Camarillas Reservoir
Background
The first studies on the feasibility of a reservoir at this location were begun shortly after the Confederación Sindical Hidrográfica del Segura had been set up in 1926.
The dam was built in two clearly separate phases. The first, from 1932 to 1935, saw the building of the tunnels, the outlets and the spillway, the service buildings and the main section of the dam to an approximate height of 13m above the foundations. After the Spanish Civil War, the studies for the dam were resumed and a series of reports and projects were drawn up before the work was finally resumed in 1953, and completed in 1961.
Since it was founded in March 1926 the Confederación Sindical Hidrográfica del Segura established among its prime objectives a plan to exploit the hydrological resources of the basin. At that time there existed only one reservoir on the Mundo river, the largest tributary of the Segura, that of Talave, whose works had been completed in 1918. Although this reservoir had been designed for flood control purposes, from the beginning it was also used for regulating the flows to be used for irrigation purposes, therefore having extraordinary benefits for its area of influence. But the capacity of the Alive reservoir was clearly insufficient to regulate the whole river, and hence the need for a new reservoir on this river course.
Following the corresponding reconnaissance to determine a potential site for the new reservoir, the location finally selected was the ravine at the entrance to the narrow pass known as Los Almandenes, in the vicinity of the confluence of the Mundo river with the Segura river and immediately downstream from the Vega de Camarillas.
This vega (fertile area) is bordered on the south by a steep limestone mountain, typical of the river, fissured by the extremely narrow Los Almadenes gorge cut out by the river, which runs for nearly one kilometre. The width at the bottom is between four and five metres and the almost sheer walls rise up some 80 metres. Once the location had been chosen, the Preliminary Plan for Los Almadenes Reservoir, Mundo river was drawn up.
The document included the proposal for the construction of a gravity dam of a total height of 44m and with an overfall spillway on its left bank and a drainage capacity of 200 m³/s. The height of the dam was conditioned by the Madrid-Cartagena railway line, for which a diversion would have to be built later.
Once the Preliminary Plan had been passed in January 1930, the Camarillas Reservoir (Almadenes del río Mundo) Project, was drawn up, undersigned by Mr. Donato Paredes Granados in August 1930 and passed in April 1931.
The uses intended for the planned dam included flood abatement, the control of waterflows for irrigation and supply of Hellín and the production of hydroelectric energy.
The reservoir capacity was set at the maximum amount compatible with the Madrid-Cartagena railway line, which was 38.4 million cubic metres, although it would still be necessary to redirect the line and lay down some three kilometres of track in order to avoid the harmful effects of the reservoir on the embankments, some of which were of considerable height.
The works began in 1932. They were carried out in various sections, some by the state and others contracted out. The main wall of the dam, the spillway and additional works of the scour outlets and water inlets were awarded to the company Marcor, S.A. in July 1932.
In October 1934, the engineer Mr. Angel Elul Navarro drew up the Proyecto Reformado del Pantano de Camarillas (Almadenes del río Mundo). The main causes for his doing such were:
- The difficulties in quarrying the blocks for the concrete masonry intended for the dam.
- The instability of the land detected when excavating the collector channel for the spillway.
- need to carry out probings and injections in both the foundations and embankments.
This Reformed Project was passed in December 1934 in an Order which also required the works to be stopped until the issue of the possible enlargement of the reservoir’s capacity was solved; reference was also made to the need to study the importance of the faults detected in the natural downstream boundary. In January 1935 the General-Directorate for Hydraulic Works (D.G.O.H.) gave orders for an immediate study of the Camarillas reservoir enlargement following the Report from the Hydraulic Works Council. The study was required to consider the role of the reservoir in the whole system of works and irrigation of the Segura river, taking into account both technical and financial issues.
The works remained at an almost complete standstill until the beginning of the Civil War.
In February 1941, the engineer Mr. Joaquín Blasco Roig began the surveying of the works already carried out and researched the background of these in order to have information abut the controversial problem of the Camarillas reservoir and to find a definitive solution.
The same engineer undersigned the Proyecto de terminación del Pantano de Camarillas (Final Project), in December 1943, and this was passed in May 1945 with the proviso that it respected the observations of the Hydraulic Works Council.
Specifically, it was proposed that the construction of the dam be completed in stages, taking into account the following precautions:
- To excavate the dike as far as the contour CP=336.50 and, after confirmation of the impermeability of the reservoir basin, to build the railway diversion.
- To observe the behaviour of the left slope where the spillway was located. Until a decision was made regarding this point, the existing discharge tunnel would be used as a spillway, which would mean not using the upper 4.72 m of the reservoir.
- Once the stability of the slope had been confirmed, the spillway basin would be constructed. Otherwise, the tunnel built would be used. An automatic sluice gate would be incorporated at the entrance, thus allowing the whole reservoir to be used.
