El Mayés Reservoir
Background
The construction of El Mayés Reservoir began on the 23rd June 1975, its Provisional Acceptance being made on the 5th November 1981.
El Mayés Reservoir
The works were fully financed by the State, which currently charges irrigation tariffs for making the supply available to the users of the Segura Right Bank Distribution Canal. These tariffs include the operating costs.
The document verifying readiness for construction was approved on 19th September 1975 and as a result, which dealt with some considerations regarding the works, in July 1977 an additional amendment document was drawn up (“Documento adicional por modificación Número 1”). These considerations were about the need to carry out a series of works connected with the location of the Hydroelectric Pumping Station, to the pump pipe and the general layout of the canal. They additionally involved a series of works regarding the regulating reservoir, specifically the speed of arrival, the huts for protecting the intake pipes, scour outlets, hollow jet valves and the alternative service road on the reservoir crest.
El Mayés Reservoir
Once the works had been completed within the due term, their “Provisional Acceptance” was made on 5th November 1981. The following works were included in the file:
-Headworks and works for the access to the Ojós Hydroelectric Pumping Station.
-Ojós Pumping Station.
-Pump Pipe at Ojós.
-Canal on the Right Bank of the Segura.
-El Mayés Reservoir.
In December 1979 the “Project for reaching El Mayés regulating reservoir. Segura Right Bank Canal. Ojós Pumping Station. (MU/Ricote)” was drawn up. Once the works had been completed within the due term, their “Provisional Acceptance” was made on the 5th November 1981.
El Mayés Reservoir
In September 1980 the “Project for the construction of floodgates in El Mayés reservoir spillway. Segura Right Canal River Bank. (MU/Ricote)" was drawn up. Once the works had been completed within the effective term, their Provisional Acceptance was made on the 10th February 1983.
In September 1982 the “Project for the consolidation and control of the abutment of the left riverbank of El Mayés reservoir (MU/Ojós)” was drawn up, as a result of the filtrations appearing in the vicinity of the discharge channel (related with a certain height of the reservoir). The fear of an increase in these filtrations meant that the maximum useful height was not achieved. The works consisted of:
The installation of six piezometers on the crest and in the downstream slope deep enough for reaching solid ground and therefore know the variations in the piezometric level downstream from the reservoir in the area in question.
Injections of cement grout at a very low pressure in the areas presumably affected.
The works began on 23rd December 1983 and their provisional acceptance was made on 6th March 1985.
Access
The access to the dam is from Murcia on the Madrid-Cartagena 301 main road, turning left at Archena and taking the MU-411 minor road, then the Archena-Mula MU-530 minor road for about six kilometres (6 km), where you will find the Segura Right Bank Distribution Canal Service Road. Follow this road and after approximately four kilometres two hundred metres (4.2 km) you will see the dam installations on the right. These installations are connected with the headquarters of the Segura Hydrographic Confederation by means of a transmitter-receiver, as well as by a telephone line with the number 968 67 10 14.
The largest nearest city is Murcia, which is 34.1 km away. Smaller towns which are also nearby are: Molina de Segura (23.6 km), Alcantarilla (30.4 km) and Cieza (33.9 km). The nearest town (without taking into account small scattered villages) is Archena, 10.2 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 | Murcia | |
| Municipality | Ojos | |
| River | Hydrographic basin | Segura |
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DETAILS OF THE RIVER
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| Length of the river | 0,9 Km | |
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DETAILS OF THE BASIN
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| Surface area of Mayés reservoir basin | 12,65 km² | |
| Maximum altitude of the Mayés reservoir basin | 1.122 m | |
| Shore length | 3,018 km |
|---|---|
| Reservoir surface area | 17,11 ha |
| Reservoir volume | 1,50 hm³ |
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BODY OF THE DAM
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|---|---|
| Type | Materials.Curved ground plan |
| Materials | Loose Materials |
| Upriver slope | 2,0/1,0 (h/v) |
| Downriver slope | 2,0/1,0 (h/v) |
| Height above course of river | 24,00 m |
| Level of crest | 278,00 m |
| Crest length | 300,00 m |
| Crest width | 9,00 m |
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SPILLWAY
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| Number of Spillways | 1 |
| Type of spillway | Surface |
| Location | Left-hand support |
| Position relevant to flow direction | Frontal |
| Situation | On dam |
| Closure type | Floodgate |
| Number of openings | 3 |
| Floodgate type | Wagon |
Imágenes
Embalse del Mayés
Embalse del Mayés
Purpose
El Mayés reservoir was designed to collect the waters received by the Ojós Reservoir Pumping Station, through the Segura Right Canal River Bank, with the purpose of meeting the irrigation demands of Zone V (Yéchar, Casa Alta and Campos del Río), Sangonera, Librilla, Alhama, Totana, Lorca, Almería and for supplying Lorca.
For the construction of the reservoir it was not necessary to inundate any village; however it was necessary to inundate some paths and some high tension cables had to be diverted. The works consisted of the construction of a reservoir of loose materials, with an impervious core, a curved ground plan and its convexity orientated downstream.
El Mayés Reservoir
The surface spillway was built on the left abutment. The headworks for the pumping station are located on the left embankment of the reservoir, a few metres from the spillway. An intake tower located in the reservoir, twelve metres (12 m) from the foot of the reservoir upstream, collects the waters destined for irrigation and the scour outlet. The water reaches the intake hut through a gallery that usually crosses the reservoir, inside which pipes have been placed, where it flows out to the canal. A walkway joins this tower with the right embankment of the reservoir. The scour outlet pipe carries on from this canal intake hut until the vicinity of the surface spillway stilling pool, into which it flows by means of its sluice.
