Glossary for Soils and Hydrology - Terms | FORS 3060, Study notes of Forestry

Download Glossary for Soils and Hydrology - Terms | FORS 3060 and more Study notes Forestry in PDF only on Docsity! CRSS(FORS) 3060 - Hydrologic Glossary 1 Hydrologic Glossary 100-year floodplain: Area inundated during a 100-year flood. 100-year flood: A flood with a 1% annual probability. Abandoned oxbows: Former river meanders that have been cut-off. River no longer flows through them. Abandoned terraces: Areas of paleo-floodplain no longer part of active floodplain. Absolute humidity: Mass of water vapor per unit volume of air. Active floodplain: Valley areas inundated by plausible stormflows. Actual evapotranspiration: Transfer of moisture from the earth to the atmosphere by evap- oration of water and transpiration from plants. Adiabatic lapse rate: Theoretical change in atmospheric temperature as a function of ele- vation occurring with no net loss or gain of energy. Aggradation: Deposition of sediment or detritus on the soil surface or on a streambed. Annual: Occurring on a yearly basis. Aquiclude: Geologic formation that does not store or transmit appreciable quantities of water. Aquifer: Geologic formation that contains sufficient saturated permeable materials to yield significant quantities of water to wells and springs. Artesian aquifer: A confined aquifer in which the potentiometric surface is above the land surface. Aquitard: A geologic unit that retards but does not prevent the flow of water to or from an adjacent aquifer. It does not readily yield water to wells, but may serve as a storage unit for ground water. Atmosphere: The gaseous envelope surrounding the earth or a heavenly body. On the earth, the air mass above the water table. Back channel swamp: Low area in floodplain near or below water table Backwater: Water that accumulates in low-energy areas of a flood plain or flood way. Bank erosion or scour: The loss of stream banks by the force of water. Usually greatest on outside bends, and near obstructions. Baseflow: That part of the stream discharge that is not attributable to direct runoff from precipitation or melting snow. It is usually sustained by ground-water discharge. Basin: A large or small depression on the surface of the land or ocean floor. It can also be used to mean a watershed. Bedload sediment: The mineral matter transported by water along the bed of a stream. CRSS(FORS) 3060 - Hydrologic Glossary 2 Blackwater: Water containing large amounts of organic acids that cause the water to appear black. Boulder: Particles larger than 264 mm (bigger than a basketball) Capillary rise: The height above a water surface to which water will rise due to capillary forces. Channel order: A ranking of channels from smallest (zero) largest. A zero-order channel is a hollow with no clear channel, a first-order channel is a headwater channel with no tributaries, a second-order channel is form when two first-order channels join, etc. Channel substrate: Material on the bed of a channel. Closed system: A system within which no external inputs or outputs are present. Cloud: A visible collection of particles of water or ice suspended in air, usually at an elevation above he earth’s surface. Coagulant: To become or cause to become thickened into a compact mass. Cobble: Particles greater than 64 mm and less than 264 mm (bigger than a softball, smaller than a basketball). Condensation: To change from a vapor into a liquid or a solid with a concomitant release of energy. Cone of depression: A lowering of the potentiometric surface near a well due to the extrac- tion of water. Cone of impression: An increase in the potentiometric surface near a well due to the injection of water. Confined aquifer: An aquifer overlain by a formation of lower permeability and where the potentiometric surface is above the top of the aquifer. Conservation equation: An identity that establishes a conservation relationship (e.g., con- servation of mass, energy) Constitutive relationship: A formula that relates inputs or outputs to state variables using parameters. Contaminant: An undesirable substance not normally present, or an unusually high concen- tration of a naturally occurring substance. Continental air mass: Referring to dry tropospheric air masses. Darcian flux: The rate of ground-water discharge per unit area of porous medium measured perpendicular to the direction of movement. Degradation: The removal of sediment or detritus from the soil surface or a streambed. Detention: The temporary capture of water which is subsequently released after a delay. Dew: Moisture condensed from the atmosphere and deposited in the form of small drops of liquid water upon any cool surface. CRSS(FORS) 3060 - Hydrologic Glossary 5 Inverse modeling: The estimation of input data or parameters using observed data and sys- tem outputs. Joule: The SI unit of work or energy, equal to the work done by a force of one newton when its point of application moves through a distance of one meter in the direction of the force. Kilogram: The base SI unit of mass; its international prototype, a platinum iridium cylinder, is kept in Sèvres, France. Kinetic energy: The energy associated with motion, or inertia, equal to the one-half the mass times the squared velocity. Lapse rate: The change in temperature with altitude. Normally, temperatures decrease with elevation. Latent heat: The heat absorbed or radiated during a change of phase at constant temperature and pressure. Latent heat of fusion: The amount of heat required to melt one gram of ice to liquid water at 0C. Latent heat of vaporization: The quantity of heat that is absorbed or released when a gram of water evaporates or condenses, respectively. It is a function of temperature and is equal to 540 cal/g at 100◦C. Leachate: The fluid that drains from the bottom or sides of a landfill or waste dump. Linear function: