一种基于指数的新型遥感建筑用地指数及其生态环境意义

A New Index-based Built-up Index(IBI) and Its Eco-environmental Significance

城市建筑用地是一种复杂的土地利用类型,在电磁波反射光谱上表现出明显的异质性。因此,很难用简单的方法将其从遥感影像中准确地提取出来。在详细研究了城市建筑用地的光谱特征以后,创建了一种不直接采用影像的原始波段,而是采用由它们衍生的3个指数波段来构成新型建筑用地指数(IBI)。通过对ASTER和Landsat ETM+两种多光谱影像进行的实验表明,新指数除了能够有效地增强影像中的建筑用地信息外,还能和植被指数、水体指数一样,用于进行数值运算,从而实现了建筑用地对城市生态环境影响的定量研究。对厦门、福州两城市的实例分析表明,新的建筑指数与地表温度呈正相关关系,而与植被指数、水体指数呈负相关关系。研究进一步发现,建筑指数与地表温度的关系不是简单的线性关系,而是一种指数函数关系,说明高建筑用地比例地区的升温效应要明显高于低建筑用地比例地区,因此,对城市热岛的形成起着更大的作用。

Urban built-up land is a complex land-use class and has a heterogeneous characteristic in reflected electromagnetic spectrum. Therefore, it is difficult to be extracted from remote sensing imagery. This paper proposes a new index-based built-up index （IBI） by careful study of spectral features of urban built-up land. The new index distinguished from other traditional indexes for its use of thematic indexderived bands rather than original image bands. The application of the IBI in ASTER and Landsat ETM ＋ imagery has shown that the new index can significantly enhance the urban built-up land information. Moreover, like vegetation and water indexes, the IBI can also be used for digital computation and thus make it possible to quantitatively study the relationship between urban built-up land and urban eco-environment. The case studies in Xiamen and Fuzhou Cities of south China shows that the IBI has a positive relationship with the land surface temperature （LST） and negative with water and vegetation indexes. Moreover, this study has discovered that the IBI has an exponential relationship with the LST, rather than a simple linear relationship. This suggests that the areas with high built-up land percentage will accelerate the increase of LST much more than the areas with low built-up land percentage and thus zontribute much more to the development of the urban heat island.