20世纪80年代以来,在气候和人类活动因素的影响下,太湖流域汛期河网水位上升明显,洪涝频发。论文基于流域腹部地区站点日降水和水位资料,对历年降水和水位进行分等级研究,分析它们的变化趋势及差异;并采用两变量弹性分析方法探讨水位对降水变化和以城镇化为代表的人类活动响应的敏感性。结果表明:①1954—2006年汛期和非汛期高等级(8~10级)降水占相应时段总降水的贡献率呈上升趋势,而低等级(1~3级)降水贡献率呈下降趋势,即降水集中程度在增加。水位变化呈现类似特点,并且高等级水位的集中程度增加更为显著。②基准期(汛期1954—1985年,非汛期1954—1987年)水位变化对城镇化的弹性系数均未达到显著性水平,而相对期(汛期1986—2006年,非汛期1988—2006年)的城镇化弹性系数比较显著,其造成水位变化的贡献率在非讯期已接近降水的贡献率。因此,以快速城镇化为代表的人类活动影响,在研究区水位变化中发挥越来越重要的作用。
The water level of river network significantly increased and flood disasters occurred frequently in the Taihu Lake Basin at the end of the 20th century under the influence of climatic and anthropogenic factors. This paper makes a classification analysis of precipitation and water level series and explores the trends of their changes based on daily rainfall and water level data. A two-parameter elasticity analysis is adopted to investigate the sensitivity of water level to precipitation changes and urbanization which is representative of human activities. The main results are as follows: First, the contribution of low ranks (Ranks 1-3) of precipitation in flood and non-flood seasons to the total precipitation in the same period is on the decrease while the contribution of the high ranks (Ranks 8-10) is on the increase, thus the concentration of precipitation increases. The characteristics of water level are similar to those of the precipitation. However, the concentration of high rank water levels increases much more significantly than that of the rainfall. Second, the elasticity of urbanization during baseline period (1954-1985 for flood season and 1954-1987 for non-flood season) is not significant at the 5% level, while it is significant during the comparison period and the contribution of urbanization is near that of the precipitation. The paper draws a conclusion that human activities characterized by fast urbanization have played an important role in the changes of water level in the core region of the Taihu Lake Basin since the 1980s. The results of the paper may provide support for flood control and urban planning and management in the study area.
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