Research Methodology

How we investigate the large-scale groundwater systems of the Yucatán Peninsula through exploration, data collection, and interdisciplinary scientific analysis.

Our Methodology

MAYAS project is based on a clearly defined hydrogeological hypothesis:
Large-scale movements of underground freshwater on the Yucatán Peninsula are primarily controlled by a limited number of major fracture systems. The known cave systems do not represent the aquifer itself, but rather are expressions and by-products of these overarching groundwater dynamics.

The objective of the methodology is to systematically investigate, empirically test, and spatially and temporally contextualize this theory. The aquifer is not regarded as a static reservoir, but as a dynamic, interconnected system, whose function can only be understood through the integration of multiple investigative levels.

Systemic Approach

The research follows a large-scale, integrative approach. Individual observations are not interpreted in isolation but are embedded within regional flow patterns, fracture networks, and recharge areas. Particular emphasis is placed on the interaction of the five major fracture systems, which are assumed to act as the primary transport pathways for large volumes of water.

The scientific development and implementation of the methodology are carried out in close collaboration with universities, research institutions, and recognized experts. For each specialized component of the project, cooperation is established with leading scientists and institutions in their respective fields to ensure methodological rigor, scientific depth, and international comparability.

Multidimensional Data Acquisition

To comprehensively assess the functioning of the aquifer, data acquisition is conducted across three closely interconnected levels. The methodology follows a clearly defined workflow, ranging from large-scale airborne detection, through surface-based validation, to direct subsurface investigation of water-bearing structures. This layered approach allows researchers to systematically link observations from different scales, uncover hidden flow patterns, and better understand how fractures, conduits, and recharge zones interact within the aquifer system. By combining data from aerial surveys, ground studies, and direct sampling, the study provides a detailed and cohesive picture of groundwater dynamics, which is essential for accurate modeling and informed conservation strategies.

Airborne Investigations

At the regional scale, various airborne investigation methods are employed. These include aerogeophysical surveys, which utilize electromagnetic waves to probe up to approximately 25 meters into the limestone bedrock of the peninsula and to determine the electrical conductivity of the penetrated materials. In addition, LiDAR data, multispectral analyses, and thermal measurements are used to document surface morphology, structural lineaments, moisture-related anomalies, and temperature variations that may indicate subsurface water movement and hydraulic connections.

Surface Investigations

At the surface, cenotes, recharge areas, and transition zones between surface and subsurface are systematically examined. This includes spatial documentation, sampling, and the correlation of surface observations with data obtained from airborne and subsurface investigations, helping to validate findings and better understand how surface features reflect underlying groundwater flow.

Subsurface Investigations

Subsurface investigations involve direct exploration of water-bearing structures through technical cave and underwater exploration. In parallel, water samples are collected and subjected to comprehensive analysis. These include water chemistry, isotope analyses to determine origin and flow paths, as well as DNA and bacterial analyses to characterize biological signatures and to identify sources of contamination and ecological interactions. These datasets provide key insights into flow directions, mixing processes, residence times, and the ecological function of the aquifer.

Integration and Analysis

All collected data are integrated within a unified analytical framework. The objective is to identify and quantify flow directions, volumes, velocities, and the interaction of the major fracture systems, and to assess their influence on cave development, water quality, and connected ecosystems.

Application to Conservation and Management

The methodology is deliberately designed to ensure that the results are directly applicable. The project provides a robust scientific foundation to support more targeted, effective, and sustainable conservation measures, management strategies, and existing environmental protection initiatives on the Yucatán Peninsula

Phase 1

Airborne Investigation

Phase 1 establishes the foundational spatial framework of the project through systematic drone-based airborne investigations. The objective of this phase is to identify large-scale subsurface structures, surface indicators, and hydrological anomalies that control groundwater movement across the Yucatán Peninsula.

Objectives

The primary objectives of Phase 1 are to:

  • Detect fractures and conduits relevant to groundwater flow
  • Identify zones of hydraulic connectivity
  • Provide a spatial basis for targeted field validation
Approach

All airborne investigations are conducted using drone platforms, allowing high-resolution, flexible, and repeatable data acquisition. The core method is aero-electromagnetic surveying, complemented by LiDAR, multispectral, and thermal sensing.

Aero-electromagnetic measurements transmit electromagnetic impulses into the subsurface, penetrating up to approximately 25 meters into the limestone bedrock. The returning signals allow determination of the electrical conductivity of all penetrated materials, including dry limestone, freshwater- and saltwater-saturated limestone, fractures, and air- or water-filled voids.

By combining individual flight lines, spatial conductivity maps are generated that reveal fracture networks and major subsurface transport structures.
LiDAR surveys provide precise elevation models and surface morphology, enabling assessment of cave roof thickness, depth to the phreatic zone, and identification of subtle karst features obscured by dense vegetation.

Multispectral imaging is used to detect vegetation anomalies associated with groundwater availability, while thermal imaging highlights temperature contrasts linked to cave entrances, cenotes, and groundwater discharge, particularly in coastal zones.

Data Processing

All airborne datasets are georeferenced and processed using specialized workflows. Aero-electromagnetic data are analyzed and interpreted by international expert teams in Austria, Switzerland, and South Korea, ensuring high scientific robustness and cross-validation of results.

Outcome

At the conclusion of Phase 1, a high-resolution, spatially coherent dataset is available, identifying priority zones, structural patterns, and potential access points. These results directly guide Phase 2 – Surface Validation, ensuring efficient and targeted field investigations.

Phase 2

Surface Validation

Surface validation forms the critical link between airborne investigations and direct subsurface exploration. The objective of this phase is to verify ground-truth the structures identified from drone-based and remote-sensing data, refine their spatial accuracy, and assess their accessibility and hydrogeological relevance.

