[Mapping environmental vulnerability from ETM + data in the Yellow River Mouth Area].

The environmental vulnerability retrieval is important to support continuing data. The spatial distribution of regional environmental vulnerability was got through remote sensing retrieval. In view of soil and vegetation, the environmental vulnerability evaluation index system was built, and the environmental vulnerability of sampling points was calculated by the AHP-fuzzy method, then the correlation between the sampling points environmental vulnerability and ETM + spectral reflectance ratio including some kinds of conversion data was analyzed to determine the sensitive spectral parameters. Based on that, models of correlation analysis, traditional regression, BP neural network and support vector regression were taken to explain the quantitative relationship between the spectral reflectance and the environmental vulnerability. With this model, the environmental vulnerability distribution was retrieved in the Yellow River Mouth Area. The results showed that the correlation between the environmental vulnerability and the spring NDVI, the September NDVI and the spring brightness was better than others, so they were selected as the sensitive spectral parameters. The model precision result showed that in addition to the support vector model, the other model reached the significant level. While all the multi-variable regression was better than all one-variable regression, and the model accuracy of BP neural network was the best. This study will serve as a reliable theoretical reference for the large spatial scale environmental vulnerability estimation based on remote sensing data.

[Spatiotemporal variation of eco-environmental frangibility based on remote sensing and catastrophe theory: a case study of Kenli County in Yellow River Delta, China].

Based on remote sensing and the nonlinear theories of entropy and catastrophe, the spatiotemporal variation of eco-environmental frangibility in Kenli County of Yellow River Delta was analyzed through the installation of sampling plots. The methods of analyzing and estimating eco-environmental frangibility were also established. The results indicated that in 1987-2005, the environment of Kenli County tended to deteriorating, and two catastrophes of environmental frangibility occurred, one in 1997, and the other in 2004. The former catastrophe was mainly caused by storm tide and the water shortage from Yellow River, with the main appearance characteristics being habitat change and dominant species substitution, while the latter one was mainly from the water shortage from Yellow River, increase of evaporation-precipitation ratio, a great deal construction of reservoir, and increases of traffic road and population density, with the main appearances of the changes in vegetation type and coverage ratio. The analysis on the spatial variations of the environmental frangibility along the directions of different distances to the Yellow River and to the ocean testified the spatial gradual change pattern of the frangibility. This research was a new attempt, and provided an effective way for the quantitative measurement of environmental frangibility.