RESUMO
Xiamen is one of China's five major special economic zones and is the core city of Haixi Economic Zone, with a high level of urbanization. Monitoring and driving force analysis of impervious surfaces can increase our understanding of urbanization process and have important significance for urban landscape pattern research and urban ecological environment construction. We used the Landsat remote sensing image data from 1978 to 2018 to reveal the temporal and spatial variation characteristics of the impervious surface landscape in Xiamen in the past 40 years, using the full-restricted least squares method, landscape pattern analysis, slope gradient analysis and correlation analysis. We further analyzed its relationship with social and economic factors. The results showed that, during 1978-2018, the impervious surface of Xiamen increased by 348.96 km2, with a mean annual increase of 8.72 km2. The impervious surface dynamics reached a maximum of 9.0% in 2005-2010. More than 86.6% of the impervious surface of Xiamen was distributed within 6° of slope, with a tendency to expand to a greater slope in 2010-2018. With the increases of slope, the proportion of impervious surface decreased, the density of plaque decreased with the shape tending to be regular and continuous, the degree of fragmentation of the impervious surface increased. The increases of impervious surface in Xiamen was significantly related to the regional economic aggregate and population. In the study period, the spatial pattern of impervious surface in Xiamen significantly altered. In the future urban planning process, the extent and speed of impervious surface expansion should be coordinated to avoid ecological problems caused by excessive impervious surface to meet the need for sustainable development of Xiamen.
Assuntos
Planejamento de Cidades , Urbanização , China , Cidades , EcologiaRESUMO
With the high requirements and long test cycle of traditional testing method of soil heavy metal, this paper tries to es-tablish the quantitative prediction model between soil hyperspectral and soil chromium content( tested by ICP-MS) to realize thIeprediction of soil chromium element quickly and accurately. The paper studied the hyperspectral response characteristics of re dsoil, with 135 soil samples in Fuzhou city. After monitoring the hypersectral reflection of soil samples with ASD (analytica lspectral device) and total chromium contents with ICP-MS, the paper gained the spectral reflection data between 350 and 2 500 nm and soil total chromium contents. Then the paper treated the hyperspectral reflection data with 6 mathematic changes such as reciprocal logarithmic change, differentials and continuum removal in advance. The next step was to calculate the correlation co-fficient of soil chromium and the above spectral information, and select the sensitive spectral bands according to the highest cor-elation coefficient. Finally, six kinds of models were selected to build the soil total chromium content model, and the final opti-al mathematic model between soil chromium and hyperspectral information was significantly determined. Results showed that 520--30, 1 440-- 450, 2 010-- 020, and 2 230-- 240 nm were the main sensitive bands to soil total chromium, y= 120. 68Ce (-7.037x)was the optimal soil total chromium predicting model( in the model, the correlation coefficient R and the RIME of total chromium were 0. 68 and 0. 19 Cµ1(-,) and the inspection correlation coefficient R and the RMSE were 0. 84 µ ?xg-('1) nd 1. 26 Iµ ?xg-(1 )respectively). The model can be used to rapidly monitor soil total chromium with hyperspectral reflection in Fuzhou. area.
RESUMO
The present paper studied the hyperspectral response characteristics of red soil, with 135 soil samples in Fuzhou city. After monitoring the hypersectral reflection of soil samples with ASD (analytical spectral device) and total nitrogen contents with Vario MAX (for nitrogen and carbon analysis), the paper gained the spectral reflection data between 350-2 500 nm (resolution is 1 nm) and soil total nitrogen contents. Then the paper treated the hyperspectral reflection data with 5 mathematic conversions such as first derivative and second derivative conversions of original reflection, reciprocal logarithmic conversion and its first derivative and second derivative conversion in advance. The next step was to calculate the correlation coefficient of soil nitrogen and the above spectral information, and select the sensitive spectral bands according to the highest correlation coefficient. Finally, by designing different proportions of modeling and validation sample data sets, the paper established the quantitative linear models between soil total nitrogen contents and hyperspectral reflection and its 5 converted information, the final optimal mathematic model between soil nitrogen and hyperspectral information was significantly determined. Results showed that 634-688, 872, 873, 1 414 and 1 415 nm were the main sensitive bands for soil total nitrogen, and Y = 5.384X(664) -1.039 (Y represents soil nitrogen content, X664 is the soil spectral absorbance value at 664 nm) was the optimal soil total nitrogen predicting model (in the model, the determination coefficients R2 and the RMSE of total nitrogen were 0.616 and 0.422 mg X g(-1), the inspection coefficient R2 and the RMSE were 0.608 and 0.546 mg x g(-1) respectively). The model can be used to rapidly monitor soil total nitrogen with hyperspectral reflection in Fuzhou area.
RESUMO
Based on the 1988, 2000, and 2007 remote sensing images of a typical red soil eroded region (Changting County, Fujian Province) and the digital elevation model (DEM), the eroded landscape types were worked out, and the changes of the eroded landscape pattern in the region from 1988 to 2007 were analyzed with the spatial mathematics model. In 1988-2007, different eroded landscape types in the region had the characteristics of inter-transfer, mainly manifested in the transfer from seriously eroded to lightly eroded types but still existed small amount of the transference from lightly eroded to seriously eroded types. Little change was observed in the controid of the eroded landscape. In the County, Hetian Town was all along the eroded center. During the study period, the landscape pattern index showed a tendency of low heterogeneity, low fragmentation, and high regularization at landscape level, but an overall improvement and expansion of lightly eroded and easy-to-tackle patches as well as the partial improvement and fragmentation of seriously eroded and difficult-to-tackle patches at patch level.
