中国江心洲河型的地域分布特征

AREAL DISTRIBUTION OF THE STABLE BRAIDED RIVER CHANNEL PATTERN IN CHINA

本文将江心洲河型在某一地域的出现作为或然率问题来处理,提出了江心洲河型频度的概念,作出了我国江心洲河型频度随纬度分布的曲线,并从不同自然带的自然地理因子的组合所决定的水沙因子的特定组合关系对这一分布曲线的形成机理进行了解释。

Starting from the comcept of river channel pattern frequency and based on the data from alluvial rivers in the monsoon-influenced eastern China, this paper deals with the areal distribution of the stable braided river channel pattern in China. The study shows that the stable braided river channel pattern frequency in the monsoon influenced eastern China exhibits a clear zonal variation, that is, the stable braided river channel pattern frequency has a high value in the zone of 22°-31° N and it declines sharply when going northward and dedreases to zero in the zone of 35°-45° N. Going further northward,the stable braied river channel pattern frequency starts to increase again, reaching another high value in the Heilongjiang River basin. This regular areal distribution can be explained by the different runoff-sediment combination in different natural zones, namely, the high value of stable braided river channel pattern frequency appears whete the runoffis abundant and sediment concentration is low. and vice versa. Since the runoff-sediment combination is controlled by the particular combination of physico-geographical factors in the river basins, the areal distribution of the stable braided river channel pattern in China can be regarded as the outcome of the latitudinal defferentiation of the physico-geographical factors in the monsoon influenced eastern China.