| The Qinhuai River Basin was chosen as the study area. The impervious and land use information was extracted by RS and GIS technology. The change of impervious surface from1986 to 2006 was breakthrough point in this study, the statistical method and L-THIA model were constructed, and the hydrological response to those impervious changes was analyzed from qualitative and quantitative methods. Moreover, the potential hydrological response to urbanization in future was evaluated based on the land use scenarios differentiated by built up land area. Those results can provide useful support for land use planning and management.1. A new approach was proposed to quantify impervious surface as a continuous variable from multi-temporal and multi-source datasets. A 30 year time series (1979-2009) of Landsat imagery and CBERS imagery for Qinhuai River Basin was analyzed to estimate the imperviousness. First, the principal component analysis (PCA) approach was performed in CBERS imagery, and all bands of CBERS image and the first two principal components were stacked to a new image with more information and bands. Second, Linear Spectral Mixture Analysis (LSMA) was used to determine the fractional composition of vegetation, high- and low-albedo and soil for each pixel. Impervious was then estimated by adding all of high-albedo and part of low-albedo fraction images. Finally, temporal rule, that minimized classification error, was developed based on each pixel's classified trajectory over the time series of imagery. The results indicated that the impervious surface was extracted accurately by preprocessing on CBERAS, temporal rule and other methods.2. Based on statistical method, hydrological effects resulted by the changes of impervious surface was analyzed from qualitative and quantitative methods in the Qinhuai River Basin. Mann-Kendall test, orderly cluster method and other time series methods were used to analyze the trend and abrupt change point of runoff, precipitation and other hydrologic factors from 1986 to 2006. The initial year and degree of hydrologic factors changes by the impervious surface were discussed on multiple linear regression analysis. The results demonstrated that the significant changes of all hydrologic factors were started in 2003. With increasing impervious surface, annual runoff, flood runoff, flood volume and runoff coefficient grew, while evaporation reduced. The relative change of runoff was the largest, and that of evapotranspiration was the least.3. A further analysis on hydrological effect of impervious was studied from quantitative method by L-THIA hydrological model. For only analyzing hydrological effects of impervious, land use scenarios by different impervious levels were developed. The L-THIA model was set up and calibrated for the study area. It was an advantaged approach to explain and predict long-term hydrological process, and was repeatedly run with different land use scenarios to investigate the hydrological effect to impervious change. The study revealed average annual runoff depth, runoff coefficient increased, and average annual evaporation decreased due to the sprawl of impervious surface area. Since 2003, all of those hydrologic factors changed greatly, and speed of average annual runoff depth increased from 4.66mm/y to 11.99mm/y. Impervious rate and average annual runoff depth was approximately linear.4. The hydrological effects of future urbanization. Base on the trend of land use from 2003 to 2006, future 2012 and 2018 land use scenarios of Qinhuai River Basin were predicted by CA-Markov model. Then the calibrated L-THIA model was applied for these future land use scenarios to access the potential impervious impacts on average annual runoff depth, evaporation and others. The study demonstrated that when the ratio of imperviousness would be 23.83%, an average annual runoff depth would be 532.44 mm, and it would increase 38.81% by comparison of observed data; When impervious ratio would be 33.13%, simulated average annual runoff depth would be 613.54mm with 59.95% higher than the observed runoff. When the impervious rito would be 30%, the greater average annual runoff depth would increase 50%, it would cause flooding and some related water environment problems. So urban construction management of Qinhuai River Basin should be strengthened.
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