5.1. REWEFe: Rapid Evaluation of the Water-Energy-Food-ecosystem nexus 

Why doing the REWEFe analysis? 

The REWEFe tool is developed to fill the gap in scenario analysis tools for the WEFe nexus, which are often location-specific, data-intensive, or sector-focused. It provides a standardized, easy-to-use, Excel-based method for analyzing interlinkages between water, food, energy, and ecosystems. The tool helps users model and evaluate different scenarios, offering a comprehensive view of the WEFe system to support informed decision-making and prioritise interventions.  The REWEFe tool can be used by accessing the following link: https://www.futurewater.eu/tools/rewefe/

Strengths  

The REWEFe tool is the first of its kind, allowing users to generate scenarios and quantitatively assess the synergies and trade-offs among the four sectors. Its key strengths include:  

• User-friendliness: REWEFe is a macro-enabled Excel-based tool that requires only a basic understanding of MS Excel to operate.  

• Easy terminologies: The variables in the Input sheet have been named in a self-explanatory manner. Each variable is clearly defined with units to guide users in entering data in the correct format. If further clarification is required, users can also refer to the user guide which provides brief descriptions for each variable.   

• Open access: The tool is publicly available and does not require any licence or subscription for use.  

• Flexibility: As REWEFe is an Excel-based tool, users can easily add new variables or modify the quantitative relationships between existing variables, as per need.   

• Wide applicability: The tool is not configured or optimised for any specific geographical region, making it versatile for assessing the WEFe nexus in any context globally. 

Limitations 

While REWEFe aims to incorporate the most relevant inter- and intra-sectoral dependencies, it should be noted that it does not provide a high level of detail. This is because the purpose of the tool is to provide a holistic assessment of the WEFe domain without being too data-intensive or too limited in terms of applicability to various contexts. Therefore, it is important for users to consider the following limitations:  

• Temporal dynamics: REWEFe provides a snapshot of the WEFe nexus at a specific moment and does not track changes over time. While users can model scenarios to reflect future changes, the tool does not allow for time-based trend analysis or visualization. 

• Spatial disaggregation: Once the nexus unit (or focal area) is defined, the calculations run for the entire area. The users, therefore, cannot zoom in on specific aspects within the area but they can run separate analyses for different nexus units if needed.  

• Level of detail: Although REWEFe covers major subcomponents of the WEFe nexus, it does not take into account details such as specific crop varieties, local biodiversity, water quality, or the impacts of ecosystems on water, energy, and food production. 

• Background knowledge of users: users should have a technical background (e.g. physical sciences or engineering), and a minimum understanding of the physical processes and data they are working with (e.g. water, land and energy data). 

• Simplification: Some of the inter- and intra-sectoral quantitative linkages are based on empirical formulas. While more sophisticated expressions may exist for certain linkages in some countries, they are not included in the tool to maintain its universal applicability. Moreover, certain variables, such as return flows from the domestic and industrial sectors, may also need to be estimated by the user in the Input sheet.