Glossary

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A
Acid precipitation Rainwater or snow containing sulphur and nitrogen compounds and other pollutants associated with industrialization. See also => Acidification
Acidification The lowering of pH in soils or water. Commonly associated with changes caused by external processes such as => Acid precipitation and acidic runoff.
AHEC Alternate Hydro Energy Centre, Roorkee, India.
Alluvial deposits (alluvium) Material such as clay, silt, sand, and gravel deposited by modern rivers and streams.
Alpine region Of or pertaining to the Alps, or to any lofty mountain. The alpine region is located above the tree-line.
Amphipods A group of crustaceans that includes freshwater shrimps.
Anadromous Used to describe fish that spawn in fresh water after spending most of their lives in the sea. The best-known anadromous fish are salmon, which hatch in small freshwater streams, go down to the sea and live there for several years, then return to the same streams where they were hatched, spawn, and die shortly thereafter. Salmon are capable of going hundreds of kilometres upriver, and human dams must install fish ladders to enable the salmon to get past. See also => Catadromous.
AQEM The development and testing of an integrated assessment system for the => Ecological quality of streams and rivers throughout Europe using =>  Benthic macroinvertebrates.
AQEM data input program Software tool to enter, store, and export European =>  Aquatic macroinvertebrate => Taxa lists in a standardised way.
AQEM river assessment program Software tool to assess the ecological status of rivers in Europe using => Aquatic macroinvertebrates.
Aquatic macroinvertebrates Macroscopic animals without backbones ("invertebrates") that are large enough to be seen with the naked eye ("macro", e.g., > 0.5 mm). At least one stage within its life cycle is bound to water (streams and rivers, lakes, groundwater). Examples of macroinvertebrates include: aquatic worms, snails, clams, crayfish, leeches, and the larval and nymph stages of many insects (e.g., dragonflies, mosquitoes, and mayflies). Aquatic macroinvertebrates are excellent indicators of water quality because of their strong relationship to pollution or various other => Pressures. They are easy to identify, capable of integrating over different temporal scales, and most frequently used for aquatic bio-indication worldwide.
Aquifer A water-bearing layer of soil, => Sand, => Gravel, or rock that will yield usable quantities of water to a well.
Aufwuchs A German word applied by ecologists to small organisms found on the surfaces of aquatic vegetation, etc., in freshwater habitats.
 
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Bar Submerged or emerged embankment of => Sand, => Gravel, or other unconsolidated material built in shallow water by waves and currents.
Basalt A type of dark gray rock formed by solidification of molten material. Fine-grained, sometimes glassy, basic (i.e., low in silica content) => Igneous rock. The rocks of Hawaii are basalts.
Base flow Sustained, low flow in a stream; ground-water discharge is the source of base flow in most places.
Bedrock General term for consolidated (solid) rock that underlies soils or other unconsolidated material.
Benthic Living at the bottom of a fresh or salty body of water. Opposed to => Pelagic.
Benthic (macro) invertebrates => Aquatic macroinvertebrates
Benthos Plants and animals that live on, in, or attached to the stream, river, lake, or sea bottom.
Biodiversity The variety of life in all its forms contained within a given space at a particular time.
Bio-indicator An organism and/or biological process whose change in numbers, structure, or function points to changes in the integrity or quality of the environment.
Bivalve A mollusc with two shells, for example, a clam or mussel.
BOKU University of Natural Resources and Applied Life Sciences, Vienna, Austria.
Bottom-up approach Often referred to in the context of => River typology, where ‘bottom-up’ means the approach from the (bottom) local => Community sampled at a site towards the deliniation of (up) large-scale geographical units, such as ecoregions or sub-ecoregions. The development of a => River typology often starts ‘top-down’ and, if sufficient biological data are available, is subject to a ‘bottom-up’ validation and subsequent refinement. Opposed to => Top-down.
Boulders Rock fragments larger than 60 cm in diameter.
Brackish water Salty water (> 0.5 ‰ salt) with less salt than seawater.
Braided river A braided river channel consists of a network of smaller channels separated by small and often temporary islands called braid bars. Braided streams are common wherever a drastic reduction in stream gradient causes the rapid deposition of the stream's sediment load. Braided channels are also typical of river deltas.
BUET Bangladesh University of Engineering & Technology, Dhaka, Bangladesh.
Buffer strip The vegetation along a stream left intact after logging or land clearing. An intact buffer strip prevents from fine sediment entry into a stream.
Buffering capacity Ability to neutralize acidic input.
 
