Characteristics of Desert Riparian Vegetation and Groundwater in the Lower Reaches of the Tarim River Basin

Natural vegetation in arid region plays an important role in biodiversity conservation and desertification reduction. However, biological activities in this area are limited and ecosystems are simple and unstable. Change in groundwater table can influence the development and composition of vegetation, which in turn affects the fragile ecosystem. The incidence of vegetation coverage is similar to that of groundwater depth. The change in vegetation coverage is explained by the change in groundwater depth.

Nevertheless, the relationship between groundwater table change and vegetation status is complicated, representing a dynamic equilibrium between groundwater, soil and vegetation. This relationship has become a key issue in the worldwide study of water resources in arid regions.

Based on the long-term research work in the lower reaches of Tarim River, Prof. CHEN Yaning et al. revealed the interactive relationship between vegetation and groundwater, presented an appropriate groundwater table for the regular growth of natural vegetation, and provided scientific evidences for the ecological restoration in arid and semi-arid regions.

The result showed that based on the analysis of the monitoring data from the groundwater level of ten times water delivery, such an extensive artificial watering takes positive effect on raising the groundwater level along the two sides of the river. A groundwater table depth of 2–4 m is probably the appropriate ecological water table level for the lower reaches of the Tarim River, and 6 m is the threshold for the local vegetation. At the lower Tarim River, 1.157×10⁸ m³ of water flow is needed for itself. The longer the duration of water releases, the greater would be the groundwater rise and the larger the range of vegetation influenced. It was found that the duration and volume of water delivery was closely related to restoration of vegetation in the lower reaches of the Tarim River.

This study offered scientific evidences for water delivery in the rigorous areas to maintain an ecological balance. The result was published online in Environmental Earth Sciences on 18 January 2014.