岷江上游流域植被覆盖度时空变化分析

Temporal and Spatial Variation of Vegetation Coverage in the Upper Reaches of Minjiang River

植被覆盖度是指示生态环境变化的重要指标。以Landsat系列遥感数据为基础,利用ENVI软件技术平台,通过像元分解法得出岷江上游流域1994-2014年20年间植被覆盖度的时空变化情况,确定植被覆盖度分类标准和等级的划分,并从研究区气象变化和人类活动对其影响及其变化规律进行探讨。研究结果表明:1994-2014年岷江上游流域植被覆盖度整体呈现波动向下减少趋势,特别是在2008年汶川大地震的影响下尤为明显,Ⅰ级植被覆盖度变化较为明显,减少面积占研究区的26. 4%,Ⅴ级植被覆盖度变化突出,增加面积占研究区6. 63%。空间格局上,岷江上游流域整体呈现出由西北河流沿岸逐渐降低的趋势,主要分布在维尔隆河和孟屯沟河流两岸以及理县西南部。岷江上游流域植被覆盖度结构趋于恶化,干涸河谷面积不断变大,需加强对干涸河谷的治理和林地保护,减少人为活动的干扰和提高抗自然灾害的能力,促进流域生态环境的可持续发展。

Vegetation coverage is an important indicator of ecological environment change.Based on a series of Landsat remote sensing data,the temporal and spatial variation of vegetation coverage in the upper reaches of Minjiang River from 1994 to 2014 was obtained through ENVI software technology platform with pixel decomposition method.The classification criteria of vegetation coverage and level of division were determined and the influence of climate change and human activities as well as their change law was discussed.The research results show that from 1994 to 2014,the vegetation coverage of the upper reaches of the Minjiang River fluctuated downward,especially under the influence of the 2008 Wenchuan earthquake.First-level vegetation coverage decreased more obviously,accounting for 26.4% of the research region,while fifth-level vegetation coverage increased,accounting for 6.63%.In terms of spatial pattern,the upper Minjiang River basin as a whole shows a trend of gradual decline from the northwest river coast,mainly distributing along the Banks of the Veron river and the Mengtungou river as well as the southwest of Lixian county.The results show that the vegetation coverage structure of the upper reaches of Minjiang River tends to deteriorate,and the area of dry valleys keeps increasing.Therefore,it is necessary to strengthen measures such as the management of dry river valleys and the protection of forestland,reduce the interference of human activities,improve the ability to resist natural disasters and promote the sustainable development of the ecological environment of the river basin.