SEBES: GIS at the Heart of Water Management

For two decades, GIS has supported the evolution of Luxembourg’s drinking water network, managed by the Syndicat des Eaux du Barrage d’Esch-sur-Sûre (SEBES). Today, longitudinal profiles, drones and infrastructure models are opening up new possibilities.

In the basement of the former treatment plant at the Esch-sur-Sûre dam, an archive room still houses hundreds of tracing-paper drawings. Site plans and longitudinal profiles of the dam, pipelines and associated infrastructure tell the story of Luxembourg’s drinking water network.

“When I arrived in 2007, these drawings were all we had. Some were extremely difficult to locate geographically,” recalls Vincent Lemarchal, GIS Coordinator in the engineering department at the Syndicat des Eaux du Barrage d’Esch-sur-Sûre (SEBES). “Finding information meant first identifying the right document, then working out exactly where it belonged on the ground, often when many of the original landmarks had long since disappeared.

Nearly twenty years later, the archives are due to be transferred to SEBES headquarters, where the GIS department is now based, at the new Eschdorf treatment plant. Much of this historical documentation has already been incorporated into the GIS, creating a digital record of infrastructure that is vital to Luxembourg.

Established in 1962 to strengthen the Grand Duchy’s drinking water supply using water from the Upper Sûre reservoir, SEBES now produces drinking water at its new Eschdorf treatment plant, inaugurated in 2023. From its main reservoir, located at one of the highest points in the country, water flows predominantly by gravity through a transmission network of approximately 190 km. This network supplies regional water distribution associations and the City of Luxembourg, which are responsible for delivering water to end users.

SEBES acquired its first Esri licences and a SQL server in 2005, becoming one of Esri Belux’s earliest customers in Luxembourg. The project began as a pilot, digitising a small section of the network to demonstrate the potential value of GIS for infrastructure management.

“The pilot was successful and convinced SEBES of the benefits of GIS,” explains Vincent Lemarchal, who remains the organisation’s principal GIS administrator and geographic data manager. “Twenty years on, we are still adding information and making improvements. New areas of application continue to emerge, and more and more people are using the system.”

The initial purpose of the GIS was relatively straightforward: to build a comprehensive record of infrastructure assets and make information much easier to access.

A pipeline was no longer simply a line on a map. It could now be linked to technical specifications, photographs, construction drawings and historical records. GIS also provides access to ProjectWise, the document management system used by SEBES.

This work is still ongoing. During the move to the new Eschdorf facility, thousands of historical drawings were scanned. They now need to be progressively catalogued and linked to the relevant infrastructure assets.

It is a task that illustrates a fundamental aspect of the project.

“At the beginning, you might have thought that once 100% of the network had been mapped, the job would be done. But a GIS is never finished. It has to keep evolving,” Vincent Lemarchal explains.

As the database has grown, so has its user base. A significant step came around 2010 with the deployment of ArcGIS Server, making GIS information accessible through a web browser. Mobile applications subsequently brought mapping directly into the field. 

Today, although Vincent Lemarchal remains almost solely responsible for editing the network's geometry, certain technicians and project managers can update attribute information. More importantly, GIS has become a resource used across much of the organisation.

The engineering department and technical teams rely on it daily, while laboratory staff use it to locate sampling points and management draws on it to support decision-making.

Its reach even extends beyond SEBES. From the outset, GIS resources were shared with other water distribution associations, removing the need for each organisation to maintain its own infrastructure and dedicated expertise. Today, approximately 120 users have access to the various applications.

In the field, SEBES teams use tablets to locate themselves and view underground infrastructure, including water mains, electrical cables, fibre-optic connections and telemetry equipment.

When construction work could affect the SEBES network, teams can extract a plan from the GIS showing the precise location of the relevant assets.

This information has become increasingly important as the surroundings of the network have changed.

Many major pipelines were originally installed during the 1960s and 1970s, outside built-up areas. Since then, Luxembourg's urban expansion has gradually caught up with them. 

