明代黄淮运交汇区域的水系结构与水环境变化

明代大运河的启用,使黄淮运交汇区域成为治水的关键区域。官方为了维护运河的畅通,采取了使水系结构与水情产生变化的措施。明前期的河道基本上沿袭了元代河道多股并流、迭为主次的特点。随着运河、淮河与黄河的治理,特别是筑堤的兴起,黄河各水道有一个从面到线,再从一线到清口一点的集中过程。第一阶段是黄河北流断绝,第二阶段是徐邳河道与上游固定于一线。黄河固定集中于徐邳一线以后,嘉靖年间河多决于徐州的上游,嘉靖四十四年以后,河多决于下游。黄运合一区域的河道治理,从一个跨越南北的扇形面,发展到南部半个扇形面,再集中于一线,最后集中于清口。总体的治理过程,基本上为保运服务。从面到点,从大区域的治理到小区域甚至于一点的工程治理,这是明代黄淮运水利工程的水流控制特色。这种随水环境变迁而进行的治水工程调整,充分体现出古人大区域地利用水环境的智慧,具有鲜明的生态特色。

Changes of the River System Structure and Water Environment in the Convergence Region of Yellow River,Huai River and Grand Canal in Ming Dynasty

The region where Yellow and Huai Rivers met the Grand Canal became a key location for water regulation because of the opening of Grand Canal in Ming Dynasty. Regulation procedures implemented by the government, aiming to keep the Grand Canal unimpeded to navigation, facilitated the evolution of river system structures and water regimen. In early Ming Dynasty, the configuration of river channels was similar to that in Yuan Dynasty, following a pattern of parallel flows with interchangeable main and tributary channels. As the Grand Canal, Huai River and Yellow River were under regulation, and especially as levees were constructed, channels of Yellow River went through a concentration process. They firstly merged from a regional network pattern into a linear pattern, and then continued converging towards a point at Qingkou. The first stage of this process was the abandonment of the northern branch of Yellow River, while the second stage was lining the Xu-Pi segment of Yellow River up with the upper stream. After flow directions of channels were fixed into the Xu-Pi segment, most levee failure events during the Reign of Jiajing Emperor occurred upstream to Xuzhou, but after the 44th year of Reign of Jiajing Emperor, most of such events occurred downstream to Xuzhou. The channel regulation near where Yellow River and Grand Canal meet started with a broader, fan-shaped target region extended from south to north, and then reduced to the southern half of the fan-shaped region, and then concentrated to a linear belt and eventually to Qingkou. The regulation generally served for maintaining the navigational condition of channels. From a regional channel network to a point, or from a broader region to a smaller region and eventually to a single point, such kind of engineering process marked the characteristic of how Ming Dynasty conducted hydrological regulation projects in the region where Yellow and Huai Rivers met the Grand Canal. This hydrological regulation process that follows the change of water environment accordingly fully reflected the wisdom of ancient people in utilizing the aquatic environment on a large regional scale. It has remarkable ecological characteristics.