Positioning Sulaymaniyah in Global Municipal Solid Waste Generation: Income-Stratified Benchmarking and Multivariate Analysis of 31 Cities

Abstract

Abstract Municipal solid waste (MSW) generation is increasingly shaped by urban growth, consumption, socioeconomic conditions, and local management capacity, yet city-level comparisons remain difficult because reporting systems and urban structures differ substantially. This study positions Sulaymaniyah City, Iraq, within an international benchmark of 31 cities using data derived from the World Bank What a Waste Global Database. The analysis combines data-consistency screening, descriptive ranking, income-matched comparison, per-capita intensity classification, population-density assessment, standardized Z-scores, regression benchmarking, clustering, principal component analysis, nonparametric income-group testing, correlation analysis, and outlier diagnostics. Sulaymaniyah generated 1.018 kg/person/day and 400,442 tons/year, placing it near the international sample mean but above the upper-middle-income-city average. It ranked fourth among ten upper-middle-income peers for both per-capita and annual waste generation. A robust log-linear model indicated that Sulaymaniyah produced approximately 30% more annual waste than expected after adjustment for population, density, and income category; this result remained stable in sensitivity analysis. PCA and clustering showed that the city was not a multivariate outlier. The findings indicate that Sulaymaniyah is internationally typical in simple per-capita terms but comparatively waste-intensive among economic peers, supporting stronger source separation, recycling, organic-waste recovery, and standardized municipal monitoring and evidence-based planning for future waste-management infrastructure and circularity transitions.