Advances in Earth Science
), Zhen ZHAO(
Raorao SU, Zhen ZHAO. The Evolution and Driving Factors of the North Canal System Since the End of the 16th Century[J]. Advances in Earth Science, 2021, 36(4): 390-398.
In this paper， based on the summary of the relationship between the evolution of river systems and the development of human society， historical archives and the Digital Elevation Model （DEM） of North Canal Basin （NCB）， we used digitizing methods to extract four geographic profiles of the river system in NCB， from the late 16th century to the present （1582s， 1820s， 1933s， 2011s）. Meanwhile， based on DEM data， we utilized river network classification and hydrologic analysis methods to calculate river system structure parameters. The results showed that from the late 16th century to now， the range of the basin was shrinking gradually， and the pattern of the river network from sub-dendritic shape was changing to mixed morphology. During A.D. 1582-A.D. 1820， which was the significant period in which River diversity （Rd）， River frequency （Rf）， Tributary development coefficient （T）， and river network complexity （CR） increased significantly. Then， the overall trend stabilized， indicating the stream structure became simpler and simpler. By comparing the past river with the present one， we find that the Continuity index （C） of the North Canal has decreased since the Ming and Qing dynasties， indicating that human have imposed deep interference in the continuity of the river. By combining historical documents and DEM data， we find that under the constraints of natural geographical conditions， human excavation of river diversion， building dams， increasing water source to ensure the operation of the canal system and coping with floods， water system changes caused by floods are the reasons for the changes in the river system structure.