A Comparative Research On The Effects Of Vegetation Change And Climate Variability On Runoff In Typical Climate Zones Of China

Water resource and forest resource are fundamental for the sustainable development of human society,which are the hot topic in hydrology research.Focus on climate change and human activities(land use changes)effected on hydrological processes are beneficial for resources management in the regional watershed.With the global warming and the incensement of land use,the water molecules changes significantly in time and space,which makes the researchers,pay more attention to interaction between water and nature.Based on the large scale experimental watersheds of three different climatic zones in China,this paper quantitatively analyses the response of climatic variability and vegetation change on runoff.The result shows that:Trend analysis is one of the indicators of change position in hydrological elements during the study period.According to the three watersheds of different climatic zones,the Mann-Kendall Tau test and Spearman Rho were used for trend analysis,which were employed for annual mean temperate,precipitation and runoff(average annual runoff,flood runoff,non-flood runoff).Moreover,combine the relationship between stream flow and climate factors to qualitatively analyze the response of climatic variability to runoff.Using sensitivity-based method and MDMC method to calculate the non-climatic factors effected on runoff later.The vegetation effect on stream flow is fundamental to modern forest hydrology.This paper is based on single watershed,which employed statistical analysis(MDMC,ARIMAX regression model)to calculate the response of runoff.This method is faster and simpler than the traditional hydrological model method.In the past 25 years in Niyang River watershed,the temperature has increased significantly.Moreover,the increasing trend of precipitation is consistent with runoff.The vegetation restoration(forest and grassland)is focus on the middle and lower region.Water consumption and transportation enhanced are the main reason why non-flood runoff had decreased in Niyang River watershed.The non-flood runoff is original from groundwater and precipitation,which had a significant positive correlation with precipitations.It is indicated that precipitation was the main reason to increase runoff.The Meijiang River Basin temperate has been heated up in the past 50 years;otherwise,the trend of precipitation is not significant change.But in July-September,the precipitation increased obviously,which was significantly leading to increase non-flood runoff.It could be seen that,climatic variability will increase non-flood runoff in Meijiang River watershed.Based on the data from 1958 to 2004 from Zagunao climatic station,the trends of annual runoff and flood runoff are changing stable,while non-flood increased insignificantly.The annual temperate is consistent with the change of precipitation.Both inter-annual and annual precipitation increase fast.According to the non-flood runoff was mainly composed from groundwater and snow melt.However,the average temperate and the highest temperate between November to April show a significant upward trend,which increased snowfall.Finally,it increases non-flood runoff.While deforestation enhances the surface convergence,it has a appositive effect during recovery.