outflow       
noun [ C ] uk/ˈaʊt.fləʊ/ us/ˈaʊt.floʊ/
 外流;流出
a movement away from a place
  I'm trying to measure the outflow of water/sewage from that pipe. 我正在设法测量从那个管道中排出的水流量/污水量。 
 The central bank has announced controls on capital outflows. 中央银行宣布了对资本外流量的管控措施。 
 Opposite: inflow