Assessment of Environmental Water Cost Through Physical Hydronomics.

The Georgescu-Roegen's statements about the connexion between the Economy and the Thermodynamics, together with the Eco-integrator approach introduced by Naredo and its relation with the water cost definitions given in the European Water Framework Directive (WFD), are the outline backgrounds of the work presented in this paper. Assuming that the physical laws are called to be the objective and universal tools to assess water costs, Physical Hydronomics (PH) has been developed as the accounting tool for the WFD application, regarding its physico-chemical objectives. PH is defined as the specific application of the Thermoeconomics to physically characterize the degradation and correction of water bodies. The Second Law of Thermodynamics, through the exergy loss calculation, is the basic working tool in this study. The final objective of PH is to use those calculated physical costs of water as a guide to allocate the environmental and resource costs introduced by the WFD. In this paper, the general framework and the basic accounting principles of PH are explained. First, from the quantity and quality measurements in the river (they give the exergy value to water bodies), the exergy profiles of the river at different statuses (those defined by the WFD) are obtained. Then, the environmental cost of water is obtained (in energy units) as the exergy needed to cover the gap between the current state of the river and the objective state defined by the applicable legislation to fulfil the European requirements. To do it, thermodynamic efficiency of water treatment technologies was introduced in the analysis. Then, the physical cost are translated into monetary units. To illustrate the application of the PH's methodology, the example of the Spanish Muga Basin, sited in the Inland Basins of Catalonia, is summarized at the end of this paper. The results show that similar results to conventional Measurements Plans to fulfil the WFD objectives are obtained. However, PH presents an important advantage: costs could be allocated according to the degradation (exergy costs) provoked by the different water users in the water bodies. [ABSTRACT FROM AUTHOR]