KMS XINJIANG INSTITUTE OF ECOLOGY AND GEOGRAPHY，CAS
| 台特玛湖干涸湖盆区沉积物含盐量对风蚀影响的风洞模拟研究 | |
| Alternative Title | Wind-tunnel Simulation on the Effect of Salt Content in Sediment of Dry Lake Basin of Taitema Lake on Wind Erosion |
| 任宏晶 | |
| Subtype | 硕士 |
| Thesis Advisor | 雷加强 |
| 2019-06-30 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Discipline | 农学硕士 |
| Keyword | 湿-干交替湿-干交替 含盐量 沙土质量比 结皮稳定性 风蚀率含盐量 沙土质量比 结皮稳定性 风蚀率 Wet-dry Alternation Salt Content Sand-clay Mass Ratio Crust Stability Wind Erosion Rate |
| Abstract | 我国干旱区尾闾湖泊面临严峻的萎缩、 咸化、 干涸及风蚀沙化问题。 以往研究主要侧重于沉积物盐分含量及盐尘扩散等方面， 而关于丰水-枯水（湿-干） 交替状况下水量、 含盐量、 机械组成对沉积物风蚀量影响的研究鲜有报道。 本文通过对台特玛湖干涸湖盆区野外调查、 原状土样风蚀模拟， 实验室制备不同水量湿-干交替、 结皮不同含盐量、 不同机械组成试样以模拟干涸湖盆真实状况， 测定了各试样结皮厚度、 硬度、 抗剪强度、 含水量、 含盐量， 并在风洞中开展不同风速及时间、 不同沙源供给条件下的吹蚀试验， 测定并计算其风蚀率， 揭示了沉积物湿-干交替、 含盐量及机械组成差异对地表风蚀的影响规律。 主要研究结论如下：（1） 台特玛湖干涸湖盆区沉积物风蚀特征： 研究区含盐量较高， 空间差异较大， 丘间湖相沉积地表及荒漠-绿洲过渡带沉积物含盐量基本小于盐渍荒漠化区； 土壤硬度、 抗剪强度表现为： 丘间湖相沉积地表＜荒漠-绿洲过渡带＜盐渍荒漠化-黑色地表＜盐渍荒漠化-芦苇根覆盖地表＜盐渍荒漠化-盐结壳地表。净风及携沙风条件下， 不同区域沉积物抗风蚀能力差异明显， 丘间湖相沉积地表与荒漠-绿洲过渡带累积风蚀率显著大于盐渍荒漠化区。 同时， 不同区域沉积物风蚀量随风速的增加也产生一定差异， 净风时， 丘间湖相沉积地表及荒漠-绿洲过渡带沉积物风蚀量随风速增加显著增大， 而盐渍荒漠化区沉积物抗风蚀能力较强，风蚀量随风速增加无显著变化。（2） 不同水量湿-干交替对风蚀的影响： 不同水量湿-干交替下， 沉积物表面结皮形态和稳定性产生显著差异， 结皮厚度、 硬度、 抗剪强度随着水量的增加而线性增加（除纯沙） ； 结皮含水量随湿-干交替时水量的增加无明显差异， 且与未经湿-干处理（CK） 试样无明显差异， 排除了因结皮含水量不同而造成蚀积差异这一干扰因素。 净风及携沙风条件下， 非纯沙试样的累积风蚀率随水量的增加而显著降低； 纯沙表面因未形成结皮， 累积风蚀率较大， 且随水量的增加无明显差异。 净风条件下， CK 试样风蚀率随风速的增加而显著增加， 与之相比， 经不同水量湿-干交替处理后， 非纯沙试样抗风蚀效率达 99 %以上， 风蚀率随风速增加无显著变化； 纯沙试样的风蚀率在各水梯度下风蚀率无显著差异， 且与 CK无显著差异， 风蚀率均随着风速的增加而显著增加。 携沙风条件下， CK 试样随风速的增加， 呈风积-风蚀-更大风蚀的变化； 与之相比， 经不同水量湿-干交替处理后，非纯沙试样蚀积率显著降低，纯沙试样的风蚀率在各水梯度下无显著差异，且与 CK 亦无差异， 随着风速的增加， 样品呈少量风积-风蚀-更大风蚀的变化。同时， 沉积物湿-干交替过程中有裂隙发育， 携沙风条件时， 沙粒在裂隙中填充且湿-干交替引起结皮稳定性增加， 使部分试样的累积风蚀量计算数值为正， 表征其产生风沙堆积， 但是， 因风蚀率计算的时距因素， 裂隙中堆积又被高风速时部分风蚀的沙粒会使累积风蚀率数值出现负值， 因此适当补充风蚀量数据可进一步说明湿-干交替产生稳定结皮并伴随裂隙发育造成的风沙堆积和风蚀抑制作用。（3） 表面结皮含盐量对风蚀的影响： 经不同溶度梯度盐溶液处理后制备的试样， 表层盐结皮形态和稳定性产生差异， 纯沙试样的盐结皮厚度、 硬度及抗剪强度随着含盐量的增加而显著增加； 含水量随着盐溶液浓度的增加无显著差异或略有增加， 排除了后期实验中， 试样因结皮含水量不同而造成蚀积差异这一干扰因素。 净风及携沙风条件下， 非纯沙试样因盐结皮的保护作用及水的固结作用，风蚀量很低， 累积风蚀率随结皮含盐量及风速的增加均无显著变化； 结皮含盐量较低时， 风蚀率受湿-干交替时水量影响大于结皮含盐量对其影响， 当表面含盐量较高时， 影响作用相反。 纯沙条件时， 因仅水无法对其产生固结作用， 在水与盐的共同作用下形成不同含盐量的盐结皮， 且随着结皮含盐量的增加风蚀率显著降低； 同时风蚀量随风速增加显著增加， 且与 CK 产生显著差异。 因风蚀率计算方法会忽略因吹蚀时距差异造成的蚀积表征误差， 针对部分抗风蚀能力较强的试样， 适当补充其风蚀量的数据更能体现和验证含盐量较高时的风蚀抑制作用并产生了风沙堆积。 |
| Other Abstract | Terminal lakes in arid regions of China are facing severe problems of shrinkage,salinization, drying up, wind erosion and desertification. Previous studies mainlyfocused on salt content in sediments and diffusion of salt dust. Until now, there arefew reports on the effects of water, salinity and mechanical composition on winderosion under the condition of wet-dry alternation. In this paper, the authenticcondition of dry lake basin is simulated by wind erosion simulation of undisturbedsediment samples in dry lake basin of Taitema Lake, samples with wet-dry alternation,different salt content and mechanical composition prepared in laboratory. The crustthickness, hardness, shear strength, water content and salt content of each sample aremeasured. Wind erosion experiment were carried out in wind tunnel under differentwind speed, time and sand supply conditions. The wind erosion rate was measuredand calculated. Effects of wet-dry alternation, salinity and mechanical composition ofsediments on wind erosion are revealed. The main conclusions are as follows:(1) The salt content in the dry lake basin of Taitema Lake is higher, the spatialdifference is larger, and the salinity of lacustrine sedimentary area and desert-oasisecotone is basically lower than that in saline desertification area; the soil hardness andshear strength are as follows: lacustrine sedimentary area < desert-oasis transitionzone < saline desertification-black surface < saline desertification-reed coveredsurface < saline desertification- salt crust surface. Under the conditions ofnon-sand-driving wind and sand-driving wind, the wind erosion resistance ofsediments in different regions is obviously different. The accumulative wind erosionof the surface of lacustrine sedimentary area and the desert-oasis ecotone issignificantly greater than that of saline desertification zone. At the same time, thewind erosion rate of sediments in different regions also have some difference with theincrease of wind speed. Under the condition of non-sand-driving wind, the winderosion of lacustrine sedimentary area and desert-oasis ecotone increases significantly with the increase of wind speed, while the wind erosion resistance of the sediments insaline desertification area is stronger, and the wind erosion has no obvious changewith the increase of wind speed.