“Roads, new residential developments, public facilities, tram lines and motorway interchanges increasingly conflict with our network. As a result, we regularly have to assess whether pipelines need to be relocated, even though some have barely moved since they were first installed,” says Vincent Lemarchal.

The Kirchberg business district in Luxembourg City is a particularly clear example. Some pipelines have already been relocated several times, first to accommodate road developments and later the construction of the tram network.

In such situations, GIS becomes an essential decision-support tool.

Technical drawings for proposed developments are integrated into the system and compared with the existing network. Potential conflicts can be identified immediately, allowing different solutions to be assessed.

“It allows us to take a technical drawing, which can sometimes be difficult for non-specialists to interpret, and turn it into a much clearer representation of how a project interacts with our network,” explains Vincent Lemarchal. 

These visualisations support the engineering department and management team, but can also inform discussions at the organisation's governing committee.

“We even use GIS to present projects to the board of directors. When a major investment needs approval, a map makes it much easier to show exactly what the money will be spent on.”

Urban development is not the only challenge. The network itself is ageing and needs to evolve.

Some of the main transmission pipelines date back to the 1960s, and replacing them is a long-term undertaking.

Planning a new pipeline route now requires SEBES to consider numerous constraints, including Natura 2000 sites, protected areas, archaeological sites, geology, water protection zones and areas designated for future development.

GIS brings together the data needed to prepare these projects. A proposed route may go through numerous iterations before a technically feasible solution is found that also meets environmental and land-use planning requirements.

GIS also plays a role in planning network operations.

SEBES uses hydraulic modelling software that draws on pipeline characteristics and elevation data. This makes it possible to simulate taking a section of the network out of service and determine whether customers can continue receiving water through an alternative route.

Maintenance work can then be scheduled according to expected demand. A network configuration that provides sufficient capacity during a low-demand winter month, for example, may no longer be adequate during a summer peak.

This capability is becoming increasingly important as pressure on water resources grows. 

SEBES was established following the serious water shortages experienced in the Grand Duchy before the 1960s, supplementing groundwater resources with water from the Upper Sûre reservoir. Additional groundwater abstraction facilities were introduced in 1991 to provide an emergency backup supply.

Today, new boreholes and pipelines are being developed to safeguard the water supply in the event of drought, water quality problems affecting the reservoir or the unavailability of part of the network.

Over the longer term, further options are being explored to diversify water sources.

In this context, GIS provides the geographic perspective needed to assess water resources, infrastructure, demand and constraints together. 

As GIS applications have expanded, the technology itself has continued to advance.

Understanding a pipeline now involves much more than knowing its route. Its elevation and depth are essential for understanding hydraulic behaviour and planning maintenance or construction work.

Where three-dimensional data is available, SEBES can now automatically generate longitudinal profiles of the network. The aim is to improve the reliability of this third dimension, although the exact depth of some older pipelines still needs to be established.

SEBES also uses Drone2Map to produce orthophotos of selected construction sites before newly installed infrastructure is buried underground.

These images help verify the position of underground networks and measure the areas affected by construction work, particularly when calculating compensation for landowners and agricultural operators.

For some recently completed projects, GIS now provides a far more accurate record of what was actually built than traditional paper drawings ever could.

The next stage could take this approach considerably further.

SEBES already has 3D scans and Revit models of several technical facilities. For now, however, GIS and Building Information Modelling (BIM) remain largely separate environments.

Vincent Lemarchal currently uses, for example, a 2D view extracted from a Revit model to represent the underground level of a pumping station.

The ambition is to connect these two environments directly.

Selecting a facility on the map could provide access to its complete Revit model, allowing users to explore its equipment and pipework in three dimensions.

“For our main facilities, we could create a genuine digital twin, with GIS serving as the gateway to that digital twin,” Vincent Lemarchal explains.

Twenty years after its first steps with GIS, SEBES is looking beyond simply mapping its network towards progressively building a digital representation of its infrastructure.

It is an approach that earned the organisation a Special Achievement in GIS (SAG) Award at the 2026 Esri User Conference in San Diego.