| Our country suffers from flood disaster frequently in history, short of water resources, and also the water ecological environment is fragile. After the found of new China, our water conservancy undertakings developed rapidly and have made remarkable achievements, effectively promote the economic development and social progress. In the process of exploitation and utilization of water resource, we also pay attention on the control of water saving and protection, the water resources development, utilization, management and protection system are compatible with socialist modernization.But with the population growth, rapid economic and social development, the problems of water resource, especially the problems between shortage of water resources and economic development are obvious. These problems threatened the sustainable development of our country. Hydrological system is a very complex system which is affected by many factors, its basin runoff features of changes affect the area's environment evolution, water resources development and utilization, also affect development process control and the development of the society in this basin. The runoff in the basin mainly affected by the climate factors and the influence of human activity. The evolution of rivers runoff of the basin mainly by underlaying surface factors, rainfall characteristics, watershed evapotranspiration features, human activities and so on, so many kinds of factors influence each other. It's a complex nonlinear dynamic process. Its evolution process shows both detemined regularity and displayed a strong randomicity. Therefore, rational development, economical utilization, effective protection of the water resources are very important to the development of our country, the analysis of rivers runoff variety trend plays a very important role in rational utilization of water resources and watershed water conservancy planning. So analysis of variation of runoff is very important practical significance.There are a lot of factors influence the runoff, domestic and overseas scholars made many research of influence factors on runoff, but most of these are single, focusing only on the one of them to analysis. This paper more fully on the major factors are discussed separately. Analysis including precipitation, climate change, the sun's activity, underlaying surface and the other factors, but in recent years, with human activity intensifies, the global temperature are gradually increasing and glaciers retreat, as a result, the underlying surface is damaged aggravatedly, ecological environment gradually deteriorated, also effect runoff. Due to climate, underlaying surface, the comprehensive function of human activities and so on, rivers runoff series are inherently a nonlinear and highly complex non-stationary system. The system is subject to periodic or non-periodic external forcing factor, making the runoff has a distinct change in time. About this nonlinear, non-stationary dynamic characteristics of the system, the best way is to use non-linear, non-stationary series approach to research and analysis.At present, there are many runoff forecasting methods, but the prediction accuracy has differences between each other. This paper mainly introduces the Exponential Smoothing, Experience Mode Decomposition and Grey Forecasting Model, and then based on the Experience Mode Decomposition and Grey Forecasting Model for runoff dynamic analysis and predict, then based on EMD decomposed Inherent Modal Functions on the basis of MATLAB to use Hilbert-Huang Transform to analysis the variation of runoff and the major influential factors. Through comparatived the annual runoff and of monthly runoff, the basin of Fenhe river during this period due mainly affected by solar activity, its runoff showed a monotonically decreasing trend from 1956 to 2000. This research supported technology about the rational use of water resources and water conservancy planning for Fenhe river.
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