Impacts of environmental flow controls on the water table and groundwater chemistry in the Ejina Delta, northwestern China

Abstract

The impacts of environmental flow controls on the water table and chemistry of groundwater in the Ejina Delta, an arid inland river basin in northwest China, were investigated with field observations in 2001 and 2009. The results indicate that the shallow groundwater level rose by 0-2 m in the upper reaches of the east tributary of the Heihe River and in the areas of Saihantaolai-Dalaikubu during the period of environmental flow controls. The chemical constituents of the groundwater show a distinct spatial heterogeneity with the total dissolved solids (TDS) in the groundwater increasing from the periphery towards the depocenter of the Ejina Basin. In addition, the rate of groundwater cycling in the south of the Ejina Delta increased, and the mineralization of groundwater declined, while the overall mineralization and salinity increased in the northern regions, especially in the depocenter of the Ejina Basin. Since shallow groundwater is important to the ecology of arid regions, and because understanding the changes in the shallow groundwater environment (groundwater level and hydrochemistry) in response to environmental flow controls is essential for the sustainable improvement of the ecological environment, the results of this paper can be used as a reference for watershed water resources planning and management to help maintain the health and proper function of rivers in arid regions.

Groundwater recharge and hydrogeochemical evolution in the Ejina Basin, northwest China

“…Yang et al, , 2010Zhang et al, 2007). In addition, the implementation of environmental flow controls (the allocation of a certain amount of water to the lower reaches of the Heihe River to protect the Ejina Oasis from deterioration) in the Heihe River since 2000 have had an impact on the surface and groundwater regime in the Ejina Basin (Wang et al, 2011a). Therefore, although remarkable advances have been made in water resources research over the past decade, the infiltration-recharge mechanisms and the hydrochemical evolution of groundwater in the study area are still not well understood, especially considering the combined effects of climate change and human activities.…”

Using hydrochemical and isotopic data to determine sources of recharge and groundwater evolution in an arid region: a case study in the upper–middle reaches of the Shule River basin, northwestern China

“…HCO 3 -and also a mNa/Cl ratio near 1. This has been observed in many of the neighboring basins in the Hexi Corridor (Chang and Wang 2010;Wang et al 2002), as well as in other inland river basins in northwestern China, such as the Ejina basin (Wang et al 2011;Gaofeng et al 2010).…”

The Impact of Ecological Restoration Projects in Dry Lands: Data-based Assessment and Human Perceptions in the Lower Reaches of Heihe River Basin, China

“…In addition to the increase of cultivated lands and afforested areas, since there was little change in the annual mean temperature and annual precipitation during 2000-2013, the increase of river discharge due to SCMPH has certainly helped to increase the vegetation cover in riparian areas of the lower reaches of the Heihe River basin [11,23,41,42]. In the meantime, grazing bans initiated by SCMPH might have contributed to the increase of vegetation cover as well, as observed in the sample plot.…”

“…Previous research in Ejina County, an oasis area located in the lower reaches of the Heihe River basin, has confirmed the effectiveness of the SCMPH towards the recovery of terminal lakes, groundwater level elevation, and vegetation restoration (Figure 1) [6,[10][11][12]. However, the above-mentioned studies cannot assess the overall effect of SCMPH.…”