The Soil Erosion Dynamical Changes In The Ecological Restoration Area Of Beipiao City In The Western Liaoning Based On GIS And RS

Using data of trimester satellite remote sensing in 1998,2003 and 2008,the paper researchs the soil erosion situations and dynamic changes of ecological restoration area of Beipiao city in western of Liaoning Province, and analyses soil erosion dynamic change pattern of different kinds of land-use types. The results showed by the research were as follows:1. Characteristics of erosion situation of Beipiao city ecological restoration area In Beipiao city ecological restoration area, the level of erosion is mainly light erosion and moderate erosion, locally serious erosion. Soil erosion area is 2193.61km~2, 49.14% of ecological restoration area, in 2008. The slight, light, moderate and serious erosion area are respectively 2270.39km~2,1255.72km~2,619.16km~2 and 318.73km~2. And light erosion is the biggest, ocupping 57.24% of total area of soil erosion; moderate erosion ocupping 28.23% of that; serious erosion is less, only 14.53%; light and serious erosion are relatively concentrated. Comparing with 1998, soil erosion area is dropping from 3727.44km~2 to 2193.61km~2 in 2008, annual average decrement 153.4km~2. The soil erosion intensity is obviously diminished. According to variable quantity of different kinds of erosive intensity area, the paper ranks them: serious erosion(1355.71km~2)>moderate erosion(742.81km~2)> light erosion(564.69km~2).2.The variation of soil erosion in different periods in the ecological restoration area of Beipiao city:(1)The main soil erosion intensity type is mild erosion,moderate erosion and serious erosion in different periods in the ecological restoration area. The area of three kinds of erosion accounts for over 50% of soil erosion in different periods, and the rates are respectively 83.5%, 63.5% and 49.1% in 1998, 2003 and 2008. But the area of all soil erosion decreases gradually in the ecological restoration.(2)Transfer matrix calculations indicate that in different periods in the ecological restoration area of Beipiao city,the area of high-intensity level of soil erosion decreases and the area of low-intensity level of soil erosion increases, that is to say, the area of serious erosion and moderate erosion reduces and the area of mild erosion and micro erosion area increases.(3)From the annual variation of the soil erosion and area of 1998~2008 in the ecological restoration area of Beipiao city, we can get that most rate of annual variation is 20.82% in micro erosion. Through comprehensive control of soil and water conservation for 10 yeas,the area of micro erosion increases from 736.56km~2 to 2270.39km~2, increasing 1533.83km~2, accounting for 34.36%. The rate of annual variation is different in mild, moderate and serious erosion, and they are respectively 8.17%, -5.45% and -8.10%.3.The changes characteristics of soil erosion and land utilizing in the Ecological Restoration Area of Beipiao City.(1)The area change of different land use types during three periods of in the Ecological Restoration Area of Beipiao City showed that the forest area, water area and water conservancy facilities and construction land showed an increasing trend generaly; the cultivated land, grassland and non-arable land area were basically decreasing; the cultivated land reduced by 420.1 km~2 from 1927.5km~2 in 2008 to1507.4km~2 in 1998, accounting for 9.41% of the total area of the ecological restoration zone; the forest land increased by 551.1 km~2 from 707.8 km~2 in 1998 to 1258.9 km~2, accounting for 12.35% of the total area of the ecological restoration area. The area change between the cultivated land and the forest land witnessed the achievement in the Ecological Restoration Area of Beipiao City gained in work returning farmland to forests during the last ten years.(2)Since the decade 1998-2008, Cultivated land soil erosion area in ecological restoration area of Beipiao city in 1998 is 1353.8km~2, accounted for 70.2% of the cultivated area during this period, the area of cultivated land Soil erosion is 513.1km~2 in 2008, accounted for 34.0% of the cultivated area during this period; forestland soil erosion area increase from 607.4 km~2 to 782.6km~2, but the proportion of forestland area reduce from 85.8% to 62.2% from 1998 to 2008; grassland soil erosion area reduce 532.1km~2, which accounts for 52.0% of grassland area; the area of other land use types are less, so the influence of soil erosion is not clear.(3)Soil erosion intensity of different land use types in ecological restoration area of Beipiao city transform by high to low from 1998 to 2008, cultivated land, forestland and grassland transformation is most obvious, they show that the soil erosion intensity of different land use types change from serious erosion to middle degree erosion and light erosion, from middle degree erosion to light erosion and slight erosion, the soil erosion intensity in this ecological restoration area decreased significantly.