Alongside the Final Project there were two annexed projects for the spillway and the railway diversion. In 1947 the D.G.O.H. ordered an additional project to be drafted, which was undersigned in April 1947 by the engineer Mr. Emiliano Sáizar Irarzábal, and which was entitled “Project for the dam, water inlets and spillway to complement the final project for the Camarillas reservoir”.
The project included a hydrological study which, when fixing the spillway capacity, allowed for a simultaneous maximum peak flow in the Talavera outlet of 278 m³/s with another of 150 m³/s for the Rambla de Minateda, thus giving a maximum flow of 428 m³/s.
The proposed solution, which was considered the most economical, consisted of entirely accepting the layout of the dam, bottom galleries and water inlets as they appeared in the Final Project of 1943 with the sole modification of the spillway designed in the last project.
Finally, in May 1953 the works were awarded to the company Construcciones Civiles, S.A., and thus work was resumed almost twenty years later. In September 1954 the railway diversion construction was appended to the Works Contract.
In August 1956 the “Reformed Project for the modification of the dam, water inlets and spillway to complement the Final Project for the Camarillas Reservoir in the municipal district of Hellín (Albacete)” was drawn up by the civil engineer Mr. Emiliano Sáizar Irarzábal, and which was approved in December 1956.
Due to the insufficiency of the left bank spillway, the abovemented document included a project for another spillway on the right bank with a capacity of 200 m³/s.
The characteristics of the two spillways were more or less in accordance with what was finally constructed.
In May 1958 the civil engineer Don Emiliano Sáizar Irarzábal undersigned the “Second Reformed Project for the modification of the dam, water inlets and spillway to complement the Final Project for the Camarillas Reservoir in the municipal district of Hellín (Albacete)”, which was passed in August 1958.
This second reform included the modifications that would affect the injections and the redirecting of the railway. Finally, in June 1959 the same engineer drew up the “Third Reformed Project” which included increases for several items, of which the most important would be that affecting the injections to the side walls.
With no further major incidents, the works were concluded in May 1961. The Settlement Project was drawn up in November 1964 by the civil engineer Mr. Justo Llácer Barrachina.
Access
Access to the dam is from Agramón, a town located beside the A-30 main road (former N-301); from there you take the road from Estación de Agramón to Las Minas as far as kilometre 11, where you turn left onto the service road leading to the reservoir.
The location of the reservoir can be seen in the following map:
Characteristics
|
LOCATION OF THE RESERVOIR
|
|
|---|---|
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Province
|
Albacete |
|
Municipality
|
Hellín |
|
River
|
Mundo |
|
Hydrographic basin
|
Segura |
|
DETAILS OF RIVER MUNDO
|
|
|
Length of the damed river
|
9,5 km |
|
DETAILS OF THE BASIN
|
|
|
Surface area of the reservoir basin
|
2.382,9 km² |
|
Maximum altitude of the reservoir basin
|
1.520 m |
|
Details of the reservoir
|
|
|---|---|
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DETAILS OF CAMARILLAS RESERVOIR
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|
|
Shore length
|
34,2 km |
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Reservoir surface area
|
359 ha |
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Reservoir volume
|
38,63 hm³ |
|
BODY OF THE DAM
|
||
|---|---|---|
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Type
|
Gravity | |
|
Upriver slope
|
Vertical | |
|
Downriver slope
|
Variable | |
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Height above course of river
|
36,00 m | |
|
Level of crest (axis of road)
|
357,36 | |
|
Crest length
|
32,00 m | |
|
Crest width
|
4,20 m | |
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Old dam materials
|
Mass concrete | |
|
Total volume of concrete
|
- | |
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Total fabric volume
|
15.920 m³ | |
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SPILLWAY
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||
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Number of Spillways
|
2 | |
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Type of spillway
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Lateral | Lateral |
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Location
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Left Margin | Right Margin |
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Position relevant to flow direction
|
Lateral | Lateral |
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Situation
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Support | Support |
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Closure type
|
Free | Floodgate |
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Number of openings
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1 | 2 |
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Free length of each opening
|
23,56 m | 6,56 m |
Purpose
The main uses of the Camarillas reservoir are flood abatement and the regulation of waterflows to meet the demands required of the Mundo river (irrigation, supply, etc.). The Camarillas dam is jointly used with the Talave dam, located some 38 km upstream, and together they regulate the flows of the Tagus-Segura Transfer.
Territorial and Administrative Context
The total catchment area of the Camarillas dam occupies an area of 2,382.9 square kilometres, of which 766.5 km² correspond to the basin of the Talave dam, located upstream. The basin of the Camarillas dam itself, therefore, has an area of 1,616.4 km².
