What type of wetlands is termed calcareous

The predominantly saturated conditions of wetlands create an environment that produces specialized species incapable of persisting outside of that environment. The rare and endangered American Globeflower Trollius laxus shown above is found only in a few of the rich fens of New York, New Jersey, Pennsylvania, and one county in Connecticut.

The nutrient rich conditions in a fen provide a diversity of plant life, which then supports a number of animal species that thrive in such highly productive habitats. Moose and deer enjoy the lush vegetation while fisher and beaver take advantage of the still waters. Black bear and lynx can often be found fishing around the edges and amphibians are widely abundant throughout.

Unlike bogs, fens can have inflow and outflow streams and may support some fish species like trout, walleye, or bluegill. The fish and shallow water draws in wading birds like cranes, herons, and rails and the diversity of plant structure provides food and shelter that attracts owls and songbirds to breed in the rich environment.

The mineral-rich groundwater that supplies fens usually comes from uplands that can be quite a distance from the fen itself. This makes conservation for fens difficult, since a pollution source may be located anywhere along that path between source and fen.

Porcupine grass and big bluestem are also common. An array of purple coneflowers, blazing stars and asters bloom among the gamma grasses. Four occurrences of regal fritillary butterflies a species of special concern have been found on the preserve among many other butterflies. Birds, including bobolinks and meadowlarks, nest among the grasses. Northern harriers, with their distinctive white tail markings, hunt from the skies above the preserves.

For more information on visiting this and other Minnesota preserves, check out our Preserve Visitation Guidelines. Back To Top.

View onto Sheepberry Fen from Marcum property. Overview Description The Sheepberry Fen preserve includes a mix of dry upland prairie and oak savanna and a large groundwater-fed wetland complex called a calcareous fen. Why the Conservancy Selected This Site In Minnesota, less than 1 percent remains of the tallgrass prairie that covered most of the western and southern parts of the state before European settlement.

It can be by overland flow following intense rainfall or irrigation events or by lateral saturated and unsaturated flow through the upper soil horizons with the reemergence of water at the foot of slopes and in areas of flow convergence. Runoff is often characterised as a coefficient representing the percentage of rainfall that has flowed away down rivers.

A body of water containing high concentrations of salt. May be measured crudely and indirectly as conductivity or more accurately by measurement of the sodium and chloride concentrations in the solution. SALT MARSH Commonly, a maritime habitat found in temperate regions, but typically associated with tropical and subtropical mangrove swamps, in which excess sodium chloride is the predominant environmental feature.

In the Mediterranean it may be found in areas with some tidal influence e. SALT PAN Dry bed of a salt lake after all water has evaporated; also refers to artificial basin created for evaporating sea water to collect salt. A common feature is the intrusion of sea water into coastal aquifers as a result of excessive pumping of fresh groundwater.

SALT WEDGE The relatively dense, saline bottom water which intrudes into estuaries with the rising tide and which can move into rivers if the freshwater flow is diminished for some reason.

Often taken to include its hydrophytic vegetation. At present the IPCC has identified a global relative sea level rise caused by thermal expansion of the oceans under the influence of global warming and, to a lesser extent, the melting of terrestrial and polar ice.

At a more local level there can be relative changes in sea level compared to the land because of tectonic movement, land subsidence and isostatic change. Also referred to as seagrass meadow. SEAWALL An earth, concrete, stone, or metal wall or embankment constructed along a shore to reduce wave erosion and encroachment by the sea. SEBKHAS North African term meaning shallow depressions which typically hold water for a longer time than chotts, usually only drying out at the height of summer although some may remain full for over a year.

It sometimes holds water for more than two years, partly because it is also supplied by an oasis. Sebkhas are also found in northern Tunisia, to the north of the arid chotts zone, and on the plateau to the south of Constantine in Algeria and Mauritania.

Vegetated and unvegetated sebkhas have been distinguished in the literature. SEEP An area where groundwater moves slowly and steadily up to, and over, the surface without forming very distinct springs or channels. Also known as an ooze. SEEPAGE The slow movement of water through small openings and spaces in the surface of unsaturated soil into or out of a body of surface or subsurface water. A dam may take conditions more like those of the headwaters an upstream shift or more like those downstream, or it may have a negligible effect.

