The G-res Tool

The GHG Reservoir (G-res) Tool is a web-based tool for hydropower companies and researchers to estimate and report net greenhouse gas emissions from a reservoir.

A decade in development, the G-res Tool was first launched in May 2017 as part of a multi-stakeholder research project led by the International Hydropower Association (IHA) and the UNESCO Chair in Global Environmental Change.

The G-res Tool uses a conceptual framework built with scientists from the University of Quebec at Montreal (UQAM), the Norwegian Foundation for Scientific and Industrial Research (SINTEF) and the Natural Resources Institute of Finland (LUKE), with financial assistance from the World Bank.

Using the tool gives investors, regulators and local communities greater confidence in the carbon footprint of a reservoir.

History and development

Since 2006, the International Hydropower Association has been working with UNESCO, the World Bank and a range of stakeholders to develop common understanding to assess the carbon profile of hydropower facilities and reservoirs.

This work resulted in the publication of the UNESCO/IHA GHG Measurement Guidelines for Freshwater Reservoirs.

The guidelines helped the hydropower industry to better understand where GHG emissions from reservoir come from and how to accurately assess them.

As the hydropower and water management industry evolves, the need for simpler ways to assess the net GHG emission was highlighted by many hydropower companies, investors, consultants, decision-makers and other stakeholders.

A major milestone on the path to developing the G-res Tool was reached with a UNESCO/IHA Greenhouse Gas Status of Freshwater Reservoirs project in 2010.

This concluded with the launch of the GHG Measurement Guidelines for Freshwater Reservoirs, a landmark publication and standard on measuring emissions from reservoirs.

The guidelines offer a comprehensive tool to assess the GHG status of freshwater reservoirs, including definitive guidance on the measurement and qualification of emissions resulting from the formation of reservoirs. The guidance covers:

  • Concepts and processes involved in making such measurements
  • The approach to conducting field measurements
  • Guidance on calculating results

With the concept of global application being at the forefront of the development of the GHG Measurement Guidelines, IHA and its partners have ensured that the methodology contained within the publication is applicable to all climate types and reservoir conditions.

By providing the tools required to measure GHG emissions in a selected set of reservoirs, the intention is to ensure that the results gained will be utilised to develop predictive tools, thereby avoiding the necessity of intensive field measurements in the future. It is anticipated that results shared from the use of these guidelines will contribute to this.

Since 2014, IHA and its partners have worked to develop scientific models to predict GHG emissions from reservoirs without going to the field to take measurements. To make those models available to a larger public, the G-res Tool interface was developed.

A beta version of the G-res Tool was first presented publicly in May 2015 at the World Hydropower Conference in Beijing, China.

The G-res Tool was officially launched at the World Hydropower Congress in Addis Ababa, Ethiopia, in May 2017.


View the list of organisations which supported the development of the G-res Tool.