Enabling more farmers to pump groundwater can boost agricultural production and rural incomes, while making communities more resilient to climate shocks. Sustaining these benefits, however, requires informed approaches for farmers and resource managers.
At present, groundwater supplies around 40% of the world’s irrigated land, so there is potentially room for many more farmers to tap into this subterranean resource – especially in areas of limited irrigation development, such as sub-Saharan Africa. However, as much as a fifth of the food currently produced with groundwater globally relies on unsustainable extraction. Depletion of groundwater is greatest in South and East Asia; the countries of the Organisation for Economic Co-operation and Development (OECD), especially the USA; and the Near East and North Africa. Overexploitation results in falling water tables, deteriorating water quality, environmental degradation, increased pumping costs and lower crop yields.
How to manage a hidden resource
During the 2016 World Water Week in Stockholm, Sweden, IWMI launched the Groundwater Solutions Initiative for Policy and Practice (GRIPP), with the aim of helping developing economies use their groundwater resources sustainably. GRIPP unites 30 international partners (research organizations, associations, networks, universities, geological surveys, NGOs, private companies, and international donors) including the International Groundwater Resources Assessment Centre (IGRAC) of the United Nations Educational, Scientific and Cultural Organization (UNESCO). Their shared aim is to advance the agenda of sustainable groundwater management globally toward achievement of the UN Sustainable Development Goals.
“Groundwater is a hidden resource that many people rely on, especially in arid and semi-arid areas and during droughts, but few countries actively manage it,” says Karen Villholth, GRIPP coordinator and leader of IWMI’s Groundwater research group. “In some locations, the resource has been severely depleted and degraded by indiscriminate pumping and unwise land use within only one generation and with detrimental impacts on societies and the environment. We need concerted efforts and global-to-local alliances for better management of a resource that is often ignored.”
The novelty of GRIPP is that it applies multidisciplinary expertise from a diverse set of international organizations to sustainable groundwater management – through joint project development, international advocacy and dissemination of lessons learned, including the GRIPP website and a series of Groundwater Case Profiles from around the world.
The overexploitation of groundwater has reached critical levels in parts of the Middle East and North Africa. Governments across the region have developed a wide array of policies in an attempt to tackle the problem. The Groundwater Governance in the Middle East and North Africa project sought to identify the most successful of these initiatives for transfer elsewhere. Among the more effective measures considered for the region were using smart meters to ensure that groundwater is used equitably and managed aquifer recharge, which tops up groundwater with wastewater or rainwater during rainy seasons for use in dry periods.
“Tunisia has been using managed aquifer recharge since the 1970s as a means to improve groundwater quality and quantity,” explains IWMI researcher Alvar Closas. “Today, wastewater in Tunisia still causes pollution, and the country continues to expand aquifer recharge with wastewater. At present, 4% of aquifer recharge originates from treated wastewater, helping aquifers to recover and preventing the salinization of coastal aquifers caused by intruding seawater – a side effect of groundwater overabstraction.”
Aquifer exploration
One challenge with using groundwater sustainably is uncertainty about the size of the available resource. Traditional survey techniques, such as drilling boreholes to create subsurface maps, are time- and labor-intensive, often requiring access to remote areas. In recent years, Danish technologists have developed a new system with the potential to revolutionize groundwater management. Called SkyTEM, it involves using a helicopter-borne transmitter and receiver to record variations in electrical resistivity. These measurements reflect the underlying soil and rock types, enabling a three-dimensional geological model to be created. From this, the water-bearing capacity and potential areas for groundwater exploration can be assessed with reasonable accuracy.
With the help of the US water exploration company XRI Blue, SkyTEM and Savannah Helicopters, IWMI scientists used the technique in 2016 to produce the first-ever three-dimensional maps of the transboundary Ramotswa Aquifer shared between Botswana and South Africa, which is one of the most important groundwater resources in the Limpopo Basin. The data were gathered through the IWMI-led Potential Role of the Transboundary Ramotswa Aquifer project, which is part of the Resilience in the Limpopo River Basin program. The project aims to develop a strategic action plan for the aquifer, so that the water needs of ecosystems, and rural and urban populations can be met in a sustainable manner.
“A better understanding of this groundwater resource will contribute significantly to overcoming water insecurity in the face of rapid climatic, demographic and socio-economic change in the border region,” says Villholth.