Multiple dams create multiple discontinuities in the expected or natural pattern of streams and rivers. SETTLING The separation by gravity of heavy from light materials; for example, the settling out of dense solids or heavy liquid droplets from a liquid carrier, or the settling out of heavy solid grains from a mixture of solid grains of different densities.

The effluent is gathered in drainage channels for discharge to water courses. This is a system suited, nowadays, only to small rural communities. They can be surface water sewers taking stormwater runoff from rainfall, foul sewers taking waste water from households and industry, or combined sewers which receive both waste water and stormwater. See overland flow. SHINGLE Pebbles 2 to 64 mm diameter , cobble 64 to mm diameter , and other beach material, occurring typically on the higher parts of a beach.

SHOAL A normally submerged bank rising from the bed of a shallow body of water and consisting of, or covered by, unconsolidated material which may be exposed at low water.

SILT Sediment 0. It initially entails identification of environmental components which may be impacted by any project at the site. It does not exclude the later identification of project activities which will impact on those environmental components.

Input variables usually include rainfall, air temperature, wind speed, humidity and an index for the degree of exposure of the site. Different countries tend to have their own national equations. The relationship is normally hysteretic.

See pF. The upper A horizon is normally rich in organics, permeable and well aerated. The lower B horizon is more compact and may be either pale and leached or the site of deposition to create hard pans. The lowest C horizon usually has a low organic content and contains pieces of partially weathered bedrock. Traditionally a paper recorder was used on a Campbell-Stokes recorder with a large globe of glass to focus the suns rays. Today, electronic instruments are used.

The data is used, amongst other things, for calculating evapotranspiration. They are less nutrient deficient than ombrotrophic mires. See rheotrophic mires. Wetlands can form a multi-functional form of source control. See spawn. In the system of binomial nomenclature, taxa with species status are denoted by Latin binomials, each species being a member of a genus e.

Homo genus sapiens species. For the great majority of animals and many plants, a species is roughly a group of individuals able to breed amoung themselves if one disregards geographical separation but not able to breed with organisms of other groups. As a result no striking differences in genetic composition and in the characters controlled by genes occur within the species, though local differences, which are recognized in classification as a sub-species, may arise through reproductive isolation which is only partial or has recently occurred.

Compare specific yield. In an unconfined aquifer, it is expressed as the volume per unit surface area of the aquifer per unit decline in the watertable.

Compare specific retention. SPIT An elongated point of land extending into open water which commonly consists of sand or gravel and is maintained by a balance new sediment and the erosion of the existing spit. See tide. Traditionally this was a float operated pen and paper mechanism but today it is computerized. See gauging station. It is usually derived by current metering at a series of different water levels. See gauging station, flume. It is an essential component of traditional river gauging stations.

See gauging station, stage recorder. Long periods of strong winds in one direction are especially effective in building up the level of the sea at the downwind end of a restricted area of marine waters. See source control. STREAM A body of running water moving under the influence of gravity to lower levels in a narrow, clearly defined natural channel.

The order of a river or stream is a dimensionless number that indicates how many tributaries it has. The smallest unbranched tributary in a watershed is designated order 1. A channel formed by the confluence of two such tributaries is designated order 2. Where 2 order tributaries join, a channel segment of order 3 is formed, and so on. In general, the higher the order number the larger the watershed and the greater the channel dimensions and discharge. It differs from a marsh in that the latter normally has a period of desiccation.

See hydrogeology. Involves creating polygons with the perpendicular bisectors of lines joining neighbouring gauges. It is the stratum in which there is a rapid rate of decrease in temperature with depth a minimum of one degree centigrade per metre in depth. Thornthwaite in the USA in the s for the calculation of monthly potential evapotranspiration rates using only mean air temperature as the input variable.

The convergence of throughflow in hollows can lead to the water flowing over land as first order streams during rainfall events. Estuarine marshes are subdivided into subtidal permanently flooded or intertidal temporarily flooded wetland systems. TIDE The periodic rising and falling of the oceans resulting from lunar and solar tide-producing forces acting upon the rotating earth.

See also underdrainage. The flow rate is measured by recording the number and timing of tips. The concept is most commonly used in telemetering rain gauges.

