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Showing 1681–1709 of 1709 reference entries

Measurement · PhysicsRadiant flux, intensity, irradiance, exitance and radiance

Optical power, directional power and surface densities are different quantities.

DefinitionMeasurement · PhysicsPhotometric weighting, lumen, candela, lux and luminance

Photometry weights radiation with a specified standard visual response.

DefinitionMeasurementWriting SI quantities and unit symbols

Symbol form, spacing and parentheses preserve the meaning of reported quantities.

DefinitionMeasurementGram prefixes and the kilogram exception

Mass prefixes attach to gram even though kilogram is the SI base unit.

DefinitionMeasurementRounding a result with its uncertainty

Report useful digits without treating extra digits as proof of accuracy.

MethodMeasurement · Physics · ChemistryCommon non-SI units and exact SI conversions

Common non-SI unit names require their correct SI scale factors.

DefinitionPhysics · ChemistryGas pressure as molecular momentum transfer

Molecular collisions link macroscopic pressure to random translational motion.

ModelChemistry · PhysicsOrdinary aggregate states and bulk behavior

Solid, liquid and gas describe bulk behavior rather than chemical identity.

ModelChemistryInferring empirical and molecular formulas from composition

Element mass ratios become atom ratios through molar masses, with uncertainty and sample identity retained.

MethodChemistryLewis structures and valence-electron accounting

A Lewis diagram accounts for bonding and nonbonding valence electrons in a specified connectivity.

MethodChemistryElectron-domain geometry and molecular shape

VSEPR distinguishes the arrangement of electron regions from the positions of atoms.

ModelChemistryElectronegativity, bond polarity and molecular polarity

Polar bonds can cancel in a molecule; molecular geometry matters.

ModelChemistrySolutions, solutes, solvents and solvation

Dissolution disperses specified molecular or ionic species in a solvent.

DefinitionChemistrySolubility, saturation and supersaturation

A saturation limit is an equilibrium property under specified conditions, not a synonym for concentration.

DefinitionChemistryFiltration separates retained solids from a fluid

Ordinary filtration separates undissolved particles; dissolved species can remain in the filtrate.

MethodChemistryDistillation and vapor–liquid composition

Distillation uses vapor–liquid partitioning and condensation, with a limit at an azeotrope.

MethodBiologyGene, allele, genotype and phenotype

Genomic sequence variants and observable traits describe different levels of biological information.

DefinitionBiology · ChemistryEnzyme substrates, active sites and induced fit

Substrate recognition and catalysis depend on a dynamic molecular environment.

ModelBiology · ChemistryMonomers, polymers and hydrolysis

Covalent subunit linkage and water-assisted cleavage explain biological polymer structure.

DefinitionBiology · ChemistrySugars, glycosidic linkages and polysaccharides

Sugar connectivity distinguishes energy-storage and structural polysaccharides.

DefinitionBiology · ChemistryFatty acids, storage lipids and membrane lipids

Lipids include several architectures rather than one repeating-monomer polymer class.

DefinitionBiology · ChemistryAmino-acid residues and peptide linkages

The peptide backbone and variable side chains are different parts of protein structure.

DefinitionBiology · ChemistryNucleotides and DNA/RNA backbone polarity

Bases carry sequence information on a chemically directional sugar–phosphate backbone.

DefinitionBiologyCell membrane, cell wall, cytosol and compartments

A cell's boundary, fluid interior and specialized structures have different roles.

DefinitionEarth & cosmos · MeasurementEarthquake location, source magnitude and local intensity

A source location or magnitude does not describe the shaking experienced at every site.

DefinitionEarth & cosmosAtmospheric composition and thermal layers

Composition and temperature structure describe different features of Earth's atmosphere.

ModelEarth & cosmosDrainage basins, outlets and water divides

Surface drainage boundaries depend on the chosen outlet and need not bound groundwater flow.

DefinitionEarth & cosmosThe celestial sphere and the observer's sky

A sky direction is an angular observation, not an object's three-dimensional distance.

ModelEarth & cosmos · MeasurementRight ascension, declination and reference epochs

Celestial angular coordinates require a declared reference system and date conventions.

Definition
DefinitionSource checked

Drainage basins, outlets and water divides

Earth & cosmos

Surface drainage boundaries depend on the chosen outlet and need not bound groundwater flow.

