Abstract: In this paper,the ecological risk of water pollution from rural urbanization at the southern parts of the lower reaches of the Changjiang River was quantitatively evaluated and correlatively analyzed. The results indicate that there exist markedly monolinear correlations between BOD₅, NO₃^--N, phenol, surface activator of surface water, pH, Pb, NO₂^--N, phenol of precipitation, NO₃^--N of groundwater and the total population.Markedly exponential correlations between chloride, total bacteria, detergent of groundwater, CODCr of surface water and total population, and markedly monolinear correlations between BOD₅, phenol, surface activator of surface water, NO₃^--N, chloride, total bacteria, detergent of groundwater, pH, phenol, Pb of precipitation and population density as well as, markedly exponential correlations between NO₂^--N of precipitation and the population density in small towns are also found. The background limit values and maximum allowable background densities of population in small towns of the area were calculated.

Key words: Urbanization process, Water pollution, Ecological risk, nature reserve, conservation efficiency, rapid assessment, landscape dynamic, Ar Horqin