TORRENT A steep stream with a strong seasonal regime and short periods with high discharges accompanied by high sediment loads including coarse bedload. The usually coarse bed material or rocky substrate creates rapids and white water conditions when flows are high. TOXIN A poisonous substance produced by certain plant and animal cells, including bacterial toxins, phytotoxins, and zootoxins. Generally three classes are distinguished but there are no set limits to each class: 1 Eutrophic means nutrient-rich.

Usually associated with low oxygen levels since the voluminous plant growth generates large organic deposits that decompose removing much or all of the oxygen from the water.

The trophic status for any one wetland is a condition determined by the surrounding catchment, landform and geology. Its watertable is controlled by gravity and the transmissivity of the rocks. Compare confined aquifer. The latter slope to deep ditches which surround the drained field and in which the water level is maintained below the outfall of the pipes.

See tile drainage system. One of the most successful and durable systems of traditional fishing used in the 10, hectares of lagoons of the Italian Adriatic, including the Po delta and the Venice lagoon. Though practised for many hundreds of years, the valli system comes close to many of the techniques of modern fish farming..

Many environmental economists subscribe to the view that the total value of a wetland is found from the summation of 1 Direct use value e. Measurements are made at several depths at a number of positions across the river, areas of the wetted cross-section are then assigned to each current meter reading and a weighted average for discharge calculated.

A channel of a watercourse in a semi-arid region that is dry except during periods of rainfall. WATER A clear colourless tasteless odourless liquid chemical formula H 2 O essential for plant and animal life and constitutes, in impure form, rain, oceans, rivers, lakes, etc.

It is a neutral substance and an effective solvent for many compounds. When appropriately expressed and using complete data without errors, inputs equal outputs plus or minus changes in storage, since water can neither be created nor destroyed in the hydrological cycle.

Also known as hydroperiod. Closely related to water level regime. More modern usage implies all of the human uses of the hydrological cycle e. Water content declines as pore pressure decreases. Finer grained soils, such as clays, have a higher water content for a given pore water pressure than coarse grained soils such as sands.. A hysteretic effect normally gives drying soils a higher water content for a given pore water pressure than that found in a wetting soil. WATER YEAR A hydrological term used to describe the 12 months starting at the end of the dryest season, passing through the wet season s , and ending with the next dry season.

In the Mediterranean the water year runs from September to August. The water year can be important in analyses that require the selection of hydrologically independent events. Principally the order Anseriformes , including the swans, ducks, geese and screamers.

For the purposes of the Ramsar Convention the following groups of species are included; loons or divers Gaviidea , grebes Podicipedidae , cormorants Phalacrocoracidae , pelicans Pelecanidae , herons, bitterns storks, ibises and spoonbills Ciconiiformes , swans, geese and ducks Anatidae. Furthermore wetland related birds of prey, as defined under the Ramsar Convention; Accipitriformes and Falconiformes , cranes Gruidae , shorebirds or waders Charadrii and terns Sternidae.

In US, known as a divide. In US, watershed is used to describe the entire surface drainage area that contributes water to a lake or river. This can be the groundwater level phreatic watertable in unconfined aquifers or that level below which the soil is saturated with water. See also piezometric surface. WEIR A structure in a river or water body that restricts discharge to water levels above the crest of the weir.

Weirs can be moveable or variable in height. Some weirs are used as fixed structures within gauging stations for measuring river flow. This wet-bulb depression is used in calculating humidity. See salt water wetland, freshwater wetland, artificial wetland. Wetland benefits are defined as any of these terms which may have a value to people, wildlife, natural systems or natural processes. Involves putting wetlands into categories according to their structural or functional characteristics.

It is characterised by a focus upon storages and water levels in storages rather than water flow which is the main focus of hydrology undertaken in river basins. Normally this is around 30 bars. Based in Geneva, Switzerland. ZONATION of the floodplain A land use planning technique to ensure the maintenance of a free floodway for the major cross-floodplain discharges, the limitation of development in the floodplain that would reduce storage capacity for floods, and the prevention of development that would be liable to serious damage when a flood occurred.

Frequently there are four zones: 1 An inner core zone without human access. Those components of an ecosystem which are not living. The removal of water from a water body, including aquifers, normally for human use. Any substance, tissue, or organism having an affinity for acid conditions. Establishment of a new forest by natural regeneration or plantation on non-forested land. The concept that all wetlands are ephemeral and follow a distinct cycle of ageing.

