Mitze et al. (2026) Validation of analog sensor measurements in hydrometeorological participatory monitoring in various tropical countries

Identification

• Journal: Frontiers in Earth Science
• Year: 2026
• Date: 2026-02-05
• Authors: Fabian Mitze, Suzanne Jacobs, Lutz Breuer, Jazmin Campos Zeballos, Fabia Codalli, Frank Shagega, Björn Weeser
• DOI: 10.3389/feart.2026.1721642

Research Groups

• Center for International Development and Environmental Research, Justus Liebig University Giessen, Giessen, Germany
• Institute for Landscape Ecology and Resources Management (ILR), Research Centre for BioSystems, Land Use and Nutrition (iFZ), Justus Liebig University Giessen, Giessen, Germany
• Faculty of Agriculture, University of Bonn, Bonn, Germany
• Water Resources Engineering Department, College of Engineering and Technology, University of Dar es Salaam, Dar es Salaam, Tanzania

Short Summary

This study validates a participatory monitoring approach using analog low-cost sensors for hydrometeorological data collection in tropical mountain regions, finding that analog thermometers and water level gauges provide reliable data, while hygrometers require correction and small rain gauges are inadequate for heavy rainfall.

Objective

• To validate a participatory monitoring approach for collecting hydrometeorological data in remote mountainous regions in Ecuador, Honduras, and Tanzania.
• To assess how well frequent and non-frequent participants can measure hydrometeorological parameters using simple analog sensors.
• To evaluate the accuracy of analog sensor measurements by participants compared to automatic sensors.

Study Configuration

• Spatial Scale: Remote tropical mountain regions across three countries: Ecuador (Cajas National Park, Cuenca, Tomebamba), Honduras (Cacique Lempira Biosphere Reserve, Celaque National Park), and Tanzania (southern slopes of Kilimanjaro National Park).
• Temporal Scale: May 2023 to May 2025 (2 years).

Methodology and Data

• Models used: Linear regression (for correcting relative humidity measurements).
• Data sources:
  • Participatory Monitoring (PM) Data: 2,982 observations collected by volunteers using analog low-cost sensors (thermometers, hygrometers, 35 mm capacity rain gauges, and 1 m rigid foam/metal staff water level gauges). Data submitted via a smartphone application or web interface, often accompanied by photos for validation.
  • Automatic Sensor Data: Reference data from automatic sensors installed at selected stations, including Lascar Electronics EL-USB-2+ loggers (air temperature, relative humidity), Metek Rain gauge 7043.0100 tipping buckets (rainfall), and Driesen and Kern pressure transducers (water level) with corresponding barometers.

Main Results

• Frequent participants contributed 84.4% of observations and showed lower error rates across all parameters compared to non-frequent participants (e.g., air temperature error rate: 2.7% for frequent vs. 3.5% for non-frequent).
• Comparison with automatic sensor data showed high correlation for all parameters (0.42 to 0.96).
• Air temperature: Achieved the best accuracy with a Mean Absolute Error (MAE) of 0.74 °C–1.65 °C and Spearman Rank correlation (rspear) of 0.92–0.96.
• Water level: Showed good accuracy with an MAE of 0.04–0.08 m and rspear of 0.81–0.87.
• Relative humidity: Initially had high deviation (MAE: 16.76%–31.69%) but acceptable correlation (rspear: 0.76–0.91). After correction using linear regression, MAE was substantially reduced to 5.45%–9.50%.
• Rainfall: Exhibited high deviation (MAE: 2.55–3.10 mm) and variable correlation (rspear: 0.42–0.80). The limited capacity of the 35 mm rain gauges led to the exclusion of up to 17% of rainfall events, and deviations increased with longer intervals between measurements.
• Analog thermometers and water level gauges are considered promising alternatives to automatic sensors for hydrometeorological monitoring. Analog hygrometers provide moderate quality data, while the small rain gauges are not suitable for accurate continuous daily rainfall monitoring, especially for heavy rainfall.

Contributions

• Validated a novel participatory monitoring approach for hydrometeorological data collection in data-scarce tropical mountain regions, demonstrating its feasibility and limitations.
• Quantified the performance differences between frequent and non-frequent citizen science participants, highlighting the value of local community engagement for data quantity and quality.
• Provided a detailed assessment of the accuracy of low-cost analog sensors for air temperature, relative humidity, rainfall, and water level against professional automatic sensors.
• Identified specific strengths (air temperature, water level) and weaknesses (relative humidity requiring correction, limited capacity of rain gauges) of analog sensors in a PM context.
• Offered practical recommendations for future PM projects, including sensor selection, station shielding, measurement frequency, and potential integration with remote sensing and hydrological modeling.

Funding

• DFG project “Biodiversity and the supply of water-related NCPs” (BR 2238/35-1/-2 and JA 3059/4-2) as part of the DFG Research Unit 5064 “The role of nature for human wellbeing in the Kilimanjaro Social-Ecological System” (Kili-SES).
• Kurt Eberhard Bode Foundation for funding the junior research group “HydroCrowd” (grant number 0122/40195/2022).

Citation

@article{Mitze2026Validation,
  author = {Mitze, Fabian and Jacobs, Suzanne and Breuer, Lutz and Zeballos, Jazmin Campos and Codalli, Fabia and Shagega, Frank and Weeser, Björn},
  title = {Validation of analog sensor measurements in hydrometeorological participatory monitoring in various tropical countries},
  journal = {Frontiers in Earth Science},
  year = {2026},
  doi = {10.3389/feart.2026.1721642},
  url = {https://doi.org/10.3389/feart.2026.1721642}
}