Evaluation Of Water Retention And Water Purification Function In The Northern Slope Of Qinling Mountains And The Surrounding Ecosystem

The ecosystem service function perform normally is the premise of guarantee for healthy and stable development of the regional ecological system.This article takes northern Qinling as the research object,using the comprehensive assessment of ecosystem service function and tradeoff model-InVEST,from the scale of the watershed and sub_watershed,respectively evaluated the water conservation and water purification ability and its spatial pattern heterogeneity in 2000 and 2010,and with the ecological environment information of the study area,analyzed and explored the sensitivity factors of water conservation and water purification function,the results showed that:(1)In 2000,the amount of water conservation in the northern slope of Qinling mountains are 40.16×108m3,the average water conservation capacity are 242.37 mm.In 2010,the amount of water conservation in the northern slope of Qinling Mountains are 44.5×108 m3,the average water conservation capacity are 265.33 mm.The main water retention area in the northern slope of Qinling Mountains are Hei River,Shitou River,Chan River and Ba River basin,and the high value area of water retention present to some sub-watershed which distributed in the south of Hei River,Shitou River,Shensha River and the south of Ba River.(2)Climate factor is closely related to the ability of water conservation,the land use and cover through vegetation changes affect the area water conservation function.From the perspective of vegetation,the highest contribution rate to water conservation is deciduous broad-leaved forest,account for 53.27%of the total conservation for each type of vegetation.And from soil properties,brown soil has the highest contribution rate,account for 37.67%of the total retention.(3)In 2000,The outputs of N in northern Qinling are 4997.17t,the retentions of N are 13966.14t,and the outputs of P are 263.32t,the retentions of P are 927.19t.As well in 2010,The outputs of N in northern Qinling are 5003.69t,the retentions of N are 13514.22t,and the outputs of P are 256.98t,the retentions of P are 886.88t.Hei River and Chan River basin has the minimum amount of N,P output in per unit area,the water quality purification ability is strong,mainly displays in the southeast of Hei River basin,the south sub-watershed of Feng River and Chan River basin.The watershed of Shitou River,Feng River,Lao River and Shensha River are taken the second place.The largest per unit N,P output are illustrated in Ba River basin and Tong River basin,and the water purification ability is relatively weak.(4)In each land use type of northern Qinling,N,P outputs and retentions keep positively correlated relationship with farmland coverage,and keep negative correlation relationship with grassland,forest and shrub coverage.Among various vegetation types of northern Qinling,farmland,deciduous broad-leaved forest and deciduous broad-leaf shrub has larger per unit N,P output,and the farmland accounted for the highest N,P output.From soil properties,bog arable soil has the highest N,P outputs in per unit.While cinnamon soil,loess soil,brown soil,alluvial soil has higher N,P output rate,these four types of soil are accounts for about 80%of the total amount of outputs.Function of water conservation and water quality purification of area is the ecological expression of water resources on the quantity and quality view,clear-out the quantitative relation and spatial distribution characteristics of area's water conservation and water purification function especially the small watershed,has great significance for the river basin water resources allocation and water quality monitoring and control.