Current Situation of Drainage Pipe Networkin China and its Detection Technology:a Brief Review

China's urban drainage pipeline systems and pipeline inspection technologies have achieved significant progress in the past 40 years, whereas the existing drainage pipelines are facing damage, defects, and aging, and thus have received growing attention.To better understand the underlying reasons for the development of China's urban drainage pipeline systems, and improve the utilization efficiency of pipeline inspection technologies, this research comprehensively analyzed the development process of China's urban drainage pipeline systems in terms of the spatio-temporal characteristics of pipeline length, the types of sewer lines, existing problems and consequences.Moreover, the widely used pipeline inspection technologies were presented and compared, and appropriate inspection techniques were proposed for pipelines that are difficult to detect with the common techniques.Finally, specific suggestions and future developments were provided for the construction, defect inspection and condition assessment, and management and maintenance of urban drainage pipeline systems.This review will hopefully assist in the management and maintenance of China's urban drainage pipeline systems, and provide a valuable experience and practices for other developing countries.