河套灌区干渠衬砌对地下水及生态环境的影响

采用统计学方法、普通克里格法和ArcGIS 9.0等工具，分析了2001和2009年9月内蒙古河套灌区地下水位埋深和矿化度的时空分布，并实地调查了杨家河干渠衬砌对植被分布的影响.结果表明：节水灌溉工程实施多年后，河套灌区年均引水量降为44.5×10⁸ m³（2009年）；浅层地下水埋深在2.5～3.0 m的区域面积由2001年9月的1.2×10⁴ hm²增至2009年9月的9.11×10⁴ hm²，浅层地下水埋深在2.0～2.5 m的区域面积（2009年9月）占灌区总面积的80%；灌区西北部的咸水带（2001年9月，矿化度>5000 mg·L^-1）变为半咸水带（2009年9月，矿化度在3000～5000 mg·L^-1）；乌拉特灌域的咸水带面积扩大，半咸水带呈扇形向灌区北部扩张；渠道衬砌后，两岸植物物种和多样性指数均降低，一些根系较浅的草本植物出现退化的迹象.灌区引水量的减少，并没有对保持乌梁素海现状水面面积产生负面影响.

Effects of canal-lining project on groundwater and ecological environment in Hetao Irrigation District of Inner Mongolia

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.