Evaluation of models for estimating land-based plastics entering the ocean in countries of the Global South

Accurate estimation of land-based plastic waste emissions into the ocean remains a critical challenge, particularly in countries of the Global South where data availability and waste management infrastructure are limited. This study conducts a systematic review of existing models used to estimate plastic emissions, applying screening criteria to identify approaches tailored or adaptable to developing regions. From an initial pool of 2521 studies, only six models met all inclusion criteria, particularly aligning with a Source-to-Sea perspective and regional relevance. Our evaluation reveals that most models rely heavily on formal waste data and lack mechanisms to address informality, socioeconomic variability, and hydrological complexity typical of the Global South. Only a subset of models demonstrate structural flexibility and data-resilient methodologies. We propose a regional fit framework to guide future model development and adaptation. Our findings highlight critical methodological gaps and support the advancement of emission estimates and environmental policies tailored to the unique realities of low- and middle-income countries. This analysis contributes to a more inclusive modeling landscape and strengthens the foundation for hazard-oriented environmental planning.