塔里木沙漠石油公路沿线沙丘移动规律

通过对肖塘南2km试验路段100m×100m沙丘移动监测区1991年10月、1992年10月及1993年10月的3次详测,总体上可以认为,沙丘各几何形态参数间存在着较好的相关性。但限于沙源供应不足,沙丘发育具有不成熟性,从而使有些沙丘几何形态参数间不存在理论上应具有的相关性。沙丘高度与宽度有较好的线性正相关关系,与底面积及体积存在较好的指数正相关关系。从而可以认为,沙丘高度是反映沙丘形成、规模及发育程度的较好示量指征。沙丘移动方向随主风向的改变而改变,并与落沙坡方向有明显的不一致性。沙丘移动强度与高度、底面积成线性负相关关系,而与体积成指数负相关关系。在不同时期,上述关系可用相似的多元线性方程表示。沙丘前移过程中,沙丘形态既有由不成熟到成熟的正向演变又有由成熟向不成熟的逆向演变过程。

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.