浙江省上虞市自 1969年围涂至今 ,已围海涂1 6万余公顷。围涂时开挖了许多河道 ,有围涂时筑堤取土后成的护塘河 ,较大垦区内的中心河。在平面上呈倒“山”字或倒“出”字形 ,有一些断头河。河道面宽 4 0～ 50ｍ ,底宽 2 0～ 30ｍ ,河底高程 2ｍ(吴淞标高 ,下同 ) ,地面高程 6～ Shangyu City, Zhejiang Province Since 1969, it has been encircled by over 60,000 hectares of sea. Excavated when the excavation of many rivers, a siege embankment after borrowing into the ponds River, a larger reclamation area within the center of the river. On the plane was inverted “mountain” or inverted “out” shape, there are some broken river. The width of the river course is 40 ~ 50m, the bottom width is 20 ~ 30m, the elevation of the river bottom is 2m (Wusong elevation, the same below), the elevation of the ground is 6 ~