农田水利开发与湖运关系演变——以唐宋时期临平湖围垦为例

Development of Irrigation and Water Conservancy and Evolution of the Relationship Between Canals and Lakes:With the Reclamation of Linping Lake During the Tang and Song Dynasties as an Example

考察唐宋时期临平湖淤积、围垦背后的水环境因素,可以透视农田水利开发与湖运关系演变之间的互动。唐代以前,杭州湾北部沿江高地分布有众多湖泊,江南运河沿钱塘江北岸狭长碟边向东北行,运河局部形态呈湖运一体。高地湖泊水域得以长期维持并且未被大规模围垦,与其特殊的潟湖湖沼淤积物以及土壤受咸水浸渍影响有关。中唐以后引西湖清水入运河,湖泊群的咸性水土环境得到改善,逐渐形成适宜荷花与水稻种植的清水生态。随着临平湖落淤扩大与围垦扩张,围湖造田、湖中筑圩使湖运关系由一体向分离转变。南宋筑永和堤以后,运堤切割临平湖水环境的格局基本确立。运堤对湖泊的切割既是适应农田水利开发的举措,亦是对漕运用水不足的因应。唐宋时期,以临平湖为中心的运河水环境在落淤、围垦与筑堤的互动中演变,湖运一体的运河水网完成了向以上塘河为纲的圩田水网的转变。

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 the 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 systems and the evolution of the lake-canal relationship in the Taihu Lake Basin in order to 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 dish edge,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 resources 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,sedimentation 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 Linping Lake,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 the 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 disputes but also causing the separation of water flows 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 resources.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.