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Abstract Since the Tang and Song dynasties, the water system of the Jiangnan Canal has changed from the Shangtang River system to the Xiatang River system. Linping Lake has become a key area for observing the changes of the canal water environment. Examining the sediment and reclamation of Linping Lake and the relationship with the canal within the scope of the historical geography is of great academic value and significance to the understanding of the development of the agricultural water development and the evolution of the Jiangnan Canal in the Taihu Lake Basin. Based on the perspectives of historical geography and environmental history, this paper mainly investigates Linping Lake during the Tang and Song dynasties. It explores the generation of clear-water ecology in Linping Lake, the process of sediment and reclamation, the mechanism and trends of the changing relationship between the lake and canal. Through examining the changes of the water and soil environment in Linping Lake, this paper seeks to explore the complex relationship between the development of agricultural water development and the evolution of the lake-canal relationship in the Taihu Lake Basin and thus deeply understand the environmental changes and humanistic interactions in the Taihu Lake Basin over a long period of time.
During the Tang and Song dynasties, the Jiangnan Canal travelled along the north bank of the Qiantang River to the northeast. This area formed a long narrow dis, which was deeply affected by the sediment of the Yangtze River mouth and Hangzhou Bay Due to the necessity of navigating through weirs to enter the river, the canal in this region came to be commonly referred to as the Shangtang River. In the northern part of Hangzhou Bay, where numerous lakes were distributed along the highlands along the river, , the canal took on a combined form with the lakes. During this period, the farmers in the Taihu Lake area mainly settled in the higher terraces, and the construction of embankments and field enclosures began in the shallow waters of the highlands. As a result, the construction of the canal water network and the development of agricultural water resourses were integrated. The fact that the water area of Linping Lake have been maintained for a long time without large-scale reclamation is related to its special accumulation of sediment and the impact of saline water on its soil.
After the middle of the Tang Dynasty, as Bai Juyi diverted the clear water from the West Lake to the highlands along the river, a canal-centered water flow regulation system was gradually formed. The clear water along the highlands along the river became increasingly robust. The enhanced clear water was able to inhibit tidal sand from entering the river and farmland, creating an excellent clear-water environment for rice cultivation. The saline soil and water environment of Linping Lake improved, leading to a clear water ecology adapted to the growth of lotus and rice crops. Over time, herbaceous plants that had been congesting Linping Lake for a long time gradually disappeared from the lake. Since then, Linping Lake experienced noticeable sedimentation, and reclamation experienced a process of expanding from shallow water areas to deeper water areas.
In the Northern Song Dynasty, the reclamation of Linping Lake was expanded due to the improvement of the saline soil and water environment. However, due to the prioritization of canal transportation, sendimentation and reclamation of Linping Lake were controlled within a certain range during this period. Although there was no obvious embankment dividing the lake from the canal, there was a tendency of complete separation of the canal from Linping Lake. Since the Southern Song Dynasty, affected by the dynamic interaction of clear water and tidal water in the north of Hangzhou Bay, especially as the pattern of clear water inflow into the canal deteriorated, the trend of Linping Lake for transport and irrigation is further obvious. This to a certain extent affects the changes in the lake environment, canal morphology and the system of embankments. With the expansion of the reclamation of Lake Linping, embankments continuously extended into the deep-water area in the lake. As embankments expended, the Linping Lake gradually shrank while the canal system and embankment network differentiated. In order to effectively control water flow and adjust the water balance between the field and the canal, the authorities constructed the Yonghe Embankment in the lake. This to a certain extent defined the boundary between the canal and embankment regions, temporarily avoiding water disputesbut also causing the separation of water flow in the lake area, canal, and embankment regions. The Linping Lake and the canal were completely isolated, and the lake-canal relation underwent a transformation from integration to separation.
This paper takes the reclamation of Linping Lake during the Tang and Song dynasties as a key area for examining the changes in the water environment of the Jiangnan Canal and the development of agricultural water resourses. Within the context of historical and natural geography, it examines the sedimentation, reclamation of Linping Lake and the relationship between the lake and the canal. This approach not only examines how the water system of the Jiangnan Canal shifted from the Shangtang River to the Xiatang River, but also contributes to the understanding of the interaction between the development of agricultural water development in the Taihu Lake Basin and the evolution of the Jiangnan Canal.
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Published: 07 March 2024
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