Abstract:s On the seasonal beaches,density of the surviving oncomelania( Y ) and the occurring rate of oncomelania ( Y r) are significantly related with the underground water table ( X 1) and the soil water content ( X 2).Y=-1 9686+0 2512X-0 004013X 2 1,Y r= -55 9720 +7 5689X 2-0 1180X 2 2; When the underground water table is under 32cm,it has a significant correlation with Y and Y r .When the underground water table is over 32cm,the relationship is negative.If the ...