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Calcareous Containing salts of calcium, for example, calcium carbonate as limestone rock or derived soil.
Carbonate rocks Rocks (such as limestone or dolostone) that are composed primarily of minerals (such as calcite and dolomite) containing the carbonate ion (CO32-).
Catadromous (Katadromous) Used to describe fish that spawn in the open sea after spending their lives in fresh water. The most remarkable catadromous fish are freshwater eels of genus Anguilla, whose larvae drift on the open ocean, sometimes for months or years, before travelling thousands of kilometres back to their original streams. See also => Anadromous.
Catchment basin See => Drainage basin, => Watershed.
CEN European Committee for Standardization (Comité Européen de Normalisation). CEN contributes to the objectives of the European Union and European Economic Area with voluntary technical standards which promote free trade, the safety of workers and consumers, interoperability of networks, environmental protection, exploitation of research and development programmes, and public procurement.
Channelization Enlargement or deepening of a river or river section, often combined with armouring of the river banks.
Clay 1. A mineral soil particle less than 0.002 mm in diameter. 2. A soil textural class containing 40 % or more clay, less than 45 % sand, and less than 40 % silt.
Cobbles Water-worn rock fragments 7.5–25 cm in diameter.
Colluvial deposit Weathered material deposited by gravity (e.g., a talus slope).
Community In ecology, the species that interact in a common area.
Conductivity A measure of the ability of waters to conduct electricity. It increases as the amount of dissolved minerals (ions) increases.
CPOM (Coarse Particulate Organic Matter) Coarse parts of organic matter, e.g., twigs, small branches, leaf packs.
Crustacean An invertebrate animal with a hard exoskeleton and at least five pairs of jointed legs on the thorax, includes crabs, lobsters, copepods, amphipods, and isopods.
Crystalline rocks Rocks ( => Igneous rock or => Metamorphic rock) consisting wholly of crystals or fragments of crystals. Opposed to => Sedimentary rock.
Current Movement in a body of water caused by major ocean circulation or tides, by waves along shorelines, and by gravity-induced flow in rivers.
Current preference A measure to explain the preference of => Aquatic macroinvertebrate => Taxa for particular flow conditions. Taxa are, e.g., divided into those preferring high current velocities (rheobiont, rheophilous) or others preferring low flow conditions (limnophilous, limnobiont), or even standing water (limnetic).
 
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Degradation The process by which a streambed is lowered in elevation by removal or => Scouring of => Sediment. This term is also used to refer to a damaged condition of => Habitat (hydromorphological degradation, physico-chemical degradation).
Detritivore Animals that feed primarily on fragments of organic matter (detritus) found in soil and bottom sediments.
Diabase An intrusive rock, usually occurring in dykes or intrusive sheets; characterized by lath-like feldspar minerals oriented in all directions, with darker minerals in the spaces between.
Discharge The volume of water that flows past a given place during a certain amount of time. Discharge is often referred to in cubic feet per second (cfs), litre per second (l s-1), or cubic metre per second (km³ s-1). 1 km³ s-1 = 1,000 l s-1.
Drainage basin The land area that contributes water to a stream or lake system or directly to the ocean; also referred to as a catchment basin.
Drainage divide A boundary between adjacent drainage basins or => Watersheds.
Driver An anthropogenic activity that may have an environmental effect (e.g. agriculture, industry, human settlements) affecting the in-stream => Community.
 
