The Han Chang’an City was the capital city of the Western Han and Xin Dynasties. It was made up of both urban and rural districts. Throughout the 200 years of Chang’an’s occupation, water infrastructure of different forms and functions were erected in both urban and rural sections of the city. The systematic and diverse blueprint of the water system promoted the waterworks of and prevented floods in Chang’an, thus providing a solid bedrock for the survival and development of the city.

The water infrastructure at Chang’an can be divided into four different functional systems: water storage, sewage drainage, urban water landscaping and water transportation. The water storage system was comprised of artificial lakes, canals, reservoirs, and water wells. These facilities allowed for the drawing and diversion of water resources, thus providing a solution for water provision in Chang’an. The sewage drainage system was comprised of drainage canals, culverts, rainwater wells, cesspools, roadside ditches, city moats, and city walls. These facilities were located in single-unit buildings, courtyards, street districts, street sides, and the city exterior. They allowed for the collection, transportation and drainage of sewage in Chang’an. The urban water landscape system included reservoirs and landscape canals, which allowed for the beautification of the city. Occasionally the artificial lakes and canals also included properties for retaining and draining water. The water transportation system was comprised of watercourses, weirs, inlet channels, and water replenishment systems; this allowed for resource provision in Chang’an. The facilities of these systems were distributed in different sections of the urban and rural regions of Chang’an, thus guaranteeing water usage, drainage, and transportation in the entire city.

Atmospheric precipitation (rainwater and melted ice and snow) provided water to Chang’an. The precipitation was stored in rivers and lakes, and amassed as free flowing surface water; sometimes it would seep into the ground and be stored as groundwater. Both surface and groundwater provided immediate water sources for the population at Chang’an. Through the water storage system, surface water was transported to the water usage facilities and at the same time supplemented the groundwater storage system. On the other hand, water wells were the means through which the populations at Chang’an exploited groundwater for daily usage. The atmospheric precipitation and sewage surplus ran into the rivers through the drainage system; a small portion seeped into the ground and was stored as groundwater. To summarize, the water infrastructure in Han Chang’an City originated from atmospheric precipitation. Through its water storage and drainage systems, the water eventually united with rivers, lakes, and groundwater – creating a self-sufficient cycle of water resources in Chang’an.

By combining archaeological analysis of water infrastructure and water systems in Han Chang’an City with the study of natural landscape, social context, and local and regional chronological development, we can conduct synchronic comparisons with water systems in other regions of the world. It is only then that we can make conclusions about the regional and contemporary characteristics of the water infrastructure in Chang’an city, and the significance of its system in the history of water infrastructure development throughout the world. This will provide a basis for understanding patterns of water infrastructure in cities across time, and thus for ideas regarding the development of better water and hydraulic infrastructure in the future.

汉长安城是中国古代西汉和新莽时期的都城，汉长安城地区由城区和郊区组成。在长达200多年的时间中，城区和郊区都修建了形制不同、功能各异的城市水利设施，共同构成整个汉长安城地区的城市水利系统，兴水利，避水患，保证了汉长安城的生存与发展。
汉长安城的城市水利系统由于主体功能的不同，可以分为城市供蓄水系统、城市排水系统、城市水景观系统和水运系统，前者由人工湖、渠道、蓄水池、水井等城市供蓄水设施构成，相互配套，解决了从引水、调蓄水到具体用水单位的供水过程。后者则包括排水沟、排水管道、涵洞、雨水井、渗水井、路沟、城壕和城墙等城市排水设施，分别处于单体建筑、院落、街区、道路两侧和城市外围，完成了自然降水和城市废污水的集中、输送和排放问题。水景观系统主要包括人工湖、景观水渠等水景观设施，起到了美化环境、愉悦身心的社会效果；有些主体功能为供蓄水的池、渠等有时也能发挥这方面的功能。水运系统包括运河和相应的拦水、引水工程和补水设施，以漕渠为主，对保障汉长安城地区的物质供应发挥了重要作用。上述设施和系统既分布于城内各处，又在郊区多有营造，整个汉长安城地区的各项用水、排水和水运等水问题，都能得到有效保障。
汉长安城地区的各项用水的最终源头是大气降水（雨水和冰雪融水），大部分以河流和湖泊的形式储存和流动于地面上成为地表水，部分渗入地下成为地下水。地表水和地下水中汉长安城地区城市用水的直接来源。地表水通过供蓄水设施将水配给到具体的用水设施，途中对地下水构成补给。地下水以水井的形式被开发利用，是汉长安城地区生活用水和生产用水的主要渠道。多余的大气降水和废污水，则通过排水系统大部分排入河流，少部分渗入地下水。总之，汉长安的城市水利系统，从河流和湖泊和地下水起源，通过供蓄水系统和排水系统，最后终结于河流、湖泊和地下水，完成了汉长安城地区范围内的水循环过程。
汉长安城地区城市水利设施和城市水利系统的考古研究，即包括对城市水利各项工程设施和整体水利系统的具体分析与总结，也包括对当地自然条件与社会状况的考察，同时还要分析与前代和后代的继承和发展关系，比对研究世界其他地区同期的发展情况。通过上述研究，我们才能归纳汉长安城地区城市水利的区域特征、时代特征，及其在历史进程中和世界范围内的地位与影响，并进而概括城市水利发展的一般规律，总结相应的成功经验与失败教训，为今天的城市水利建设服务。

Zhang Jianfeng holds a bachelor’s degree and master’s degree in history from the School of History and Culture at Shandong University. Zhang obtained his doctoral degree in history from the Institute of Archaeology at the Chinese Academy of Social Sciences. Since 1997, he has been a research associate at the Institute of Archaeology at the Chinese Academy of Social Sciences. Zhang has been participating in the archaeological research of Han Chang’an City, mostly focusing on the archaeology of the Qin-Han period and the study of water management systems in ancient cities. Zhang’s most prominent work is The Archaeological Study on the Water Infrastructure and System of Han Chang’an City。

张建锋，男， 1972年生于山东省泗水县。1990—1997年就读于山东大学历史文化学院，先后获历史学学士学位和历史学硕士学位。2011—2014年就读于中国社会科学院研究生院考古学系，获历史学博士学位。1997年以来在中国社会科学院考古研究所工作，现为副研究员。长期从事汉长安城遗址的考古工作，研究领域为秦汉考古，研究方向为城市水利考古和都城考古，主要成果有《汉长安城地区城市水利设施和水利系统的考古学研究》。