Advancing numerical models for land-to-ocean litter transport: A review of hydrodynamic processes and inland contributions

Litter pollution, particularly from plastic waste, has escalated into a global crisis that poses substantial risks to aquatic ecosystems and human health. This comprehensive review systematically explores litter transport dynamics from terrestrial sources to marine environments, focusing on key objectives that include examining the intricate hydrodynamic processes involved in the movement of litter from land to sea. It identifies significant inland contributors to marine litter, such as rivers, urban runoff, and stormwater drainage outflows, as critical sources often overlooked in current studies. Natural factors, such as rainfall and riverine flow, and anthropogenic ones, such as urbanization and waste management practices, make litter mobilization and transport processes very complex. A key finding is that current techniques and data cannot grasp this complexity, pointing to the need for an improved holistic modeling framework. By synthesizing insights from diverse studies, the need for cross-disciplinary collaboration and robust data-sharing frameworks is highlighted to enhance model reliability and predictive capacity. Ultimately, these findings provide critical insights and guidance for environmental policymakers, researchers, and community organizers, empowering them to implement effective measures to combat litter pollution and safeguard marine habitats for future generations.