Topographic Survey and Forest Inventory on Mount Gibralfaro (Málaga)

At Dendron Soluciones, we carried out an ambitious topographic survey and forest inventory project based on aerial LiDAR technology using drones on Mount Gibralfaro, an iconic location in the city of Málaga. With an analysis area of 36 hectares, this zone is of great value to citizens due to its recreational use and scenic value, with privileged views of La Malagueta beach. The execution of this project has made it possible to obtain key information for decision-making in the management of this emblematic natural space.

A Little History of Mount Gibralfaro

Mount Gibralfaro is one of the most emblematic natural spaces in Málaga, with a history dating back to Phoenician times, when it was already used as a strategic point due to its privileged location above the bay. Later, the Romans took advantage of its position to build a series of fortifications. However, it was during the Islamic period, in the 14th century, when the Nasrid King Yusuf I ordered the construction of the Gibralfaro Castle, with the aim of reinforcing the defense of the city and the nearby Alcazaba.

After the Christian reconquest in 1487, the mountain and its castle acquired a new role, becoming used as a military garrison. Over the centuries, the mountain gradually lost its original vegetation due to logging and urban pressure, becoming largely deforested.

In the 20th century, important reforestation works were carried out with species such as the Aleppo pine (Pinus halepensis Mill.) and eucalyptus, with the aim of recovering the mountain’s vegetation cover.

 

VIDEO OF THE 1942 REPOPULATION NODE.

Today, Gibralfaro is an essential green space for the city, offering a natural environment for recreation and unparalleled views of Málaga.

A Key Project for Environmental Restoration

The main objective of this project was to obtain precise information to support the restoration and environmental recovery of the mountain. Through LiDAR technology and multispectral cameras, it was possible to carry out a detailed analysis of the current state of the forest mass, providing key data for decision-making in the management of the space.

The Málaga City Council is creating a new sustainable model for the re-naturalization, conservation, and management of green areas of a natural character, which will serve as a reference for its implementation in the city’s green infrastructure network. In addition, this experience can be applied to the development of the future Green Ring of Málaga, an ambitious project included in the Málaga Climate Plan.

Increasing human pressure and the effects of climate change have significantly affected the health of the mountain, which has made it essential to obtain updated data that allows us to understand its state and define appropriate conservation and recovery strategies. In this sense, LiDAR technology has proven to be a fundamental tool for obtaining detailed models of the terrain and its vegetation with unprecedented precision.

Technology Used and Products Obtained

For this survey, state-of-the-art drones equipped with high-precision LiDAR sensors were used, capable of capturing a dense point cloud, reaching resolutions of up to 200 points per square meter. In addition, a multispectral camera was integrated, which allowed obtaining additional information on the health of the vegetation, evaluating aspects such as water stress and foliar density.

Among the derived cartographic products obtained are:

• Digital Terrain Model (DTM): Detailed representation of the relief, eliminating vegetation and construction elements, allowing the morphology of the terrain to be understood with great precision.
• Digital Surface Model (DSM): Capture of the entire surface cover, including vegetation and structures, essential for urban planning studies and land use planning.

• Contour lines: Generated with high precision to facilitate topographic studies, restoration projects and optimization of water resources.
• Shadow map: Useful for analyzing the distribution of sunlight on the ground, fundamental for the development of reforestation projects.
• Slope map: Key tool for infrastructure planning and prevention of erosion and landslide risks.
• Orientation map: Important for evaluating the exposure of the terrain to climatic factors and defining planting and forest management strategies.
• RGB Orthomosaic: With a GSD resolution of less than 3 centimeters, allowing a detailed visualization of the area with centimetric precision, useful for planning and forest management.

Multispectral Analysis and Vegetation Assessment

One of the most outstanding aspects of this project was the use of a multispectral camera to assess the vigor of the vegetation. Thanks to the analysis of the Normalized Difference Vegetation Index (NDVI), a significant percentage of dry trees of the Aleppo pine species (Pinus halepensis, Mill) were identified. The early identification of these phytosanitary problems is essential to design reforestation and pest control strategies efficiently.

The results obtained through multispectral analysis allowed the identification of areas with water deficit, areas with decay and low foliar density, and sectors where the vegetation presents symptoms of stress, crucial information for decision-making.

Conclusion

The topographic survey and forest inventory carried out on Mount Gibralfaro has provided an invaluable database for decision-making in its restoration and sustainable management. Thanks to the combination of LiDAR technology and multispectral analysis, key problems such as the loss of vigor in the forest mass have been identified, which will allow effective corrective actions to be taken.

At Dendron Soluciones we continue to bet on technological innovation to contribute to the conservation of natural spaces and guarantee their enjoyment by the citizens of Malaga and future generations. This project represents a step forward in forest management based on precise and updated data, contributing to the well-being of citizens and the biodiversity of the area.