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台特玛湖干涸湖盆区风沙活动特征
俞祥祥
学位类型硕士
导师李生宇
2016
学位授予单位中国科学院大学
学位授予地点北京
学位专业水土保持与荒漠化防治
关键词风沙流结构 粒度 风沙运动参数 风动力 台特玛湖
摘要风沙活动特征研究是风沙危害防治的一项重要基础工作,也是实现风沙危害因地制宜、因害设防的重要基础。本研究依托214省道建立观测断面,通过野外观测取样及室内实验分析,对台特玛湖干涸湖盆区沙物质、风动力和风沙活动的时空变化特征进行了系统分析。主要结论如下: (1)台特玛湖干涸湖盆区地表基本不含水,土壤呈弱碱性,从A点至C点,沙粒粒径逐渐变细,分形维数逐渐增大,分选性由好变为较差,偏度逐渐由正偏变为极正偏,峰态逐渐由中等变为窄峰态。该区地表物质以极细沙和粉沙为主,细沙次之,不含中沙及以上粗沙粒。从A点至C点,细沙、极细沙含量降低,粘土、粉沙含量增加。该区沙物质主要来源为风成沙,运动方式以跃移质为主,A、B点蠕移质次之,C点悬移质次之。 (2)台特玛湖干涸湖盆区观测时间内6-9月为主要起风月份,9月之后风速迅速减小,A点月平均风速约为5m/s,C点约为3.5m/s,A点风速比C点大40%以上。A、B点风速主要分布在1-4m/s之间,分别占全部风速的51.56%和65.28%,A点91.50%的风在10m/s以下,C点92.54%的风在7m/s以下,A点大风(>6m/s)较C点多,C点<2m/s风较A点多, 3-6m/s风速A、C点占比相近。风速在一天中也有明显的变化规律,主要分为:夜间低风速段,日间高风速段、风速迅速增加段和风速迅速减小段。 (3)台特玛湖干涸湖盆区风向较为单一,主要以ENE及其相邻方向为主,A、C点差异不大,除主风向外,A点反向风(WSW及其相邻方向)出现频率较高,C点WSW、SE和SSE方向风出现频率较高,反向风出现规律并不明显。各向风平均分速方面,A点均大于C点,A、C点同为ENE方向风速最大,WSW方向风速次之,其余方向风速较小。因此,该区风沙活动以ENE及其相邻方向为主,偶有反向风沙活动。 (4)该区沙质荒漠化、盐渍荒漠化和荒漠-绿洲过渡带3种下垫面粗糙度平均值分别为0.0048m、0.0067m和0.1288m,临界摩擦速度分别为0.2423m/s、0.5374m/s和1.1727m/s,2m高度临界起沙风速分别为3.65m/s、7.65m/s和8.03m/s。说明台特玛湖干涸湖盆区不同下垫面状况对风蚀起沙有很大影响,该区沙质荒漠化下垫面易风蚀起沙,而盐渍荒漠化硬化的地表以及荒漠-绿洲过度带上稀疏的植被均能有效制止风蚀起沙的发生。 (5)台特玛湖干涸湖盆区不同下垫面风沙流特征差异明显。总输沙量上表现为A>>B>C。风沙流结构方面,测点A、B输沙量百分含量随高度增加呈幂函数形式降低,测点C随高度增加呈多项式形式先减小后增大。测点A、B输沙量主要分布在距地表20cm和50cm高度内,分别占观测高度输沙总量的77%和60%以上,测点C输沙量在各高度层分布较为平均。风沙流粒度特征方面,由A点至C点,平均粒径在各高度上均逐渐减小,分选性均逐渐变差,机械组成逐渐由以极细沙为主变为以粉沙为主。垂直方向上,随着高度的增加,平均粒径逐渐减小,分选系数逐渐增大,细沙及极细沙含量降低,粉沙及粘土含量增加。峰态和偏度方面,逐渐由正偏变为极正偏,由中等峰态变为窄峰态。
其他摘要Characteristics study of blown sand activity is an important basic work of sand dunes hazard control, also is an important foundation of adjusting measures to local conditions and specific hazard. This study based on 214 provincial highway establish the observation cross-section, use the field observation and indoor experimental analysis methods, systemic analyze time-space distribution character of the sand materials and wind regime and blown sand activity on dry up lake-basin region of Taitema lake. The primary conclusion is as follows: (1)The earth's surface is no water and soil take on slightly alkaline on dry up lake-basin region of Taitema lake. From A to C, particle size gradually become fine, fractal dimension gradually increase, sorting coefficient gradually from good to poor, skewness gradually from positive to extreme positive, kurtosis gradually from mesokurtic to leptokurtic. The deposition are mainly composed by very fine sand and silty sand, fine sand comes second and does not contain more than middle sand. From A to C, fine sand and very fine sand content decrease, clay and silty sand content increase. The deposition of the study area is derived from wind-blown sand, and the ways of grain transportation is mainly saltation, creep comes second at points A and B, suspension comes second at point C. (2) During the period of observation, 6th-9th months are mainly wind months, and wind velocity decreases after 9th month. The average wind velocity is about 5m/s at point A and about 3.5m/s at point C. Wind velocity at point A is larger than point C more than 40%.Winds of 1-4m/s account for 51.65% of all winds at point A and account for 65.28% at point C. 91.50% of winds under 10m/s at