Hydrology Concepts Quiz

Hydrology Terminology

• Accumulative precipitation gauge: A precipitation gauge used at stations visited at intervals.
• Active basin area: Basin area excluding undrained parts.
• Actual evaporation: The quantity of water evaporated from an open water surface or the ground.
• Actual evapotranspiration: The sum of evaporated water from soil and plants with natural moisture.
• Advection: The transfer of air mass properties by atmospheric velocity.
• Altitude: Vertical distance from mean sea-level.
• Annual exceedence series: A series of events exceeding a base value, equivalent to the number of years in the record.
• Annual flood: Highest peak discharge in a water year. Or the flood which was equaled or exceeded once each year on average.
• Annual flow: Total volume of water flowing in a river basin during a year.
• Annual maximum series: Extreme-value series containing largest annual values.
• Annual minimum series: Extreme-value series containing smallest annual values.
• Annual runoff: Total volume of water flowing in a river basin during a year.
• Annual series: Hydrological characteristic/element for a series of years.
• Annual storage: The volume of water stored in reservoirs to cater for seasonal variations in inflow and demand.
• Annual storage capacity: The volume of water a reservoir can store to partly or completely manage seasonal inflow and demand variations
• Antecedent precipitation index: A measure of soil moisture using past daily precipitation.

Additional Topics

• Area-elevation curve: Curve showing the relationship of the area of a river basin to specified elevation.
• Areal precipitation: Average depth of liquid water over an area.
• Areal reduction factor (of rainfall): Ratio of mean areal to mean point rainfall.
• Arithmetic mean: Sum of a set of values divided by their number.
• Arithmetic mean (of a frequency distribution): First moment.
• Automatic station: Station with instruments to make observations automatically.
• Average velocity: Discharge divided by cross-sectional area.
• Average year: Year with observed hydrological/meteorological quantity equal to long-term average.
• Bankfull discharge: Discharge when water course does not overtop banks.
• Bankfull stage: Stage at which a stream just overflows its natural banks.
• Base-width (of a flood hydrograph): Interval between the start and end of direct runoff.
• Basin: Drainage area of a stream, river, or lake.
• Basin response: Manner a basin reacts to meteorological events.
• Basin response (catchment response): Manner in which a basin reacts to meteorological events.
• Basin response: Pattern of reactions of any water body to meteorological conditions.
• Baseflow: Water in river as a result of groundwater discharge.
• Bubble gauge: Gauge using gas-purged system for water level measurement
• Calibration: Experimental determination of relationship between measurement quantity and instrument indication.
• Catchment: Area with a common outfall for surface runoff.
• Catchment area: Area with a common outlet.
• Catchment response: Manner in which a basin reacts to meteorological events.
• Channel frequency: Count of stream segments (all orders) within a drainage area, divided by the area..
• Channel network: Arrangement of drainage channels within an area.
• Clear overflow weir: Weir where flow is not submerged by downstream water (tail water).
• Climate: Synthesis of weather conditions, long-term statistics of weather elements.
• Climate change: Significant variation in regional climate.
• Climatic change: Significant long-term change in regional climate.
• Climatological station for hydrological purposes: Station placed in a drainage basin to supplement climatological network (to meet hydrological requirements).
• Coefficient of determination: Square of the correlation coefficient, proportion of the dependent variate's variance explained by independent variates.
• Coefficient of variation: Ratio of standard deviation to mean, statistical parameter describing a stochastic variable.
• Compound weir: Weir with two or more sections (of different types and/or dimensions).
• Conceptual hydrological model: Simplified representation of hydrological cycle processes.
• Conditional probability: Probability of one event given the occurrence of another.
• Confidence interval: Interval that includes the true value with a prescribed probability.
• Confidence limits: Values that define the lower and upper bounds of the confidence interval
• Constant-rate dilution gauging: Flow measurement/determination using tracer injection with known concentration.
• Continental hydrology: Hydrological processes within continental areas, emphasizing continental phase of water cycle.
• Continuity equation: Equation describing conservation of mass for flowing matter.
• Convective precipitation: Precipitation due to convective motion in the atmosphere.
• Correlation: Interdependence between two measurable variates.
• Correlation coefficient: Measures interdependence of two variables.
• Crest gauge: Device to record maximum water stage.
• Cumulative precipitation gage: Precipitation gauge visited periodically.
• Cup-type current meter: Current meter with cups rotated by water flow.
• Current meter: Instrument to measure water velocity.
• Cyclonic precipitation: Precipitation due to atmospheric depression.
• Data bank: Comprehensive files of related data for specific applications
• Data base: Comprehensive files of related data for specific applications.
• Data collection system: Co-ordinated system for collecting observations from a hydrological network and transmitting to a data-processing facility (or location)
• Data processing: Handling of observation data until ready for a specific purpose.
• Datum level: Horizontal reference surface for elevations.
• Decay rate: Rate of decrease in concentration (or activity of radioactive isotopes), often expressed as half-life.
• Depletion curve: Curve showing a decreasing rate of runoff.