Calculating design drainagedischarge have important significance for water safety and derating economic losses of waterlog in the polder areas.
圩区设计排涝流量计算，对圩区的水安全，有效减免涝灾经济损失有着重要意义。
2
The concepts and methods of the urban development departments and water conservancy departments used to reckon the drainagedischarge are not completely in the same.
由于城市排水计算排水流量与圩区排涝计算排涝流量在概念、方法上不尽相同。
3
The Liujiang is polluted because industries and the city drainage system directly discharge into it significant raw sewage and rainwater.