关键词: 绿洲, 耗水量, NDVI, 地表径流量, 降水量, 阿克苏河流域

Abstract: Based on the remote sensing data derived with the advanced very high resolution radiometers, the normalized difference vegetation index (NDVI) in an arid oasis is of sensitive response to surface runoff.According to the experience, a region with NDVI value > 0.2 is recognized as an oasis, so the oasis in the Aksu River Basin is also recognized based on its total accumulative NDVI.In this paper, the total accumulative NDVI was substituted for the index of human activities dominated by farming.Based on the data of surface runoff volume, the relationship between human activities and surface runoff in oasis in the Aksu River Basin during the period from 1982 to 2006 was analyzed.Results revealed that, during the period from 1982 to 2006, the mountainous runoff volume in the Aksu River Basin was increased by 21.4% compared with that at the beginning of the study, water consumption in the oasis was increased by 53.2%, total accumulative NDVI of the oasis was increased by 35.3%, and the oasis area was enlarged by 33.4%.There were the positive correlations among the runoff volume at Aral, water consumption and stream inflow in the oasis, which revealed that the increased water consumption was mainly caused by the oasis expansion in middle reaches of the Aksu River Basin.The change of total accumulative NDVI of the oasis was gradually accelerated from the central area to the marginal zone of the oasis.In the same period, the trend of total accumulative NDVI was gradually intensified from the marginal zone to the central area of the oasis.According to the correlations among the total accumulative NDVI of the oasis, stream inflow and water consumption in the oasis, precipitation in the oasis could not be ignored, which means that precipitation in the oasis was of support and maintenance function for stability of the oasis, and the contribution of precipitation in the oasis was 25.2%.Among the variation coefficients of glacier runoff and mountainous runoff volumes as well as precipitation in the basin, the contribution of glacier runoff in the oasis was 33.4%, which showed that glacier runoff was of the functions of adjusting runoff and maintaining a stable oasis scale.Moreover, under climate change in the future, the relationship between surface runoff and oasis scale in the Aksu River Basin was further analyzed.The results show that temperature is the main factor affecting surface runoff regardless at present or in the future.It is estimated that the lacier runoff volume will be decreased under climate change in the future, and oasis scale will be expanded except the scenarios that temperature will be stable and precipitation will be increased by 10%, 20% and 30%.It is also estimated that the water consumption in the oasis will be increased significantly, and it will be much higher than the mountainous runoff volume, which will cause an obvious reduction of runoff volume at Aral, so it will be very necessary to control water consumption in the Aksu River Basin so as to achieve a sustainable development in the whole Tarim River Basin.

Key words: oasis, water consumption, NDVI, surface runoff volume, precipitation, Aksu River Basin