Argos Reservoir
Background
The idea of building a dam in the Argos river in order to control floods within the municipality of Cehegín (almost adjacent to the municipality of Calasparra) dates back to 1866, when it was included in the Flood Defense Plan.
But it was not until 1929 when the dam was also considered to guarantee irrigation volume in that area.
In 1940, the project for the construction of a dam in the Argos river was drafted, but it was never exectued.
As early as the 60's, the Segura Hydrographic Confederation requested authorization to drill to assess the possibility of building a reservoir in the Argos river for land irrigation purposes in the municipality of Calasparra.
The General Directorate of Hydraulic Works authorized the Geological Service to carry out the drilling. Once the study was completed, the “Report on the survey to assess the building of an irrigation reservoir in the Argos river for Calasparra (Murcia)” was drafted on October 15, 1964. The real purpose of the drilling concerning the works was to find out the strength of the bed debris layer and the drift sides, probe the permeability, particularly in limited sides, verify the existence of a fault at the bottom of the scarpment on the right bank and, finally, take ground samples at the site where the dam would be located in order to perform lab tests.
The project eventually executed in the Argos dam was drafted in December 1964 by the road engineers José Antonio Jiménez Salas and Ventura Escario. This project was returned by the General Directorate of Hydraulic Works on October 16, 1965, to modify certain parts of the plan and to detail certain paragraphs according to the notes contained in the reports by the engineers of the Confederation, as well as in several briefing notes from the Dam Supervision Section. The most important change was the breakdown of the main surface spillway project because of the need to perform scale model testing. Such changes were completed and the project was finally approved on July 8, 1966.
Development of the main project
The works included in the project concerning the Argos dam were awarded to “ Obras y Servicios Públicos, S.A.” on June 20, 1967. On July 17 of the same year, the works were reassessed including the benefits of undertaking different works that presented no question as they were included in that current Project, while some other important element modifications were anticipated.
In the meetings of the Dam Supervision Section, the changes to the original project were specified; and before their final approval, the General Directorate of Hydraulic Works was asked to draft a reformed project.
Such a reformed project, drafted in January 1969 by Alfonso Botía Pantoja, intended to introduce a number of changes aimed at updating the dam to more modern techniques, improving structural performance, avoiding unnecessary routine operations and improving dam monitoring, while, at the same time, adjusting the soundings of the project to reality, since some works were already quite advanced. The deadline to complete the works was established for April 30, 1970.
Supplementary projects
Supplementary project Nº 1 dealt with access to the work site.
Supplementary project Nº 2 covered residential water supply to the area.
Supplementary project Nº 3 was drafted for the project tender, supply and assembly of metal sluices for the Argos reservoir spillways.
Supplementary project Nº 4, drafted by road engineer Alfonso Botía Pantoja, provided for the construction of the surface spillway.
Supplementary project Nº 5 included the facilities to record reservoir contributions.
Supplementary project Nº 6 established the necessary works for dam lighting, as well as the final electric installations.
Supplementary project Nº 7 focused on defining the irrigation canal on the right margin, while Nº 8, defined the Canal on the left margin.
Supplementary projects Nº 9 and 10 specified the works for the high canals on both of left and right margins respectively.
The dam began operating in 1973.
In March 1997, the classification proposal according to potential risk of breakage or malfunction was presented, and the dam obtained category A.
Characteristics
| SITUATION OF THE DAM | |
|---|---|
|
Province
|
Murcia |
|
Municipal territory
|
Cehegín |
|
River
|
Argos |
|
Hydrographic basin
|
Segura |
|
BASIN DATA
|
|
|
Surface of the reservoir basin
|
451.87 km² |
|
Maximum height of the reservoir basin
|
1,752 m |
|
Reservoir surface at the maximum normal level (ancient)
|
136.05 ha |
|---|---|
| Volume of the reservoir at the maximum normal level ( ancient) | 8.07 hm³ |
| DAM BODY | |
|---|---|
| Type | Separated materials with clay core |
|
Height above foundations
|
36.50 m |
|
Height above the bed
|
23.60 m |
| Top spot height | 414.60 and 414.66 m |
|
Top length
|
316.00 m |
|
Foundation spot height
|
378,10 m |
|
Top width
|
8,00 m |
|
Category according to the possible risk
|
A |
|
Bank waters on the top
|
2,25H/1V |
|
Bank waters on the bottom
|
2H/1V |
| CHUTES | |
|
Number of chutes
|
1 |
|
Capacity at the relative height of 28 m
|
567,90 m3/s |
|
Adjustment
|
Yes, doors |
Purpose
Its main mission is to supply the watering of the zone and the lamination of the basin floods.
From the dam, it is possible to provide the water inspections included in the Reservoir Irrigation Community of the Argos river in Calasparra, in the low plain of the Argos river.
Furthermore, through the construction of such a dam, it is possible to avoid flows which would be added to the ones of the Segura river in case of flood in the Segura basin and, on the other hand, it will be possible to reduce the risk of flooding Valentín and the plains of Calasparra, in case of flood in the Argos basin.
Vista del comienzo del canal aliviadero Argos-Quípar, presa desde aguas bajo.
Territorial and Administrative Context
Geology and Geotechnics.
Regional geology and geotechnics
The Argos reservoir is located in the northernmost part of the Baetic System which, in turn, represents the north-western segment of the Peri-mediterranean Alpine Orogen (alignment of mountain chains with asymmetric topologies created during the Cretaceous and Tertiary eras, centrifugally arranged relative to the sea; Martín Algarra, 1987).
