Detecting canopy water fluctuations with low-cost GNSS receivers
Field activities will be in summer 2024, and some preparations may be required in spring.
Suitable for both M-SE and M-GEO.
The researchers involved in the projects are:
Dr. Roelof Rietbroek and Dr. Paul Vermunt from WRS Dpt
Forest health worldwide is under pressure as a result of prolonged droughts. Monitoring the water content in trees is essential for studying their vulnerability to water stress, wildfires and insect attacks. However, there is little known about how to monitor the water content in the leaves or needles continuously. An upcoming low-cost method is based on GNSS (or GPS) signals. GNSS signals are available everywhere and recently the attenuation of these signals has been linked to tree water content. Low-cost GNSS receivers are now widely available on the mass commercial market. However, we do not yet fully understand how these low-cost GNSS receivers can be deployed for measuring tree water content.
The key questions for this MSc project are: (1) Can we use low-cost GNSS receivers to quantify water dynamics in a forest? (2) What would be the requirements for a large-scale network of GNSS receivers for forest drought monitoring? To answer these questions, you will conduct field experiments and compare time series from suitable low-cost and medium-cost GNSS receivers. The GNSS receivers will be located in Speulderbos, an enclosed coniferous forest site in the centre of the Netherlands, managed by the faculty of ITC.
Humphrey, V., & Frankenberg, C. (2023). Continuous ground monitoring of vegetation optical depth and water content with GPS signals. Biogeosciences, 20(9), 1789-1811.
Chew, C., n.d. Soil Moisture Remote Sensing using GPS-Interferometric Reflectometry 175.
Liu, J., Hyyppä, J., Yu, X., Jaakkola, A., Kukko, A., Kaartinen, H., ... & Hyyppä, H. (2017). A novel GNSS technique for predicting boreal forest attributes at low cost. IEEE Transactions on Geoscience and Remote Sensing, 55(9), 4855-4867.
The topic can be adapted to Spatial Engineering by describing the problem from a broader perspective/angle. For instance, climate change can both increase (CO2 availability) and decrease (prolonged droughts) forest health. And there are many different views on how to manage our forests in a changing world, from ecological, hydrological, climate, and economic perspectives. Meanwhile, the time is pressing and forests grow slowly. The student can elaborate on the question to what extent monitoring tree water content can contribute to these discussions.