Research On The Soil And Water Conservation Ecological Effects At Slop And Small Watershed Scales In The Rocky Mountain Areas Of Northern China

Rocky mountain areas of Northern China is one of the most serious soil and water losses areas in China.Soil and water loss is the main problem of the ecological environment.In recent years,the evaluation of the ecological effect of soil and water conservation is becoming a hot spot of research in the area Baima small watershed that located in Pinshun County,Shanxi Province is a typical small watershed of Tai Hang in the rocky mountain areas of Northern China.Based on the observation data of slope runoff plots and hydrological stations of Baima small watershed,analyzed the characteristics of rainfall systematically in the region.On slope scale,observed the runoff and sediment use positioning observation method at runoff plots,using statistical methods to classify erosive rainfall to analysis the benefits reducing runoff and sediment of different soil and water conservation measures in detail.On small watershed scale,using the distributed hydrological model of SWAT(Soil and Water Assessment Tool)to simulate runoff and sediment of Baima small watershed and using the method of extreme situation subjunctive to analysis the change of runoff and sediment at the situation of different landuse.The main conclusions are as follows:(1)Rainfall mainly concentrated in May to August in Baima small watershed,achieving the annual highest in July and August;The number of erosive rainfall in July and August account for 65.33%of the total number of erosive rainfall.It is easy to cause soil erosion during this period.(2)Runoff and sediment yield is affected by rainfall patterns at slope of plant measures.The benefits reducing sediment of herbs measures will not be able to give full play to in growth and germination stage.Arbor,shrub and herbosa should be used in combination in order to maximize the benefit of water and soil;Under the condition of different types of rainfall,the benefits reducing runoff of 5 plant+engineering measures:stone dike terrace>interval terrace>level bench>level trench>scale ripple;the benefits reducing sediment:stone dike terrace>interval terrace>level trench>level bench>scale ripple.(3)Collected the basis data of Baima small watershed,builded attribute database and spatial database of small watershed.At the same time,generated water system diagram of Baima small watershed,divided the Baima small watershed into 12 subbasin,45 hydrological response units(HRU).(4)Collected meteorological observation data of Baima small watershed from 2008 to 2014 and simulated the runoff and sediment of Baima small watershed use the SWAT model.Sensitivity analysis of model parameter was performed by SWAT-CUP software.There were 11 sensitivity parameters that affected the flow and 6 sensitivity parameters that affected the sediment.The SWAT model was calibrated and validated at the same time.(5)In calibration period and verification period of monthly runoff simulation,the relative error(Re)respectively are-23.67%,-18.58%;the correlation coefficient(R2)ratio respectively are 0.825,0.860;the efficiency coefficient(Ens)respectively are 0.798,0.806;In calibration period and verification period of monthly sediment simulation,the relative error(Re)respectively are 22.50%,14.81%;the correlation coefficient(R2)ratio respectively are 0.743,0.796;The efficiency coefficient(Ens)respectively are 0.699,0.627.It proves that SWAT model has a good application to Baima small watershed in rocky mountain areas of Tai Hang.(6)Assumed four kind of land use condition used the extreme land use method.The results showed that:grassland,forestland,shrub land can effectively control soil and water loss,cultivated land will make the region's soil and water loss problem more serious.