QUALITOOL 2.0: Aplicativo WEB para modelagem da qualidade de água em ambiente lótico

Abstract

This paper presents the development of QUALITOOL 2.0, a web application for simulating water quality in lotic environments, contributing to river basin management. The application models key parameters such as dissolved oxygen, biochemical oxygen demand, nitrogen and phosphorus (including their fractions), as well as coliforms, based on well-established mathematical equations in the literature. These equations account for the advective transport of pollutants and the kinetic decay of water quality parameters. The application supports both georeferenced and non-georeferenced topological data inputs, including point and diffuse pollution sources, as well as point withdrawals. Additionally, it allows for the incorporation of time series data, enhancing result management. In the hydrodynamic modeling process, for rectangular or trapezoidal cross-sections of the watercourse, the Manning equation and the continuity equation are employed to estimate the average water depth and flow velocity for each discretized segment of the watercourse. Users have flexibility in defining the longitudinal discretization scale of the watercourse, which is utilized in the numerical solution of the differential equations governing pollutant transport and biochemical reactions, solved using the finite difference method. The application also features integrated sensitivity analysis and kinetic coefficient calibration through the Particle Swarm Optimization algorithm, an evolutionary approach that refines its estimates iteratively. Modeling results can be visualized through dynamic graphs, spreadsheets, and geospatial representations when georeferenced data is available. A comparative analysis with two other computational tools – the initial version of QUALITOOL and the QUAL-UFMG tool – validated the QUALITOOL 2.0 application. Its main advantage lies in its high computational processing speed, achieved through the implementation of parallel and object-oriented programming methodologies. It is expected that QUALITOOL 2.0 will serve as a decision support system for assessing environmental impacts in lotic aquatic ecosystems.