In the Baetic System, the area of interest is delimited within the External Areas or South Iberian Domain. The materials in this area occupy a vast extension in the mountain range and represent a time period which goes from the Triassic to the Miocene. Its structure is characterized by a general detachment between the base rock (Hercynian Paleozoic) and the deformed covering (Mesozoic and Cenozoic folds, faults and buckled strata), where the clayish-evaporitic Triassic level acts as the detachment material and the buckled strata are generally inclined towards the W and NW. The Paleozoic base does not surface, remaining at a depth of 5-8 km, and it is made up of materials analogous to the Iberian Massif.
According to the nature of the materials and strain rate, it is possible to clearly distinguish two areas:
- Pre-Baetic, with facies located in shallow areas which represented the nearest area to the continent during the Mesozoic, formed by the Iberian Massif.
- Sub-Baetic, with pelagic facies from the middle Liassic which represent the most distant marine area from the continent with materials from the oceanic basin and, possibly, volcanic effusive rocks during the Mesozoic.
Between them, it is possible to observe the Intermediate Units in some areas of the continental slope with generally turbitidic facies linked to the deposit in submarine flares and which could locally reach a relevant width. They have their own features with important lateral differences from the Pre-Baetic and the Sub-Baetic.
Furthermore, it is possible to distinguish the autochthonous materials of our area of study, corresponding to the post-orogenic formations which were deposited there after the allochthonous units were placed, representing the Quaternary layer.
Basin geology and geotechnics
The basin is made up of Triassic clays, apart from a small section located on the left abutment, exactly to the left of the structure above the Argos-Quípar Channel, where slightly sandy marls and marly limestones from the Lower Cretaceous emerge.
The basin slopes are quiet soft and stable, so there should not be significant disturbances due to the natural operation of the reservoir.
Geology and geotechnics of the enclosure
Geologically, the enclosure area is mainly characterized by alternate layers of limestone and marl, which are more or less calcareous. On the left abutment, the limestone and marl (Lower Cretaceous) drop (about 15º) towards the riverbed.
On the right margin, which is a hard escarpment (part of the Cabezo de Teruel peak), it is possible to observe limestone and dolomites alternating with grayish-black marly layers which turn ochre on the surface due to weathering. Such limestone and dolomites (Upper Cretaceous) are more fractured and split than those on the right margin over which they ride.
Before this over-thrust, another took place in which Triassic clay were thrust on the Cretaceous marl limestone; later on, favored by this more fluid layer which acted as a lubricant, the limestone and dolomites that make up the Cabezo de Teruel thrusted over the remaining series.
Thus we have, between the two marly-limestoney formations, a multicolor clay coat deeply nestled on the other side of the peak, which extends towards the watercourse, although it is covered by debris for the entire segment of the river occupied by the dam, and it appears at the bottom of the right margin escarpment upstream and downstream from the site.
Due to such an anomaly (the presence of the clayey coat and Triassic gypsum under the Teruel peak), a plug was built on the entire front side of the impermeable core of the dam, after excavating the altered rock at the bottom of the peak escarpment, with subsequent injection and, in addition, a battery of injections so that they vertically reached under the Triassic layer, and traversed the peak horizontally until it closes the Triassic trace East of it, thus guaranteeing the dam's impermeability and stability.
Seismology.
The seismic hazard is different from one place to another, and it has been common practice to classify areas according to this hazard. Taking into account the recommendation criteria included in the “Dam Safety Technical Guidelines. Geological and Material Prospecting Studies” published by the Spanish National Committee on Large Dams (SNCLD), paragraph 3.3, there are three large groups:
- Low seismicity areas. Coefficient ab < 0.04 g
- Medium seismicity areas. 0.04 g < ab < 0.13g.
- High seismicity areas. 0.13 g < ab
(ab is the standard acceleration of the area.)
According to this classification, the Argos reservoir is located in an area of medium seismicity, given that the standard acceleration for the Calasparra Municipality is 0.07 g (data from the Seismic Resistance Regulation NCSE-02).
Environmental information.
The Argos reservoir is located in a SPA (Special Bird Protection Area) known as “Sierra del Molino, Embalse del Quípar y Llanos del Cagitán” code ES0000265, established by resolution on May 8, 2001. Furthermore, because it is a SPA area, the dam is included at the same time in the Wildlife Protection Area known as Alfonso XIII, Cagitán y Almadenes Reservoir.
(323 KB)Situation
The reservoir associated with the barrier of Argos and its surroundings are in the Segura basin, north of the Autonomous Community of Murcia, and towns of Calasparra Cehegín. Specifically it is located in your 890 (CALASPARRA), IGN (National Geographical Institute) at 1/50.000.
The constructed Argos-Quípar spillway channel which leaves from the Argos reservoir, is located in the south of Calasparra. It runs along the side of los Cabezos de Juan González, which it practically borders..
The dam is situated on the river Argos, in the Borough of Cehegín (Murcia), about three kilometers upstream of the boundary between this term and Calasparra, at the foot of Cabezo Teruel.
The intersection of the axis of the dam to the river occurs in the following geographical coordinates:
Geographical coordinates (based on the Greenwich meridian):
X: 1º 43' 58" West
Y: 38º 10' 25" North
U.T.M. coordinates:
Reference system ETRS89. Time zone= : 30
X=610.929
Y=4.225.703
Access to the dam and reservoir
The location of the reservoir can be seen in the following map:
