This paper explores the water level changes of river networks under the changes of underlying surfaces represented by urbanization based on water level duration curve(LDC)method,taking the Taihu Lake basin as an example.According to the result from LDC analysis,the LDC slope of the 1980sand 1990sis steeper than the other decades.Then the study period is divided into two periods:1950s-1970sand 1980s-2000s,and normal years are selected to make further investigation.Results indicate that the LDC slopes of all the gauges in the1980s-2000sare steeper than those in the 1950s-1970s,and the LDCs of the former are also above those of the latter.What's more,the relative variations between the two periods are significant in the high water level end,and the variations are the least in the low water level end.Analyses of the precipitation and water level trend in the study area indicate that the significant increase of average water level is not consistent with the trend of precipitation.It is concluded that the above results are due to the influences of urbanization,i.e.,changes of underlying surfaces cause the slope of LDC to increase,thus the changes of water levels respond more quickly to rainfall,and the high water levels increase more significantly as well.