The whole basin lies at an average altitude of 818 m and is spread over the provinces of Albacete, Murcia, Jaén and Granada. The main tributaries of the Mundo river in the basin are the Rambla de Bogarra, before the Talave reservoir, and the Rambla de Minateda and Rambla de Bayco, which flow into the Mundo between the Talave and Camarillas dams.
The Camarillas reservoir has a surface area of 320 ha at its usual maximum contour height, and all of the area lies within the municipal district of Hellín, in the province of Albacete. The capacity of the reservoir at the given contour is 35.84 million cubic metres. The perimeter of the reservoir measures 34.2 km, while the length of the bed inundated by the reservoir is 9.5 km.
The main characteristics of the Camarillas reservoir and its catchment area are detailed below:
| Catchment basin | |
|---|---|
| Surface area of own basin | 1.616,4 km² |
| Surface area of whole basin | 2.382,9 km² |
| Average altitude of own basin | 818 m |
| Average altitude of whole basin | 705 m |
| Maximum altitude of basin | 1.520 m |
| Average annual rainfall | 322 mm |
| Runoff |
0,08
|
| Average water collected annually in the basin |
39,8 hm³
|
| Maximum recorded flood | 755 m³/s (oct. 1.982) |
| Reservoir | |
| Maximum normal level altitude (NMN) | 354,63 |
| Projected flood level (NAP) | 355,63 |
| Minimum level of Exploitation | 320,95 |
| Total capacity (at NMN) | 35,84 hm³ |
| Total capacity (at NAP) | 38,63 hm³ |
| Reservoir surface area (at NMN) | 320 ha |
| Reservoir surface area (at NAP) | 359 ha |
| Section of river regulated | 9,5 km |
| Length of shore | 34,2 km |
Environmental information.
The Camarillas dam and reservoir are included in the LIC (Site of Community Importance) of “Sierra de Alcaraz y Segura y los cañones del Segura y del Mundo” (Code ES4210008). These “LICs” are natural areas so chosen on applying the European Directives on Birds (79/409/EEC) and Habitats (92/43/EEC), and they are characterized by their contributing to maintaining and re-establishing a type of natural habitat or species in a state of favourable conservation within the biogeographical area to which they belong. The LICs form part of the Network of Protected Areas of Castilla-La Mancha.
The LIC in question occupies a surface of about 1,750 km² of the province of Albacete and comprises a group of mountain ranges interspersed with narrow river valleys, which together make it a place of extraordinary beauty.
However, given the period in which the projects and the building of the dam were carried out, no study on environmental impact was made. It should be pointed out that numerous reforestations have been performed by the Confederación Hidrográfica del Segura over the years. These were carried out in places like Las Higuericas, Soto de la Montiela, Los Colorines, Soto del Quinto, etc. And were all directed by an engineer of the Confederación Hidrográfica del Segura - Mr. Luis Aycart Benzo.
As regards any environmental conditioning in the exploitation of the dam, it should be mentioned that the Hydrological Plan of the Segura River Basin lays down a minimum flow rate of 1.5 million cubic metres/month (0.58 m³/s) for the stretch of the Mundo river between Camarillas dam and the confluence with the Segura.
Geology y sismology.
Regional Geology.
The Camarillas dam is located to the north of the Cordilleras Béticas in an area of a transitional nature between the structural units of the Cordillera Ibérica and the tectosedimentary units of the Prebético Externo. It is an area of highly irregular reliefs with extensive plains surrounded by reliefs of between 350 and 800 m or more. It is crossed by the Segura river and its tributary, the Mundo river, with the dam located on the course of the latter. Around the Camarillas reservoir basin Mesozoic and Cenozoic geological materials exclusively appear.
The overall geological framework presents flake tectonics sloping always towards the Meseta, in which Keuper gypsiferous-clay deposits act as the surface on a regional scale, being injected in favour of fractures or diapiric forms.
The Jurassic lithologic units are well represented by the Lias, Dogger and Malm groups, generally of a secondary dolomitization nature on the left and right embankments of the reservoir basin tail-end, in the mountain ranges known as Los Donceles and El Alto de las Cabras.
From the Lower Cretaceous era one can observe only small outcrops comprising conglomerates, various coloured sands and clays, located on the left embankment of the reservoir basin tail-end. The Upper Cretaceous is likewise sparse, with a few remains in the area of the natural downstream boundary where there is a superficial level of limestones.
Directly over the Upper Cretaceous there are some formations from the marine Miocene. These are folded and fractured and link up with others of a clearly continental influence. The latter formations, in the Pliocene, have a clearly fluvial and alluvial fan character, which correspond to a greater network than the hydrographical one existing today.
The Quaternary deposits are present in several surface deposits of irregular forms and varied extensions. They are frequently encrusted and located at the foot of an area of sharp relief, between the morphological ledge and the areas of gentle slopes or at the foot of a mountain. They are alluvial fans, debris cones, accumulations, alluvial or wadi deposits and flood plains.
