We present a global model of ocean tide loading (OTL)-induced surface deformation for the M2 harmonic constituent. The model quantifies three-dimensional displacement amplitudes and phases across the horizontal (west and south) and vertical (up) components. Computations were performed using the advanced VILMA-E software (Tanaka et al., 2021; Huang et al., 2021), which integrates the TPXO9.5 global tide model (Egbert & Erofeeva, 2002) with a three-dimensional anelastic Earth structure optimized for OTL observations (Huang et al., 2025). The final output is provided as a high-resolution global grid (0.1° × 0.1°) in netCDF format, compatible with standard geospatial processing tools such as NCO and CDO for efficient data access and analysis.
Knowledge of groundwater flow is of high relevance for groundwater management and the planning of different subsurface utilizations such as deep geothermal facilities. While numerical models can help to understand the hydrodynamics of the targeted reservoir, their predictive capabilities are limited by the assumptions made in their set up. Among others, the choice of appropriate hydraulic boundary conditions, adopted to represent the regional to local flow dynamics in the simulation run, is of crucial importance for the final modelling result. In this publication we present the hydrogeological models to obtain results to quantify how and to which degree different upper hydraulic boundary conditions and vertical cross boundary fluid movement influence the calculated deep fluid conditions Therefore, we take the central Upper Rhine Graben area as a natural laboratory. The presented three models are set up with different sets of boundary conditions. The Reference Model uses the topography as upper hydraulic pressure surface of 0 kPa. In model S1, a subdued replica of the topography, which was built on the base of hydraulic head measurements is applied as the upper hydraulic boundary condition and in model S2 vertical cross boundary flow is implemented.
Based on our results, we illustrate in the landing paper that for the Upper Rhine Graben specific characteristics of the flow field are robust and insensitive to the choice of imposed hydraulic boundary conditions, while specific local characteristics are more sensitive. Accordingly, these robust features characterizing the first order groundwater flow dynamics in the Upper Rhine Graben include: (i) a regional groundwater flow component descending from the graben shoulders to rise at its centre; (ii) infiltration of fluids across the graben shoulders, which locally rise along the main border faults; (iii) the presence of heterogeneous hydraulic potentials at the rift shoulders. The configuration of the adopted boundary conditions influence primarily calculated flow velocities and the absolute position of the upflow axis within the graben sediments. In addition, the choice of upper hydraulic boundary conditions exerts a direct control on the evolving local flow dynamics, with the degree of influence gradually decreasing with increasing depth.
With respect to regional flow modelling of basin hosted, deep water resources, the main conclusions derived from this study are: (i) the often considered water table as an exact replica of the model topography (Reference Model) likely introduces a source of error in the simulations in regional hydraulic modelling approaches. Here, we show that these errors can be minimized by making use of a water table as upper boundary condition derived from available hydraulic head measurements (model S1). If the study area is part of a supra-regional flow system - like the central Upper Rhine Graben is part of the whole Upper Rhine Graben - the in- and outflow across vertical boundaries need to be considered (model S2).
The need for the software is based on being able to make a statement as to whether the operation of a Pumped Hydropower Storage (PHS) facility in a former open-pit lignite mine can have a negative impact on the water quality in the lower reservoir and associated aquifers. The research question arises since flooded lignite mines are often associated with acidification and/or increased sulphate and metal concentrations. Thus, the software aims at modelling geochemical processes during the PHS operation in open-pit lignite mines.
The reaction path modelling framework comprises a Python framework for data management and a solver for geochemical reactions (phreeqc/phreeqpy; Parkhurst and Appelo, 2013; Müller, 2011). The software is based on a conceptual geochemical model that includes the main geochemical processes that are expected to influence the hydrochemistry. It integrates different non-dimensional batch reactors, each representing the water composition of the reservoirs, and water sources or sinks in the PHS system (groundwater, rainwater, surface run-off, mine dump water). These waters are cyclically mixed with ratios deducted from flow rates and time-dependent influxes of a hypothetical PHS system.
The water influxes have different chemical compositions based on the geochemical scenarios defined with the input data. An instant flooding of the mine with scenario-specific mixing ratios of rainwater, groundwater and mine dump water is simulated to provide an initial solution in the LR for the PHS operation. For the simulation of the PHS operation, the water volume of the UR is extracted from the LR and equilibrated with atmospheric partial pressures of oxygen and carbon dioxide to represent the water composition after pumping. The water composition evolving at the reservoir-mine dump interface layer is simulated by a kinetically controlled reaction of pyrite (Williamson and Rimstid, 1994) and calcite (Plummer, 1978) with the LR water. During the PHS discharge cycle, water flows into the adjacent mine dump sediments due to the increasing hydraulic head gradient in the LR compared to the surrounding groundwater aquifers. Water from the LR is mixed with rainwater, groundwater, surface run-off, and water from the reservoir-mine dump interface layer according to the water volumes that enter the reservoir during the respective cycle. Finally, the new water composition in the LR is mixed with the water from the UR to simulate the PHS discharge into the LR. Apart from gas exchange, evaporation and precipitation, no reactions are simulated for the water in the UR, as the reservoir is assumed to be artificially sealed.
Pump and discharge cycles are simulated until the pH and sulfate concentrations in the LR do not change by more than 1 x 10-4 and 1 x 10-5 mol kgw-1 within two consecutive PHS cycles, respectively. Otherwise, the simulation is terminated after 7,300 PHS cycles, representing 20 years of operation with a duration of one day per cycle. Input parameter ranges can cover a wide range of potential hydrogeochemical scenarios. In the software provided with this manual, a small range of generic data is defined as input to limit the simulation time and data output. However, the input can be modified to simulate a broader range of geochemical scenarios as described in the associated data description file.