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通过对历史文献资料的统计与分析,以宁夏吴忠一带1644-1911年的洪涝灾害等资料为依据,应用了MATLAB软件包中的最小二乘法意义下4次多项式拟合,研究了清代宁夏吴忠一带洪涝灾害时间变化特点,通过MapInfo制图来分析空间变化特征,并仔细研究了该时期这一带洪涝灾害的等级序列。结果表明,该地区清代共发生洪涝灾害92次,平均每2.91年发生一次;整个清代宁夏洪涝灾害分布很不均匀,晚期为洪灾多发期,早期和中期为洪灾较少发生期。在这一带的七个地区中,整个清代中卫、灵武遭受洪涝灾害最为频繁,同心受灾较轻。该地区洪涝灾害以中度涝灾为主,发生频次为53次,占洪涝灾害发生总次数的63.10%,轻度涝灾次数为25次,占总次数的27.17%,大涝灾和特大涝灾发生的次数较少,分别发生了7次和3次,发生频率各占涝灾总数的7.61%和3.26%。大面积洪涝灾害(三、四级)平均每26.7年出现一次,占洪涝灾害发生年总数的11.90%。
Based on the statistics and analysis of historical documents and the data of flood disasters in 1644-1911 in Wuzhong, Ningxia, the fourth polynomial fitting in the sense of least square method in MATLAB software package was applied to study Wu Qing The characteristics of time-varying flood disasters were analyzed. MapInfo cartography was used to analyze the spatial variation characteristics and carefully studied the rank order of flood disasters in this period. The results showed that there were 92 floods in the Qing Dynasty in the Qing Dynasty, with an average of 2.1 floods in 1991. The distribution of floods and floods in Ningxia in the whole Qing Dynasty was very uneven. Floods occurred frequently in the late period and less frequently in the early and middle stages. In the seven regions in this area, the entire Qing Dynasty Zhongwei, Lingwu suffered the most frequent flooding, concentric disaster. Floods in this area are mainly moderate waterlogging, with a frequency of 53 times, accounting for 63.10% of the total number of floods and water disasters, 25 times of mild floods, accounting for 27.17% of the total, and the number of floods and floods Less, respectively, occurred 7 times and 3 times, the frequency of occurrence of the total number of floods accounted for 7.61% and 3.26%. Large-scale floods (three, four) occur once every 26.7 years, accounting for 11.90% of the total number of floods and disasters occurred.