Soil Erosion Estimation And Comparison In The Tibetan Plateau During 1980-2009

Tibetan Plateau is one of the most sensitive areas with climate change,and soil conservation is one of the cornerstones of terrestrial ecosystem that have impact with the activities of plants and animals.The Tibetan Plateau mainly is alpine steppe grassland and degradation is serious now,it's direct impact ecological and economic development on regional.This research through the estimation rainfall erosion,wind erosion and freeze-thaw erosion assessment of the different soil ecological system in the Tibetan Plateau,analysis spatial distribution and the law of development of soil erosion in Tibetan Plateau for the protection and rehabilitation of soil erosion of the Tibetan Plateau provide the basis of the theory basis.This study on the Tibetan Plateau,through the basic data about factor of influence rainfall erosion,based on GIS and soil loss equation(USLE),Fixed Wind Erosion Equation(REWQ)and freeze-thaw erosion model to estimation erosion and degree and explore the main factors of influence the spatial distribution and control mechanisms.The main results were as follows:The study area rainfall erosion overall is lighter,but local erosion degree is serious.Range of different rainfall erosion area is? level(fs<1000>? level(1000<fs<2500>? level(2500<fs<5000>?level(5000<fs<8000)>V level(8000<fs<15000>VI level(fs>15000).I level area is largest about 205.46 × 106 hm2 and gradually increase over time,? level area is second about 20.96 × 106 hm2 and after the first increased reduction over time in 1980 to 1989.The study area most region is reduce erosion degree,which ?,?level rainfall erosion area ratio have increase trend,and ?,?,?,? level of rainfall erosion area proportion have decreasing trend.The increased of rainfall erosion degree in qinghai-tibet plateau is alpine meadow grassland ecosystem,followed by alpine steppe grassland ecosystem,and the reduction of rainfall erosion degree is alpine steppe grassland ecosystem and alpine meadow grassland ecosystem.As 10 years for a period,the study area rainfall erosion after the first increased reduction in 1980 to 2009,the maximum value appeared in the period 1990-1999.Rainfall erosion serious areas are mainly distributed in the eastern to the southeast of Tibetan Plateau.The study area wind erosion have certain spatial distribution pattern.No erosion(I<0.28)area are 2.36 x 108 hm2,and Slight erosion(0.28<I<0.34),Mild erosion(0.34<I<0.40),moderate erosion(0.40<I<0.46)and intensive erosion(0.46<I<0.54)area are 4.57 × 105,6.18 × 105,8.67 × 105,5.78 × 106and 1.84 × 105 hm2,respectively.Wind erosion mainly distributed in the west of Tibet,northern and central of Qinghai to Qinghai and Xinjiang border,central to western for the north of Qinghai and Tibet and wind erosion to the benign development of Xinjiang border of Qinghai province.During the 1980-2009,area of Mild erosion,Moderate erosion and Intensive erosion were reduce,wind erosion lighter areas has widened.The most Wind erosion increased area is alpine steppe grassland,the area of wind erosion intensity changes that alpine wetland and alpine desert grassland reduce are most.The change area of slope less than 3 ° is the wind erosion for the unit to reduce is less than 0.1 Kg/m2,followed by slope is 3-6 ° and the area of 6-9 °,the smallest region of wind erosion change is slope over than 12 °.Changes in wind erosion grade higher area will be smaller.The freeze-thaw erosion occurrence of Tibetan Plateau is very serious.The area of severe erosion is 74.25 × 106 hm2,followed by moderate,covers an area of 50.17 ×106 hm2,the area of mild and micro degrees were 34.14 ×106 and 18.28×106hm2.Alpine desert grassland and alpine meadow grassland,alpine steppe grassland and forest for different freeze-thaw erosion intensity area from micro to severe increase in tum.Different freeze-thaw erosion intensity area of alpine wetland by micro degrees to severely reduce in turn.Temperature less than 5 ° area,the area size of micro degrees(1.38<I<2.07)<heavy(2.71<I<3.81)<moderate(2.36<I<2.71)<mild(2.07<I<2.36).Freeze-thaw erosion area of the altitude less than 2000 meter is very small,the area of 2000 meter to 5000 meter above sea level is increase with altitude.Within the scope of the Tibetan Plateau rainfall,severe levels of freeze-thaw erosion area were highest with same level area under rainfall.In addition,the area is also the basic on aggravating the degree of freeze-thaw erosion increasing trends under the precipitation gradient.