矿区生态监测的地理加权遥感生态指数构建及评价

    Constructing and evaluating geographically weighted-remote sensing ecological index for ecological monitoring in mining areas

    • 摘要: 矿区生态是陆地生态系统的重要组成部分,准确监测矿区生态对保护生态环境、维持生态平衡具有重要意义。遥感技术为矿区生态监测提供了有效手段,针对遥感生态指数(remote sensing ecological index,RSEI)在矿区生态监测中存在监测精度低、针对性弱和指标权重空间上均一化问题,该研究对RSEI进行了改进。首先,考虑矿区特殊的生态成因,在绿度、热度、湿度、干度的基础上加入煤尘污染因子构成矿区遥感生态指数;然后,利用地理加权主成分分析法确定各指标的空间权重,构建了地理加权遥感生态指数(geographically weighted-remote sensing ecological index,GW-RSEI);最后,以山西省大同煤田为例,基于多期遥感影像对GW-RSEI在矿区生态监测中的有效性、适用性进行了验证。结果表明:GW-RSEI能准确捕捉矿区大气中的煤尘污染,从整体和局部尺度实现了矿区生态的精准监测,有效提高了矿区生态监测的精度;地理加权主成分分析法能够明确表征矿区生态的空间异质性和生态环境变化的空间连续性;2000—2020年大同煤田的GW-RSEI均值分别为0.51、0.48、0.46、0.59、0.56,整体生态环境经历了先恶化后改善的过程,其东南部生态环境变化趋势与整体一致,而西北部生态环境呈现先改善后恶化的变化趋势。研究成果为准确监测矿区生态提供了一种更加科学、有效的方法。

       

      Abstract: The ecology of mining areas has been one of the most crucial components in terrestrial ecosystems. However, the over-exploitation of mineral resources has posed a great threaten to the ecosystem in recent years, leading to frequent environmental issues, such as land degradation, vegetation loss, and water scarcity. Therefore, accurate monitoring of mining ecology is of great importance to protect the ecological environment and balance. Remote sensing technology can be expected to provide an effective means for the ecological monitoring in mining areas. In this study, Remote Sensing Ecological Index (RSEI) was improved to realize the overall spatial average on the indicator weights for the ecological monitoring of mining sites. The factor of coal dust pollution was also added into the conventional greenness, wetness, dryness and heatness. The indicator weights were then determined using Geographically Weighted Principal Component Analysis (GWPCA). The indicator was finally selected to construct Geographically Weighted-Remote Sensing Ecological Index (GW-RSEI). Taking the Datong coal field in Shanxi Province as an example, the validity and applicability of GW-RSEI were verified for monitoring mining area ecology using multi-phase remote sensing images from 2000 to 2020. The results showed that the indicator weights of GW-RSEI were varied continuously over the space, indicating the spatial heterogeneity within different local surface areas. GW-RSEI shared the average correlation coefficients with universal normalized vegetation index (UNVI), normalized difference moisture index (NDMI), soil index (SI), temperature vegetation dryness index (TVDI) and index-based coal dust index (ICDI) of 0.76, 0.78, -0.77, -0.82 and -0.41, respectively, (P<0.05). Furthermore, the GW-RSEI was integrated each indicator to fully reflected the ecological environment of mining areas. The overall monitoring that obtained by GW-RSEI was similar to that by RSEI over the past two decades. However, the GW-RSEI was focused on the real ecological impacts at the surface, indicating the more reliable at local scales. Whether in areas with single or complex land use types, GW-RSEI exhibited the higher correlations with soil moisture (SM), net primary productivity (NPP) and particulate matter 2.5 (PM2.5) than RSEI. The GW-RSEI monitoring was more consistent with the actual surface, in order to effectively reflect the ecological environment of the mining areas. Therefore, the GW-RSEI was successfully used to monitor the severe pollution of coal dust in local coal mining activity areas. The grade of GW-RSEI was lower than that of RSEI in the areas with the severe pollution of coal dust. The trend was the gradually increasing from the area with the high level of coal dust pollution as the center to the surrounding areas, indicating the spatial pollution in mining areas. The GW-RSEI values were higher than RSEI ones in urban areas of the county with the medium to high vegetation cover, and in rural areas where the land type was mainly arable land and grassland. There were significantly more medium to low GW-RSEI value in the mining area and surroundings, compared with the RSEI. Furthermore, the gradual trend was highlighted the spatial continuity in ecological environment quality. GW-RSEI averages were 0.51, 0.48, 0.46, 0.59, and 0.56, indicating that the overall ecological environment experienced a process of first deterioration and then improvement. The trend in the southeastern region of Datong Coal field was consistent with the overall trend, while the northwestern region showed a trend of first improvement and then deterioration. The GW-RSEI can provide the more effective way to accurately monitor the ecology of the mining area.

       

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