Effects of Climate Change on Future Groundwater Availability

Climate change is a conspicuous and imperious global challenge of the 21st century that has far-reaching influences on various aspects of the ecosystem, environment, and human life. Scientists and researchers around the world have predicted the consensus that climate patterns are changing. One of the most concerning and often overlooked aspects of this crisis is the impact on groundwater, which is a reliable resource for drinking water, agriculture and other resource processes. Groundwater constitutes about 30% of the worldwide freshwater resources, which are vital for human life and the ecosystem. Of the remaining 70%, approximately 69% is stored in ice caps and mountain snow/glaciers, while only 1% is found in rivers and lakes. On average, groundwater accounts for one-third of the freshwater consumed by humans, but in certain regions of the world, this percentage can reach 100%. An overview of the distribution of water on Earth is provided in the figure below.

Source: Earth’s water distribution (Shiklomanov, 1993). https://www.un-igrac.org/what-groundwater.

Significance of the Groundwater

Groundwater is the most resource water found underground in the crevices and spaces in soil, sand, and rock. It is stored in and moves gradually through geological formations of soil, sand, and rocks called aquifers. However, Groundwater is a censorious constituent of the hydrological cycle, which also consists of surface water sources such as lakes, rivers and oceans.

Drinking Water: The primary source of groundwater in various regions, especially in dry and semi-arid areas is drinkable water.

Agriculture: Groundwater is the most important resource for irrigation and supporting food production worldwide.

Industry: Most industrial processes use substantial amounts of water, which is mostly drawn from underground sources.

Ecosystems: Groundwater underwrites the robustness of various significant threats to ecosystems, as well as wetlands and rivers, by preserving improper flow during dry periods.

Climate Change and the Hydrological Cycle 

Climate change does not only affect the hydrological cycle like evaporation and precipitation in different ways with significant implications for groundwater quantity but also its quality. Sea level rise could be leading to saltwater interruption in coastal aquifers, which can infiltrate freshwater sources and affectation substantial challenges for water management.

Source: Amobichukwu C. Amanambu (2020): Groundwater systems interaction with Earth's components in the face of climate change. Directly, changes in precipitation (amount, timing and form), evaporation, transpiration and, indirectly, extraction, affect the groundwater system. All these may separately or together impact the numerous processes and mechanisms of the groundwater system. GDEs—Groundwater Dependent Ecosystems.

Changes in Precipitation Patterns:

Climate change indicates that rising temperatures intensify alternating patterns of precipitation worldwide. In general, some regions are encountering increased precipitation, while others are facing protracted droughts. These climate changes impact the groundwater recharge rates which are important for sustaining groundwater levels.

Increased Precipitation: In areas facing more enormous precipitation, there can be a higher amount of surface runoff, resulting in less water penetrating the ground and recharging aquifers.

Decreased Precipitation: In areas with a reduction in precipitation, there is a decrease in groundwater recharge, thereby causing water deficiency.

Seasonal Shifts: The recharging of groundwater could also be influenced by fluctuations in the timing of precipitation. For instance, rainfall occurring beyond the growing season may have less effect on plant absorption and instead provide increased potential for recharge.

Temperature Increases

Increased temperatures induced by climate change affect evaporation rates, soil moisture and water use by plants, which in turn impacts groundwater.

Evaporation: Increased temperatures cause more water to evaporate from soil and surface water bodies, which lowers the amount of water that can seep into the ground.

Soil Moisture: Rising temperatures can have the potential to enhance plant transpiration, which would further decrease soil moisture content and recharge rates.

Plant Water Use: Increased temperatures have the potential to increase plant transpiration, which would further reduce soil moisture content and recharge rates.

Sea-Level Rise

Sea-level rise caused by the melting of polar ice caps and thermal expansion of seawater poses a major threat to coastal aquifers.

Saltwater Intrusion: Increased sea level could be due to saltwater infringe on coastal freshwater aquifers, interpreting of the water as unsuitable for drinking and irrigation.

Coastal Flooding: Increased frequency and intensity of coastal flooding could be leading to the contamination of freshwater supplies with saltwater water.

The Indo-Gangetic Plain

The Indo-Gangetic Plain is a large area in parts of India, Pakistan, Bangladesh, and Nepal, which are mostly densely populated and agriculturally productive regions. Furthermore, there are several faces challenges including agriculture and over-extraction of groundwater due to significant declines in water levels. Arsenic and fluoride are also being faced in most of the areas. Additionally, changes in monsoon patterns, regular drops in rainfall, continued dry spells of groundwater recharge, and temperature increases are amplifying evaporation rates.

Reference:

1. IGRAC, the International Groundwater Resources Assessment Centre

2. Amanambu, A.C., Obarein, O.A., Mossa, J., Li, L., Ayeni, S.S., Balogun, O., Oyebamiji, A. and Ochege, F.U., 2020. Groundwater system and climate change: Present status and future considerations.