Hydrological Frequency Calculation Method Study of Urban Rivers Runoff under Changing Environment

The consistency of hydrological series has been destroyed by the impact of human activities and climate change. Hydrological series is consist of certain component and random element. The random and certain components of hydrological series are identified and separated through statistic analysis. The certain element is determined by using hydrologic model while the consistancy of random element is confirmed directly by hydrological frequency curve. And then add them together. The runoff series of the Huangtai Hydrometric Station in the Xiaoqing River is for example. It proves effective and feasible and the result accord with the reality of the basin.