南方圩区,从自然条件来讲,大体上可以分为两大类型:一种是大江大河下游的滨海地区,如浙江、广东、江苏、上海等省、市一带,它的特点是,河网密,地势平,有潮汐影响,洪枯水位变化幅度小,排灌揚程低,在 Southern polders, in terms of natural conditions, can be roughly divided into two types: one is the coastal areas of the lower reaches of the major rivers, such as Zhejiang, Guangdong, Jiangsu, Shanghai and other provinces and cities, which is characterized by the river network Dense, flat terrain, tidal effect, low amplitude of flood water level, low irrigation and drainage head in