里下河流域是江苏北部著名的渔米之乡,隔江与太湖流域遥遥相对。这两个洼地在构造和成因上相同,很早以前还都是滨海一带的两个浅滩。后因海势东迁以及海岸沙堤和江岸沙嘴逐渐的堆积,浅滩逐渐围淤变成盐湖(或泻湖)。盐湖进一步受淡水冲洗和泥沙淤塞,碱性消失并渐渐陆出成为平原。不过太湖流域成陆较早(约六千年左右),农业历 Lixiahe River is famous in northern Jiangsu Yumizhixiang, across the river and the Taihu Lake basin distant relative. The two depressions are structurally and genetically the same, and long ago they were two shallows along the coast. Later, due to the seaward eastward migration and the gradual accumulation of coastal sandbanks and riverbank spouts, the shoals gradually turned into salt lakes (or lagoons). The salt lake was further washed by fresh water and silting, alkaline disappeared and gradually became a plain on land. However, the Taihu Lake into land earlier (about six thousand years), agricultural calendar