官渡河流域植被覆盖变化与地形因子相关性

以南水北调中线水源区源头之一的官渡河流域为研究区域，区域内以山地为主，生态环境脆弱。基于GIS和RS技术，利用1990年、1999年、2004年、2007年、2010年Landsat TM遥感影像，基于像元二分模型和变化斜率法，从数理统计角度定量估算了研究区各时期植被覆盖度及其时空分布特征。结果表明:（1）植被覆盖度在不同河段呈现明显的规律性，上、中、下游植被覆盖度5期平均值分别为94.52%，87%，81.69%。（2）植被覆盖变化受地形因子影响比较明显，植被覆盖度与不同地形因子响应程度不同，对不同时期植被覆盖度，高程和坡度对其影响明显高于坡向。随着坡度的不断增加，植被覆盖度也随着增大；整体上向阳区植被覆盖度要大于同区域的背阳区；官渡河流域不同时期植被覆盖度随着高程的增加均出现先增加后减少的趋势。（3）不同地质单元组植被覆盖变化各不相同。

Variation of Vegetation Cover and Its Correlation of Topographic Factors in Guandu River Basin

In South-to-North Water Transfer Project source, Guandu River Basin was selected as the study area. The area is mainly mountainous and the ecological environment is fragile. Based on GIS and RS technology, using 1990, 1999, 2004, 1999 and 2010, Landsat TM remote sensing image, binary model based on pixels, and changes the slope method, vegetation coverage of different periods in the study area was quantitatively estimated and its space-time distribution characteristics were analyzed. The results showed that:(1) the vegetation coverage had obvious regularity in different river sections, the average values of the five periods of vegetation coverage in upper, middle and lower reaches were 94.52%, 87%, and 81.69%, respectively; (2) the change of vegetation cover was obviously influenced by topographic factors, the vegetation coverage was different from that of different terrain factors, and the effect of vegetation coverage, elevation and slope on different periods was significantly higher than that of aspect; as the slope increases, the vegetation coverage increases; the vegetation coverage of the whole area was greater than that of the region in terms of slope aspect; the vegetation coverage of Guandu River Basin increased with the increase of elevation in different periods; (3) vegetation cover changes in different geological units were different.