Hydrological conditions are the decisive factors of wetland properties. Sources of water (such as precipitation, groundwater, tides, rivers, lakes, etc. ), water depth, flow pattern, duration and frequency of floods determine the diversity of wetlands. Water has a profound influence on the development of wetland soil. Wetland soil is usually called wet soil or hydraulic soil.

Wetlands are basically divided into five categories.

sea area

Subtidal waters: shallow waters with a water depth of less than 6 meters at low tide, including bays and straits, where there are no permanently growing plants; The aquatic vegetation layer in the subtidal zone, including various seaweeds and tropical marine meadows; cay

Intertidal waters: rocky beaches, including reefs and rocky beaches; Gravel beach; Vegetation-free intertidal sediments and saline-alkali beaches; Intertidal beach with vegetation, including mangroves on the continental shelf.

river mouth

Subtidal estuary: the estuary waters are permanent estuary waters and delta estuary system.

Intertidal estuary: intertidal mud, sand or saline-alkali beach with sparse plants; Intertidal marshes include saline-alkali meadows, tidal semi-saline marshes and freshwater marshes; Intertidal forest wetlands include mangroves, Nepalese palm trees and tidal freshwater swamp forests.

Lagoon wetland: a brackish water to a saltwater lake with one or more narrow waterways similar to the ocean.

Salt lake (inland basin): permanent and seasonal saline or alkaline lakes, mudflats and swamps.

river

Permanent rivers: permanent rivers and streams, including waterfalls; Inland delta.

Temporary rivers: rivers and streams that flow seasonally and intermittently; Flood plain, including flood plain, flood valley and seasonal flood grassland.

lake

Permanent lakes: permanent freshwater lakes (above 8km2), including lakesides that flood seasonally or intermittently; Permanent freshwater pond (above 8km2).

Seasonal lakes: seasonal freshwater lakes (above 8km2), including floodplain lakes.