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The Invisible Giant: Understanding, protecting and managing the Amazon Aquifer System to complete the Amazon puzzle

GEF-UNEP/ACTO Amazon River Basin Project

By IW:LEARN

March 21^st, 2022

GEF IW:LEARN World Water Day 2022 Special Bulletin

Everything about the Amazon is huge, complex, and connected. We are familiar with the majestic view of the immense Amazon river flowing for close to 7,000 km from the Andes mountains through dense rainforest, traditional villages or modern cities, to discharge a 15-20% of the global freshwater into the Atlantic Ocean. Many of us are also aware of the ‘flying rivers’ above the Amazon transporting billions of tons of water vapor to ensure sufficient rainfall for people and ecosystems far away in the South-East of the continent. But there is still another invisible piece to the complex Amazon puzzle: the little-known giant lying beneath much of the basin - the Amazon Aquifer System.

The Amazon region is a complex mosaic of various geological, geomorphic, climatologic, hydrographic and biological processes, enacted mainly by the dynamics of the hydrological cycle. In this system, the rich Amazon surface drainage network, shared by Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, Suriname and Venezuela, is strongly and intrinsically connected to transboundary aquifer systems, which are crucial pieces in sustaining the functioning of the Amazon watershed and ecosystems and ensuring its role in the regional and global water and climate cycle, and ecological equilibrium. Groundwater is also a strategic reserve for water, food, and environmental security, an improved quality of life for the local population, and socio-economic sustainability in the Amazon region.

The largest transboundary groundwater system and water reserve on the planet?

The Amazon aquifer system is considered as one of the largest transboundary groundwater systems in the world, maybe the largest. But we still don’t know. Initial estimates by the National Water and Basic Sanitation Agency (ANA) of Brazil suggest an extension of more than 3.9 million km2 with a total volume of 952,600 km3 and 123,838 km3 of permanent water reserve in Brazil alone, and with a potential extraction yield of 250 km3/year (ANA, 2015).

Although the Amazon’s freshwater supply exceeds by far the demands of the region, water quantity and quality are being negatively impacted by economic activities (agriculture, industry and mining, among others), accelerated urbanization and land occupation (Amazon TDA, 2018), which turns users in urban centers and settlements to groundwater sources. It is estimated that almost two-thirds of municipal centers in the Brazilian Amazon use groundwater as the only source of supply.

As urban settlements grow, new productive activities develop, and extreme events intensify, and thus the human dependency on groundwater supply throughout the Amazon region also tends to increase considerably, exerting pressures on the aquifer systems and demanding improved, sustainable and coordinated management of the resource. But how to advance management of this invisible and vulnerable transboundary resource when its hydrogeological characteristics, ecosystem functions and socio-economic importance are still not fully understood?

Fully aware of this barrier, the Amazon countries agreed to cooperate to expand the knowledge of the Amazon aquifers, assess the conjunctive use of surface and groundwater use for water supply and promote transboundary planning and source protection.

Amazon Transboundary Aquifer System. Image credit: GEF-UNEP Amazon SAP project

The GEF Amazon Project: Integrating groundwater in regional strategic planning

The GEF Amazon project, implemented by UNEP and executed by the Amazon Cooperation Treaty Organization (ACTO), was a milestone in incorporating groundwater in the integrated water resources management in the Amazon Basin through the agreed Strategic Action Programme (SAP).

The process leading to the development of the SAP built on the results from the targeted research study of the aquifers in the Amazon Hydrogeological Province (AHP) in Brazil, carried out by the National Water Agency of Brazil (ANA). Including a 3D lithological analysis, using 189 wells from the Petroleum Exploration Database and a hydrogeological flux model of the AHP in Brazil and detailed studies in selected pilot cities, the targeted study covered many information gaps of the hydrogeology of the AHP (ANA 2015). The main problems identified in the use of aquifers in the Amazon were overexploitation, erosion in upwelling areas, water contamination from urban and industrial wastewater sources, and conflicts between users. Nevertheless, the study made it evident that there is still lack of basic information and knowledge about the extent and permeability of the aquifer systems in Brazil and the other riparian countries, while confirming the challenges of managing shallow level groundwater systems at local, national and regional levels.

At the municipal level, the GEF Amazon Project carried out two pilot projects: (i) Sustainable Groundwater Use in Amazon Urban Centers: the Case of Manaus (Brazil) and (ii) Conjunctive Use of Ground and Surface Waters in the Tres Fronteras Region (Brazil, Colombia, Peru). The activity in Manaus, executed by ANA Brazil, consolidated the geological characterization of the Alter do Chão Aquifer and assessed the aquifer management in the urban area, including main water users (Manaus industrial complex; residential condominiums; and Manaus Ambiental public supply company), existing water management plans, groundwater catchment points, vulnerability maps and identification of potential point source pollution. The pilot recommended solutions to the most pressing issues of: aquifer overexploitation, vulnerability and pollution and for conjunctive surface/groundwater management in the city of Manaus (estimated population: 2.255.903 (IBGE-2021).

