关键词: 河流管理, 河流分类, 人为季节河, 人为季节河敏感带

Abstract: 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 Chian such as the lower Yellow River and Haihe River and some of their tributaries are all located in these susceptible zones.

Key words: river management, classification of rivers, man induced seasonal river, susceptible zone of man induced seasonal rivers