Surplus surface water can be relocated underground to refill aquifers by a process called artificial recharge. Artificial recharge increases groundwater storage, which usually has fewer environmental impacts than surface reservoirs and may result in better water quality.
There are several ways that communities can practice artificial recharge. Surface spreading is the least expensive method, yet it is still very efficient. As the name suggests, the concept includes “spreading” water across large surface features like ponds, channels, or individual catch basins. In these areas, it can percolate naturally through the ground and into subterranean water supplies.
This simple but effective method can only be used with shallow aquifers that fluctuate with the rise and fall of the water table (unconfined aquifers) and not those deeper aquifers that are encapsulated by geological features such as thick layers of clay.
Surface water must be collected and directed to spreading/seepage areas through channels, pipes, barriers, check dams, and other diversionary devices. Nature plays a major role in surface spreading. More aggressive recharge techniques employ injection methods, such as recharge wells, to deliver water quickly and directly underground.
Recharge wells are constructed much like the traditional wells designed to take water out of subterranean storage. They can reach deep into the earth and can also transfer water to encapsulated aquifers.
Once the recharge wells move water underground, it is not subject to the evaporation losses common in surface spreading systems. However, the wells are subject to clogging and, even when running smoothly, represent a more expensive and energy-intensive method of water storage and recovery than surface spreading systems.