人为季节性河流的初步研究

A preliminary study of man-induced seasonal rivers: examples from China

由于人类引水量的激增 ,我国北方的一些天然常流河频繁断流 ,已经成为季节性河流。文中提出了人为季节河的概念 ,在分析天然常流河与天然季节河的形成条件的基础上 ,查明了人为季节河形成的敏感带和在这种敏感带中 ,常流河向季节河转化的条件。

Natural rivers may be classified into two categories, natural permanent rivers and natural seasonal rivers. However, due to strong human activities, some permanent rivers in north China have been changed into seasonal rivers, and the most striking examples are the lower Yellow River and other major rivers in North China Plain. These rivers can be regarded as a new category of rivers, and are termed “man induced seasonal river” in the present study. To elucidate the formation of man induced seasonal rivers, this paper first discusses the conditions for the formation of natural permanent and seasonal rivers, including the influences of climate, topography, vegetation and lithology. The factors responsible for the formation of man induced seasonal rivers can be divided into two classes; the first are specific natural settings and the second are unreasonable human activities. In zones with some specific combinations of natural factors, the transformation from permanent to man induced seasonal rivers is most likely to occur. These zones can be regarded as susceptible zones of man induced seasonal rivers. In the present study, three susceptible zones of man induced seasonal rivers have been identified, i.e., the transitional zone from arid to semi arid climates, the zone of “hanging river” development, and the zone with unbalanced land water coupling. To a great degree, the formation of man induced seasonal rivers in these susceptible zones is the result of the excessive water diversion by man for irrigation and other water demands during low water seasons. In these susceptible zones, deforestation may also lead to the transformation from permanent to seasonal rivers. This study shows that the major man induced seasonal rivers in China such as the lower Yellow River and Haihe River and some of their tributaries are all located in these susceptible zones.