Groundwater recharge rates for regional groundwater modelling: a case study using GROWA in the Lower Rhine lignite mining area, Germany

Herrmann, Frank; Jahnke, Christoph; Jenn, Florian; Kunkel, Ralf; Voigt, Hans-Jürgen; Voigt, Jens; Wendland, Frank

Groundwater recharge rates for regional groundwater modelling: a case study using GROWA in the Lower Rhine lignite mining area, Germany | Taux de recharge dans la modélisation hydrogéologique régionale : un cas d’étude utilisant GROWA dans la région minière riche en charbon du Bas Rhin, Allemagne Ritmos de recarga de aguas subterráneas para el modelado regional de aguas subterráneas: un caso de estudio usando GROWA en una zona minera de lignito en el Rhin inferior, Alemania 区域地下水模拟中的地下水补给量确定: 德国莱茵河下游褐煤矿区应用GROWA模型的实例研究 Taxas de recarga de águas subterrâneas para a modelação regional do escoamento subterrâneo: um estudo de caso utilizando o modelo GROWA na zona de exploração mineira de lignito do Baixo Reno, Alemanha

2009

Groundwater recharge rates calculated with the GROWA model have been applied as the recharge boundary condition for the regional groundwater model Rurscholle. This model simulates groundwater dynamics in the Pleistocene aquifers of the Lower Rhine lignite mining area (Germany). GROWA uses an area-differentiated approach to calculate recharge rates depending on runoff-relevant site characteristics, which are represented by a set of baseflow indices. The regional accuracy of the coupled groundwater and GROWA models has been checked using groundwater hydrographs as validation criteria. The results suggest that the current (unadjusted) version of GROWA underestimates the regional groundwater recharge rate by 10–20 mm/yr. The comparative analysis identified areas where recharge calculations could be improved by adjusting the baseflow indices for areas where runoff is dominated by slope, low water-logging and a low degree of sealing. Using the adjusted set of baseflow indices, the mean groundwater recharge rate of the Rurscholle region was modelled as approx. 170 mm/yr. This study highlights the benefit of using a coupled approach and being able to independently calibrate and validate groundwater recharge boundary conditions in regional groundwater models.

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