应用模糊分级统计研究西北干旱地区河流类型

河流类型的研究,一直是区域水文研究的重要课题,尤其是在干旱地区,可以为缺乏资料河流提供径流年内分配方面的依据。河流类型的研究,通常采用逐日平均流量过程来进行,但由于过程线的起伏较大,难以抓住主要特征。因此需要用模糊分级统计方法加以处理。应用模糊分级统计,首先要确定模糊分级的隶属函数。在一般情况下,可以写成:模糊频数a_i=∑u;a_na_i=a_i+x_1(a_(i+1)+a_(i-1) +x_2(a_(i+2)+a_(i-2))+x_3(a_(i+3)+a_(i-3))+……+x_n(a_(i+n)+a_(i-n))在西北干旱地区选择典型站和典型年进行河流类型的研究。研究结果,西北干旱地区河流动态的类型一共划分为9个类22个型。

A RESEARCH ON THE TYPE OF RIVER BY APPLYING FUZZY CLASS STATISTICS IN ARID REGION OF THE NORTHWSET OF CHINA

The research on the type of the river has been a principal and importantproject in the field of the regional hydrology. The research can also be usedto provide basis of the distribution of the runoff for the rivers which arelack of the relevant material, especially in the arid areas. Normally, the research on the type of river should be carried out byadopting the process line of the diural average rate of the flow. However, theundulation of the process line is so considerable that the main characteristicsare difficult to be grasped, therefore the fuzzy class statistics is adopted. Adopping the fuzzy class statistics, the subordinate fuction should be firstdetermined, which can be written like that: Frequency of Fuzzy: ?=∑μ_ia_n ?=a_i+x_1(a_(i+1)+a_(i-1))+x_2(a_(i+2)+a_(i-2))+x_3(a_(i+3)+a_(i-3))+……+x_n(a_(i+n)+a_(i-n)) The research has been made in the selected typical hydrological station and in the typical year in the Northwest arid rigion, The result indicates that the types of river trends in the arid region of Northwest in China have been divided into nine classifications and twenty-two types.