Vegetation responses to integrated water management in the Ejina basin, northwest China

The Ejina basin, which is located in arid and semi-arid areas of northwest China, has experienced severe environmental deterioration in the past several decades, and an exploratory project was launched by the Chinese Government in 2001 to restore this degraded ecosystem. In this study, multi-scale remotely sensed data and field investigations were used to quantify the responses of vegetation to the implementation of integrated water management under this project. In terms of the seasonal accumulated Normalized Difference Vegetation Index (SAN) variation, (1) the vegetation in 80.4% of the oasis regions showed an increasing or recovering trend, and increasing SAN trends with a magnitude greater than 0.14 a(-1) mainly resulted from cultivated land reclamation; (2) the vegetation in 91.5% of the desert regions presented an increasing trend, and the statistically significant trends mainly appeared in the middle and lower Ejina basin; (3) the vegetation in 19.6% of oasis and 5.1% of desert regions showed a decreasing or degrading trend, mainly where rivers diminished and along artificial concrete canals; and (4) opposite signs of vegetation trends occurred simultaneously along some natural rivers experiencing water reduction, with a decreasing trend generally appearing in the high SAN regions, whereas an increasing trend was seen in the low SAN regions. The broad vegetation recovery observed was due to the comprehensive improvement of the water environment, which was attributed to both the increase in runoff entering the Ejina basin and the adoption of engineering measures. Vegetation degradation in the area mainly resulted from deterioration of the local water environment, which was closely related to the problems of water management. The results of this study can be used as a reference for adjusting the current water resource management strategy to effectively restore this ecosystem. Copyright (C) 2011 John Wiley & Sons, Ltd.