The establishment of integrated water resources management based on emergy accounting

• Variability of emergy and filling index were proposed as basis in a water management.
• Several strategies were identified for two basins (UCLR and SCR) in México.
• An extreme fragility, in both basins, was seen according to renewable resources used.
• Renewable resources use can be increased due to emergy variability analisys (UCLR).
• According to filling index, 2.5% of demand could be mitigated by groundwater (SCR).

With modules developed in an informatics package for geographic information systems (GIS), the present work calculates the emergy of groundwater and the inter-annual variation in emergy of surface water resources in basins that encompass the metropolitan areas of Toluca and Monterrey, Mexico; that is, Upper Course of the Lerma River (UCLR) and the Santa Catarina River (SCR) basin, respectively. In addition, a criterion has been found to identify the intensive exploitation of aquifers. This allows for considering those volumes as non-renewable resources, when applicable, in processes to define integrated water resources management.The transformity weighted mean of water resources due to chemical potential energy in the SCR basin (9.32E + 06 sej/J for surface water and 6.47E + 06 sej/J for groundwater) was greater than in the UCLR basin (5.75E + 05 sej/J for surface water and 2.83E + 05 sej/J for groundwater). Nevertheless, based on the analysis of the variation in emergy, some strategies were identified to improve the efficiency of the joint management of water resources. Standing out among these is the determination of a monthly variability in the volumes of water provided, making it possible to observe a decrease in emergy per unit volume in the SCR basin and an increase in the percentage of renewable resources in the UCLR basin.