Development of a water state index to assess the severity of impacts on and changes in natural water resources

Abstract

Lifecycle assessment (LCA) is a standardised methodology that is used to assess the impact of techno-economic systems on the natural environment. By compiling an inventory of energy and material inputs and environmental releases or outputs of a system, and evaluating the potential environmental impacts associated with the inventory, one can make an informed decision regarding the sustainability of a techno-economic system in question. However, the current lifecycle impact assessment (LCIA) methodologies that form part of LCA studies do not effectively consider the impacts of techno-economic systems on ground and surface water resources in South Africa (and elsewhere). It is proposed that a microbiology based index method, similar to methods proposed for terrestrial resources, can establish the states of water resources for six classes of current economic exploitation: protected, moderate use, degraded, cultivated, plantation, and urban. It is further suggested that changes in these classes (and states) can be used meaningfully in LCIA methodologies to quantify the extent to which techno-economic interventions may alter natural water resources. Research is recommended to further improve the accuracy and reliability of the water state index.