Collective name of a large group of chlorophyll-containing plants, comprising the seaweeds and various freshwater forms, ranging in size from single cells to long stems. Dramatic increase in algal growth resulting from high levels of nutrients or pollutants. A plain covered with alkaline salts formed by the evaporation of water in a slight depression. Sediment of the clay grade which has been transported by rivers from the place of its origin, as distinct from that which has originated in situ.

An alluvial fan with steep slopes formed of loose material washed down the slopes of mountains by ephemeral streams and deposited as a conical mass of low slope at the mouth of a gorge. Clay, silt, sand, gravel and other material which has been carried in suspension by river or floods, and is deposited where the velocity of flow is insufficient to maintain the material in suspension. A plain formed from the deposition of alluvium usually adjacent to a river that periodically overflows.

Fish that ascend rivers from the sea at certain seasons for breeding e. Of organisms ability to live anoxically i. A listing in rank order of the largest event each year in an environmental data series. See Recurrence interval. Involving the impact of man on nature: induced or altered by the presence and activities of man.

A structure, normally a sluiced embankment or low dam, erected in the lowest reaches of a river to prevent the upstream movement of the estuarine salt wedge. Cultivation of natural faunal resources of water, normally freshwater fish, marine fish and shellfish.

The animal species which complete their life cycle in the water and which cannot reproduce without the permanent presence of water. A permeable body of rock capable of yielding quantities of groundwater to wells and springs. The increase in water storage in the saturated zone as a result of water percolation through the aeration zone.

A recent concept involving the release of a sufficiently large volume of water from an upstream dam and reservoir to cause beneficial flooding in wetlands downstream. The simulation of natural wetland features and functions by topographic and hydraulic modification of non-wetland landscapes.

A general term for all the metabolic processes by which nutrient material is built up and utilized by plants. Water with ionic proportions quite different from the dissolved salts in sea water main characteristic of many mediterranean saline wetlands.

An instrument to measure evaporation rates. An instrument that records the rate of rainfall continuously. An area of relatively still water where drainage is impeded by an obstruction such as a sediment bar across a partial oxbow lake or a sandbar across a coastal lagoon outlet etc.

Methods of supporting the structural integrity of earthen stream channel banks with structural supports to prevent bank slumping and undercutting of riparian tress, as well as overall erosion. Submerged or partially submerged ridges, banks, or mounds of sand, gravel, or other unconsolidated sediment built up by waves or currents within stream channels, at estuary mouths and along coasts.

An artificial dam which increases the depth of water of the river or watercourse, or diverts it into a channel for navigation or irrigation. That portion of river flow that originates from transfers from the saturated zone.

An area of sand or shingle sloping down to a sea or lake, esp. That part of the sediment load of a river which moves downstream by bouncing saltation , rolling or sliding along the bed of the river. Organism attached to or rooted in the substratum at the bottom of a water body. A particularly impermeable type of clay often used to seal piezometers and wells.

A horizonatal terrace, usually underwater, found in streams or in sheltered coastal areas. A method for quantitatively determining the concentration of a substance by its effect on the growth of a suitable animal, plant, or microorganism under controlled conditions.

The variety of all life on earth: the variability amoung living organisims from all sources including terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems.

Control of pests using biological means, with or without the assistance of biotechnology, for example 1 use of another organism or virus which can be parasitic to the former 2 use of an organism which is the predator of the former, 3 massive release of sterilized organisms.

The total quantity of matter the non-aqueous component frequently being expressed as dry mass in organisms, commonly those organisms that form a trophic level or population, or inhabit a given region. Major regional ecological complex of communities extending over large natural areas and characterized by distinctive vegetation and climate; e.

Periodic surveillance of aspects of living organisms in order to record the status of an ecosystem. Animal and plant life; all living organisms of a certain area. A methodology and set of techniques based on the estimation of environmental quality through the assessment of the condition of living organisms, both plant and animal species.

Those features of the environments of organisms arising from the activities of other living organisms; as distinct from such abiotic factors as climatic and edaphic influences.

In strict ecological sense it is the non-living structural part of an ecosystem e. Broadly speaking, any animal with a shell in two parts hinged together e. A deposit of sodium carbonate that has formed on or near the surface in arid to semiarid areas.

