Hydraulic gradient map for Germany

Hydraulic Gradient Map for Germany Overview This dataset provides a spatially resolved map of the hydraulic gradient across Germany. The hydraulic gradient represents the spatial rate of change of hydraulic head and is a key parameter in regional groundwater flow analysis. It is required to estimate advective groundwater flow velocities using Darcy’s Law. The dataset was compiled to support geospatial hydrogeological analyses within the GeoNinja modeling framework and related groundwater flow applications. Geographic coverage: GermanySpatial domain: National extentDataset unit: Percent (%)Coordinate reference system: (EPSG:3857)Spatial resolution: 446.93 m (pixel size), raster dimensions 2284 × 3101.Data format: GeoTIFF Purpose This dataset is intended to provide spatially explicit hydraulic gradient values for: Estimation of regional groundwater flow velocity using Darcy’s Law Screening-level hydrogeological suitability assessments Advective heat transport estimation in Aquifer Thermal Energy Storage (ATES) studies Integration into geospatial decision-support tools Within GeoNinja, the hydraulic gradient is used to compute Darcy flow velocity: v = K ⋅ i where: K = hydraulic conductivity i = hydraulic gradient (this dataset) The map therefore represents a core input parameter for estimating subsurface advective transport. Data source The hydraulic gradient is derived from an estimated map of absolute hydraulic head. The hydraulic head was approximated by subtracting the groundwater table depth from the surface elevation. The groundwater table depth was taken from the global dataset of Y. Fan, H. Li, G. Miguez-Macho: Global Patterns of Groundwater Table Depth, Science 339(6122), 2013. DOI: 10.1126/science.1229881. which provides spatially distributed estimates of groundwater table depth. The surface elevation was obtained from the German digital elevation model DGM200, https://gdz.bkg.bund.de/index.php/default/digitales-gelandemodell-gitterweite-200-m-dgm200.html Processing The hydraulic gradient was calculated from the estimated hydraulic head raster using the GDAL slope algorithm implemented in QGIS 3.36.3. This computes the slope based on the Zevenbergen–Thorne algorithm with the output expressed as percent slope. Edge calculation was enabled to ensure that the gradient was computed across the full raster extent. Limitations The hydraulic gradient represents a large-scale regional estimate and does not resolve local heterogeneities. Values do not reflect transient seasonal variations. The dataset should be used for screening and regional assessments rather than site-specific engineering design. Intended Use in GeoNinja Within the GeoNinja backend, this dataset is used for: Location-based parameter lookup Darcy velocity calculation Estimation of advective thermal transport effects The dataset is not intended to replace detailed site-specific hydrogeological investigations.