
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Título documento num. n | Galería fotográfica |
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Situation
The Santomera dam is situated on the River Santomera, a tributary of the Segura river which it meets from the left at a place known as "Los Ásperos" in the Municipal District of Santomera (Murcia). It was designed and constructed as part os the so-called “Construction works for the retention and exploitation of waters of the wadis of Santomera and Abanilla by means of the Santomera reservoir and as flood control for the Vega Baja del Segura”, although the main purpose was to protect the Vega Baja del Segura fertile lands from the disastrous floods caused by the Santomera and Abanilla wadis.
The coordinates of the point where the river meets the dam comes as follows:
Geographical coordinates (based on the Greenwich meridian):
X 1º 05’ 14” West
Y 38º 05´ 37,3” North
U.T.M. coordinates:
Reference system ETRS89. Time zone= 30
X=667.608
Y=4.218.123
