THE SAND DUNE MOVEMENT ALONG THE TARIM DESERT OIL-TRANSPORTATION HIGHWAY

This project was carried out along the 2 km test section of the Tarim Desert Oil transportation Highway, south of Xiaotang from October, 1991 to October, 1993. The monitoring sample plot selected was 100 m×100 m in area and located on 200 m east of the highway. Detailed morphological survey method was adopted. Three times of morphological survey were made in October of 1991, 1992, 1993 respectively. The corresponding landform maps were prepared. Measured geometric parameters of dunes were used to derive their quantitative relationships by regression method. By comparing the morphology maps of different terms, the magnitude, direction and morphological change of dune movement were derived. Results indicate that the range of dune movement is closely related to dune height, base area and volume. The distance of sand dune movement decreases linearly with the increase of dune height and base area, but exponentially with the dune volume. Similar multivariate function can be applied to express the relationship between dune movement and height, base area, as well as volume for different terms. The range of dune movement from October, 1991 to October, 1992 was greater than that from November 1992, to October, 1993, but the direction of slipfaces changed less. This indicates that the faster movement from October, 1991 to October, 1992 was determined by the more intensive wind and less morphological adaptation. The dune movement direction depends on the annual resultant wind direction, but is also influenced by the extent of dune development. The underdevelopment of the sand dunes within the survey plot results in the instability of dune movement direction. In the course of sand dune movement, some small dunes merged into bigger ones, while some typical barchan dunes degraded into sand sheets or disappeared. In summary, the underdevelopment resulting from insufficient sand supply can be shown by the relationships between different dune geometric parameters, dune movement and the morphological change.