基于NDVI分析渭干河流域绿洲耗水对地表径流的影响

利用NOAA/AVHRR NDVI遥感资料提取渭干河流域绿洲区1982―2006年NDVI数据,将绿洲区NDVI值和绿洲面积指标作为绿洲区以农业活动为主的人类活动综合因素,结合流域地表径流,分析了1982―2006年渭干河流域绿洲耗水与流域地表径流之间的关系。结果表明,近25年来,渭干河流域绿洲区来水量、绿洲总耗水均呈增加趋势,且绿洲总耗水在1995年发生突变,相对绿洲来水量的突变点滞后1年;流域绿洲NDVI值相对研究初期增加94%,表现为持续增加,绿洲面积相对研究初期扩张73.7%,表现为持续扩张;从流域绿洲NDVI值和地表径流变化关系看,绿洲降水对绿洲植被生长有较大作用,冰川径流起了调节绿洲来水量和维持绿洲稳定的功能;从绿洲面积和流域地表径流变化看,绿洲降水对绿洲规模的贡献为22%,冰川径流对绿洲的贡献为44%,绿洲来水量中降水径流对绿洲的贡献为34%。由气候变化和冰冻圈变化情景假设得出,未来冰川径流对绿洲贡献除气温不变外均呈减速增加趋势,绿洲降水对绿洲的贡献呈增加趋势。

Impact of oasis water consumption on surface runoff of the Weigan River Basin based on NDVI

The relationship between oasis water consumption and surface runoff of the Weigan River Basin was analyzed by using NOAA/AVHRR NDVI remote sensing data collected from 1982 to 2006. The results showed that during the recent 25 years, both of oasis zone inflow and oasis water consumption were increased. The oasis water consumption was broke in 1995, which was delayed by 1 year compared to the break point of oasis inflow. Comparing with the beginning stage of the study, oasis NDVI and oasis area were increased by 94% and 73.7% respectively, both showed a continuous increased trends. From view of the relationship between oasis NDVI and surface runoff, oasis precipitation played an important role in oasis zone vegetation growth, while glacier runoff was regulating oasis inflow and maintaining stability of oasis. Changes in oasis area and basin surface runoff, the contributions of oasis precipitation, glacier runoff and precipitation runoff to oasis scale were 22%, 44% and 34%, respectively. However, from the assumption of scenarios of climate change and cryospheric change, the contribution of glacier runoff to oasis scale will be increased slowly in the future except under the scenario of the stable temperature; meanwhile the contribution of oasis precipitation to oasis scale will increase.