Author(s): Miguel Angel Diaz Hurtado; Sara Espinosa; David Aguilera; Susana Gonzalez; Manuel Argamasilla; Alicia Pinero

Linked Author(s): Miguel Angel Diaz Hurtado

Keywords: Desalinated water; Corrosion risk; Alternative water resources; Water quality; Distribution network

Abstract: In the last years, alternative water resources such as desalinated water have become a solution for the natural water resources scarcity in the coastal Mediterranean areas. According to the recent Water Management Plans in the Spanish Mediterranean water bodies, the amount of desalinated water volume destined for water supply is becoming increasing in order to preserve groundwater and freshwater resources for the future. Hence, it is necessary to assess the potential risk associated with the water quality changes within the existing water supply networks. Historically, on exploitations where desalinated water has been introduced without remineralization post-treatment, alterations have been observed both in the functioning of the network and in the quality of the water supplied. As well, corrosion problems and a higher incidence of breakdowns have been reported when the quality of the water suffers significant variations on exploitations where water of different origins (surface, ground, desalinated and mixed) is supplied, as in the case study of Roquetas de Mar. A deterministic methodology has been developed for estimating corrosion risk (R) assessment based on the same tenets used in hydrogeology and civil engineering: hazard (H), vulnerability (V) and exposure (E). So, the corrosion risk equation for drinking water networks would be: R= H*V*E, where “H” is defined by the external agent (pressure and water quality) to which the asset is exposed, “V” is the factor related to the properties of the water supply network (material, diameter and length of the pipe). “E” factor is defined by the population density in each of the sectors of the supply network (inhabitant/km2). In addition, different weights have been assigned according to the relevance of each variable. These weights have been determined based on the results of several surveys of experts in drinking water network. Finally, for a better visualization and interpretation of the results, the risk distribution has been represented by a cartographic map using QGIS. Risk calculation and visualization have been automatized by a developed Python script. Also, a laboratory test has been carried out to evaluate and detect the possible effects of desalinated water on the most common materials in the network. In conclusion, this risk estimation methodology fits well in the study case. A higher risk is expected in the short term due to a sudden mineralogical change of the water than in a long-term exposition to a water with a stable composition.

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221799

Year: 2022