分形方法在洪涝灾害预测中的应用——以广西梧州为例

APPLICATION OF FRACTAL METHOD TO PREDICTION OF FLOOD DISASTER-A CASE STUDY ON WUZHOU CITY, GUANGXI ZHUANG AUTONOMOUS REGION

洪涝灾害是由暴雨洪水形成的一种突发性、最常见的自然灾害,它的发生在时间序列上具有分形特征.以广西梧州解放以来发生的特大洪涝灾害年份建立灾变日期序列,运用分式布朗运动模型中的R/S分析对洪涝灾害发生的时间序列进行模拟,计算了H指数值,建立R(t)/S(t)的幂函数关系式等,并以此为依据,预测下次灾年将在1999年出现.

The flood disaster, caused by rainstorm and flood, is a sudden and the most common natural disaster. The occurrence of the flood disaster is neither of full certainty nor of thorough haphazard. It is both periodic and chaotic. It reappears on the different time scale and has the self-similarity. So the occurrence of the flood disaster has the fractal characteristics on time sequence. Wuzhou City is in the southeast of Guangxi. With the disproportionate distribution of the time and space of precipitation, susceptibility to the typhoon plus its location at the lower reaches of three rivers, with 90 percent of the river's water flowing into Guangdong by the Xunhe River, the flood disaster frequently occurred in the history. This paper establishes the catastrophic time sequence with the years of the greatest flood disasters since 1949. The time sequence of the flood disaster is simulated by the rescaled range analysis of the fractional Brownian motion model and the 'H' exponent is calculated and the power function of 'R(τ)/S(τ)' is established. According to this calculation, the next disaster will appear in 1999.