B0606
Title: A changepoint approach to modelling soil moisture dynamics
Authors: Mengyi Gong - Lancaster University (United Kingdom) [presenting]
Rebecca Killick - Lancaster University (United Kingdom)
Christopher Nemeth - Lancaster University (United Kingdom)
Abstract: Soil moisture is an important measure of soil health that scientists model via soil dry-down curves. The typical modelling process requires manually separating the soil moisture time series into segments representing the drying process and fitting exponential decay models to them. This can be time-consuming for a large data set. The result is a static overview of the dry-down property. Motivated by the spike-train problem in neuroscience, we propose a novel changepoint-based approach to automatically identify structural changes in the soil drying process. Changes caused by sudden rises in soil moisture over a long time series are captured and the parameters characterising the drying processes are estimated simultaneously. We allow segment-specific parameters to capture potential temporal variations in the drying process. The method can be considered as a complement to the conventional soil dry-down modelling. An algorithm based on the penalised exact linear time (PELT) method was developed to identify the changepoints. A simulation study was carried out to access the performance of the method. The result demonstrated its ability to locate structure changes and retrieve key parameters. The method was applied to the 2-year hourly soil moisture time series from the NEON portal.
