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- abandoned channel
part of a stream which has been separated from the main stream by natural or artificial means. No surface water flows in it. - abiotic
Components of an ecosystem which are not living. A term often used for the result of chemical and physical impacts on organisms. - abundance
large quantity of individuals of a species present in a survey of flora or fauna - acidity
Water with a pH below 7 (elevated level of free hydrogen ions H+). See pH. - adduction zone
area where water is collected, and where human activities are regulated to avoid pollution - aerobic
an organism or tissue, requiring air for life; - aggregates
a name for all the materials extracted from a river bed: sand, gravel, rocks... - agrochemicals
chemical substances which spread on the ground for agriculture improvement - algae
Collective name of a large group of chlorophyll-containing waterplants, comprising of seaweeds and various freshwater forms, ranging in size from single cells to long stems. - alkaline
The opposite of an acid, having a pH of more than 7. An alkaline solution will react with acids to yield a salt. - alkalinity
1) Water with a pH above 7 (elevated level of free hydrogen ions OH-). See pH. - alluvial
1) Formed by or deposited by river flow processes e.g. alluvial plains - alluvium/fluvial sediments
Alluvium : Sediment deposited by flowing water - amphibians
An order of vertebrate animals that begin life in water, but as an adult are at home both in water and on land: eg. frogs, toads, newts, salamanders... - Amplitude
Difference between flow during a flood and average flow rate - anaerobic
Living in the absence of air or free oxygen; pertaining to or caused by the absence of oxygen - Anoxic
General - describes conditions in water in which oxygen is absent: such conditions are fatal for many organisms, in particular for fish. Technical - conditions in water in which no oxygen is chemically available, even from compounds from which some micro-organisms can “extract” oxygen (eg. nitrates); to be distinguished from anaerobic = conditions in which dissolved oxygen is absent – anoxic conditions represent a more extreme absence of oxygen than anaerobic conditions. - anthropic
Man-made modifications of the natural environment and, in particular for rivers, transformation into an artificial system - anura
Amphibians (see definition) which do not have tails: eg. frogs, toads. - aquaculture
The science and practice of farming organisms that live in water, such as fish, shellfish, and algae - aquifer
A geologic formation, such as fractured bedrock, sands or gravels, which holds water underground and supplies water to springs and wells; also used to refer to the water stored in such formations, that is ground water - aquifer
a formation, group of formations, or part of a formation that contains sufficient saturated permeable material to yield significant quantities of water for wells and springs - Arm
Natural or artificial length of river or water, for example a secondary channel parallel to the main river, which remains connected to the river at the downstream end. - Artificial
Something that is man made. (Lake, stream, dam) - Average flow
Average annual flow (in m3/second) of a river (average flow over the whole year, taken from a number of years’ data)
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