A series of planning scenarios for the Mediterranean basin developed under the aegis of the Barcelona Convention. A plant community that develops and grows in areas with permanently waterlogged peat substrates. An excavation dug to provide material borrow for a nearby embankment or fill elsewhere. Rivers with mid-channel bars, exposed as islands at low flow, with a network of channels between them. A river channel that diverges from the main channel. Small phylum of the plant kingdom, including mosses, liverworts, and hornworts, characterized by the lack of true roots, stems, and leaves.

The mass per unit volume of soil. A Castilian term which is also used in the USA. An artificial water course with controlled water levels for the transport of water or for navigation. The area above the upper edge of the zone of saturation which is kept particularly moist by surface tension and adsorptive forces drawing water up the narrow capillary openings in the rock or soil.

Small stream that feeds into a larger stream, or connects two parts of a larger stream. Fish that live in fresh water and go to the sea to spawn e. An area drained by a river and all its tributaries; also referred to as a drainage basin, river basin or, in North America, as watershed. Straightening of the meanders in a river system to create more navigable waterways, or when accompanied by channel deepening to provide flood control.

Organic content of waste obtained by measuring the amount of oxygen required for its stabilization. Large, shallow depressions, found in North Africa, that fill with water from flash floods.

A conduit for conveying free-flowing materials at high velocity to lower levels. A sedimentary rock consisting of aluminium silicates and other minerals which are derived from the weathering of other rocks. Mature vegetation in a steady state equilibrium with existing natural environmental conditions. An accretion of sand or silt formed by continental tide movements, and by conflicting or contributory discharges from inflowing rivers.

An approximately level zone which is between the sea and the nearest hills or mountains. An imprecisely defined area that includes the inter-tidal zone, the coastal plain, estauries, lower portions of rivers and the shallow offshore zone.

The chemical analysis of water using reagents which give a coloured response in proportion to the amount of the solute of interest that is present in the sample. Ecological term for any naturally occurring group of different organisms inhabiting a common environment, interacting with each other, especially through food relationships, and relatively independent of other groups. The shape of the depression of the water table around a well that is being actively pumped for water.

An aquifer overlain by an impermeable aquiclude where the water in the aquifer is under hydrostatic pressure as a result of recharge at a higher level. The use of surface water bodies and groundwater sources in conjunction so as to derive a greater yield than would be possible by operating the two resources separately. See goundwater, reservoir. Water trapped in the interstices of sedimentary rocks at the time of their deposition.

A system of economic analysis involving the determination of the ratio total benefits of a project measured in cash terms: total cash costs of the project. A fresh-water lake formed by the accumulation of rain and groundwater in a caldera or crater. An instrument, often of very simple construction, that records the maximum water level reached at a site since the last observation.

A recently developed concept that derives from acidification studies which describes the maximum loading of a pollutant onto an ecosystem which will not cause significant change to that system. An engineered structure which takes a water course underground through a bridge or for longer distances in urban areas. An instrument for measuring the velocity of flow in a channel. Single-cell or filamentous organisms, also known as blue-green algae that are able to convert atmospheric nitrogen into forms that can be utilized for plant growth.

Rainfall associated with depressions where air rises as a result of frontal activity. A barrier constructed to obstruct the flow of a watercourse and to impound a reservoir behind the dam. A deepwater habitat is predominantly flooded land lying below the deepwater boundary of wetlands. A gently sloping alluvial deposit, usually triangular in shape, which forms where a river meets the sea or lake and consists mainly of silt, sand, and gravel, the coarsest deposits being near the head of the delta and the fine material being in the face of the delta below the level of the sea or lake.

Process carried out by various facultative and anaerobic soil bacteria, in which nitrate ions act as alternative electron acceptors to oxygen during respiration, resulting in release of gaseous nitrogen. Removal of oxygen as free or loosely combined oxygen as from water, sewage or blood.

A precisely defined drought that in extremis could be kept under control by a water resources management scheme. The largest flood discharge which an engineering scheme is designed to accommodate without adverse effects. Microscopic plant abundant in plankton. The measurement of river discharge through the assessment of the degree of dilution of a tracer injected into the flow.

A shallow up to around 4m lined hole in a wetland substrate which allows the measurement of shallow groundwater levels.

