基于TVDI方法的黄土高原地表水分时空分异研究

该文选择陕北黄土高原地区作为研究区域,选用了基于地表温度和植被指数的经验关系构建的地表干燥度指数(Temperature-Vegetation Dryness Index,TVDI)。该指数对Ts/NDVI特征空间的生态特征的解释,对土壤和作物的水分含量具有一定的指示意义。通过对地表干燥度进行分级,分析陕北黄土高原区地表含水状况的空间差异。文中利用该指数综合评价了研究区域地表水分状况的时空分布差异,并进一步对TVDI进行了相应的验证。研究结果表明,TVDI能在不同季节综合体现植被覆盖和地表温度特征对地表水分的影响,从而能较好地反映区域地表水分状况的时空变化特征。各区域的TVDI值季节分布上皆为4~7月高于10~11月,但各区TVDI值的季节变化则存在显著不同,而各流域内部TVDI值的空间变异性也存在季节差异,其中在10月较为显著。

STUDIES ON SEPARATION OF TIME AND SPACE FOR SURFACE WATER AT THE LOESS PLATEAU BASED ON TVDI METHOD

Surface water is an important index for surveying land deterioration.It is also a major parameter in the fields of metrology,hydrology,ecology and agriculture,etc.This paper chooses the Loess Plateau in Northern Shaanxi as research target,selects and utilizes Temperature-Vegetation Dryness Index(TVDI).This index has certain indication significance for explaining the ecological characteristics of Ts/NDVI space,and for the moisture content in soil and crops.Through grading the dryness degree of land surface,this paper analyzes the difference between time and space distribution in land surface moisture contents at the Loess plateau in Northern Shaanxi,and further validates TVDI.The result shows that TVDI is able to comprehensively embody the influence of vegetation coverage and land surface temperature to land surface moisture content indifferent seasons.Therefore,it can reflect in a better way the time and space changing characteristics of land surface moisture content in this region.In various regions,the seasonal distribution of TVDI value is higher from April to July than from October to November,but the seasonal change of TVDI value in each region is remarkably different.There is seasonal difference within each drainage area in space variability of TVDI value,among which October is notable.