Freshwater ecology

terrestrial water source

area of land where precipitation collects and drains off into a common outlet, such as into a river, bay, or other body of water

thumb|upright=1.3|Lake Hāwea, New Zealand

line that separates neighbouring drainage basins

thumb|Aerial view of Flevopolder, the [[Netherlands]] alt=|thumb|Satellite imagery|Satellite image of [[Noordoostpolder, the Netherlands (595.41 km2)]] A polder () is a low-lying tract of land that forms an artificial hydrological entity, enclosed by embankments known as dikes. The three types of polder are:

start of a river or stream

channel bottom of a stream, river, or creek

in geography, area between high and low tide marks of water bodies (both still and moving), or a raised landform on the side of a water body

interface between land and a river or stream

thumb|A variety of mire types in Carbajal Valley, Argentina thumb|right|Avaste Nature Reserve|Avaste Fen, one of the largest fens in Estonia thumb|right|A valley mire creates a level ground surface in otherwise dramatic topography. Upper Bigo Bog, Rwenzori Mountains, [[Uganda.]] A peatland is a type of wetland whose soils consist of organic matter from decaying plants, forming layers of peat. Peatlands arise because of incomplete decomposition of organic matter, usually litter from vegetation, due to water-logging and subsequent anoxia. Peatlands are unusual landforms that derive mostly from b

subset of Earth's aquatic ecosystems

type of aquatic ecosystem with flowing freshwater

management of watersheds

A rheophile is an animal that prefers to live in fast-moving water.

scientific study of freshwater ecosystems and biology

work to improve the environmental health of a river or stream

thumb|right|200px|The Markerwaard would be on what is now the Markermeer

conditional descriptions of a plain based on elevation above sea level