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ECODAT (Eco-data Management tool) => Eco-data Management tool.
Eco-data management tool Designated software product of ASSESS-HKH to aid => Ecological assessment based on => Aquatic macroinvertebrates, to visualize the results in => Water quality maps, and to support the data interpretation and derivation of management options.
Ecological (quality) status Terminus defined in the => EU Water Framework Directive (WFD) to classify a surface => Water body into five quality classes: high = reference, good, moderate, poor, and bad.
Ecological assessment (system) Assessing the => Ecological status using biological quality elements, e.g., => Aquatic macroinvertebrates.
Ecological quality => Ecological status
Ecological zone Term used by the FAO to delineate ecologically distinct geographical entities with respect to the principal wooded vegetation. In context of ASSESS-HKH ecological zone is used synonymous with => Ecoregion.
ECOPROF Software tool to analyse and assess freshwater bodies in Austria, based on => Aquatic macroinvertebrates, ciliates, and algae, to analyse and visualize the ecological function, and to contribute to the => Quality assurance of biological surveys.
Ecoregion An ecoregion is "a relatively large area of land or water that contains a geographically distinct assemblage of natural communities." An ecoregion is associated with characteristic combinations of geology, topography, climate, landform, flora, and fauna that characterise that region. In the context of ASSESS-HKH, ecoregion and => Ecological zones are used synonymously.
Ecosystem The interacting populations of plants, animals, and micro-organisms occupying an area, plus their physical environment.
Emergent plant A plant rooted in shallow water with much of the stem and most of the leaves above water.
End moraine Ridge-like accumulation of till along the terminal margin of a glacier.
Endemic Confined to a specific geographic area.
EU Water Framework Directive (WFD) Directive 2000/60/EC establishing a framework for community action in the field of water policy. The WFD provides the legal framework by the European Commission to obtain a ‘good => Ecological quality’ in all surface and ground waters of the European Union by the end of 2015. The WFD passed the European Parliament on December, 22nd 2000.
Eutrophication The process by which water becomes enriched with plant nutrients, most commonly phosphorus and nitrogen.
 
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FAME The development of a fish-based assessment method for the ecological status of European rivers – a tool to support the implementation of the European => Water Framework Directive (WFD).
Feeding type A measure to explain the preference of => Aquatic macroinvertebrate => Taxa for particular food, such as => Sediment feeders, => Filter feeder, or => Predators.
Filter feeder An organism that obtains its food by straining particles from the water. Either passive solely driven by the current or active by moving the body or specific filtering parts.
Floodplain The land bordering a stream, built up of sediments from stream overflow and subject to inundation when the stream floods.
Fluvial Pertaining to rivers.
Fluvial deposits All sediments, past and present, deposited by flowing water, including => Glacio-fluvial deposits.
FPOM, Fine particulate organic matter Small parts of organic mattes, e.g., leaf fragments.
 
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Glacio-fluvial deposit Material moved by glaciers and subsequently sorted and deposited by streams flowing from the melting ice. These deposits are stratified and may occur in the form of outwash plains, deltas, or terraces.
Glide A part of a stream that is characterized by a smooth, easy movement of water, usually just upstream of a riffle.
Gneiss A coarse-grained metamorphic rock with a characteristic discontinuous layered structure and a composition generally similar to => Granite.
Granite An intrusive rock consisting mainly of alkali feldspar and quartz. The term may be loosely used for any light-coloured, coarse-grained => Igneous rock.
Gravel Rock fragments 2–7.5 cm in diameter.
Greywacke An impure sandstone consisting of rock fragments and grains of quartz and feldspar in a matrix of clay-sized particles.
Ground moraine Rolling plain that has gently sloping swells, sags, or basins made of till.
Groundwater Water in the zone of saturation where all open spaces in sediment and rock are completely filled with water.
 
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Habitat Habitat is the place where a particular species lives and grows. It is essentially the environment – at least the physical environment – that surrounds (influences and is utilized by) a species population.
Habitat preference A measure to explain the preference of => Aquatic macroinvertebrate => Taxa for particular => Habitats, such as => Stones, => Sand, or => Large wood.
Herbaceous Descriptive of non-woody plants with no above-ground persistent parts.
Herbicide A chemical or other agent that applied for the purpose of killing of undesirable plants. See also => Pesticide.
Herbivore An animal which feeds on living plant material.
Hindu Kush-Himalayan region The region delineated by the Hindu Kush and Himalayan mountain ranges, from Pakistan in the west to Myanmar in the east. The HKH region comprises eight countries: Afghanistan, Bangladesh, Bhutan, China, India, Myanmar, Nepal, and Pakistan, extending some 3,500 km from west to east and 300-500 km from north to south. The HKH region inhabits 140 million people. The research area of ASSESS-HKH comprises five countries: Bangladesh, Bhutan, India, Nepal, and Pakistan.
HKH region (Hindu Kush-Himalayan region) => Hindu Kush-Himalayan region
HOBENT Software tool to evaluate the => Ecological status of river systems in the Czech Republic.
Hydrography The mapping of the characteristics of oceans, lakes, and rivers.
Hydrology The science of the properties, distribution, and effects of water.
Hydromorphology The physical characteristics of the shape, the boundaries and the content of a water body.
 
