The rate at which an aquifer is replenished depends on the climate and environment in the location where recharge is happening. Aquifers in an area of low rainfall might take centuries to get refilled. In contrast, shallow aquifers in an area of substantial rainfall may be replenished almost immediately. Thus, climate change, which results in more intense droughts, but also more intense localised rainfall, has an impact on how fast aquifers refill and, by extension, on how much groundwater people can use sustainably.
The intensive use of groundwater for human activities, such as agriculture and industry, at a scale that exceeds the speed at which aquifers refill, may put at risk not only the integrity of the aquifers, which risk collapse if they are drained, but also the global amount of water that people can use, because groundwater constitutes an important part of the world’s available freshwater.
Additionally, groundwater may not always be clean enough for human use. Human activities carried out on the surface, such as sewage disposal and the overuse of pesticides and fertilizers, including animal manure, are among the main sources of contamination and pollution of groundwater. Knowing the origin of pollutants, therefore, is the first step toward addressing problems of water quality.