Key knowledge

A surface-water drainage basin, catchment or watershed is the land area contributing surface drainage to a specified outlet. Neighboring basins are separated by drainage divides, commonly associated with topographic high ground. Changing the outlet changes the basin; smaller basins can nest within larger ones. Infiltration, storage and evaporation mean precipitation does not all immediately become streamflow. Groundwater divides describe subsurface flow systems and need not coincide with surface-water divides.

Conditions and scope

  • Here 'watershed' means the contributing basin. State the outlet and whether a boundary describes surface drainage or groundwater.
  • Water transfers, engineered drainage, geological pathways and changing hydraulic heads can affect a water budget; a topographic boundary does not prove hydrological closure.
Sources · 3

References

Sources retain their recorded scope. A source link alone does not establish verification of every statement.

  1. Watersheds and drainage basinsU.S. Geological Survey, Water Science SchoolReference guideusgs.govRead source
  2. Simulation of regional groundwater flow in southeastern Wisconsin (2004), groundwater and surface-water dividesD. T. Feinstein, D. J. Hart, T. T. Eaton, J. T. Krohelski and K. R. Bradbury · Wisconsin Geological and Natural History Survey and USGSReference guide · PDFdata.wgnhs.wisc.eduRead source
  3. Water catchmentsUniversity of Waikato / Science Learning HubTextbook chaptersciencelearn.org.nzRead source

Evidence and review

Outlet-dependent and nested surface drainage areas, incomplete precipitation-to-streamflow conversion and distinct groundwater divides.

2026-10-10 · Independent Mathematics and Information editor (AI editorial/source review; not the Chemistry/Biology/Earth author). The specified introductory inventory has no unresolved demonstrated material gap after the changes and body-based reuse. Existing advanced references retain their historical scoped approvals. English-only reference prose and explicit Lithuanian-translation-pending status are preserved.

Foundational review

2026-10-10 · Independent AI editorial inspection of this new compact reference entry, its equations, applicability, sources and knowledge connections.

Sources from other places

Scope or convention differs

Land drainage to an outlet and nested catchment examples.

The regional catchment examples do not imply coincident surface and groundwater divides.

  • University of Waikato / Science Learning Hub

    • Water catchments
      New ZealandEnglish

      Opening definition; Catchments can be small or large; Why catchments matter

Related reference entries

Explore relationships within this area of study and its connections to other areas.

Showing 1–3 of 3 relationships

Scientific relationships · 3 / 3

The relationship type describes the connection. Its linked statements, sources and conditions define the scope.

  1. Related to
    Relationship sources · 2

    Linked statements

    • A surface-water drainage basin, catchment or watershed is the land area contributing surface drainage to a specified outlet. Neighboring basins are separated by drainage divides, commonly associated with topographic high ground. Changing the outlet changes the basin; smaller basins can nest within larger ones. Infiltration, storage and evaporation mean precipitation does not all immediately become streamflow. Groundwater divides describe subsurface flow systems and need not coincide with surface-water divides.

    The selected outlet organizes part of the water cycle, with infiltration, storage and atmospheric exchange affecting the basin budget.

  2. Related to
    Relationship sources · 2

    Linked statements

    • A surface-water drainage basin, catchment or watershed is the land area contributing surface drainage to a specified outlet. Neighboring basins are separated by drainage divides, commonly associated with topographic high ground. Changing the outlet changes the basin; smaller basins can nest within larger ones. Infiltration, storage and evaporation mean precipitation does not all immediately become streamflow. Groundwater divides describe subsurface flow systems and need not coincide with surface-water divides.

    Surface catchment geometry and groundwater flow/storage describe connected but potentially different domains.

  3. Related to
    Relationship sources · 2

    Linked statements

    • A surface-water drainage basin, catchment or watershed is the land area contributing surface drainage to a specified outlet. Neighboring basins are separated by drainage divides, commonly associated with topographic high ground. Changing the outlet changes the basin; smaller basins can nest within larger ones. Infiltration, storage and evaporation mean precipitation does not all immediately become streamflow. Groundwater divides describe subsurface flow systems and need not coincide with surface-water divides.

    A water budget must state its domain and include cross-boundary exchanges rather than assume topographic closure.

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