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ICIMOD International Centre for Integrated Mountain Development, Kathmandu, Nepal.
Igneous rock One of the three main groups of rock. Igneous rocks characteristically appear crystalline and were formed by the crystallization of magma.
Impact The environmental effect of a => Pressure directly acting on the in-stream community , e.g., fish killed, lowered biodiversity, shift of community functional, loss of sensitive species.
Impoundment A structure built to maintain desired water level; commonly used in waterfowl management.
INCO International Cooperation programme by the European Union (EU) to help ensure Europe’s strong and coherent participation in the research initiatives conducted at international level in order to push back the boundaries of knowledge or help to resolve the major global issues for example as regards health and environment.
Index (plur.: Indices) Statistical measure to compare the development with respect to an earlier time. Stock indices characterize the temporal development of stock exchange rates, biotic indices characterize the temporal alteration of the => Ecological status.
Indicator organism => Bio-indicator
Indo-Gangetic Plains The Indo-Gangetic Plains are named by the rivers Ganges and Indus. The plains stretch from Kashmir in the north, the Punjab region of Pakistan and Aravalli Range of Rajasthan in the west, the Himalayan foothills in the east and the Deccan Plateau in the south. The fertile Terai region is the Nepalese extension of the plains.
Infauna Benthic animals that burrow into the substrate.
Insecticide A substance or mixture of substances intended to prevent, destroy, or repel insects.
Introduced species Non-native species brought into an area intentionally or accidentally by humans.
ISO International Organization for Standardization. Network of the national standards institutes of 151 countries, on the basis of one member per country, with a Central Secretariat in Geneva, Switzerland, that coordinates the system.
 
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Karst topography A landscape typical of gypsum and limestone areas, where sinkholes have formed as a result of the dissolution of rocks by rainwater; narrow, crumbling ridges separate the sinkholes.
KU Kathmandu University, Dhulikhel, Nepal.
 
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Lacustrine deposits Material deposited by or settled out of lake waters and exposed by the lowering of water levels or the elevation of land. These sediments range in texture from sand to clay and are usually varied (layered annual deposits).
Large wood (LW) Coniferous or deciduous logs, limbs, or root wads twelve inches or larger in diameter that intrudes into a stream channel or nearby.
Large woody debris (LWD) => Large wood (LW)
Lentic Related to slow-moving water, such as in lakes and bogs.
Life cycle The series of changes or stages undergone by an organism from fertilization, birth or hatching to reproduction of the next generation.
Limnetic Related to the environment of lakes and ponds.
Littoral The zone between the extreme high-tide and extreme low-tide levels in the sea; also the zone from the shore to the light-compensation level of the sea and lakes.
Load The transfer of material, dissolved or particulate, associated with a flow of water.
Loam A soil mix of coarse => Sand, => Silt, => Clay, and organic matter.
Loess Deposits composed primarily of windblown silt and lacking visible layers.
Log => Large wood of at least 10 cm diameter, e.g., a large branch, tree stem, tree trunk.
Lotic Related to fast-moving water, such as in most streams and rivers.
 
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Macroinvertebrates => Aquatic macroinvertebrates
Macrophyte All aquatic higher plants, mosses and characean algae, but excluding single celled phytoplankton or diatoms.
Macrozoobenthos (MZB) => Aquatic macroinvertebrates
Management plan The management plan lists the selected water quality and quantity objectives and defines the provisions and action priorities to be implemented to achieve the assigned objectives.
MU Masaryk University, Brno, Czech Republic.
Meander A loop-like bend in a stream or river that develops when a watercourse flows through level land and erodes its floodplain.
Mesohabitat Apparently distinguishable => Habitat entities within a river stretch, e.g., => Riffle, => Pool, river margin, mussel bank, => Riprap, or fallen tree.
Metadata Description of the characteristics of a set of data.
Metamorphic rock Metamorphic rock is the result of the transformation of a pre-existing rock type (protolith), which is subjected to extreme heat (> 150° C) and pressure causing profound physical and/or chemical change. The protolith may be => Sedimentary rock, => Igneous rock or another older metamorphic rock.
Metamorphic rocks Rocks whose physical and chemical properties have been changed by elevated temperature and pressure.
Metric A numerical measure known to monotoneously respond to the degree of human-induced impact. With respect to => Ecological assessment, a metric is a communitie’s attribute that is suited to measure the degradation (e.g., number of => Taxa, proportion of => Current preferences, certain sensitive species, a => Saprobic Index, etc.)
MHS => Multi-habitat sampling
Microhabitat The parts of a => Habitat an individual organism encounters in the course of its activities. Often microhabitat is used synonymous with => Mesohabitat, which is rather related to entities, such as a riffle, pool, river margin, or a mussel bank.
Microscopic Of such a size as to be invisible to the unaided eye but readily visible through a microscope.
Mitigation measure A certain activity to reduce the impact of a => Pressure. For example, a waste water treatment may reduce organic pollution, re-meandering of a river section may reduce hydromorphological degradation.
Molluscs Unsegmented invertebrate animals that possess an external or vestigial calcium carbonate shell; they include clams, snails, sea slugs, and squid.
Monsoon A periodic wind, especially in the Indian Ocean and southern Asia. The word is also used to label the season in which this wind blows from the southwest in India and adjacent areas that is characterized by very heavy rainfall, and specifically the rainfall that is associated with this wind.
Moraine Accumulations of material, mainly till, deposited directly by glaciers.
Mud Loose slushy fine sediment consisting of clay, silt, fine sand, and organic material. Often water-formed and deposited on the bottom of lakes and rivers.
Multi-habitat sampling (MHS) A sampling technique that aims at sampling all => Habitats encountered at a sampling site related to its proportion at the site. Originally, 20 sampling units are taken, each of which represents 5 % substrate coverage of the stream bottom, and pooled to one multi-habitat sample.
Multi-metric index An => Index that consists of several single => Metrics, combined to one multi-metric index.
 