The dissolution of oxygen into water. A narrow channel dug in the earth, usually used for drainage, irrigation or as a boundary marker. Water in a ditch which may be flowing, static or about to be desiccated depending upon the season and the water regime. Removal of groundwater, surface water, or water from structures by gravity or pumping. An area in which surface runoff and baseflow contributions from groundwater collects and is carried by a drainage system, as a river and its tributaries.

The magnitude of the change in water surface level in a well, reservoir, or natural body of water resulting from the withdrawal of water. A period of water shortage which may be brought about by a number of causes, often interacting. A wall or embankment of timber, stone, concrete, fascines, or other material, built as training works for a river, to confine the flow rigidly within definite limits.

A proposed draft Directive on ecological quality of water presented by the EU Commision on 15th June A community of organisms, interacting with one another, plus the environment in which they live and with which they also interact; e.

A transition zone between two or more diverse communities as between forest and grassland. That portion of a rainstorm that runs off from the catchment to create a flood hydrograph. The treated water which emerges from a sewage works or similar purification facility. The measurement of river discharge utilizing the distorting effect that flowing water has on an electromagnetic field. Aquatic plants that are rooted in the sediment, but which leaves are at or above the water surface. Species that are unique to one region, i.

A process designed to ensure that potentially significant environmental impacts are satisfactorily assessed and taken into account in the planning, design, authorization and implementation of all relevant types of action.

In a thermally stratified lake, the turbulent layer of water that extends from the surface to the metalimnion. Plant attached to another plant, not growing parasitically upon it but merely using it for support; e. The lowest section of a river where mixing of salt and fresh water occurs under the influence of the tide. Able to tolerate a wide variation of salinity osmotic pressure of environment.

Of lakes rich in nutrients; highly productive in terms of organic matter produced. Usually rapid increase in the nutrient status of a body of water, both natural and occuring as a by-product of human activity.

Loss of water from a free water surface or from the soil surface by vaporization. An instrument for measuring open water evaporation rates. The prevailing and real rate of evapotranspiration from an area of land.

Combined loss of water from the earth surface by evaporation from open water and soil surfaces and transpiration from the leaves of plants. Fenced area from which grazing animals are excluded for the study of the ecosystem without grazing pressure. Fan-shaped deposit. Food and Agricultural Organisation of the United Nations. Peatland covered by water, especially in the upper regions of old estuaries and around lakes, that can be drained only artificially.

Refers most commonly to a chemical substance synthesized by man and applied to the soil in order to maintain or increase soil productivity. The maximum amount of water that a soil can hold against the pull of gravity. Microscopic organisms bacteria or algae that use whip-like filaments, called flagellae, to locomote. A sudden local flood of short duration and great volume; usually caused by heavy rainfall in the immediate vicinity.

Inundation that occurs when water overflows from a river or channel or accumulates because of poor drainage over low-lying areas. A natural or artificial basin, also a wetland, designated in land use and catchment planning as an area that receives flood water. An engineering approach which uses leeves, walls, reservoirs, floodways, and other structures to prevent water overflow and consequent flooding.

Fencing anchored in such a way that it is either able to withstand the force of floodwaters or hinge over when the water rises significantly. The relationship between discharge and flood recurrence interval for a point on a river system. The rise and subsequent recession of flow in a river as a flood discharge passes downstream.

The idea that the pulsing of river discharge, the flood pulse, is the major force controlling biota in river-floodplain systems. Space used or available for floods. A sluice that is used to control the flow of water, for instance in a dam when water needs to be released to prevent the reservoir spilling or in a levee when it is necessary to allow controlled flooding of part of the floodplain. The management of river flows through dams, barrages, sluices and in some cases groundwater pumping.

Rectangular or U shaped structure, generally made of concrete, installed in rivers for measuring discharge. Chain of organisms, existing in any natural community, through which energy is transferred.

All the food-chains in a community make up the food-cycle or food-web. The time that it takes for the water content of a wetland to be renewed. Water that has been in an aquifer since prehistoric times and is not a part of the hydrological cycle i. Marsh containing water with no significant amount of salts, such as water derived from rainfall, rivers, freshwater lakes. A fish trap consisting of a net suspended over a series of hoops, laid horizontally in the water. An installation e. A mass of land ice, formed by the further recrystallization of firn, flowing slowly at present or in the past from an accumulation area to an area of ablation.

