生态输水对塔里木河下游植被恢复价值的影响

以生态输水后地下水动态变化引起的地表植被生物量差异为出发点,探讨生态输水对塔里木河下游植被恢复价值的影响。首先,利用生态输水前后地下水动态变化和地表植被响应的长期监测资料,以塔里木河下游考干断面为例,在垂直于河道方向上长2 000 m、平行河道方向宽100 m的样带内,选取2000年10月、2007年9—10月、2015年10月的植被监测与称重资料数据;其次,借鉴国内外生态经济价值量化方法,综合地表植被响应价值和地下水抬升的潜在价值计算输水后地表植被恢复价值。结果显示:(1)在塔里木河下游地区,生态输水使得地下水位明显抬升,水位的抬升幅度随着距河道距离的增加逐渐降低,植被盖度也随着距河道距离的增加呈现降低趋势;在距河道1 000 m以外,地下水位与植被盖度变化不明显;(2)2000—2007年植被新增生物量占2000—2015年植被新增生物量的57.02%,并且这两个时段植被新增生物量与距河道距离均呈现显著相关;(3)根据16次生态输水监测资料,计算出2007年与2015年该区间100 m宽的样带因输水而投入的水资源价值分别为8 266.5元、14805元,输水后植被总体恢复价值分别为53 811.67元、83 334.62元,投入产出比分别为1∶6.507、1∶5.63,说明生态输水的经济效益十分明显。

Effects of ecological water conveyance on recovery value of vegetation in the lower reaches of Tarim river

The effects of ecological water conveyance on the recovery value of vegetation in the lower reaches of Tarim river was investigated on the basis of change in biomass of surface vegetation caused by groundwater dynamic change after ecological water conveyance.The long-term monitoring data on groundwater dynamic change and responsiveness of surface vegetation before and after the ecological water conveyance were referenced in the study.The Kaogan section in the lower reaches of Tarim River was selected as the test area.The monitoring and weighing data on the vegetation in October 2000,September to October 2007 and October 2015 were collected in the belt transect,which was 2000 meter long in the way perpendicular to the river channel,and 100 meter wide in the way parallel to the river channel.The computing methods of ecological value quantization home and abroad were referenced,and the response value of surface vegetation and potential value of groundwater lifting were used in calculating the recovery value of surface vegetation after the water conveyance.The results are as follows:① In the lower reaches of Tarim River,there was an obvious lift in groundwater level because of the ecological water conveyance,and the lift range of groundwater level decreased with the increase in the distance from river,and the same was true for the vegetation coverage;The changes of groundwater level and vegetation coverage were not obvious in the distance 1000 meter away from the river.② The newly added biomass from 2000 to 2007 accounted for a proportion of 57.02％ to the newly added biomass from 2000 to 2015;In addition,the newly added biomass in this two period were all correlated to the distances from river significantly.③ According to 16 groups of monitoring data of ecological water conveyance,in the period from 2000 to 2007 and the period from 2000 to 2015,the value of water resource invested because of water conveyance at the belt transect were 8 266.5 yuan and 14 805 yuan respectively,and the whole recovery value of vegetation after water conveyance were 53 811.67 yuan and 83 334.62 yuan,with the input-output ratio being 1∶6.507 and 1∶5.63 respectively,which indicated the economic benefit of ecological water conveyance was very obvious.