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NECS National Environment Commission Secretariat, Thimphu, Bhutan.
NEPBIOS (Nepalese Biotic Score) Biological method which promises a quick, less expensive and easy way of making judgments on surface water quality. The method is simple to apply and takes into account the presence and absence of families of => Aquatic macroinvertebrates.
NGO Non-governmental organisation. Organisation not constituded by official governmental delegates of the member countries (e.g., Greenpeace, => CEN).
Non-point source A pollution source that cannot be defined as originating from discrete points such as pipe discharge. Areas of fertilizer and pesticide applications, atmospheric deposition, manure, and natural inputs from plants and trees are types of non-point source pollution. See also => Point source.
Nutrient Element or compound essential for animal and plant growth. Common nutrients in fertilizer include nitrogen, phosphorus, and potassium.
 
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Oligochaete The group of annelid worms that includes the earthworm.
Omnivore An animal that can feed on almost anything, including living and dead plant and animal material.
Organic matter The organic fraction of the soil; includes plant and animal residues at various stages of decomposition, cells and tissues of soil organisms, and substances synthesized by the soil population. See also => FPOM, => CPOM.
Organic pollution Any organic or partly organic => Load polluting streams and rivers with dissolved and particulate organic matter, e.g., sewage, manure, industrial effluents. Due to aerobic bacterial decomposition of the organic material organic pollution causes severe oxygen decrease in rivers and lakes and, hence kills fish and => Aquatic macroinvertebrates.
Oxbow lake A lake formed when river => Meanders are cut off from the main channel.
 
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Pamir Mountains The Pamir Mountains are located in Central Asia and are formed by the junction of several mountain ranges (Tian Shan, Karakoram, Kunlun, and Hindu Kush). They are among the world's highest mountains.
Parameter Indicative attribute of a quality element (physical data, chemical data, => Aquatic macroinvertebrates, fish, etc.) to assess the => Ecological status of a => Water body. Examples on parameters relevant for the biological quality element ‘composition and abundance’ of => Aquatic macroinvertebrates are.: number of species or groups of species, presence of sensitive species or groups of species, and proportion of tolerant/intolerant species.
PCRWR Pakistan Council of Research in Water Resources, Islamabad, Pakistan.
Peat A dark-brown or black organic material produced by the partial decomposition and disintegration of mosses, sedges, and other plants which grow in marshes and wetlands.
Pebble Term often synonymously used for => Gravel, grain size 2–7.5 cm diameter.
Pelagic Living and feeding in the water column, as opposed to living associated with a sea or lake bottom, => Benthic.
Pesticide A chemical applied to crops, rights of way, lawns, or residences to control weeds, insects, fungi, nematodes, rodents, and other "pests." See also => Herbicide, => Insecticide.
pH The intensity of acidity and alkalinity, expressed as the negative logarithm of the hydrogen ion concentration. A pH of 7 is neutral; lower values indicate acidity and higher values alkalinity.
Physiography Description and interpretation of landforms.
Phytoplankton Microscopic plants that float or drift almost passively in oceans, lakes, or rivers.
Point source A source at a discrete location such as a discharge pipe, drainage ditch, well, or concentrated livestock operation. Point source pollution arises from a discrete source , e.g., the discharge from a sewage treatment works. See also => Non-point source.
Pool A relatively deep, still section in a stream.
Predators A => Taxon feeding on other life animals, e.g., dragonflies or stoneflies.
Pressure The direct environmental effect of a => Driver (e.g., altered flow conditions, changing water chemistry, => Organic pollution, => Water abstraction).
Pressure (stressor) gradient A gradient describing the different levels of impact caused by a pressure (stressor).
 
