## 2 Geological and Hydrogeological Context
### Hydrogeological Context  
In the research area, Precambrian and Palaeozoic terrains are mostly impermeable, with the exception of Cambrian limestone outcrops, which have the capacity to store significant amounts of water. Highly competent rocks can also act as good aquifers if they are highly fractured. However, most other materials present very little potential as aquifers from a general point of view. Only small water uptakes can be expected, especially in areas where fracture zones exist or in areas that have undergone high geological alteration. In summary, the region has limited availability of significant aquifers, with the most significant being Cambrian limestone outcrops and highly fractured rocks. It is important to take these geological characteristics into account when approaching any water resource exploitation project in the area. Tertiary and/or quaternary deposits are materials that are characterised by their crumbly nature, i.e., their composition is brittle and easily eroded. These materials are deposited or formed on an impermeable substrate, resulting in what is known as a hanging deposit. These deposits, being on an impermeable base, allow water to flow into the existing streams in the area. This situation is clearly perceptible, and a series of springs can be identified at the same level, indicating the level of contact between these materials and the impermeable substrate. Water abstractions in these reservoirs tend to be quite shallow, generally with depths ranging from 0 to 20 m. The flows obtained from these catchments tend to be moderate, as the permeable nature of the reservoirs does not allow for the accumulation of large volumes of water. It is very interesting to know that in the surroundings of the study area, there is a borehole catalogued by the Guadiana Hydrographic Confederation (CH-1). This borehole represents a valuable source of information on the availability and quality of water in the region. The cataloguing by the confederation indicates that these boreholes have been subject to rigorous monitoring and analysis, which provides a reliable database for the hydrogeological study and sustainable management of water resources in the area. We are thankful for the information provided on the borehole present in the study area. According to the data provided, this borehole has a depth of approximately 50 m, while the water level is around 10 m. The recorded flow rates are 11 L/s. It is important to note that the lithology of the borehole is composed of metagranites, quartz schists and/or ultramylonites, according to the data provided by the data platform [12]. This information is relevant for the hydrogeological analysis of the region, as it indicates the existence of aquifers in the area. The depth of the boreholes suggests that the groundwater is at an accessible distance, which may favour its use by means of appropriate extraction techniques. Variable flows are indicative of the dynamics of groundwater flow, which can be influenced by various factors such as seasonality and local hydrological characteristics. These moderate flows represent a significant source of water, which can satisfy various water requirements, provided they are managed in a responsible and sustainable manner. The presence of metagranites, quartz schists and/or ultramylonites in the borehole is relevant, as these metamorphic rocks have the capacity to contain and transport groundwater. These lithological characteristics offer promising potential as natural aquifers in the region. It is relevant to mention that, in addition to the boreholes catalogued by official bodies, additional research was carried out in boreholes close to the study area carried out by private individuals. These boreholes are not officially registered, which means that it is not possible to be absolutely certain about the quality and reliability of their data. Nevertheless, the information obtained through this research is valuable, as it sheds light on the existence of SH-1 flows of 2-2.5 L/s, SH-2 of 1-1.5 L/s and SH-3 of 1 L/s.