解:?$(1)$?由題意可得,星期三這個(gè)監(jiān)測(cè)點(diǎn)的實(shí)際水位為?$ 155-6.02=148.98($?米?$)$?
?$(2)$?根據(jù)數(shù)據(jù)知,星期六的水位為?$155+4.47=159.47($?米?$)$?,
星期四的水位為?$155+1.02=156.02($?米?$)$?
∵?$(159.47-156.02)×7.2=24.84($?億立方米?$)$?
∴星期六的蓄水量比星期四的蓄水量增加了?$24.84$?億立方米