The most outstanding structures of the area correspond to the diapiric dome in the narrow gorge of Los Almadenes and the structural arch of the Sierra de los Donceles, together with the system of discontinuities from the tearing of the base, forming a wide band of highly complex structure, which has led to diapiric alignments (among them the dome where the dam is located) in which Keuper units appear locally, which are the structural elements that end up defining the geological framework of the surroundings of the reservoir.
The natural downstream boundary of Camarillas dam is located at the entrance of Los Almadenes gorge, on a rocky massif in the form of a diapiric dome, with centripetal surface draining, basically formed by calcareous materials which appear on both embankments with numerous exokarstic features and signs (hollows, open diaclases with sealing by decalcification) and signs of important endokarstic development (caves, clayey fillings with rock fragments, stalactites and stalagmites, etc).
The massif is made up of a massive calcareous layer which often presents a brechoidal aspect, at times cemented, and which is associated to tectonic and Karstic phenomena. Stratigraphic dating reveals a Cretaceous age for these formations, very probably from the Senonense-Maastrichtian epochs.
Field surveys show up the existence of a large variation of directions and dips in the calcareous formation, from the site of the dam downstream and at the exit of the gorge of the Mundo river, revealing a dome formation with dips in all directions which are often cut short by geological discontinuities delimited by raised or sunken blocks.
The many Karstic processes, ranging from moderate to highly developed, are seen on the surface on both banks of the ravine- on the upper part of the right embankment on the tunnel leading to the dam crest and on the left embankment, downstream from the natural boundary, at the joining systems and the bedding planes as well as in the caves that were opened by the explosions carried out in the works on the main body of the existing dam.
Field surveys have led to the definite identification of a dome structure (of double deformation axis with an ellipse with the lesser axis in the direction of the Mundo river), with tilting and sinking of the central blocks of the structure, forming lax folds on the surface of the dome which are more vertical in the materials at the base of the cliffs, where the ascending effect of the diapir is stronger.
The general fracturing of the rocky massif is intense. The diaclase families identified show preferential distribution directions in the immediate surroundings of the dam, while as they move away from the Mundo river gorge, the directions and dips become widely dispersed.
Subhorizontal families also appear, which are rare but well developed, and these reveal greater brecciations as well as traces of karstification.
The combination of these diaclase families and the bedding planes causes the appearance of rocky wedges which locally have been the cause of instability. On both outcrops of the gorge, there are geometric wedge forms whose stability is at times extreme.
The microfracturation of the rocky massif may be considered to be generalized, with a high level of brecciation or milonitization in places. This phenomenon appears in all the materials of the natural downstream boundary as well as on both embankments and is present through to the rocky formations at the tunnel exits.
Sismology.
The location of the Camarillas dam lies within the area of the intersection of the Baetic and Iberian mountain ranges, an area which is seismogenetically generally active in neotectonic terms and is, therefore, seismic.
Within the seismotectonic compartments of the area around the reservoir, the Camarillas reservoir lies within Zone 4 (Prebético Central). Its eastern and western limits are determined by the geological faults of Caudete-Elda and by that of Hellín. Seismic activity in the area is lower than that of the Prebético Oriental (Zone 2), and the most outstanding activity was the Salinas earthquake (1916) of force VIII. The seismicity of the area is mainly diffuse and of low intensity and is generally associated to halokinetic and diapiric phenomena.
The Seismoresistant Construction Regulations NCSR-02, approved by Royal Decree 997/2002 –in Section 2.1 includes a chart of seismic hazard areas. The latter is expressed according to the basic seismic acceleration “ba” –a characteristic value of the horizontal acceleration of the surface according to gravity g– and of the contribution coefficient K, which takes into account the effect of the different types of earthquakes to be expected regarding seismic hazard at each point.
The range of “ba” values in the areas of our country considered to have seismic hazard runs from 0.04g to 0.24g, while the K figure stands between 1.0 and 1.3.
According to the above-mentioned map and Annex 1 of the Regulations, which includes a list of the “ba” and “k” values for different municipal districts of Spain, the characteristic parameters of the seismic hazard for the area of the Camarillas dam are: ba=0.07g; K=1.0.
Orthophotos
(5,5 MB)Situation
The Camarillas dam is situated on the Mundo river, in the gorge called Cañón de los Almadenes. Both the dam and the reservoir behind it are located within the municipal district of Hellín, in the province of Albacete.
The intersection of the axes of the dam and the river course occurs at the geographical coordinates given below.
U.T.M. coordinates
Reference system ETRS89. Time zone= 30
X=618.085
Y=4.244.400
Geographical coordinates (based on the Greenwich meridian):
X 1° 38' 51,18" West
Y 38° 20' 28,18" North
