This study conducts a comprehensive bibliometric analysis of literature from 2000 to 2025, aiming to map the intellectual landscape and evolving trends in research on heavy metal transport within watershed ecosystems. By leveraging the Citespace literature visualization tool, we analyzed publication trends, intellectual bases, and, most importantly, the dynamic shifts in research fronts through keyword co-occurrence and clustering analysis. The findings reveal a clear trajectory from basic geochemical theories to specific applications, characterized by three prominent themes: (1) the evolution of pollution source tracking from single-method tracing to coupled multi-method quantitative modeling; (2) the establishment of a comprehensive risk evaluation chain spanning regional assessments to targeted analyses of sensitive receptors; and (3) the analysis indicates that the current research on heavy metal transport in watershed environments remains somewhat fragmented, with limited cross-comparative synthesis across different metal species and watershed contexts, and uneven progress in applying advanced data-driven and multi-model approaches. Addressing these issues is crucial for enhancing the predictive power of models and formulating effective strategies. This study thus provides a detailed overview of the field’s development while highlighting critical pathways for future research to strengthen the scientific foundation for preventing and controlling heavy metal pollution in watershed ecosystems.

Watershed-scale simulation of heavy metal transport and transformation is an important tool for pollution source identification, environmental risk assessment, and watershed management decision-making. Existing hydrological and water quality models provide essential process-based foundations for heavy metal transport simulation, including runoff generation, soil erosion, sediment transport, and channel routing. However, limitations remain in the coupling of geochemical reactions, representation of metal speciation, response to extreme events, and separation of multiple uncertainty sources. Based on literature records from the Web of Science Core Collection, this study integrates a PRISMA-based screening procedure, CiteSpace bibliometric analysis, comparative assessment of representative hydrological and water quality models, and an AHP—MCDA semi-quantitative evaluation method to systematically review modeling frameworks for watershed-scale heavy metal transport and transformation. The SWAT model and its extended module SWAT-HM are further used as representative cases to analyze the coupling mechanisms among hydrological processes, sediment processes, and heavy metal transport and transformation. The results indicate that the SWAT model has relatively high overall applicability in terms of hydrological process representation, sediment/erosion process representation, and heavy metal coupling basis, making it suitable for long-term pollution load assessment in medium- and large-scale watersheds. However, for urban storm runoff, high-frequency water quality responses, surface water–groundwater exchange, and detailed reactive transport processes, other models or coupled modeling frameworks are still required. The SWAT-HM model links dissolved, particulate, and sediment-associated heavy metal transport with runoff, erosion, and sediment transport processes, but its representation of complex speciation transformation, valence state changes in redox-sensitive elements such as As and Cr, and colloid-facilitated transport remains simplified. Future research should move toward an integrated modeling system that coordinates mechanisms, data, and uncertainty, with particular emphasis on breakthroughs in multi-scale dynamic coupling, element-specific parameter systems, dynamic pH–Eh modules, and standardized uncertainty decomposition workflows, thereby improving model interpretability, predictive reliability, and management relevance.