This book addresses environmental challenges related to pollutant transport in rivers and estuaries through computational and mathematical modeling, optimization techniques, and computational intelligence. The authors explore methods for estimating the influence of physical processes that govern the distribution and concentration of pollutants. Special emphasis is placed on identifying parameters that characterize pollutant dispersion, as well as the location, intensity, and temporal dynamics of pollutant discharges. Optimization techniques are also presented to estimate the origin and magnitude of pollutant releases, enabling the assessment of environmental liabilities resulting from industrial activities or accidents.