The Study On The Multiple Time Scales Of Hydrological Time Series In Karst Drainage Basins

The water resources is the most precious foundational natural resources, is the strategic natural resource which the national economy and the society develops at the same time. Shortage of water resources and eco-environment degradation were the serious situation in karst drainage basins. There are doublely soluble aquifer media, unique hydro-geomorphological structure and the functional effects in karst drainage basins, whitch lead to a huge difference from non-karst drainage basins about the water system development and the hydrological dynamic. Hydrological process is a complex dynamic process, because it is affected by geography, climate, environment, human activities and so on. Hydrological time series demonstrated highly nonlinear and multiple time scales features, including identify and random compositions. Scale is a hot issue in the field of hydrology and water resources. Using the research of multiple time scales of hydrological time series in karst areas, we can enhanced the understanding of the laws on hydrological scale changes, guide the rational development and utilization of water resources, coordinate sustainable development including population, resources, environment and economy.In this article, using statistics, wavelet theory, spectrum analysis method, the multiple time scales of hydrological time series in karst drainage basins are studied. Main research results and conclusions are as follows:(1)In this study, taking the typical karst areas Xiangjiang River Basin as an example, using Morlet wavelet, the multiple time scales of the annual runoff time series analysed, the cyclical regularity is abtained. The annual flow time series has a mainly time scale cycle, which is 26 years. There is also a secondary time scale cycle of 7 years. At the two scales, runoff evolution shows obviously oscillation of rain and draught.(2)The multiple time scales of hydrological series are studied through the sliding average method and spectral analysis, different analysis methods have basically the same results, whitch shows that runoff cycle of the Xiangjiang River basin analysed with the wavelet theory is reliable.(3)The reasons of the evolution of annual runoff series are importantly analysed about the climate and human activities in karst drainage Basins, and the trend of their evolution in the future is discussed. The results show that the runoff changes are mainly affected by the average annual precipitation, the overall runoff will increase slightly on the various impacts of the human activities. Based on the "National Climate Change Assessment Report", the annual runoff will be likely to increase in karst drainage basins in Guizhou Province.