基于植被指数的开都河第一分水枢纽工程生态效应分析

Ecological effects of the First Water Diversion Hub Station in Kaidu River based on the vegetation index

水利工程建设在生态环境较恶劣,水资源严重短缺的干旱区其表现更为突出。科学的分析水利工程的生态效应可为区域水利工程与生态环境协调发展提供重要的理论依据。本文以Landsat遥感影像和水文数据为主要数据源,分析开都河流域第一分水枢纽工程建成前后的土地利用/土地覆被、径流量与生物量变化趋势,进一步讨论水利工程建设对开都河流域植被覆盖变化的影响。结果显示:1)第一分水枢纽工程建成以后,研究区土地利用动态度增加,其中耕地面积直线增加;2)通过对水利工程建设前后的水资源利用效率与流域生态环境质量进行对比分析,得知水利工程可以调节开都河水量在时间和空间上的分配,适应人类对水资源利用的要求;3)水利工程运行后,研究区植被覆盖度与生物量逐渐增加,裸地面积逐渐减少,说明水利工程的建设对生态环境有修复作用。

[ Background] Human activities including water conservancy projects construction and water diversion affect the regional hydrological process and ecological environment. Water conservancy construction is a double-edged sword, due to coexisting both advantages and disadvantages for environmental security and socio-economie development. The impact of water division on ecological water uses has become the focus of environmental impact assessment for water diversion projects in arid regions. Scientific analysis and precise evaluation of the water conservancy project construction provide an important theoretical basis for the harmonious development of regional water conservancy project and ecological environment. Many water conservancy projects have been built to meet the needs of economic and social development in the Yanqi basin, Xinjiang, China since several decades. The First Water Diversion Hub Station built in 1999 is a most important water conservancy project in Kaidu River, and it leads to change of land cover and alter the underlying surface conditions obviously. In this paper, theecological effects of the First Water Diversion Hub Station in Kaidu River were carefully studied by the technologies of geographic information system and remote sensing. [ Methods] Considering the vegetation situation of study area, the land cover was classified as bare land, sand, cultivated area, wetland and water from Landsat images. In order to eliminate the influence of the soil background on the vegetation index as far as possible, the adjusted soil-vegetation index （SAVI） was used as the vegetation index of the vegetation cover types. The biomass in different land cover types were calculated using SAVI respectively. Then, the impact of water conservancy project construction on the change of vegetation cover and biomass was discussed together with hydrological data encompassed the period between 1974 and 2014. [ Results] After The First Water Diversion Hub Station completed, the land use dynamic degree increased （Rt= 0. 29） , the growth of cultivated land and water body were especially obvious. The cultivated land increased approximately 104.9% during 1994 and 2015 ; at the same time, the bare land decreased about 53.8%. Based on the comparative analysis of water resources utilization efficiency and ecological environment quality before and after the water conservancy project built, the annual ineffective water loss amount decreased about 1. 045 × 10^8 m3. It is understood that the water conservancy project effectively adjusted the spatio-temporal distribution of water resources in Kaidu River oasis area, and met the human requirements for water resources utilization. After the operation of water conservancy project, the vegetation coverage and biomass of the study area increased, and bare land decreased gradually. [ Conclusions] On the one hand, the First Water Diversion Hub Station in Kaidu River improved the water diversion and allocation conditions, the original goal of efficient water resources utilization were achieved. On the other hand, it plays an important role in the ecological environment by increasing the regional vegetation coverage.