Advances in liners leakage detection technologies and case applications in municipal solid waste landfills

This paper presents a comprehensive review of the evolutionary development of global landfill liner systems. It elaborates on the critical and prevalent issue of liner system leakage， while analyzing the complex interactions and coupled effects of multiple contributing factors to such failures. It surveys the current mainstream leakage detection technologies for landfill liners， classifying them into three distinct categories based on their evolutionary trajectory： single electromagnetic technologies， synergistic multi-geophysical technologies， and in-situ real-time monitoring technologies （note： "in-situ" and "real-time" are hyphenated only when used as compound adjectives）. For each category， a thorough summary is provided， covering representative methods， typical application scenarios， and core advantages and disadvantages. Furthermore， This paper articulates the prevailing challenges encountered in practical applications and proposes substantive future research directions. As a key contribution， it provides the first integrated analysis of various applied case studies to critically evaluate and illustrate the practical effectiveness and inherent limitations of these three technology types when deployed in real-world scenarios. By synthesizing insights from the root causes of liner leakage， the challenges in practical applications， and the specific problems revealed by case studies， three strategic future directions are proposed. First， deepen and advance "synergistic multi-geophysical technologies" to realize a paradigm shift from conventional data fusion to intelligent predictive modeling. Second， focus on the research and development of non-contact and minimally invasive survey technologies to explore feasible pathways for effective monitoring of aging and legacy landfills. Third， actively promote the development of low-cost and networked leakage detection technologies， aiming to significantly lower the threshold for long-term monitoring and enhance risk management for the vast number of existing landfill sites.