CREATE TABLE table_25983027_1 (rainfall_by_depth__mm_year_ VARCHAR(255), land_area__km_2__ VARCHAR(255))
In the Central region, where the land area (km 2) is 8,543.2, what was the rainfall by depth (mm/year)?
    
SQL: SELECT rainfall_by_depth__mm_year_ FROM table_25983027_1 WHERE land_area__km_2__ = "8,543.2"