Maps of soil moisture like this one are very rare, particularly in today's world as all major governments are cutting funding of base-line environmental data collection. An extensive network of agricultural soil moisture stations over the Former Soviet Union have been interpolated to illustrate the major seasonal and regional differences in soil moisture observed over many years. This illustration is derived from depth-profile measurements that estimate the amount of water in a 2 meter column that would be available for plant growth.
Water is transported by a variety of processes.
Even if our data is not wide-spread, we can compare local concentrations of measurements with model output at that location. This schematic diagram illustrates the processes scientists try to model at the land-surface and couple to atmospheric transfers of energy and mass.