Fig. 2: A machine learning approach can synthesize ~ 1 M water table depth observations with high-resolution data products to develop a fine-scale estimate of the quantity and accessibility of groundwater over the US.
From: High resolution US water table depth estimates reveal quantity of accessible groundwater

This product is national in scope and covers 7.3 M km2 yet provides detail at one arc-second (~30 m) resolution. Insets A and B demonstrate these changes in scale, starting at a pixel 100 km on a side, scaling down to show the range of water table depths (WTD) present in even a 1 km cell. Note the log scale in this figure.