Groundwater is central to the fight against poverty, to food and water security, to the creation of decent jobs, to socio-economic development, and to the resilience of societies and economies to climate change. However, this natural resource is often poorly understood and consequently undervalued, mismanaged and even abused. The United Nations are trying to change this by making groundwater the theme of this year’s “World Water Day”, celebrated on March 22, and of the new edition of the “World Water Development Report” (WWDR 2021), published a day ahead by UNESCO. The report, entitled ‘Groundwater: Making the invisible visible’, describes the challenges and opportunities linked to the development, management and governance of groundwater across the world. The authors argue that the vast potential of groundwater, and the need to manage it sustainably, must no longer be overlooked. Therefore, they call on States to commit themselves to developing adequate and effective groundwater management and governance policies in order to address current and future water crises.

According to the report, groundwater accounts for 99% of all liquid freshwater on Earth. Groundwater currently provides half of the volume of water withdrawn for domestic use worldwide, including the drinking water for the vast majority of the rural population who do not get their water delivered to them via public or private supply systems. Groundwater also provides around 25% of all water withdrawn for irrigation, serving 38% of the world’s irrigated land. The authors estimate that water use will grow by roughly 1% per year over the next 30 years and dependence on groundwater is expected to rise because surface water availability becomes increasingly limited due to climate change. There are many challenges related to groundwater: “Groundwater is being over-used in many areas, where more water is abstracted from aquifers than is recharged by rain and snow. Continuous over-use leads eventually to depletion of the resource,” says the report. Pollution is also a problem in many areas and remediation is often a long and difficult process. “More and more water resources are being polluted, overexploited, and dried up by humans, sometimes with irreversible consequences,” warned UNESCO Director-General Audrey Azoulay. “Making smarter use of the potential of still sparsely developed groundwater resources, and protecting them from pollution and overexploitation, is essential to meet the fundamental needs of an ever-increasing global population and to address the global climate and energy crises,” she added.

One chapter of the report provides an overview of the role of groundwater in agriculture, the sector with the largest use of the resource at a global level. “As population and income growth drives demand for more intensive and higher-value food production, for which groundwater is well suited, irrigated agriculture, livestock and related industrial uses, including food processing, are becoming increasingly reliant on this resource,” says the report. Approximately 70% of global groundwater withdrawals, and even more in arid and semi-arid regions, are used in the agricultural production of food, fibres, livestock and industrial crops. Regions heavily reliant on groundwater for irrigation include North America and South Asia, where 59% and 57% of the areas equipped for irrigation use groundwater, respectively. In Sub-Saharan Africa, where the opportunities offered by the vast shallow aquifers remain largely underexploited, only 3% of farmland is equipped for irrigation and only 5% of that area uses groundwater. The provision of cheap energy for pumping groundwater for irrigated agriculture is a problem epecially in water-scarce countries because it can lead to groundwater depletion and declining water quality. Another threat to groundwater quality is the use of fertilizers and pesticides in agriculture. Nitrate, from chemical and organic fertilizers, is the most prevalent anthropogenic contaminant in groundwater globally. Insecticides, herbicides and fungicides can also pollute groundwater with carcinogens and other toxic substances. The authors find that laws and regulations to prevent or limit pollution from agriculture, and especially their enforcement, are generally weak. Policies addressing water pollution in agriculture are thus urgently needed.

The report highlights that groundwater – which is distributed over the entire globe, albeit unequally – has the potential to provide societies with huge social, economic and environmental benefits, including climate change adaptation. The quality of groundwater is generally good, which means it can be used safely without requiring advanced levels of treatment. Groundwater is often the most cost-effective way of providing a secure supply of water to rural villages. With regard to climate change adaptation, the capacity of aquifer systems to store seasonal or episodic surface water surpluses can ensure that more freshwater is available over the entire year as aquifers have lower evaporative losses than surface reservoirs. “Decision-makers must begin to take full account of the vital ways in which groundwater can help ensure the resilience of human life and activities in a future where the climate is becoming increasingly unpredictable” says Gilbert F. Houngbo, Chair of UN-Water and President of the International Fund for Agricultural Development (IFAD). “Improving the way we use and manage groundwater is an urgent priority if we are to achieve the Sustainable Development Goals (SDGs) by 2030.”

The report also contains recommendations on what needs to be done to unlock groundwater’s full potential. First, it is necessary to collect more data on groundwater. The authors emphasizes that groundwater monitoring is often a ‘neglected area’. An entire chapter is dedicated to “Building and updating the knowledge base”. The authors mention that the private sector, particularly, the oil, gas and mining industries, already possesses a great deal of data, information and knowledge on the composition of the deeper domains underground, including aquifers. As a matter of corporate social responsibility, they should share these data and information with public sector professionals. Second, environmental regulations need to be strengthened in order to avoid groundwater pollution. According to the WWDR, preventing contamination requires suitable land use and appropriate environmental regulations, especially across aquifer recharge areas. Prevention measures listed in the report include: prohibiting or limiting certain polluting and water-using activities; limiting the use of pesticides, herbicides and fertilizers; restricting certain cropping patterns; reducing animal grazing intensity; reclaiming agricultural land; and managing drainage. Third, it is necessary to reinforce human, material and financial resources. In many countries, the general lack of groundwater professionals among the staff of institutions and local and national government, as well as insufficient mandates, financing and support of groundwater departments or agencies, hamper effective groundwater management. Governments should use limited financial resources more efficiently through tailored initiatives. The authors also write that in many countries, publicly funded activities in other sectors contribute to the depletion or pollution of groundwater resources, e.g. farm subsidies that encourage crops with high water demands. Reforming harmful subsidies and aligning them with groundwater policies should also be part of the water financing agenda. “Unlocking the full potential of groundwater will require strong and concerted efforts to manage and use it sustainably. And it all starts by making the invisible visible”, the authors conclude. (ab)