Studies On The Process Of Urbanization Of Hefei City And Their Climate Effects

Hefei is capital and economic and cultural center of Anhui province. Since the reform and openning, Hefei has been developed rapidly. With the expansion of city scale and socio-economic development, climate effects of city have become increasingly prominent in Hefei. Urbanization process generated urban air pollution,the increasing of waterproof road surface ,uneven buildings etc.,which caused urban effects of heat island, dry island, dark island and so on. Environment of people's working,living and city's ecology have been brought about disadvantageous effects.This paper analysed the annual and seasonal changes of sevaral meteorological factors in Hefei climate (temperature, relative humidity, precipitation, sunshine hours). On the basis of these analysis , the climate causes forming and process of urban were studied, which demonstrated thate it existed the relationship between urbanization and climate change. The ways of improving the urban climate conditions were discussed,which can provide a theoretical basis for urban planning, urban construction, urban environmental protection, urban building design and management etc..The main conclusions were as following.1. Using 9 key indicators of Hefei development for principal component analysis,which indicated that urbanization level increasingly improved in Hefei .The average growth rate was 15.58 percentage points in every 10 years.2. The average temperature, relative humidity, annual precipitations and sunshine duration were analysed, which indicated that there were effects of heat, dry and dark islands in Hefei.But the effect of rain island was not obvious. Hefei urban precipitations was generally larger than the suburb's in the past 32 years. but urban has the trend of the precipitation reduced gradually. Seasonal changes analysis showed that: Heat island effect of the winter was most significantly in Hefei ,growth rate was 0.1℃in every 10 years; The weakest is summer growth rate was 0.049℃in every 10 years; spring growth rate was 0.068℃in every 10 years;autumn growth rate was 0.081℃in every 10 years; spring and autumn are between the winter and summer .The most change ofâ–³RH_u-r(%) absolute value was in January in the winter.The weakest was in June in the summer.3. Urban heat island and the urbanization level was positively correlationand in Hefei Fitting equation: y=0563-0.027x+0.001x²-1.1E-05x³, (R²=0.706,p<0.01). 4. The regression equation of precipitation and the urbanization level did not pass the 0.05 significant test.It showed that increasing trend of precipitation was not obvious as the Hefei development.5. Affected by the urbanization,the yearly relative humidity showed the declining trend in Hefei.The change rate was -0.709% in every 10 years; The urbanization level and the difference between suburb and urban existed bigger correlativity .Its intended equation: y=7.4049-2.7585x+0.2674x²-0.0125x³+0.0003x⁴-3E-06x⁵+2E-08x⁶(R²=0.6675,p<0.01).6. The yearly sunshine duration was steady decline in Hefei.The difference of urban and suburb sunshine hours have gradually increased .The sunshine duration and the urbanization level existed negative correlation .Fitting equation:y =1926.454+2.980x+0.4 23x²+0.005x³(R²=0.6675,p<0.01).The urbanization level and the difference between suburb and urban existed bigger correlativity.The regression equation:y=88.752-21.995x +1.1609x²-0.0259x³+0.0002x⁴(R²=0.7318,P<0.01).It indicated that the sunshine duration and the difference between suburb and urban have trend of steady decline as Hefei development.