point A and 92.54% of winds under 7m/s at point C. Strong wind(> 6 m/s)of point A are more than points C, under 2m/s winds of point C are more than point A, A and C are similar at 3-6 m/s winds. There is a marked change in wind velocity in a day and it can be mainly divided into: low wind speed stage at night, high wind speed stage at daytime, wind speed increase rapidly stage and wind speed decrease rapidly stage. (3) The wind direction is relatively single at study area. Wind direction of A and C point are mainly in ENE and its adjacent direction. Except main wind-direction, WSW and its adjacent direction have higher frequency of occurrence at point A, WSW SE and SSE have higher frequency of occurrence at point C and its rule is not obvious. The aspects of average wind speed of each direction, point A are larger than C. At point A and C, the ENE direction has maximum wind speed, the WSW direction is second and other directions are small. Therefore, in this region blown sand activity is mainly in WSW and its adjacent direction, reverse blown sand activities is by accident. (4) The average roughness value of three typical underlying surfaces of sandy desertification, saline desertification and desert-oasis ecotone at study area are 0.0048m, 0.0067m and 0.1288m, the threshold friction velocity are 0.2423m/s, 0.5374m/s and 1.1727m/s, the friction velocity of 2m high are 3.65m/s, 7.65m/s and 8.03m/s, and it is show that different underlying surface has a great influence on winderoded dust. In this region, underlying surface of sandy desertification is easily winderoded dust, hardened surface of saline desertification and sparse vegetation of desert-oasis ecotone can effectively prevent wind erosion. (5) Characteristics of blown sand in different underlying surfaces have significant difference. Total sand transport shows A>>B>C. The aspects of sand flow structure, the sand transport flux of point A and B decreased with height by power function, the sand transport flux of point C decreased first and then increases with height by polynomial function. The sand transport flux of point A and B are mainly distribute within 20cm and 50cm high from the earth's surface, them are account for over 77%and 60% of the total sand transport flux in observed altitude. The sand transport flux of point C is average in each high. The aspects of characteristics of Aeolian transport particle size distribution, from point A to C, the mean grain-size is decreases and the sorting coefficient becomes poor and the mechanical composition of sand gradually changed from mainly very fine sand to silty sand at each heights. In the vertical direction, with the increase of height, the mean grain-size is decreases, the sorting coefficient gradually increase, fine sand and very fine sand content decrease, clay and silty sand content increase. The skewness is gradually from positive to extreme positive and kurtosis is gradually from mesokurtic to leptokurtic.
学科领域水土保持与荒漠化防治
语种中文
文献类型学位论文
条目标识符http://ir.xjlas.org/handle/365004/14743
专题研究系统_荒漠环境研究室
作者单位中科院新疆生态与地理研究所
推荐引用方式
GB/T 7714
俞祥祥. 台特玛湖干涸湖盆区风沙活动特征[D]. 北京. 中国科学院大学,2016.
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