Effects of canal-lining project on groundwater and ecological environment in Hetao Irrigation District of Inner Mongolia
河套灌区干渠衬砌对地下水及生态环境的影响

The canal-lining project in Hetao Irrigation District (HID) for water-saving irrigation has been implemented for many years. By using statistical method, ordinary Kriging, and software ArcGIS 9.0, this paper analyzed the spatiotemporal variation of groundwater table depth and salinity in HID in September, 2001 and 2009. In the meantime, the vegetation distribution on the both shores of the lining part and non-lining part of Yangjiahe channel was also investigated.After the many years implementation of the project, the water diversion amount in HID in 2009 was reduced to 44.5×108 m3. The region area of groundwater table with a depth of 2.5-3.0 m was increased from 1.2×104 hm2 in 2001 to 9.11×104 hm2 in 2009. The region area of groundwater table with a depth of 2.0-2.5 m in 2009 took 80% of the total area of HID. In the northwestern region of HID, the groundwater salinity had reduced from 5000-10000 mg·L-1 to 3000-5000 mg·L-1. In Wulate irrigation region, the areas of salt water belt and half-salt water belt were increasing. After the canal-lining of Yangjiahe channel, the plant species and diversity index on both shores reduced, and some herbaceous plants with shallow roots showed degradation signs. The implementation of the project and the reduction of water diversion for irrigation did not exert negative effects on the maintenance of water surface area of Wuliangsuhai Lake.