Objectives

Based on the integrated interpretation of aero-electromagnetic, LiDAR, multispectral, and thermal datasets, priority target areas are defined. Phase 2 focuses on systematically examining these areas on the ground in order to:

  • -confirm or refine airborne interpretations,
  • -identify natural access points to the subsurface
  • -and select suitable locations for subsequent subsurface investigations.
Approach

Surface work concentrates on the identification and documentation of features indicative of subsurface voids and active groundwater movement. These include:

  • -Cenotes and open water bodies
  • -Karst windows, collapse features, and sinkholes
  • -Subtle surface depressions and structural lineaments
  • -Transition zones between different geomorphological units

All observations are georeferenced and cross-checked against airborne datasets to further improve the spatial resolution and reliability of the structural interpretation.

Hydrological and Ecological Indicators

In addition to geomorphological observations, hydrological and ecological indicators are assessed. These include vegetation patterns, soil moisture, temperature anomalies, and evidence of seasonal or permanent water availability. Such indicators provide valuable insight into the activity and functional importance of identified structures within the aquifer system.

Outcome

At the conclusion of Phase 2, a validated set of access points and investigation sites is established. These locations are confirmed to be both structurally and hydrogeologically relevant and form the basis for the targeted planning of Phase 3 – Subsurface Exploration, reducing uncertainty in subsequent technically demanding operations.

Phase 3

Subsurface Exploration

Subsurface exploration represents the core phase of the project, enabling direct investigation of the aquifer system. In this phase, the access points identified and validated during Phase 2 are used to reach, document, and measure water-bearing structures directly. The primary objective is to verify large-scale flow models through direct observation and in-situ measurement.

Objectives

Phase 3 focuses on the confirmation and quantification of hypotheses developed in the preceding phases. Key objectives include:

  • direct observation of fractures, voids, and cave systems,
  • determination of flow directions and flow dynamics,
  • collection of samples for physical, chemical, and biological analyses.
Approach

Exploration is conducted through technical cave and underwater operations, following internationally recognized safety and scientific standards. Investigations focus on selected key areas of the aquifer, particularly where major transport pathways and fracture intersections are expected.

On site, the following activities are carried out systematically:

  • documentation of cave geometry and subsurface structural characteristics,
  • determination of flow directions using visual observations and tracer-supported methods,
  • estimation of flow velocities and hydraulic activity,
  • collection of water samples at strategically relevant locations.
Analytical Investigations

Collected samples are subjected to comprehensive laboratory analyses to characterize water origin, composition, and dynamics. These include:

  • Water chemistry analyses to identify composition and mixing processes
  • Isotope analyses to assess water origin, residence time, and flow paths
  • DNA and bacterial analyses to characterize biological signatures, ecological connectivity, and potential contamination sources

These analyses enable local observations to be placed within a broader regional context and allow assessment of the connectivity of the aquifer system.

Scientific Value

Phase 3 provides the critical empirical evidence required to determine whether identified structures function as active groundwater transport pathways. The combination of direct observation and analytical data allows models developed in Phase 1 to be confirmed, refined, or, if necessary, revised.

Outcome

At the conclusion of Phase 3, a robust dataset derived from direct subsurface measurements is available. These results form the foundation for the integrated analysis of all project phases and for the development of a coherent model of large-scale groundwater movement across the Yucatán Peninsula.

Phase 4

Integration, Modeling and Assessment

Phase 4 represents the analytical and conceptual culmination of the project. In this phase, all data collected throughout the previous stages are integrated into a coherent, large-scale functional model of the aquifer system. The objective is not only to describe groundwater dynamics, but to understand the system as an interconnected whole.

Data Integration

Results from airborne surveys, surface validation, and subsurface exploration are combined within a unified spatial and analytical framework. These include:

  • aero-electromagnetic conductivity models,
  • LiDAR-derived elevation and terrain models,
  • multispectral and thermal surface data,
  • subsurface measurements, sample analyses, and flow observations.

All datasets are georeferenced, scaled, and cross-correlated to reveal structural, hydraulic, and ecological relationships.

Aquifer Function Modeling

Based on the integrated datasets, a functional model of groundwater movement is developed. The focus lies on:

  • the spatial distribution and connectivity of fractures, voids, and cave systems,
  • identification of primary transport pathways and flow corridors,
  • interactions between freshwater and saltwater, including transition zones,
  • the role of individual structures in regional water availability and the transport of nutrients and contaminants.
Risk and Dependency Assessment

Using the functional model, hydrogeological dependencies and risks are evaluated. These include:

  • potential pathways for the spread of contamination,
  • vulnerability of specific aquifer zones,
  • interactions between groundwater, terrestrial ecosystems, and marine environments,
  • impacts of human activities and future development.

This assessment enables the identification of critical areas where protection, monitoring, or management measures will be most effective.

Relevance for Conservation and Future Projects

Phase 4 translates scientific results into actionable knowledge. The model serves as a scientific foundation for:

  • Future conservation and environmental protection initiatives on the Yucatán Peninsula
  • Optimization of existing projects, such as reef and ecosystem restoration efforts
  • Informed decision-making in policy, planning, and scientific research

In this context, the project fulfills its role as a baseline study, explaining the functional behavior of the aquifer system upon which all inland and coastal ecosystems of the region depend.

Outcome

At the conclusion of Phase 4, an integrated, scientifically robust functional model of the Yucatán Peninsula aquifer system is delivered. This model represents both the endpoint of the research effort and a starting point for targeted protection, monitoring, and follow-up projects.