Utilization of Hydrometeorological Participatory Monitoring in Data-Scarce Remote Tropical Mountainous Regions

Abstract

Climate change is an ever‑present anthropogenic problem that affects all regions of the earth. Reliable hydrometeorological data are essential for the evaluation of the impacts of climate change, with a robust data basis providing a foundation for climate research and the development of mitigation and adaptation measures. Ground-based monitoring stations that provide such data are distributed very unevenly across the globe, and remote sensing methods may be limited in terms of spatial or temporal resolution for specific applications. This is why there is clearly a need for alternative monitoring approaches, particularly in remote tropical mountainous regions that may lack the necessary resources. Participatory monitoring, in which the public is involved in data collection, might be part of a cost-effective solution. Therefore, this work aims to investigate, how hydrometeorological participatory monitoring can be used for (1) efficient hydrological model calibration, (2) alternative observation of different hydrometeorological parameters and (3) enhancing the accuracy of other observational datasets. This methodology was tested in remote tropical mountainous regions in Ecuador, Honduras, Kenya and Tanzania, where conventional data collection methods are severely limited or unavailable. The first chapter of this dissertation analyzes how many daily participatory monitoring water level measurements at what stages of the hydrological cycle are required to achieve satisfactory hydrological model performance. A simple rainfall-runoff model was used to test this in a tropical mountainous catchment in Kenya. The analysis shows that the starting conditions of the monitoring (wet vs. dry season) influence the required amount of data. Good model performance was achieved within one month when monitoring started in the wet season, while multiple months were required when starting in the dry season. The subsequent chapter evaluates (1) how the ability of measuring air temperature, relative humidity, rainfall and water level using simple analog sensors differs between frequent and non-frequent participants and (2) how suitable the analog sensors are in terms of accuracy compared to automatic sensors. Between May 2023 and May 2025, 2,982 hydrometeorological observations were received from 52 low-cost stations in Ecuador, Honduras and Tanzania, of which frequent participants submitted the majority (84.4%), with slightly better accuracy. The analog sensor measurements showed mixed results when compared to automatically measured data. Air temperature and water level performed best with the lowest mean absolute errors (0.74 – 1.65 °C; 0.04 – 0.08 m) while relative humidity data required correction to obtain moderate accuracy (5.45 – 9.50 %) and rainfall was generally underestimated (2.55 to 3.10 mm). In the final chapter, the use of the participatory monitoring air temperature data from the previous chapter to bias‑correct a large‑scale continuous air temperature data was tested. Simple linear regression models were trained using ERA5-Land reanalysis and participatory monitoring air temperature measurements from one station in Ecuador (n = 67), Honduras (n = 23) and Tanzania (n = 275). The models were then used to correct the ERA5-Land air temperature bias over a period for which automatically measured hourly reference air temperature data was available (up to one and a half years). ERA5-Land air temperature bias was reduced at all stations, but with varying degrees. The most significant reduction was obtained in Ecuador, with the mean absolute error decreasing from 5.49°C to 1.76°C. To conclude, this research shows that hydrometeorological participatory monitoring has the potential to improve overall data availability in remote tropical regions with limited financial resources. The knowledge gained from this research could help to inform future participatory monitoring programs and strengthen the acceptance of data collected using such alternative approaches.