El Mayés Reservoir
Territorial and Administrative Context
Regional Geology
El Mayés Reservoir is located between the Sierras de Ricote and Cajal. The area corresponds to an anticline with a Triassic core, partly diapiric, featuring great masses of sandy limestone and loams from the Miocene epoch. Mixed with the Triassic soils, some loams and limestone probably from the Eocene can also be found.
To the north-west of the area lie the mountains of Sierra de Ricote, mainly consisting of limestone from the Jurassic period. The Sierra de Cajal forms the northern side of the great syncline in Miocene soils that stretches toward the South and whose basal sandy limestones, here very thick, rise vertically. Two other small synclines from the Miocene epoch appear as faulted to the south of Ricote.
The great masses of sandy limestone and loams from the Miocene epoch are cut by large faults, along which the Triassic in diapiric form sometimes appears. Special mention must be made of the faults on the northern side of Sierra de Cajal and the Rambla del Carcelín, of great longitude, stretching westwards and nearly reaching the Albacete-Murcia railway line (km 435). Through them, a strip of diapiric Triassic has risen, which, to the south of Villanueva del Río Segura, has overflowed onto the Miocene loams. This fault has significantly influenced the Miocene thicknesses, much thinner to the North.
Following the depositing, folding and erosion of the materials from the Triassic, Eocene (or Cretaceous) and Miocene periods, some not-very-consolidated sediments were deposited, with gentle horizontal slopes, from a recent age (Quaternary or Pliocene) that form a great alluvial fan. These alluvial fans are formed by erosion materials from the Ricote and Cajal mountains and have been deposited with gentle slopes over old erosion levels, very flat, in loamy soils. These erosion levels in the loams have consequently eroded (due to the descent in the base level) into narrow ravines that have pushed out the unaltered loams.
Geology and Geotechniques of the downstream boundary.
El Mayés reservoir is located in the wadi of the same name, which is made up of loams from the Miocene, which, in this area, have the same directions (ENE-WSW), parallel to the riverbed and dips to the South of about ten or twenty-five degrees (10º-25º), although not very visible.
The loams appear intact on the steep slopes that have recently been eroded by the river and are compact loams which are quite calcareous (55-60% of CaCO3) with conchoidal fracture. On the gentle slopes, intact loams cannot be seen, but their fluvial material can, consisting of yellow-ochre silty clays of medium to low plasticity. The thickness of this fluvial material is between one (1.00) and three (3.00) metres.
On the left embankment, over old levels of erosion of the loams, deposits appear with gentle slopes of gravel and sand, poorly cemented and quite permeable. Lastly, in the riverbed there are deposits of gravel, sand and silt sometimes covered in superficial white powder, produced by the salts swept along by the water.
The downstream boundary is totally impervious, with the exception of the possible presence of some vein of gypsum and the existence of Quaternary deposits on the left embankment, below the area of the spillway.
Geology and Geotechniques of the Storage Area Upstream of the Dam.
This area is formed by the same materials as the natural downstream boundary for the storage area, that is to say, by loams with altered surface areas, gravel, sand, silt and clay in the low areas and alluvial fan debris or terraces at the top of the platforms, mainly on the left embankment. Its structure is the same as that of the downstream boundary, i.e., the loams are parallel to the wadi and with gentle dips to the South. The same as the downstream boundary, the storage area upstream of the dam is totally impervious and the possible appearance of some vein of plaster does not present any significant problem.
When the location of the dam and its maximum reservoir level were defined, a survey was made of the reservoir surface which was going to hold the water. This survey concluded that the reservoir basin was completely impervious, although some areas of permeability were detected in a side valley and on the left abutment of the dam. Permeability tests were made regarding the atmospheric pressure - drill length - , and the pressure sustained by means of a pump. The latter test was carried out after having advanced every 5.0 m, and so the possible waterproofing that could be generated by the detritus caused by the drill when filling the small fissures was very limited since the water injected under pressure cleaned them out. The result of the permeability tests determined that the fissures were very deep, and so cement was injected.
Planos
Plans
(10 MB)Ortophotographs
Situation
El Mayés Reservoir is located in the Municipal District of Ojós (Murcia). It was designed and built as part of the “Works for the Canal on the Right Bank of the Segura. Ojós Pumping Station. Regulating Reservoir” for the purpose of collecting the waters received by the Ojós Reservoir Pumping Station in order to, by means of the Canal on the Right Bank of the Segura, meet the demands for irrigation of Zone V (Yéchar, Casa Alta and Campos del Río), Sangonera, Librilla, Alhama, Totana, Lorca, Almería and for supplying Lorca. It was built in a downstream boundary for the storage area existing in the Rambla del Mayés, a small stream that is a tributary of the Segura river.
The coordinates of the point where the river meets the reservoir comes as follows:
Geographical coordinates (based on the Greenwich meridian):
X 38º 6´ 44,53” North
Y 1º 22´ 30,56” West
Reference system ETRS89. Time zone= 30
X=642.308
Y=4.219.561
The nearest railway station is Archena-Fortuna, exactly 10.2 km away, on the RENFE Madrid–Albacete-Murcia-Cartagena line (Line LR15). The nearest airport is Murcia-San Javier, 73.2 km away.
