Drought propagation and its impact on groundwater hydrology of wetlands

Abstract. Drought can be described as a temporary decrease in water availability over a significant period and affects both surface and groundwater resources. Droughts propagate through the hydrological cycle and may impact vulnerable ecosystems. This paper investigates drought propagation in the hydrological cycle, focusing on assessing its impact on a groundwater-fed wetland ecosystem. Meteorological drought indices were used to analyze meteorological drought severity. Besides, a method for assessing groundwater drought and its propagation in the aquifer was developed and applied. Groundwater drought was analyzed using the variable threshold method. Furthermore, meteorological drought and groundwater drought on recharge were compared to investigate drought propagation in the hydrological. This research is carried out in the Doode Bemde wetland in central Belgium. The results of this research show that droughts are strongly attenuated in the groundwater system. The number and severity of groundwater discharge drought events were smaller than for groundwater recharge drought. However, the onset of both drought events occurred at the same time, indicating a quick response of the groundwater system to hydrological stresses. In addition, drought propagation in the hydrological cycle indicated that not all meteorological droughts result in groundwater drought. Furthermore, this drought propagation effect was observed in the wetland.