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Quality assurance (QA) Procedures implemented to ensure results of monitoring programmes meet the required target levels of precision and confidence. Can take the form of standardised sampling and analytical methods, replicate analyses, ionic balance checks and laboratory accreditation schemes.
Quartzite A granulose metamorphic rock made essentially of quartz.
 
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Reference (condition) Natural or near-natural status, characterized by least impairment due to human activities, such as agriculture, settlement, => organic pollution, eutrophication, water abstraction, etc. For any => Water body type or => River type reference conditions or ‘high ecological status’ is a state in the present or in the past where there are no, or only very minor, changes to the values of the hydromorphological, physico-chemical, and biological quality elements which would be found in the absence of anthropogenic disturbance.
Reference criteria Selected environmental and biotic criteria to define reference conditions, such as hydrologic and morphologic status, physical-chemical parameters, land use characteristics, channel and bed form.
Restoration measure Activities to restore (re-naturalize), e.g., a river stretch by re-meandering, re-damming, or waste water treatment.
Riffle A shallow section in a river or stream where the water flows swiftly; may be less turbulent than rapids.
Riffle-pool section Regular alternation of shallow (=> Riffle) areas with higher current velocities and gravel-cobble substrates followed by deeper slow-flowing => Pool areas with finer substrates. Mountain streams often have a fixed riffle-pool sequence.
Riparian (area) The area adjacent to a stream or river with a high density, diversity, and productivity of plant and animal species relative to nearby uplands.
Riparian habitat The aquatic and terrestrial habitat adjacent to streams, lakes, estuaries, or other waterways.
Riprap (rip-rap) Common bank fixation method by introduction of loose boulders, which are poured on the bank.
River basin The whole river system including all tributaries and springs from the source to the mouth (sea).
River basin scale The spatial extent of a whole river system.
River type A river type is a constructed ecological entity with limited internal variation in its biotic and abiotic components, which shows a minimal and constant biotic and abiotic discontinuity in comparison with other entities. Such river types might serve as „units“, for which an assessment system can be applied. A river type should always be defined on the basis of natural or near-natural reference sites.
River typology A typological framework to group rivers or river reaches according to their similar abiotic and biotic characteristics and to distinguish them from other river types. See also => Typology
Riverine habitat The aquatic habitat within streams and rivers.
Runoff The part of rain and snowmelt that runs over the ground and into a stream or other water body.
 
