Retrieval of vegetation cover using remote sensing in the groundwater-fluctuating belt in lower reaches of Heihe River, northwest China

The vegetation cover is an important parameter to characterize the canopy evapotranspiration of regional vegetation. For studying the ecological water requirement of vegetation, the vegetation cover was retrieved using the dimidiate pixel model and the Normalized Difference Vegetation Index (NDVI) from the image of Landsat TM in the groundwater-fluctuating belt in lower reaches of Heihe River, northwest China. And the precision validation of the retrieval results was conducted by the field survey data from 40 sample plots in the study area. The conclusions show that the vegetation cover is very low and maldistribution in the study area. The dimidiate pixel model based on NDVI can be used in the retrieval of vegetation cover in the study area and similar desert region. This study lays the foundation for estimating the regional water requirement of ecology, understanding the canopy properties of the natural vegetation and the environmental change in the groundwater-fluctuating belt in the lower reaches of Heihe River.