Abstract
An essential factor in the propagation of drought, from meteorological drought to groundwater drought, is the delay between a precipitation event and the groundwater recharge reaching the groundwater table. This delay, which mainly occurs in the vadose zone of the hydrological cycle, is often poorly studied. Therefore, this paper proposes a method for estimating the spatially distributed delay in the vadose zone using the kinematic wave approximation of Richards’ equation combined with the van Genuchten–Burdine and Brooks–Corey parametric model. The modeling was approached (1) using a detailed parametrization of soil and geological layers and (2) using lumped hydraulic and physical properties of geological layers. The results of both approaches were compared against the physically based flow model Hydrus-1D. This analysis shows that using a detailed parametrization of soil and geological layers results in good comparison, with a Nash–Sutcliffe efficiency of 0.89 for Brooks–Corey and 0.80 for van Genuchten–Burdine. The delay result of the Brooks–Corey model was incorporated into the groundwater recharge time series from 1980 to 2013 to analyze the effect of this delay on groundwater drought. The results show that the delay in the vadose zone influences groundwater drought characterization features such as the number, duration, and intensity of drought events.
Highlights
Drought can be described as a temporary decrease in water availability over a significant period of time
The van Genuchten–Burdine model gives a higher estimation of soil moisture than the Brooks–Corey
Spatially distributed groundwater recharge delay through the vadose zone was estimated in the Dijle and Demer catchments in Central Belgium
Summary
Drought can be described as a temporary decrease in water availability over a significant period of time. The first refers to a period with little or no precipitation; the second refers to a shortage of water in the soil and as such for vegetation; the third describes the impact on hydrological water bodies. It can affect both surface and groundwater resources. Groundwater drought can be defined as a temporary decrease in groundwater availability over a significant period of time This drought causes decreased groundwater levels and discharge to the surface water system [1]
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