CREATE TABLE table_25983027_1 (rainfall_by_depth__mm_year_ VARCHAR(255), infiltration__km_3__year_ VARCHAR(255))
How many regions had rainfall infiltration (km 3/year) of 9.3?
    
SQL: SELECT COUNT(rainfall_by_depth__mm_year_) FROM table_25983027_1 WHERE infiltration__km_3__year_ = "9.3"