I am working on a project that focusses on groundwater of the Marico Biosphere Reserve in South Africa and I would like to determine the general direction groundwater flows through the study area. Using the South African National Groundwater Archive, I requested information for 3000 boreholes within and surrounding the study area:
For the selected boreholes in the above image, I have the depth of the latest water level reading as well as the elevation of the borehole itself. Using either QGIS or Global Mapper, what would be the best way to determine the general flow of groundwater?
"borehole_elevation" - "water_depth". Interpolate the points to create a smooth surface of groundwater elevation, then create a slope raster. Those last two steps are explained in the link @cyril provided.