Having a response or output which is directly proportional to the input, that is y(2x) = 2 y(x). Lower cloud limit: The lowest elevation within a cloud at which the ambient temperature equals the dew point temperature. Maritime air mass: Referring to wet tropospheric air masses. Matric suction: The volumetric energy content of the water expressed as a negative pressure. Mean annual flow: The average of all flows during the water year. Mesotrophic: Having sufficient nutrients to promote moderate levels of biological productiv- ity, resulting depletion of oxygen below the photic zone. Meter: The base of the SI unit of length, equivalent to 1/299,792,458 of the distance that light travels in a vacuum in one second. Millibar (mb): A unit of pressure equal to 0.07493 cm of mercury or 1.015 cm of water. Mean sea-level air pressure is 1013.2 mb, or the equivalent of 10.28 meters of water. Moisture characteristic curve: The relationship between matric suction and water content for a porous material. Newton: The SI unit of force, equal to the force that produces an acceleration of one meter per second per second on a mass of one kilogram. CRSS(FORS) 3060 - Hydrologic Glossary 6 Oligotrophic: Having low amounts of nutrients and biological activity with normal concen- trations of oxygen at all depths. Open system: A system in which inputs are received from external to the system, or outputs are discharged from the system. Ordinary high water mark: Indicated by a change in vegetation along a channel. Typically marks the level of the annual flow (the 1.01-year flow). Overflow channels: The channels used by river during out of bank flows Overland flow: Water that flows across the surface of the earth that is not in a defined channel. Paleo-floodplain: Valley areas covered by alluvial deposits. Parameter: A coefficient that relates inputs, outputs or state variables. Pascal: The SI unit of pressure or stress, equal to one newton per square meter. Peak flow: The maximum rate of streamflow in response to a heavy rainfall. Peak annual flow: The largest peak flow in a water year. Percolation: The downward movement of water through the unsaturated zone. Perennial: Plants that have a life cycle lasing more than two years. Permeability: A measure of the ability of a porous material to transmit fluid in response to a fluid potential gradient. Petiole: A slender stalk at the base of a leaf that attaches to the stem. Phreatic zone: Same as saturated zone. Plume: The volume within an outline of a substance that has moved or is moving through space. Polar air mass: Referring to cold tropospheric air masses. Point bar: A sediment deposit on the inside turn of a river where flow velocities are slower Porosity: The total volume of voids per unit volume of porous material. Potential energy: The energy of matter due to its position or arrangement of its parts. Potential evapotransporation: The possible maximum transfer of moisture from the earth to the atmosphere by evaporation of water and transpiration from plants. Water loss from a short green crop completely shading the ground and never short of water. Potentiometric surface: The surface to which water would rise in a well. Power: The work done or energy performed per unit of time. Precipitation: The falling products of condensation in the atmosphere, such as rain, snow, and hail. CRSS(FORS) 3060 - Hydrologic Glossary 7 Radionuclide: An element that decays by spontaneously emitting particles or energy. Rate: The change of a variable with respect to time. Rating curve: The relationship between stream stage (i.e., water level) and stream discharge (i.e., streamflow). Recharge: The addition of water to the saturated zone. Relative humidity: The amount of water vapor in the air, expressed as a percentage of the maximum amount that the air could hold at the given temperature. Computed as the ratio of the actual vapor pressure to the saturation vapor pressure. Relative hydraulic conductivity: The ratio of the unsaturated hydraulic conductivity to the (saturated) hydraulic conductivity. Residence time: The period of time during which a substance remains present, adsorbed, suspended, or dissolved. Retention: The complete capture of water without subsequent release. Riffle: A shallow section of a river or stream associated with higher water velocity. Rill or rille: A long, small gully, usually found together in large numbers on steep slopes and oriented parallel to the slope and to each other. Riparian zone: Area where vegetation is influenced by the river, and the river microclimate is directly influenced by the vegetation. Saltation: The skipping of particles across a surface, usually over a solid surface driven by water or wind. Saturated zone: The region within the earth below the water table where all the pores are completely saturated with water and the fluid pressure exceeds the atmospheric pressure. Saturation vapor pressure: Maximum vapor pressure that is thermodynamically stable, meaning that water usually condenses into droplets when the saturation vapor pressure is reached or exceeded. Actually, however, condensation requires small particles to initiate drop formation, so clean air can exceed the saturation vapor pressure. Second: The base of the SI unit of time, equaling 9,192,631,770 cycles of radiation in a change in energy level of the cesium atom. Sediment delivery ratio: The ratio between point and regional estimates of sediment pro- duction per unit area; normally a number less than one. Sensible heat: Heat absorbed or radiated due to a temperature change at constant pressure and without a phase change. SI: The international system of units. The basis of the metric system. Sink: An output from a system, which is usually the input of another system. Source: An input into a system, which is usually the output of another system. Stage: The height of water in a stream or lake.