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Sand 1. A mineral soil particle between 0.05 and 2.0 mm in diameter. 2. A soil textural class containing more than 85 % sand and less than 10 % clay.
Sandstone A => Sedimentary rock composed predominantly of sand-sized quartz grains.
Saprobic Index Biological index system derived from the => Saprobic System to measure the impact of => Organic pollution. Several saprobic indices are currently used in Europe, e.g. the Austrian, Czech, and German indices. Saprobic indices are based on a selection of => Aquatic macroinvertebrate taxa or aquatic microorganisms that are proved either sensitive or tolerant to => Organic pollution.
Saprobic System The Saprobic System was founded at the end of the 19th century to evaluate the impact of organic pollution and subsequent oxygen depletion on aquatic organisms. Today, a refined system based on some 500 => Aquatic macroinvertebrates and additional microorganisms is applied in several European countries (e.g., Austria, Czech Republic, Germany). Several Saprobic Indices (sing.: => Saprobic Index) are applied throughout Europe to indicate the impact of organic pollution on => Aquatic macroinvertebrates.
Schist A medium- to coarse-grained metamorphic rock with strong foliation that results from a parallel orientation of platy minerals such as micas.
Scour(ing) Removal of sediment from the streambed by flowing water.
Sediment The silt, sand, rocks, wood and other solid material that gets washed out from some places and deposited in others.
Sediment feeders A => Taxon feeding on fine particulate matter, often a mixture of mineral and organic particles, e.g., many aquatic worms.
Sediment rock => Sedimentary rock
Sedimentary rock One of the three main groups of rock; rocks formed of material derived from pre-existing rocks by processes such as weathering, erosion, and precipitation.
Sessile Attached directly to a base without a flexible joint; used when describing parts of organisms, such as leaves or flowers.
Silt 1. A mineral soil particle between 0.002 and 0.05 mm in diameter. 2. A soil texture class containing more than 80 % silt and less than 12 % clay.
Siltstone A very fine-grained consolidated clastic rock composed predominantly of particles of silt.
Slate A fine-grained metamorphic rock easily split into flat, smooth plates.
Sludge A soft water-formed fine sedimentary deposit which normally can be removed by blowing down. Similar to => Mud
Socio-economic aspect Any relation to societal or economical attributes. Socio-economic aspects of water management are, e.g., drinking water supply, water-borne-deseases, or other water uses.
Species Any subspecies of fish or wildlife or plants, and any distinct population segment of any species of vertebrate fish or wildlife that interbreeds when mature.
Species (taxa) richness The number of species (taxa) present in a defined area or sampling unit.
Species diversity An ecological concept that incorporates both the number of species in a particular sampling area and the evenness with which individuals are distributed among the various species. See also => Biodiversity.
Species trait Biological properties of species or higher taxonomical units. Species traits may be attributed to the life cycle (e.g., voltinism, number of progeny), morphology (e.g., respiration, body size), or ecological behaviour (e.g., => Habitat preferences or => Feeding types).
Stakeholder A person or organisation with an legitimate interest (or "stake") in what may affect the economy or environment.
Standardisation Standardisation, in the context related to technologies and industries, is the process of establishing a technical common framework (= standard) among competing entities in a market or any other community, where this will bring benefits without hurting competition. Standadisation aims at broadening the applicability of, e.g., methods, manuals, or specifications, such as in case of cellular phones which today can be used worldwide.
STAR Standardisation of river classifications. Framework method for calibrating different biological survey results against => Ecological quality classifications to be developed for the => Water Framework Directive
Stones Rock fragments greater than 25 cm in diameter.
Stratification 1. Applied to rocks: the presence of layers, or strata; typical of => Sedimentary rock. 2. Applied to water: division of the water column into layers of different temperature or salinity.
Stream order (Strahler) A first-order stream is the unbranched section of a river or stream. The tributary initiated by the confluence of two first-order streams is the second-order stream and so on (Strahler system).
Stream type => River type
Stream bed The stream bottom.
STREP (Specific Targeted Research Projects) The Specific Targeted Research Projects are an evolved form of projects under the 5th Framework Programme of the European Union.
Stressor => Pressure
Subtropical mountains In the subtropical mountains along the Himalayan ranges the rainfall increases from west to east and from the inner to the outer parts of the ranges. At the sub-alpine and alpine levels, rainfall ranges from less than 1,000 to 1,500 mm per year with at least one or two dry months even up to seven or eight. The mean temperature of the coldest month varies from around 15° C in the sub-alpine zone to less than 10° C above 2,000 m. Snow occurs above 3,000 m, with frequent winter frost. Precipitation ranges from 500 to 1,000 mm.
Surface water All moving and standing water naturally open to the atmosphere.
Sustainable development Development activities with regard to the future usability and availability of environmental resources.
Sustainable water use Deliberate use of water that ensures the long-term maintenance of a sufficient quality and quantity water.
 
