This area is located in the north of Zhejiang, across the banks of Hangzhou Bay, bordering the East China Sea in the east, the southern Jiangsu and Shanghai-Nanjing plains in the north, and the hilly foothills in the west and south, including the Hangjiahu and Xiaoshaoning plains. It is the largest plain distribution area in the province. The area is flat and controlled by the Yangtze River and Qiantang River estuaries, with thick Quaternary lacustrine and coastal loose sediments. Affected by Taihu Lake, the northern part of the plain in northern Zhejiang Province is dominated by lacustrine deposits. The coastal area from Qiantang River to Hangzhou Bay is dominated by tidal action, and tidal flat deposits are widely developed. According to the landform, sedimentary environment and lithologic characteristics, the northern Zhejiang plain can be divided into six sub-regions: alluvial marine plain, lagoon siltation plain, coastal plain, lacustrine alluvial plain, lakeside plain and terrestrial feather.

(1) alluvial marine plain community (Ⅰ1)

Located on both sides of the Qiantang River estuary, it is the largest alluvial marine plain in the province. The dynamic condition of sediment transport is the interaction between river and tidal current, with tidal current as the main force, and landing with the help of tidal flat siltation and sandbar merger. The sediments are mainly blue-gray and gray clayey silt, containing more fine sand, medium sand and more iron and manganese. From the mouth of the bay to the inner side of the plain, the soil types are distributed in sequence: salty sand-coarse silt coated-tidal closed soil, night overcast soil, yellow silt-small silt field, small silt field and mud coated field, with coastal saline soil and tidal soil as the main ones. The soil is rich in mgO, CaO, Na2O, P, Cl, B, but deficient in N, S, Mn, Cu, Zn, Mo, Fe and organic matter, with good tillage, poor structure, easy hardening and poor water and fertilizer conservation.

(2) lagoon silting plain community (Ⅰ 2)

It is distributed in Xiaoshaoping Plain, Yaojiang Plain and Ningbo Plain, with low terrain, numerous lakes and high water network density. The sediments are mainly blue-gray and gray-black organic loam, rich in plant residues or peat, and the top is often yellow-brown iron-bearing manganese loam. The main soil types are blue mud field, mud field, blue purple mud field and yellow purple mud field. Rotten blue-purple mud fields are scattered in the low-lying areas, mainly paddy soil. The soil is deep, with high contents of mgO, CaO, Na2O, N, P, S, Cu, Zn, B, S, Fe and organic matter, good storage performance and sticky texture.

(3) coastal plain community (Ⅰ 3)

It is distributed on both sides of the estuary and in the bay, forming a relatively wide plain dominated by marine deposits, and its land-forming age is relatively close. The main plains are Pinghu, Haiyan, Bates and Zhenbei. According to the grain size of sediments, it can be divided into two types: coastal silt and coastal silt. The former is mainly ancient coastal sand dikes, while the latter belongs to intertidal sediments. The formed soil can be divided into yellow mud field, green mud field, yellow heart green purple mud field and small powder field, yellow pine field, combined loose mud field and yellow sand moisture field. Soil is rich in nutrients and oxides, such as iron, magnesium oxide, calcium oxide, sodium oxide, phosphorus, chlorine, manganese, copper, zinc and boron. It has good permeability and plowability, water-gas coordination, and good fertilizer supply and storage performance.

(4) The alluvial plain of lakes and marshes (Ⅰ 4)

Deqing, Tongxiang and Jiashan, which are distributed in the central and western parts of Hangjiahu Plain, have low terrain, with an average elevation of about 3m, gentle slopes, dotted lakes and dense water networks. They belong to the remnants of ancient Taihu Lake shrinkage, mainly composed of lakes and swamps, with a small amount of plain river facies and coastal facies. The sediments are mainly grayish brown and grayish black loam, with high organic matter content and thin peat in some areas. Soil types are mainly purple mud fields, yellow-spotted purple mud fields, pink-cored purple mud fields and yellow-cored purple mud fields, with a small amount of rotten purple mud fields, small pink fields and yellow-spotted fields. The soil is deep and rich in nutrients and oxides such as iron, magnesium oxide, calcium oxide, sodium oxide, phosphorus, chlorine, manganese, copper, zinc and boron. The soil is sticky, with more water and less gas, and waterlogging is common.

(5) lakeside plain community (Ⅰ 5)

Changxing-Huzhou area, located in the south bank of Taihu Lake, was formed during the shrinking of Taihu Lake. From the inside out, the sedimentary environment can be divided into two types: lakeside facies and lacustrine facies. The former is mainly light yellow sand and coarse silt, with a small amount of gravel, and the thickness of the sedimentary body can reach several meters. The soil types are hard mud field, Tingsha white soil field, lake white soil field, Songtian lake and fluvo-aquic soil from outside to inside, with blue mud field and yellow mud field in the middle. The former is mainly lacustrine parent material, while the latter four are mainly lakeside parent material. The soil is deep and light, mainly sandy loam; Symptoms of soil nutrient deficiency and element deficiency.

(6) Lu Yu (Ⅰ 6)

It is a few hills scattered on the plain with an altitude of 50 ~ 200 m. Generally, the ridge is gentle, the top of the mountain is mostly round, the valley is vertical and horizontal, and thick weathered residual layer is developed locally; The soil type is mainly yellow-red soil, with a small amount of red soil, red soil and lime (rock) soil.