清代民国时期黄河上游洪水灾害--以兰州地区为例

Flood disasters in the upper reaches of the Yellow River during the Qing dynasty and the Republic of China:a case of Lanzhou area

借助红噪声分析软件Redfit35和Excel软件，整理、计算和分析大量历史资料，对清代民国时期兰州地区洪水灾害做时间和空间上的特征分析。结果表明，清代民国时期兰州地区洪水灾害发生频次为2．78年／次。轻度水灾发生频次为6．38年／次，中度水灾8．74年／次，大水灾11．77年／次，特大水灾306年／次；前期洪水灾害较少，中后期有四个集中高发时段，越到后期，严重水灾发生越频繁，灾害危害越大；洪水灾害主要是夏季水灾，其次为秋季水灾；洪水灾害的发生具有周期性，其存在的2～8年周期、准22年周期、70—80年周期说明该地区洪水灾害的发生与低纬海洋大气活动、太阳黑子活动和太平洋年代际振荡之间可能存在着某种关联；兰州地区所辖四地中，皋兰是最易发生洪水灾害的地区。兰州发生的洪水灾害主要为大水灾和轻度水灾；皋兰发生的洪水灾害主要为中度水灾和轻度水灾；榆中发生的洪水灾害主要为大水灾；永登共发生3次洪水灾害，全部为大水灾。

A lot of researches have been conducted on the characteristics and reasons of the flood disasters in the Yellow River basin, but the researches on the historical flood disasters in the upper reaches of the Yellow River is scarce and the research object is mainly to the palaeoflood events. In the paper, taking Lanzhou area of Gansu Province for example in the upper reaches of the Yellow River, detailed and system researches were made on the flood disasters in historical periods to explore the occurrence regularity of the flood disasters, which present some bases for preventing and decreasing floods of Yellow River. Based on lots of historical materials, according to the index of the condition of floods, the rank series of floods were set up and the historical floods in Lanzhou area were divided into four ranks of the light flood, the moderate flood, the grave flood and the extreme flood. Through calculating and analyzing historical materials, the paper obtained the space-time characteristics of flood disasters in Lanzhou area during the Qing dynasty and the Republic of China. With the soft of Redfit35, the periods of flood disasters were analyzed. The results indicate that in Lanzhou area the period of flood disaster is 2.78 years. The periods of light flood, moderate flood, grave flood and extreme flood are respectively 6.38 years, 8.74 years, 11. 77 years and 306 years. The floods occurred scarcely in the earlier time and in the later time there are four high occurrence stages of flood disasters, i.e. 1740 - 1789,1800 - 1869,1880 - 1909 and 1920 - 1949, respectively, and there existed such a period of per ten years. The grave flood is more frequent and the harm is heavier in the later time. The floods is mainly the summer flood, next is the autumn flood, the summer-autumn flood had a considerable proportion and the spring flood and the winter flood are scarce. The flood disasters in Lanzhou area during the Qing dynasty and the Republic of China have the characteristic of explicit periodicity. The periods of 2 - 8 years, 22 years and 70 -80 years are corresponding to the period of ENSO, macula activity and the PDO, which indicated that the flood occurrence is possibly relate to the atmosphere activity above ocean in low latitude, macula activity and the PDO. The occurrence mechanism of the period of about one hundred years is not certain and need deeper research. In Lanzhou area, Gaolan County is the place where floods occurred most frequently. The floods in Lanzhou are mainly grave floods and light floods, in Gaolan county are mainly moderate floods and light floods, in Yuzhong County are mainly grave floods, and there are three floods in Yongdeng County and they are all grave floods.