Precipitation and Runoff Changes and Their Driving Forces of Marshy River in the Sanjiang Plain, China

摘要

Over the 68% of the Wetland has vanished and been turned into agricultural fields with large-scale reclamation in the Sanjiang Plain of Heilongjiang Province of China since 1956. This study investigated precipitation and runoff changes and their driving forces of marshy river in the plain over the second half of the 20th century. The sample study area is located in 46°13′-46°20 ′N and 132°27′-133° 20 ′ E, between Baoqing Station in upper course of the Naoli River (a mountain-marshy river in the Sanjiang Plain) and Caizuizi Station in the lower course. The results indicate that the decline trend with close correlation (r=0.92, α=0.01, n=40) in annual precipitation and runoff of marshy river since 1950 reflects the changes, but a sharp surge of the precipitation in 1960s is exceptional. With decrease of wetland and increase of agricultural fields, the relationship of annual precipitation between upper and lower courses of marshy river, is changing from nonlinear to linear status. The gradually disappearing annual precipitation follows the vanishing of the wetland in the area. The flood retarding of marshy river is loosing its function. Research of the driving force illustrates that human activities, such as large-scaled reclamation, were probably the most important and direct factor that resulted in abrupt change of annual precipitation and runoff and further affected regional water balance and the hydrological cycle