Study On Ecological Hydrology In The Headwater Region Of Changjiang River

The ecological hydrology system in the headwater region of changjiang river is a characteristic system, which is vulnerably disturbed by environment change and human activities. Currently, to a certain extent, the typical ecological system is degrading especially for that is most interrelated to hydrological effect, for the example of rivers, glacier, frozen earth, swamp and marsh. The headwater of changjiang river, which is typical hydrological system in the high-cold region, becomes hot study area for the variation of drought and cold ecology system. It is important scientific value that the research in ecological hydrology of high-cold system is to understand evolvement rules.This study bases on field investigation and academic analysis to ecology problems of headwater region, and takes the ecological system theory and method to analyze vegetation as the key of environment in the headwater region of changjiang river. The aim of this study is to find the rules and reasons of the change of eco-hydrology environment.The data is GIMMS(Global Inventory Modeling and Mapping Studies)-NDVI(Normalized Difference Vegetation Index) that is long time series, low spatial and high time resolution, and the technology is geographic information system combined with statistics methods. The results show that the character of vegetation cover change has 1 year obvious cycle period as is seasonal, and early May is decisive time for vegetation change. Growing in the returning green period is most important factor to vegetation innerannual change trend and differences in spatial variation.The main trend of vegetation cover is rising through the recent 22 years, but spatially some areas is seriously degrading. The vegetation succession tends to be acidification, and vegetation change shows vertical nature and aspect nature. In conclusion, heat and water is the main condition for the vegetation growing and distributing in the cold arid region.Spring rainfall, temperature, surface land temperature is important for vegetation growing and changing in cold and arid region. May temperature change in the returning season has an important role to high-cold vegetation, and March rainfall is the important term for vegetation growing.The degree of ground water-rich impacts grow and distribution of vegetation. In the headwater region of changjiang river, all of rivers is the main drainage of groundwater, and the distance of affected area is 8km. After rain season, September, vegetation growing mainly depends on groundwater.As animal husbandry development and road construction, human activities speed up disturbing to vegetation ecology system of low elevation area. Settlements and roads are 24km of the affected area.To sum up, in recent 20 years, vegetation coverage is increasing trend in the headwater region of changjiang river, and its distribution and diversification changes accompany with the topography factors as elevation, aspect and slope. The key factor to influence vegetation spatio-temporal change is climate condition in returning green season, and the secondary factor is hydrological conditions as surface water and ground water. In addition, animal husbandry development and road construction accelerate breaking ecosystem of region.According to research of ecology hydrology environment changing rules and causing factors in the headwater region of changjiang river, this paper provides basic rules about eco-hydrology system evolvement, which is helpful to understand the cold and arid region ecology system, and which has some reference value to recover ecological environment.