Research Of Impervious Surface Area Change Impact On Dianchi Lake Surface Water Temperature In Recent 30 Years

The impervious surface is an important indicator of the frequency and intensity of human activity.With the growth of urbanization,the rapid expansion of the impervious surface of Dianchi Lake basin,Dianchi Lake aquatic environment had taken place major changes in recent 30 years.Lake surface temperature is the most important indicators of lake ecological environment,which is the main reason for the outbreak of cyanobacteria bloom.Lake surface temperatures affect the energy exchange between gas,ground and water.This study has extracted impervious surface and lake surface water temperature by using several kinds of method,and compare with the advantages and disadvantages.Quantitative analysis of spatial and temporal variations of impervious surface process by several kinds of indicators,such as: ISA,ISC,Impervious surface conversion rate,and Impervious surface expansion index.This study has described the impervious surface related to the lake surface water temperature by using spatial analysis,statistical analysis and other methods.The preliminary research conclusions are as follows.(1)This paper USES the thermal infrared data based on image fusion method to extract impervious surface,and effect is good,the overall accuracy is 93.48%,the kappa coefficient is 0.823.So we can use this method to extracting impervious surface data with a good accuracy and continuity.(2)With the increasing impervious surface in the dianchi lake basin,the impervious surface index is growing exponentially in recent 30 years.Natural surface area decreased by 33%,which is about 938.24 square kilometers.FDISA coverage area is increased by 5.78%,about 164.33 square kilometers.There have a great change in impervious surface conversion rate with the rapid urbanization in recent 30 years.(3)We can calculate the atmospheric transmittance with the atmospheric transmittance equation estimating by ?-e empirical formulae methods and the Magrath empirical formulae,the result error is only 0.013,through the test of significance.(4)The measured temperature data analysis shows that dianchi lake annual average temperature was increased by 2.7? during 1988 to 1999,that the water quality has been deteriorating and exceeded worse V and the trophic level has been constantly rising.(5)We can obtain the spatial distribution of dianchi lake water surface temperature with using the lake surface temperature inversion method.Found that impervious surface coverage was associated with lake surface water temperature,and there was a positive correlation between impervious surface and lake surface water temperature during 1988 to 1999.With the increasing of impervious surface,the lake surface water temperature distribution is stratified in distance,when water more and more close to higher impervious surface coverage areas,the lake surface water temperature is higher and higher.