Ecohydrological responses on water diversion in the lower reaches of the Tarim River, China

During the past 30 years, water ceased to flow in the lower reaches of the Tarim River in northwest China. A project was initiated that aims for ecosystem recovery and rehabilitation by means of transporting water through an open canal to the lower reaches of the Tarim River. In this study, the ecohydrological responses of this rare type project are assessed. Water loss-runoff relationships and an index model for water loss rates and runoff are analyzed. The detected ecohydrological responses of the canal project include that water diversion dominates the dynamics of (1) the groundwater depth and (2) the tempo-spatial variation of riparian vegetation close to the water channel. The relationships between groundwater depth, vegetation coverage, species richness and soil water content are clearly the main factors contributing to the riparian vegetation. Variations of water mineralization are significant, both temporally and spatially, at each sampling station within the lower reaches of the Tarim River. The study provides basic information on water diversion and stream corridor restoration in the lower reaches of the Tarim River. The results show associated mechanisms between riparian vegetation and hydrological variation in arid zone. This lays the theoretical and practical foundation for improving the evaluation system for supplementary water delivery and comprehensive improvement in the Tarim Basin. It also provides information on strengths and weakness in current practices. These are needed for the planning of ecological recovery and rehabilitation of damaged ecosystems in this and other arid areas in western and northern China.