【作者】 周宝佳；

【导师】 周宏飞；

【作者基本信息】 石河子大学 ， 农业水土工程， 2009， 硕士

【摘要】 古尔班通古特沙漠是我国唯一在冬季存在稳定积雪的沙漠。研究该地区的雪面蒸发-凝结特征,是研究古尔班通古特沙漠地区水文过程的重要内容,是研究沙漠冬季降水的有效储存以及荒漠植物对春季融雪水利用的基础,对于深入理解干旱区冬季水循环特征以及降水资源的有效利用具有重要的意义,同时,可以为揭示古尔班通古特沙漠植被多样性和稳定性成因奠定基础。本文根据2007年11月-2008年3月在古尔班通古特沙漠南缘的野外实验观测资料,结合冬季气象资料及其他相关数据,分析了古尔班通古特沙漠地区雪面蒸发-凝结规律,雾凇凝结特性以及季节性冻土条件下融雪水的入渗特性,得出以下主要结论。(1)雪面蒸发-凝结方面。沙漠空地日均雪面蒸发率为0.015mm,绿洲区为0.02mm,观测期日蒸发为负值的天数占总观测日数的31.9%,主要分布在12月份和1月份;沙漠区积雪日最大蒸发率为0.3mm,绿洲区0.46mm,冬季沙漠区和绿洲区空地雪面蒸发总量分别为1.73mm和1.95mm,各占冬季降水量的6.51%和7.37%。沙漠垄间开阔地雪面蒸发比梭梭林内蒸发强,冬季12月~2月垄间林内总蒸发量为-0.41mm,开阔地蒸发量0.86mm。相关分析结果表明:影响古尔班通古特沙漠地区冬季雪面蒸发的主导因素为气温。与天山山地及世界其它干旱地区相比,沙漠地区冬季雪面蒸发是最小的,低温、多雾天气是低蒸发的重要原因。(2)植株冠层雾凇凝结方面。实测结果:古尔班通古特沙漠植株冠层雾凇凝结水量可达4.1mm(3.1- 8.8mm),约占冬季降水量的15.5%;冬季绿洲开阔地积雪表面水汽凝结总量约为3mm,冠层雾凇凝结量为5.2mm,占冬季降水量的19.6%,可见,植株雾凇凝结对古尔班通古特沙漠地区冬季水资源的增加作用明显。对雾凇形成的条件、雾凇与气象因子以及植株形状的相关分析结果表明:温度越低,雾凇形成要求的大气最小相对湿度越小;雾凇凝结量随离地高度呈指数函数增长、与枝条长度呈线性关系。(3)季节性冻结土壤入渗方面。沙漠地区季节性冻土具有较高的入渗能力,入渗能力随着土壤含水率的升高而减小。沙漠冻结砂土的稳渗率约为0.26-0.30mm/min,是非冻结砂土的1/10,是田间冻结壤土的10-20倍,可以保证融雪水及时入渗进入土壤,为融雪水的高效储存创造了有利条件,2007-2008年积雪期融雪水土壤入渗量约为冬季最大积雪量的92%。沙地土壤初始的低含水率、土壤大孔隙结构特征是沙地冻结土具有较高入渗能力的主要原因。(4)雪面蒸发、雾凇凝结以及沙地入渗实验研究结果表明,古尔班通古特沙漠冬季积雪的低蒸发、高凝结以及沙地的高渗透性为冬季降水的有效保存以及春季积雪集中融化后的有效储存创造了有利条件,植株凝结等隐匿降水对古尔班通古特沙漠地区局地水资源的增加作用明显。在准噶尔盆地荒漠植被恢复与重建过程中应充分考虑利用这一部分冬季天然水资源,从而减少对河川径流以及地下水资源的利用。更多还原

【Abstract】 Gurbantonggut desert, which is located in northwest of China, is the only one desert that existence steady snow cover in winter. Snow evaporation-condensation characteristic researches are the important content of hydrological process, and the foundation of snow conservation efficiency and snowmelt utilization ratio of plants studies in desert. The studies are also of important values to further apprehend the water cycle characteristic and effective utilization of precipitation within winter period in arid-area. Furthermore, these studies provide a basis data for reveal the causes that plants have the characteristic features of diversity and stability in desert.Based on the data of field experimental observation and the weather data in the southern part of Gurbantunggut desert from November 2007 to March 2008, the snow evaporation-condensation, rime accumulations and the infiltration characteristics of seasonal frozen soils in desert were analyzed. Main results are concluded as follow:(1) Snow evaporation-condensation. The daily snow evaporation is 0.015mm for inter-dune clearing and 0.02mm for oases, the days of net condensation, which is mainly in February and January, represent 31.9% in total measured days. The maxest snow evaporation rate is 0.3mm/d for inter-dune and 0.46mm/d for oases; the total winter snow evaporation is 1.73mm and 1.95mm; this represents 6.51% and 7.37% of the winter precipitation, respectively. Snow evaporation in openings is higher than under H.ammodendron stands, there is a net condensation 0.41mm under stands and evaporation 0.86mm in openings during Dec.2007 to Feb.2008. The results of correlation analysis show that snow evaporation in the area of Gurbantunggut Desert mainly depends on the air temperature; the evaporation in desert is lower than in Tianshan Mountains and other arid-areas in the world, the reasons of lower snow evaporation are low air temperature and foggy weather conditions in desert.(2) Rime buildup on plant crowns. Field experimental observation indicated that water equivalent of rime caught on crowns is 4.1mm for desert; it represents 15.5% of the winter precipitation. Snow surface condensation at night is 3mm, rime accumulation on crowns is 5.2mm in winter in oases, and this represents 19.6% of the winter precipitation. It is obvious that the water equivalent of rime caught in entire winter is an important supplement to water input in the area. The conditions of riming, main meteorological elements in riming and the shape of plants were analyzed, results showed that the lower of air temperature, the lower humidity riming need; rime accumulations are grower with heights in power functions and have a positive linear correlation with branch lengths.(3) Infiltration characteristics of seasonal frozen soils. There was a higher infiltration capacity of seasonal frozen soils in desert district; results indicated that infiltration rate into seasonal frozen soil decreases along with increasing initial soil moisture content. The stable infiltration rate of frozen sandy soils in desert was about 0.26-0.30mm/min which is about 1/10 of unfrozen soil, but it is still 10-20 times for frozen loamy soil in farmland. Higher infiltration rate of frozen sandy soils ensure the snowmelt infiltration into soil layer rapidly and create favorable conditions for effective storage of snowmelt water. From November 2007 to March 2008, there is 92.1% of the snowfall water infiltrated into soils. The low initial moisture content and macropore texture of sandy soils are the major reasons for higher infiltration capacity of frozen sandy soils.(4) The experiment results of snow evaporation, rime accumulations and infiltration of sandy soils showed that the lower snow evaporation, more condensation and higher infiltration capacity of sangy soils in Gurbantonggut desert can provide advantage for effective conservation of winter precipitation and effective store of snowmelt in spring, occult precipition shch as rime is an important supplement to water input in local areas of desert. In Junggar basin desert vegetation rehabilitation and reconstruction process, we should take full account of this part of the winter natural water resources, and this can reduce the use of runoff and groundwater resources.更多还原