Modelling the Water Table in a Bog

Abstract: Over the past five years, an ongoing study at INES, Lund University, have examined the encroachment of trees and vegetation into a bog ecosystem in northern Scania, Sweden. While several factors have been identified as contributing to this ecological transformation, including, nutrient availability, and climate, the hydrological aspect remains a key area of investigation. This thesis aims to deepen our understanding of how the groundwater table in the bog changes over time in response to various environmental factors. To achieve this aim, extensive fieldwork was conducted during the late winter and early spring, during 2023, to measure the water table and gather data on rainfall and evapotranspiration. The measurements were taken using a combination of manual techniques, such as pressure transducers, and automated data loggers. These measurements were then combined with existing data on the bog’s hydrological regime, as well as data from SMHI (Sveriges meteorologiska och hydrologiska institut) covering the local area, to create a model of the groundwater table. The model revealed several important insights into the hydrological dynamics of the bog. Firstly, it showed that the water table responds rapidly to rainfall, with a sharp increase in water levels observed following periods of heavy precipitation. Additionally, there is also occasionally an unknown source pushing the water tables to even higher levels. Secondly, it demonstrated the importance of evapotranspiration in regulating the water balance of the bog. Thirdly, it revealed a steady rate of water runoff, indicating that the bog acts as an important water regulator for the surrounding landscape. These findings have important implications for the management and conservation of bogs and wetland ecosystems. The model created in this thesis allows forecasting of fluctuations in the groundwater table through numerical analysis of the given data, thus enabling the tracking of water table changes. Furthermore, the model can be adapted for use in other bogs and wetlands with minor adjustments, providing a valuable tool for future research in this field.