Abstract:

Located in the south-central part of Qaidam Basin in Qinghai Province, the Golmud River Basin is arid and its ecology is fragile. Vegetation dynamics are of great significance to ecological conservation in arid regions. Based on continuous record of MODIS NDVI data, the spatial-temporal characteristics of vegetation index in the Golmud River Basin were analyzed via remote sensing, and the influencing factors were discussed. The results show that the annual average NDVI value is generally small, but increased from 0.10 to 0.12 during 2001 to 2016. Areas of increasing NDVI trend are distributed to the east and west of Golmud City, while constant and decreasing trends of NDVI occur in the desert and the northern salt pond area, respectively. Both areas of low-density and high-density vegetation show an increasing rate, whereas the bare soil shows a decreasing trend in the vegetation coverage. Generally, the vegetation variation depends on various attributes such as climate change, soil moisture and groundwater depth. The correlation between NDVI and temperature is good (correlation coefficieis=0.822), and precipitation also has a certain impact on the growth of vegetation. There is a strong correlation between NDVI value and the apparent thermal inertia (correlation coefficieis=0.979). The corresponding range of groundwater depth to vegetation in the study area is from 0 to 12 m, and the vegetation growth is the best when the groundwater depth is about 6.5 m.

Key words: vegetation coverage, MODIS NDVI, apparent thermal inertia (ATI), groundwater depth, Golmud River Basin