Remote Sensing application in soil erosion studies on the loess plateau
Lin Pei , Liu Liming
National Center of Agricultural
Remote Sensing Application
and Training
Beijing Agricultural University,
Beijing ,China
Abstract
Remote sensing application in soil erosion studies has been made on the Loess Plateau, northwest of China, which is one of the national projects taken on in the 7th -five-year plan period. This paper tries to introduce a methodology of quantitative analysis of soil erosion taking small watershed for the study cell of the erosion system. A match of the results of remote sensing interpretation and experimental measurements was made, and a series of models based on the most important erosion factors were developed. Finally, the technological process of quantifying soil erosion with remote sensing information supported by Soil Erosion Information System was established. A trial small watershed was selected to test the method, and the results showed that the technological process is logically available.
Introduction
The Loess Plateau that is famous for its deep deposit and wide distribution of Loess is located between 103-112E and 34-38N in the Northwest of China, with an area of 357.000 km2 and average elevation of 1.000-2,500 meters. Severe erosion with a long history not only has produced a great impact to agriculture in this area, but also silted up the reservoirs and riverbeds in the lower reaches. So it has been seriously damaging the ecological systems in the Loess Plateau and the near areas. Since 1950's, this problem has been payed great attention, to study and now the remote sensing application on the loess Plateau is one of the 7th -five -year national projects.
General situation of soil erosion on the loess plateau and study programme of Remote Sensing application
The Loess Plateau is located in semi-arid region with annual precipitation of 350-500mm. About 70% of the precipitation falls in storms in July and August. Because of the deep deposited Loess and steep descent of hillslope, soil erosion is very severe in this region. However, intensive cultivation has not been limited and vegetation cover is very low (<20%). As a result, the whole plateau is incised into small scraps. According to some references , about 16-18 billion tons of soil is transported into Bohai Sea by Yellow River, over 80% is from the Loess eau , especially from the gorge between shanXi and shann Xi provinces, Reasonablely, the main trials of remote Sensing application in soil erosion were taken on in Mizhi county, Ansai county, and county, and Shenmu county in this region.
From remote sensing images, we can distinctly three types of landforms: the uplands deeply incised by gullies (Yuan), the narrow hills (Liang) and the round hills (Mao). Especially, soil erosion in the Liang and Mao regions are more serious than that in the Yuan regions, because of much steeper slope and more strap land. We usually call the Liang and Mao regions "hilly -gully regions".
