Digital Photogrammetric Techniques as a Tool for Estimating Sediment Production of Gully Erosion in a Semi-arid Catchment of the Loess Plateau, China
Soil erosion not only represents the intense geomorphologic process of the Loess Plateau but also the symbol of the environment deterioration, soil erosion and the geomorphologic evolvement are interdetermined. Present research shows gully plays a leading role in the catchment morphologic evolution and ground surface dissected extension. The semi-arid cathchment of the Loess Plateau of China is severely affected by soil erosion as it is revealed by the commonly occurring deep and wide gullies. Recent studies in the loess hillgully terrain area show gully erosion has a very significant contribution to total soil loss. Traditionally, gully erosion had been measured u-sing field survey techniques, the advances in computing powering digital photogrammatric solution are now offering an affordable and cost effective way of estimating the gully erosion. This paper used the digital elevation models (2 m grid) , which constructed from multi-date (1959 - 1981 and 1999) aerial photographs (1: 55 000, 1: 20 000 and 1: 35 000) as a tool to compute the sediment yield by gully erosion in a small catchment of 9. 06 km2 located in the Loess Plateau of China. Soil loss of two periods; 1959 ~ 1981 and 1981 ~ 1999 was estimated from computed gully volumes using soil bulk density, compared the measured data with the estimated result of which, valued the DEM-based techniques for estimating soil loss, indicated that it should be possible to rapidly estimate soil loss, and recommendations were made for future applications of DEMs for assessment of soil loss as well. Based on the estimated results the impacts of human activities were analyzed: human activities is a double-edged sword which can improve the environment and accelerate the erosion at the same time, people still needs to do more to reduce soil erosion. Combined the statistic data with the DEM-based spatial analysis, it is clear that most of the soil loss are due to overland flow, mass movements and gully deepening.
gully erosiondigital elevation modelssediment production ratesemi-arid catchment
NETL
NSTL
万方数据
维普