(2) Influence of wet-dry interaction of different water quantities on wind erosion:Under the condition of wet-dry alternation, the surface morphology and stability ofsediments were significantly different. The thickness, hardness and shear strength ofthe soil crust increased linearly with the increase of water (except sand); the watercontent of crust has no significant difference with the increase of water gradient, andthere is no significant difference with CK. Under the conditions of non-sand-drivingwind and sand-driving wind, the accumulative wind erosion rate of clay samples andclay/sand mixed samples decreased significantly with the increase of water gradient;the surface of sandy soil did not have crust, the accumulative wind erosion rate washigher, and there was no significant difference with the increase of water gradient.Under the condition of non-sand-driving wind, wind erosion rate of CK increasesignificantly with the increase of wind speed; compared with CK, the anti-winderosion efficiency of clay samples and clay/sand mixed samples treated by wet-dryalternation with different amounts of water is over 99 %, the wind erosion rate doesnot change significantly with the increase of wind speed, and the wind erosion rate ofsandy soil samples has no significant difference with different water gradientstreatment.Under the condition of sand-driving wind, the erosion rate of CK sampleschanges significantly with the change of wind speed. The samples show the change ofaccumulation-wind erosion-greater wind erosion with the increase of wind speed.Compared with CK, the erosion rate of clay samples and clay/sand mixed samplesdecreases significantly after wet-dry treatment with different gradients of water. Thewind erosion rate of sandy samples are not significantly different under differentwater gradients, and there are no difference with CK. With the increase of wind speed,the samples show a change of a small amount of accumulation-wind erosion - a largeramount of wind erosion.(3) Influence of surface salt content on wind erosion: The morphology andstability of salt crust of samples prepared with different solubility gradient salt solution are different, the thickness, hardness and shear strength of salt crust of sandysamples increase significantly with the increase of salt content of crust, and the watercontent has no significant difference or slightly increase with the increase of saltconcentration, which is excludes the interference factor of different erosion anddeposition caused by different moisture content of soil crust. Under the condition ofnon-sand-driving wind and sand-driving wind, the wind erosion of clay samples andclay/sand mixed samples is very low because of the protection of salt crust and theconsolidation of water. The cumulative wind erosion rate does not changesignificantly with the increase of salt content and wind speed. At the same time, whenthe salt content of crust is low, the wind erosion rate is more affected by wet-dryalternation of water gradient than by salt content. When the surface salt content ishigh, the effect is opposite. Under the condition of sandy soil, the water only can notconsolidate it, soil crusts with different salt contents what are formed under thecombined action of water and salt. With the increase of salt content in soils crusts, thewind erosion rate decreases significantly, while the wind erosion rate increasessignificantly with the increase of wind speed, and there is a significant differencebetween them and CK. |
| Subject Area | 水土保持与荒漠化防治 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xjlas.org/handle/365004/15285 |
| Collection | 中国科学院新疆生态与地理研究所 研究系统 |
| Affiliation | 中国科学院新疆生态与地理研究所 |
| First Author Affilication | 中国科学院新疆生态与地理研究所 |
| Recommended Citation GB/T 7714 | 任宏晶. 台特玛湖干涸湖盆区沉积物含盐量对风蚀影响的风洞模拟研究[D]. 北京. 中国科学院大学,2019. |
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