Combined water table and temperature dynamics control CO ₂ emission estimates from drained peatlands under rewetting and climate change scenarios

Abstract. This study integrates process-based hydrological modeling and empirical CO2 flux modeling at a daily temporal resolution to evaluate how peatland hydrology influence CO2 emissions under scenarios of rewetting and climate change. Following the calibration of a three-dimensional transient physically-based hydrological model for a peat-dominated catchment, daily groundwater table dynamics were simulated to represent hydrological conditions in drained peat soils. These simulations were coupled with an empirical CO2 flux model, developed from a comprehensive daily dataset of groundwater table depth, temperature, and soil CO2 flux measurements. The empirical CO2 flux model captures a clear temperature-dependent response of soil CO2 emissions to variations in groundwater table depth. By applying this coupled modeling framework, we quantified CO2 emissions at daily timescales. The results demonstrate that incorporating both temperature sensitivity and high-resolution temporal variability in water level significantly influences projections of CO2 fluxes. Especially the co-occurrence of elevated air temperature and low groundwater table significantly influence CO2 emissions under scenarios of rewetting and climate change. These insights highlight the importance of including changing climate conditions in future peatland management strategies for emission inventories. The study illustrates the value of combining detailed hydrological simulations with emission models. It also emphasizes the need for detailed monitoring of greenhouse gas emissions across multiple sites and the development of robust empirical models that can be generalized and spatially upscaled.