Chapter 21 - Artificial recharge techniques in coastal aquifers

Abstract

Artificial recharge is the process of spreading or impounding water on the land to increase the infiltration through the soil and percolation to the aquifer or of injecting water by wells directly into the aquifer. Confined aquifers can be recharged with wells that penetrate the aquifer. Groundwater levels are declining across the country as our withdrawals exceed the rate of aquifers to naturally replenish themselves called recharge. Artificial groundwater recharge is one method of controlling declining water levels. Artificial recharge is the practice of increasing the amount of water that enters an aquifer through human-controlled means. For example, groundwater can be artificially recharged by redirecting water across the land surface through canals, infiltration basins, or ponds, adding irrigation furrows or sprinkler systems, or simply injecting water directly into the subsurface through injection wells. When groundwater is continuously overpumped, year after year, the volume withdrawn from the aquifer cannot be replaced by recharge. Eventually, the groundwater level is much lower than its initial level, and even when pumping stops, the aquifer has trouble rising once again to its original level. In continental zones, overexploitation can lead to groundwater drawdown and, ultimately, to subsidence through the development of sinkholes when underground caverns or channels collapse. In coastal areas, the decrease in groundwater recharge results in saltwater intrusion into the aquifer formation. Preserving local groundwater resources is an environmental and economic issue in coastal zones and is vital in an island context. The increasing demand for water caused by a growing population can lead to the salinization of groundwater resources if these are systematically overexploited.