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Taxa (sing.: Taxon) A group of any size used in the classification of things, particularly plants and animals.
Taxonomical adjustment Procedure to prepare => Taxa lists with different levels of taxonomical resolution to increase its analytical comparability. Usually, taxa lists originating from differently skilled researchers need to be taxonomically adjusted before statistics can be applied.
Taxonomical bio-indication unit => Taxonomical resolution
Taxonomical resolution The taxonomical level of determination reached, e.g., species, genus, family, order, class, etc.
Terrace A nearly level surface or bench bordering a steep slope, such as a stream terrace or wave-cut terrace.
Tertiary A geological term. One of the major divisions of the geologic timescale, from about 65.5 million years ago to about 1.6 million years ago.
Top-down (approach) Often referred to in the context of => River typology, where ‘top-down’ means the approach from (top) large-scaled environmental attributes (e.g., Ecoregion, geology, or altitude) towards (down) relatively small-scaled => River types or even sub-units. The development of a river typology often starts ‘top-down’ and, if sufficient biological data are available, is subject to a ‘bottom-up’ validation and subsequent refinement. Opposed to => Bottom-up.
Topography Description of the geographical surface features of a region.
Tributary A stream that feeds into a larger stream. Also called a feeder stream.
Tropical and subtropical moist broadleaf forests Also known as => Tropical rainforests, a tropical and subtropical biome. Tropical and subtropical moist broadleaf forests are found in a belt around the equator and in the humid subtropics, and are characterized by warm, humid climates with high year-round rainfall. The rainfall of the tropical moist deciduous forest is generally between 1,000 and 2,000 mm with a dry season of three to six months. Temperatures are always high, with a mean temperature of the coldest month slightly lower than 20° C. Tropical and subtropical regions with lower rainfall or distinct wet and dry seasons are home to tropical and subtropical dry broadleaf forests and tropical and subtropical coniferous forests. Temperate rainforests also occur in certain humid temperate coastal regions.
Tropical mountains The tropical mountains of the south-eastern part of the Himalaya, altitude between 1,000 to 1,500 m and 4,000 m, show annual precipitation more than 1,000 mm, sometimes more than 2,000 mm. There is a pronounced dry season of three to five months in the sub-alpine zone of the eastern Himalayas, with the mean temperature of the coldest month above 15° C. Everywhere else, the dry season, if it occurs, is very short. The mean temperature of the coldest month rapidly decreases with increasing elevation. Above 4,500 to 5,000 m there is permanent snow.
Tropical rainforest The tropical rainforest that occurs at the eastern Himalayan foothills are very wet owing to the monsoon rains. Annual rainfall is everywhere more than 1,000 mm and often more than 2,000 mm, e.g. Bhutan approximately 5,000 mm. There is a short dry season, generally one to four months. Temperatures are always high. See also => Tropical and subtropical moist broadleaf forests
Tuff Rocks consolidated from volcanic material containing a predominance of fragments not greater than 2 cm in diameter.
Typology The study and interpretation of types. A typology provides the framework to group => Water bodies into appropriate types (streams, rivers, lakes, etc.). A stream typology covers all stream types encountered in a pre-defined region (usually an entire country or => River basin) and provides supplementary data to describe the abiotic and biotic characteristics of the stream types.
 
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UDE University of Duisburg-Essen, Essen, Germany.
UMAG Otto-von-Guericke University Magdeburg, Germany.
 
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Valley form The shape of the cross-section of a valley formed. e.g., by a scouring river or tectonic activities. Examples include:
Canyon: Hill slopes are almost vertical, no floodplain existing, like the Grand Canyon in the USA.
V-valley: Hill slopes V-shaped, no floodplain existing, restricted to small streams only.
U-valley: Hill slopes U-shaped like a bowl. A distinct floodplain is present.
Trough: Parabolic valley, often formed by glaciers and ice streams. A small floodplain may be developed.
=> Meander valley: Flat valley characterized by a meandering river flowing through its distinct floodplain.
Volcanic One of the main groups of rocks that form the earth's surface.
 
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Water abstraction The deliberate removal of water from a => Water body, either surface or groundwater.
Water body Distinct and significant volume of water. For example, for surface water: a lake, a reservoir, a river or part of a river, a stream or part of a stream. For groundwater: a distinct volume of water within one or more => Aquifers
Water management Planned development, distribution, and use of water resources.
Water quality map Map with streams, rivers, lakes, or other => Water bodies coloured according to their ecological status. Within the European Union (EU) water quality maps display the => Ecological status with five colours: blue (high status = reference), green (good), yellow (moderate), orange (poor), and red (bad).
Water quality criteria Specific levels of water quality which, if reached, are expected to render a body of water unsuitable for its designated use. Water-quality criteria are based on specific levels of pollutants that would make the water harmful if used for drinking, swimming, farming, fish production, or industrial processes.
Watershed A planning term that refers to the area from which surface water drains into a common lake or river system or directly into the ocean; also referred to as a => Drainage basin or catchment basin.
Woody debris => Large wood (LW)
 
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Yield The mass of a material or constituent transported by a river in a specified period of time divided by the drainage area of the => River basin.
 
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Zonation The occurrence of species or communities in specific zones, each with a characteristic dominant species; commonly used to define aquatic environments. E.g., longitudinal zonation of streams and rivers: crenal, rhithral, and potamal.
Used sources