How to save the sea
Shaping reality with Spain’s first digital twin
In 2016, the Menor Sea collapsed
It’s the largest saltwater lagoon in Europe, beloved by both tourists and generations who have spent their entire lives there.
The water turned to a "green soup" due to algae that couldn’t photosynthesize in the sun. Tonnes of dead fish washed up on shores. Residents were heartbroken.
Authorities knew they needed to restore the lagoon. One of the first steps was awarding the Menor Sea its rights to personhood to help protect its status. Only a handful of bodies of water in the world hold this designation. Officials then committed hundreds of millions of euros to restoring "Mar Menor" and its surrounding area by 2026.
But restoring the lagoon would prove complicated. Many factors could have contributed to the Menor Sea's accelerated degradation. Economic development had exploded due to the lagoon's popularity. Agriculture and livestock farms had grown exponentially in the surrounding region. Water runoff with pesticides and sewage often ran into the sea or polluted the groundwater. Mining waste also brought arsenic and heavy metals into the sea.
To solve these problems, authorities needed to map the surrounding area - at least 1,600 sq.km. - known as the Campo de Cartagena region. They wanted to gather data for why the Menor Sea collapsed and what problems they should fix first. They turned to TRAGSATEC to develop a digital twin to help them find a solution.
Campo de Cartagena digital twin
TRAGSATEC and digital twins in government decisions
TRAGSATEC is an environmental protection entity owned by the state and based in Madrid. TRAGSATEC had one goal: figure out what the top contributing factors were to the region’s decline and propose a plan of action.
Isabel Quiles, a geographic information systems (GIS) and digital twin specialist at TRAGSATEC, helped lead the project. “One of the state’s main priorities was improving what we know and can monitor,” she said. “They wanted to know how water flowed on the surface and underground, and they wanted to monitor water quality and soil humidity. We believed creating a digital twin of the entire Campo de Cartagena region was the best way to do that.”
Digital twins are an exact interactive and predictive digital representation of the real world. They offer automatic feedback loops between the digital world and the real world. Digital twins allow users to experiment, automatically observe the results and make changes accordingly.
Many businesses and corporations are already using digital twins to aggregate and visualise data. But small towns, large cities and even entire nations can also use digital twins to simulate environmental scenarios, visualise new urban developments and help determine the future of their cities. TRAGSATEC’s proposal marked the creation of Spain's first digital twin.
“Digital twins allow for an inventory of critical infrastructures along with 3D modelling to predict terrain behaviour during flooding,” said Quiles. “A digital twin lets us ask questions. What happens if we make this change? What is happening with the area’s agriculture? Are all these farms really impacting the lagoon's survival? Then we can run simulations to determine the answers.”
In essence, a digital twin helps governments understand what each decision means in reality.
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A digital twin lets us ask questions. What happens if we make this change? Then we can run simulations to determine the answers."
Isabel Quiles
Collecting terabytes of data
Creating a digital twin of the entire Campo de Cartagena region would require massive amounts of data. TRAGSATEC decided to use an all-in-one solution for geospatial data management to autonomously connect, manage and publish the data needed to map the region. They also used a situational awareness solution to visualise and analyse the data in 3D.
Work began in mid-2022. TRAGSATEC used a multi-view camera to create nadiral (straight down) and oblique (angled) images through photogrammetric flight. Those images were then combined with light detection and ranging images (LiDAR). Each photo was just five centimetres apart. Every element of the terrain appeared in at least 13 images.
“Just to give an idea of the magnitude of this project,” Quiles said, “Mapping 1,600 square kilometres takes over 51,000 nadiral images, 200,000 oblique images and more than four terabytes of LiDAR data.” For context, the Hubble Space Telescope captures about 10 terabytes per year. TRAGSATEC used all these images to recreate a 3D scenario of the region with lifelike precision and realism.
nadrial images
oblique images
LiDAR data
nadrial images
oblique images
LiDAR data
The 3D mesh offers an immersive experience in the Campo de Cartagena digital twin.
Creating the final product
TRAGSATEC used VADSTENA, another of Hexagon’s technologies, to process the data through ground control points and aerotriangulation. They also implemented true orthophotos and a high-quality 3D mesh that mapped trees and buildings. “These advanced products from Hexagon gave us some very valuable outputs,” Quiles said.
A TRAGSATEC simulation measuring the distance between underground water and the surface.
TRAGSATEC simulated flooding scenarios using its Campo de Cartagena digital twin.
Activating reality to make a more sustainable city
Once the data was visualised, the team ran their first two simulations in the digital twin. The first evaluated flooding scenarios in the mining boulevards and drainage systems throughout the region. The team wanted to know how modifications would impact river dynamics, terrain and the Menor Sea.
“The digital twin simulates floods with pre- and post-event conditions,” she said. “It helps us predict the hydraulic behaviour of each channel in a large flood.” The digital twin also allows dragging and dropping of BIM files to show how obstacles, like a wall, would redirect flooding.
The team also simulated groundwater blooms. TRAGSATEC wanted to study the distance between the terrain and the underground water compared with sea level. This helped detect areas where groundwater could bloom to the surface. By using piezometers (a measurement for underground water pressure), they were able to calculate the distance between surfaces where farms stood and the groundwater beneath them. TRAGSATEC used these simulations to determine how fertiliser filtration was affecting the underground water.
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The digital twin is much more than a 3D visualisation tool – it’s a platform that can simulate the future and facilitate powerful decision-making."
— Isabel Quiles
Building on the model
The final product of the Campo de Cartagena digital twin was released in November 2023 and is now available to the public. Quiles said the digital twin is already helping recover the sustainability of the Campo de Cartagena region and keeping a good balance between human activity and nature.
“We’re beginning to answer the questions we wanted to ask, like how tourism is affecting the ecosystem, or how farming and agriculture are contaminating the surface water,” said Quiles. “The digital twin is much more than a 3D visualisation tool – it’s a platform that can simulate the future and facilitate powerful decision-making.”
The Menor Sea ecosystem has already begun to stabilise. The water has started to clear. People are returning to the beaches. But the work isn’t over. TRAGSATEC intends to improve their digital twin tools and include more simulation scenarios. They also plan to expand these digital twin capabilities to the country’s other hydrographic departments.
For Spain, the Campo de Cartagena digital twin is just the beginning. It’s a blueprint that can be replicated throughout Spain and other countries as they try to combat climate crises like the destabilisation of the Menor Sea.
Explore the digital twin ↘
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