Fractal Characteristic Of The Runoff Process And Relation Between Ecologic Environment And It In Weihe Watershed

Hydrological system is a complex system, hydrological factors of temporal and spatial variation of highly nonlinear characteristics. Fractal theory on the hydrological system evolution of nonlinear regularity, available from complex hydrological system movement found its intrinsic, ordered and deterministic laws, more fully reveal the hydrological dynamical systems complex movement, at the same time, runoff process variation of complexity is the fractal dimension and ecological environment of the closely related.Wei River Valley,with a rich ancient civilization accumulation,is the cradle of Chinese civilization and history, its ecological environment have a direct relationship with the regional people's life quality and social, economic and sustainable development in all watershed. Therefore, establish a closely relatationship betweenn fractal dimension of regional runoff and the ecological environmentis plays a very important role in the regional developmentin both on qualitative and quantitative respects,and has a dual significance in theoritic and in practice.The papers focus on the improvement of ecological environment and it construction needs Of Wei River Valley, based on runoff series fractal, using GIS tools,calculated the fractal dimension about the year, month, ten days and different times of the process of runoff on Weihe River and the major tributaries cross.establishing a relationship between the runoff fractal dimension and the regional ecological environment state, in order to acquire the evaluation of regional ecological environment of fractal measuremen Attempt to use the annual runoff series fractal characteristics as parameters to the annual runoff forecasting model, implemented based on fractal theory of river runoff predictionAfter study, the main conclusions of the paper are:(1) Monthly discharge procedure has a certain amount of similarity, can be considered exist fractal characteristics; runoff process are more complex, the greater the fractal dimension value; on the contrary, larger the fractal dimension is, more complex runoff process.(2) The fractal dimension can be used to characterize the complexity of the runoff. Wei River basin monthly runoff fractal dimension maximum usually occurs on August or September,the minimum value is usually on February or March. Mainly because in the flood season of August and September,river runoff change greatly Influenced by rainfall; and on February and March the runoff is stable(3) In general, changes of the fractal dimension on the river station is flatter than the tributary stations, and relatively small amplitude,and the amplitude is relatively small. Analysis of the reasons are:river runoff factors are complex, runoff adjustment is ability, but the tributaries are simple in structure,poorly in adjustment. In this sense, may also interpret thar, larger tributaries' fractal dimension are bigger than small watershed(4)The relationship between vegetational coverage and runoff, related with climate topography, geology, soils, and other environmental conditions in the watershed. Different topographic and geologic conditions,lead to effect of vegetation cover on the runoff process are different.Through establish the relationship between fractal dimension of Weihe River runoff process and the state of ecological environment, this article try to obtain fractal measurement method on evaluation of regional ecological environment,result shows:in Wei River watershed, higher forest coverage not means smaller fractal dimension,and,highter cropfield area means bigger fractal dimension and worse state of ecological environment, but highter forest-grass vegetation coverage related to the smaller runoff fractal dimension.So, forest-grass vegetation coverage could be take as important indicator to judge the state of the ecological environment in Weihe area.That is, the high the forest-grass vegetation coverage, the excellent of the eco-environmental, if on the contrary, the ecological environment is poor. From this, change more cropfield into grassland is the effective way toimprove the regional ecological environment of Weihe watershed.(5)According to analysis of the relationship between Wei River's main basin and the tributaries, try to introduce a simple cubic polynomial with tributaries'annual runoff,take fractal dimension as parameter. Results shows that,the forecast values is not very accurate, but generally fit.