Based on shared concerns for water environment and water resources, five contributors in this symposium articulate their viewpoints from their respective case studies in the field of Chinese environmental history. In pre-modern China, how to deal with the Yangzi River and the Yellow River, the two largest rivers, were key environmental issues on national water resource solutions, and the Chinese played an active role in their constant interactions with nature.  Brian Lander’s research on the early environmental history of the Central Yangzi valley aims to understand the history of the Yangzi lowlands in the context of the destruction of the world’s wetlands by the spread of agricultural societies. The wetlands on the Lianghu Plain were originally one of biologically productive areas in the world. A rich variety of aquatic lives, plants and wildlife in this region earned it the reputation of “wealth of Yunmeng.” However, why has it mostly been converted to farmland? According to him, archaeological discoveries have revealed thousands of years of immigration, farming and dike building in this region. He argues that over the long run agricultural development and hydraulic construction by increasing population steadily reshaped the original regional ecological system.  Ruth Mostern introduces her large project of exploring the long-term and large-scale history of the Yellow River, covering three thousand years of time and integrating the history of middle-course erosion with the history of lower-course flooding, and highlights data approach from environmental science. Focusing on why the Yellow River shifted from a long-term condition of relative stability to a later state of frequent floods and course changes, she argues that such changes resulted from intensification of human activity in the grasslands of the Ordos basin. From the mid-eleventh century, mounting contention between Chinese and Tanguts led both sides to fortify the region. The fields, pastures and lumber operations of these remote and largely self-supporting outposts destroyed fragile ground cover and exposed erosion-prone sand and soil that made its way into the Yellow River through a process of wind and water deposition, thereby transforming the entire fate of the North China Plain. Chinese activism in nature was exemplified more intensively in the construction and maintenance of the Grand Canal hydraulic network. Sun Jinghao explores the managements of water resources to sustain the Grand Canal in late imperial China, by investigating the fluctuations of reservoirs in the Jining Region of western Shandong. The operation of the Grand Canal heavily relied on continual construction, reconstruction and maintenance of a comprehensive water conservancy system in which reservoirs played a vital role in the northern sections. In order to combat the tremendous problems of water shortage, as well as flooding in monsoon seasons, massive reservoirs were vigorously installed or modified in the Jining region to reserve and moderate water for canal navigation. Although the state’s manipulations of water resources by reconfiguring the regional hydrological network generally achieved its anticipated objective, this was an extremely difficult accomplishment due to the complex reactions from both nature and local society. Water is people’s basic necessities in everyday life, and in China the lack of drinking water in urban and rural areas and the lack of fresh water, related to how to survive, on the coast are lasting severe issues. Using the term “brackish water,” Xiong Yuanbao depicts water consumption in late imperial Beijing, involving natural conditions of water resources, water consumption by citizens, as well as municipal rules and institutions that regulated the extraction of underground water. Mostly shallow and close to the land surface, these “brackish water” wells were both a product of soil and mineral contents and a consequence of human activity. Besides the absence of basic infrastructures for water and sewage treatment and the government’s negligence of administrative and legal regulations, the urban residents of Beijing played significant roles in creating, disposing, and neglecting various kinds of waste that infiltrated the land to pollute the underground water. Lu Xiqi turns his attention to the livelihood of coastal fishers and salt-workers with regard to water environment. In his views, the mainstream scholarship on the history of the Chinese ocean has neglected the people living in the coastal regions and their livelihoods as well as the relations between those people and the sea. He focuses on sea food and sea salt, trying to reconstruct the livelihood of fishers and salt-workers living in the coastal regions during the medieval age from an ecological perspective. The structural shortage in the subsistence system of coastal fishers and salt-workers, especially in terms of necessities of living and production such as freshwater, cereals and shipbuilding timber, iron pans for boiling seawater and netting fabrics, forced them to acquire daily necessities from the external environment by means of trade and even robbery. Their lack of self-sufficiency contributed to the openness of the economy in the coastal region, and the fluidity of coastal society.