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Reservoirs

Morrón Reservoir

Territorial framework.

Physical characteristics of the basin.

The Morrón watercourse, affluent of the Judío on its right margin, has a length of about 12 km and a basin of 20 km², approximately, up to its mouth. A few kilometers from its origin, it crosses a limestone block shaping a soft 1.5 km canyon, where the Morrón dam is located.

The upper segment of the watercourse, from its origin to the dam itself, has a catchment basin surface of 13.213 km², with many small affluents, quite a rugged terrain and sharp slopes. Several riverbeds draining into the dam already have small dikes which contribute to fix the beds and retain a large volume of dragged solids. Such dikes have been built by what used to be known as the Institute for the Preservation of Nature (ICONA).

Drainage system. View from downstream
Drainage system. View from downstream

The basin is generally covered by short brush of low-medium density. On some slopes, there are still some trees whose percentage does not exceed 10% of the total surface. The flatter intermediate area supports numerous rain-fed crops, basically grapevines, almond trees and some olive trees. The Morron dam crest height has been recorded at different values in different documents reviewed. After the cartographic works carried out for the current Technical Assistance, the crest height has been confirmed at 595.54 a.m.s.l. Based on this reference, the rest of the dam height has been determined.

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Environmental information

There is no environmental report or environmental impact assessment associated with the building of this dam or any related works. Regarding exploitation, the environmental integration regulations are part of the Moro watercourse Exploitation Regulations drafted in this Technical Assistance.

In these integration regulations, the current environmental legislation that could affect exploitation is reviewed, but there is no measure worth mentioning, basically because normal exploitation is the empty reservoir. On the other hand, the dam and its reservoir are not located in an area under environmental protection.

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Geology.

The Morrón reservoir is located in the northernmost part of the Baetic System, which at the same time is the north-western segment of the Peri-Mediterranean Alpine Orogen (aligned mountain chains with a structure of runoff cover created during the Cretaceous and Tertiary, centrifugally arranged in reference to the sea.; Martín Algarra, 1987).

Return flows. Unclad spill basin closed by cross dike
Return flows. Unclad spill basin closed by cross dike

Within the Baetic System, the area under consideration is framed within the External Areas or South-Iberian Domain. Materials in this domain occupy an extensive area in the system and represent a time period from the Triassic to the Miocene. Their structure is characterized by a detachment between the base (Hercynian Paleozoic) and the deformed cover (Mesozoic and Cenozoic folds, faults and buckled layers), where the clayey-evaporite Triassic act as detachment material, and the buckled layers have a general vergence towards the W and NW. The Paleozoic base does not surface and remains at a depth of 5-8 km, and it is made up of the same materials as the Iberian Mountains.

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, during the Mesozoic, represented the area nearest to the continent, formed by the Iberian Massif.
  • Sub-Baetic, with pelagic facies from the middle Liassic, representing the most distant marine area from the continent with oceanic basin materials and, possibly, volcanic effusive rocks from the Mesozoic.

The materials of the area of study are post-orogenic formations belonging to the Tertiary and Quaternary. The emerging Tertiary materials are of neogenic formation (Serravaliensis-Tortoniensis).

The dam enclosure rests on Miocene marly-limey materials, covered by granular materials from the Quaternary (red conglomerates). Miocene materials appear close to the dam and are characterized by fractures or faults, filled by Quaternary materials, which are not affected.

Miocene marl has a whitish color with fossils and well-defined stratification layers which sometimes appear micro-folded. Sandy limestone produces small highlights in the sequence. Regarding the waterwheels which are placed in the Miocene marl, they seem well-preserved, although some of them are partially buried.

Criteria to determine the Flood Project and Extreme Flood is based on acceptable risk according to the dam category, as established by the Technical Safety Regulations for Dams and Reservoirs, which in this case is A.

The Morrón watercourse upstream from the dam. View from the crest.
The Morrón watercourse upstream from the dam. View from the crest.

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