Algeciras reservoir

In the Algeciras Wadi situated 2 km. up Alhama Impulsion, one encounters Algeciras reservoir. This structure has a double mission, to regulate the resources of the distribution canals, and to contain the floods of the wadi upstream of the confluence with the river Guadalentín.

CHARECTERISTICS OF THE BASIN OF ALGECIRAS RESERVOIR

Area: 46 km².
Average annual rainfall: 393 mm.
Average annual runoff: 1 Hm³
Altitude range : 1320-200 msnm
Distance : 20 km
Maximum flood registered (1948): 310 m³/s.

RESERVOIR

Capacity: 50 hm³
Area flooded: 244 has.
Height MNC : 267,50

DAM

Type Heterogeneous (loose material): 80
Length: 636 m.
Height of crest: 272,50
Height MNN: 265
Gradient upstream face: 3/1 a 3,5/1
Gradient downstream face: 2,75/1
Volume of material: 5,5 hm³.

PUMPING STATION

Number of groups: 6
Installed power : 6.000 Kva.
Nominal flow rate : 8 m³/s
Aspiration: 1 Ø 1800
Impulsion: 2 Ø 1300

Structurally the dam is a heterogeneous mixture of soils with thick nucleus constructed with blue loams extracted from the area now flooded by the reservoir, and polygenic conglomerate extracted from down stream of the dam. Their main technical characteristics are those that figure in the precedent table and the section types are reflected in the enclosed figure.

The mechanical dimensioning of the section has been designed bearing in mind the location of the area in a medium seismic risk zone.

The regulating reservoir has been located on the site of the polygenic conglomerate quarry, following adequate preparation of the excavated surfaces. Its capacity is 350,000 m³; with a depth of 7 m (useful range 6 m with a security margin of 1 m). It has an irregular rounded form, with a gradient in the dyke bank of 1.75/1

Impermeability is achieved via the use of armed concrete flagstones (20 cm thick), over a sheet of polyester reinforced P.V.C.

The pumping station is necessary to permit the storage of water from the canal (during the times of under consumption of the irrigation areas) in the reservoir, since the reservoir is elevated above the maximum level of the canal.

It is located between the regulation reservoir and the derivation gallery, on the right bank 200 m from the base of the dam.

The aspiration collector (1 Ø 1800) is connected to the regulation reservoir and the canal, with possibility of abstracting water from both sources. The impulsion consists of twin pipes (2 Ø 1300), connected to the lower outlet works at the mouth of the derivation gallery.

There are 6 groups with horizontal centrifugal bombs prepared to provide a nominal flow maximum of 8 m³/s. The motors are three-phase asynchronous of 1000 CV. The total power installed is 6000 KVA.