Water Quality Index For Urbanized Watersheds

Objective: The objective of this study was to design a Water Quality Index (WQI) sensitive to the limits established by current legislation, focusing on the sustainable management of urban water bodies. Theoretical Framework: The research addresses the importance of regionalizing water quality indices to improve the monitoring of urban water management. Furthermore, it highlights that the indices used in urban streams lack good sensitivity to isolated parameter variations, which justifies the need for a new index. Method: The development of the new WQI consisted of four stages: parameter selection, normalization method, weight selection, and aggregation method. The initial parameters, such as total nitrogen, total solids, and temperature, were replaced by ammonia, nitrate, and surfactants. Normalization curves were also created, and the parameter weights were adjusted. Results and Discussion: The WQIBHU (IQABHU) demonstrated greater sensitivity to parameter variations compared to the WQICETESB (IQACETESB), with the exception of the ANH-01 point. Most of the quality values of the IQABHU were lower than those of the IQACETESB, indicating non-compliance with legal limits for urban stream classes. The IQABHU showed better performance in turbidity and dissolved oxygen (DO), while the IQACETESB masked the real water quality conditions, especially regarding the E. coli parameter. The new "±" tool allowed for more detailed monitoring of water quality, making the IQABHU more suitable for continuous monitoring and supporting decision-making by the competent authorities. Research Implications: The research has significant practical implications, as the proposed new WQI can be used as a tool to improve urban water management, contributing to the sustainability of water bodies and ensuring compliance with current environmental legislation. Originality/Value: The value and originality of this work lie in the proposal of a more sensitive index adapted to the reality of urban water bodies, using a systematic methodology for modifying and improving parameters and weights, which could represent an important advancement in water quality management.