Assessing the response of groundwater quantity and travel time distribution to 1.5, 2 and 3 degrees global warming in a mesoscale central German basin

Abstract

Abstract. Groundwater is the biggest single source of high-quality fresh water worldwide, which is also continuously threatened by the changing climate. This paper is designed to investigate the response of regional groundwater system to the climate change under three global warming levels (1.5, 2, and 3 °C) in a central German basin (Nägelstedt). This investigation is conducted by deploying an integrated modeling workflow that consists of a mesoscale Hydrologic Model (mHM) and a fully-distributed groundwater model OpenGeoSys (OGS). mHM is forced by five general circulation models under three representative concentration pathways. The diffuse recharges estimated by mHM are used as outer forcings of the OGS groundwater model to compute changes in groundwater levels and travel time distributions. Simulation results indicate that under future climate scenarios, groundwater recharges and levels are expected to increase slightly. Meanwhile, the mean travel time is expected to decrease compared to the historical average. However, the ensemble simulations do not all agree on the sign of relative change. The ensemble simulations do not show a systematic relationship between the predicted change and the warming level, but they indicate an increased variability in predicted changes with the enhanced warming level from 1.5 to 3 °C. This study indicates that a higher warming level may introduce more uncertain and extreme events for the studied regional groundwater system.

Automatic regionalization of model parameters for hydrological models

“…The mesoscale Hydrological Model (mHM) (Samaniego et al, 2010;Kumar et al, 2013;Thober et al, 2019) is a distributed hydrological model that was already applied in numerous studies and for a wide range of different tasks, covering different hydroclimatic conditions (e.g., Kumar et al, 2013;Thober et al, 2018;Peichl et al, 2018;Jing et al, 2020;Imhoff et al, 2020;Saha et al, 2021). mHM is unique, as it has already TFs defined for all its parameters, which were chosen by Samaniego et al (2010); Kumar et al (2013); Thober et al (2019) based on pedo-transfer functions from literature, a "step-wise" method (Samaniego & Bárdossy, 2005) and a "trial-and-error" approach.…”