黑河下游径流量与额济纳绿洲NDVI的滞后模型

Modelling of Lagging Response of NDVI in Ejina Oasis to Rnoff in the Lower Reaches of Heihe River

将黑河下游年度均流量作为激励,将由NOAA/AVHRR卫星数据处理得到的归一化植被指数NDVI指标作为响应,建立起线性系统模型,从区域尺度模拟了额济纳绿洲植被发育相对于来水量的滞后过程。模型显示出,黑河来水对当年及后5 a的绿洲植被产生显著影响,其中对次年影响最大,并逐年递减,6 a后滞后效应不明显。分析认为滞后效应受含水层、包气带结构、绿洲范围等物理与几何参数因素控制,是绿洲生态系统具有自维持功能的一个体现。

A linear system modeling for Ejina oasis vegetation was established by regarding lower downstream annual volumes of the Heihe River, the second major inland river of China, as exciting inputs, NDVI （ Normalized Difference Vegetation Index） of the oasis interpretated from NOAA/AVHRR data as the system＇ s responses. The model can simulate vegetation lagged development of the oasis behind of Heihei River＇ s runoff at regional scale, and shows that downstream runoff of the Heihe River each year can significantly affect the oasis vegetation development in current year and subsequent 5 years in which the most remarkable effect appeares in second year, and declines year by year. It is recorgnized that lagging oasis scale, and is the concrete embodiment effect is adjusted by structure of aquifers and vadose zone and of sustainability of the oasis ecosystem.