A loose or unconsolidated deposit of rounded pebbles, often within a sandy matrix. The common name for members of the plant division Chlorophyta. The natural accumulation in the atmosphere of gases, such as carbon dioxide, that trap heat, due to their property that allows the inflow of short wave solar radiation and prevents to a certain extent the outflow of long wave thermal radiation from the earth.

The flow of water from the zone of saturation to the surface of the earth as springs, seeps and resurgences within river beds. The addition of water to the zone of saturation. North African term meaning desert river-bed pools. Place or environment in which specified organisms live, e. Definition in the Habitat Directive of the EU: terrestrial or aquatic areas distinguished by geographic, abiotic and biotic features, either entirely natural or semi-natural.

Plants that grow in very salty soil typical of shores of tidal river estauries, saltmarshes, or alkali desert flats. Metals of high specific gravity. Glacial deposits with rounded conical hills and depressions formed under stagnating ice-sheets. The sum of the elevation head and the pressure head in an aquifer. Inadequately drained soil whose profile down to a depth of 45cm or less is saturated with water for a considerable part of the growth period of natural vegetation and which is dominated by reduction phenomena.

The science dealing with the occurrence of groundwater, and its utilization, pollution and management. A small area of land with largely uniform geomorphological and hydrological conditions. Discharge at a point in a river recorded over time. The complete cycle through which water passes, from the oceans, through the atmosphere, to the land, and back to the ocean. The study of the cycle of water movement on, over and through the surface of the earth.

A series of instruments in an area, usually a catchment, dedicated to recording the stores and transfers of water in the hydrological cycle. A plant that grows in a moist habitat. Collective term for all stages in a succession beginning in water or wet habitats.

Part of the earth composed of water i. Containing high concentrations of salt. In a thermally stratified lake, the layer of water below the thermocline and extending to the bottom of the lake. The saturated zone beneath a river or stream consisting of substrate, such as sand, gravel, and rock, with water-filled interstitial pore. International Council for Bird Preservation based in Cambridge. A thick glacier, more than 50, square kilometers in area, forming a cover of ice and snow that is continuous over a land surface and moving outward in all directions.

The movement of water into the surface of a soil under the influence of gravity and soil suction forces. A series of relationships derived from long periods of data from autographic rain gauges that quantify the relationships between rainfall intensity, the duration of that rainfall and the frequency with which is it is likely to recur.

The transfer of water by human agency from one river basin to another. The trapping of precipitation on the leaves of vegetation.

The area between the high and low water marks which is exposed at low tide. The part of the littoral zone above low-tide mark and below the high-tide mark. Systematic collection, treatment and presentation of data on the number of wetlands of a geographical region and on the parameters of each wetland such as location, type, area, abiotic and biotic characteristics, functions, values, uses, adverse effects induced by human activities, ownership, legal status etc.

Limestone areas with topographically distinct scenery and a distinct hydrology brought about by the permeability of the rocks, the limited amount of surface water, the occurrence of underground caverns, swallow holes for rivers and strong resurgences.

A bowl-shaped depression with steep sides in glacial drift deposits that is formed by the melting of glacier ice left behind by the retreating glacier and buried in the drift.

The delay between rainfall and runoff. A small body of normally shallow water isolated from related and normally much larger water bodies by some form of barrier. The accumulation of sediment in a shallow arm of the sea, which is cut off from the outer ocean by a barrier which prevents free communication. Brackish to salty lagoons with one or more relatively narrow connections to the sea.

An inland body of water, small to moderately large, with its surface water exposed to the atmosphere and which may occasionally be saline. The improvement of drainage conditions on a piece of land usually by a combination of means including: embankments to exclude river or sea water, dredging river channels, cutting deep arterial drainage ditches and shallower secondary ditches to feed into them, installation of tile drains and mole drains, planting of certain crops, such as Eucalyptus to increase evapotranspiration and the commissioning of pumps to raise water out of the area at critical locations in the drainage system.

Gaining land in a wet area, such as a marsh or by the sea, by planting maritime plants to encourage silt deposition, by dumping dredged materials in the area or by the creation of embankments and polders. An emerging specialization that deals with the patterns and processes of biological systems in spatially and temporally heterogeneous environments.