1987～2016年红崖山水库面积时空变化分析

Analysis on spatial and temporal changes of Hongaishan Reservoir area from 1987 to 2016

【目的】红崖山水库是亚洲最大的沙漠水库,对水库的水域变化进行监测与评估,目的在于保障水库调水能力和评估民勤绿洲水资源承载能力.【方法】利用收集的1987~2016年间95景Landsat TM/OLI影像和2景GF-1卫星遥感影像,选用基于阈值分割的改进归一化差异水体指数法(MNDWI),对红崖山水库近30a的水域动态信息进行提取.【结果】红崖山水库水域面积变化具有明显的季节性,水库水域面积总体呈现波动上升趋势,1987~1991年先下降,平均每年减少约2.1km^2;1991~1997年先上升后下降,期间水域面积总体增加,即由1991年的7.85km^2增加到1997年的11.44km^2,增加了3.59km^2;1997~2009年面积再次出现以2006年为转折点的先升后降的倒"V"型变化,即从1997年的11.44km^2增加到2006年的21.37km^2,再降到2009年的9.84km^2;2009~2016年间水域面积再次波动上升,上升了10.71km^2,其年际变化总体呈"W"型趋势.【结论】定期的农业灌溉、长期的扩建加固工程及人工增雨增雪是影响水库水域面积月际和年际变化的主要原因,人口数量下降和产业结构调整是间接影响因素.

【Objective】Hongaishan reservoir is the largest desert reservoir in Asia and the lifeline of people in Minqin County.Monitoring and evaluation of the water area of the reservoir is critical for protection and evaluation of water resources and carrying capacity in Minqin Oasis.【Method】95 Landsat TM/OLI and 2 GF-1 remote sensing imageries were collected for monitoring changes of water surface and analyzing the influencing factors by using Modified Normalized Difference Water Index(MNDWI)based on the threshold segmentation method from 1987 to 2016.【Result】The water area of Hongaishan reservoir showed an obvious seasonal variation and general increasing trend.It decreased from 1987 to 1991,and the average annual reduction was about 2.1 km 2.From 1991 to 1997,it increased firstly and then increased,and it increased by 3.39 km 2 from 1991(7.85 km 2)to 1997(11.44 km 2).And from 1997 to 2009,it increased form 11.44 km 2(1997)to 21.37(2006),and then to 9.84 km 2(2009).From 2009 to 2016,the area reached 10.71 km 2.【Conclusion】Regular agricultural irrigation,long-term expansion and reinforcement projects,and artificially increasing rainfall and snowfall were the main factors affecting the monthly and interannual changes of reservoir water area.Population reduction and adjustment of industrial structure were the indirect factors.