At the same time, the pilot project in the Tres Fronteras region, evaluated the transboundary aquifer system connecting the twin cities of Leticia (Colombia) and Tabatinga (Brazil). The project characterized the aquifers, assessing their vulnerability in terms of pollution, exploitation and climate change in the context of urban drinking water supply based on a conjunctive use of ground and superficial water resources, and projected water demand and supply scenarios for 2040. Through local stakeholder meetings and a bi-national validation workshop (Leticia, September 2015), the activity facilitated public participation and regional coordination for joint border planning and cooperation strategies for future use and protection of the groundwater resources. In Colombia, the results of the study “Evaluation of the Aquifer Systems of the Leticia-Colombia Region” supported the development of the master plan for Leticia’s aqueduct and sewer system. The assessment also identified the main knowledge gaps and the need for additional coordinated studies in the region.

The knowledge, experiences and recommendations resulting from the targeted study and the pilots in Manaus and Leticia-Tabatinga informed the formulation of two strategic actions on groundwater included in the regional SAP: (i) Developing a groundwater use and protection program for public supply in the Amazon Region, and (ii) Protecting, managing and monitoring aquifers in the Amazon River Basins.

Thus, the 8 Amazon countries agreed on the importance of local level management systems in urban areas due to the widespread contamination and relevance of groundwater for human use, while at the same time prioritizing the study of the basin level aquifer systems in order to ensure their protection, monitoring and sustainable management at the system level, as an essential life-sustaining element of the Amazon society and ecosystems.

Leticia. Image credit: GEF-UNEP Amazon project

Implementing the Amazon SAP: assessing and managing groundwater at the local level

Under the recent Amazon SAP Implementation Project (ACTO/UNEP/GEF), the eight Amazon countries are advancing local level interventions focusing on understanding and managing water supply from groundwater and providing source protection solutions to reduce contamination, in the context of adaptation to climate change.

The Project is carrying out a hydrogeological, vulnerability and risk assessment for development of groundwater use and protection policies in the transboundary region of Leticia (Colombia) and Tabatinga (Brazil), building on the results from the previous pilot project. At the same time, monitoring networks for quantity and quality of groundwater are being established in important urban aquifers of the Madeira River basin, including the cities of Santa Cruz de la Sierra and Sacaba, in Bolivia.

Technological alternatives for groundwater use in public supply systems of isolated communities of the Amazon Basin will be developed and implemented in Brazil, while a watershed management plan for the Rupununi Area in Guyana will be designed to include protection of aquifer recharge zones in the Upper Takatu Region.

These interventions will advance data and implement solutions as input to a regional program for rational use and protection of aquifers in urban centers, considering adaptation to climate change.

Nevertheless, the knowledge of the aquifers in the Amazon is still not sufficient to have a coherent integrated understanding of its features at the transboundary level supporting coordinated regional protection and management. Moreover, there is a need to create and implement national public policies aligned to the peculiarities of the Amazon Region, improve technical and legal capacities, and promote coordinated actions, further enhancing the understanding of the functioning of the aquifer system in the Amazon surface-groundwater environmental continuum.

The eight Amazonian countries are ready to face this challenge.

Amazon. Photo credit: GEF-UNEP Amazon project

References

ANA (2015). Avaliação dos Aquíferos das Bacias Sedimentares da Província Hidrogeológica Amazonas no Brasil (escala 1:1.000.000) e Cidades Pilotos (escala 1:50.000). Volume XI – Resumo Executivo. Brasília.

ACTO (2018). Regional Transboundary Diagnostic Analysis of the Amazon basin.

About the GEF-UNEP/ACTO Amazon River Basin Project

The GEF funded, UNEP implemented and Amazon Cooperation Treaty Organization (ACTO) executed "Implementation of the Strategic Action Programme to Ensure Integrated and Sustainable Management of the Transboundary Water Resources of the Amazon River Basin Considering Climate Variability and Change" project aims to implement the Strategic Action Program (SAP), promote Integrated Water Resources Management (IWRM) and source-to-sea approaches, to improve ecological, social and economic benefits and, enabling the countries to meet their relevant SDG and convention targets in the Amazon basin.

For more information kindly contact the Project Manager, Maria Apostolova (maria.apostolova@otca.org), the Secretary General of ACTO Alexandra Moreira (alexandra.moreira@otca.org), visit the website, or the dedicated webpage on iwlearn.net.