Hypsometry
Measurement of Earth's surface elevation and depth relative to sea level.
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Hypsometry is the science of measuring how high or low features on Earth's surface sit relative to average sea level. Elevations can be above sea level (positive) or below it (negative). Scientists believe the global distribution of these elevations has two distinct peaks—a bimodal pattern—because continental crust is lighter than oceanic crust, which is denser. On other planets in our solar system, elevations usually follow a single-peaked, unimodal distribution, since those worlds lack plate tectonics.
A hypsometric curve is a histogram or cumulative distribution function that shows the range of elevations within a given area. Differences in these curves from one landscape to another reflect differences in the geomorphic processes shaping the land.
When drawn as a two-dimensional histogram, the curve plots elevation on the vertical axis and the area above that elevation on the horizontal axis. The curve can also be standardized by scaling both elevation and area to their maximum values, which helps hydrologists and geomorphologists compare watersheds. The hypsometric integral is a single number summarizing the curve's shape.
In the original paper on the topic, Arthur Strahler proposed a three-parameter curve to fit different hypsometric relations: a, d, and z. Later research using two-dimensional landscape evolution models has questioned how well this fit works in general, as well as the curve's ability to handle scale-dependent effects. A modified curve with an extra parameter has been suggested to improve the fit.
Hypsometric curves are also common in limnology, where they show the relationship between a lake's surface area and its depth, and are used to calculate total lake volume. These graphs help predict lake characteristics such as productivity, how incoming chemicals dilute, and the potential for water mixing.
Quick Facts
- Field
- Geomorphology
- Hydrology
- Limnology
- Known for
- Measurement of elevation and depth relative to mean sea level; hypsometric curve
Facts from the source article.
Lore & Background
Hypsometry derives from Ancient Greek words for 'height' and 'measure.' It involves measuring the elevation and depth of Earth's surface features relative to mean sea level. On Earth, elevations can be positive or negative, and the distribution is theorized to be bimodal due to the density difference between lighter continental crust and denser oceanic crust. On other planets in this solar system, elevations are typically unimodal because those bodies lack plate tectonics. The hypsometric curve is a histogram or cumulative distribution function of elevations in a geographical area.
Differences in curves between landscapes arise because geomorphic processes shaping the landscape may differ. When drawn as a 2-dimensional histogram, the curve displays elevation on the vertical axis and area above that elevation on the horizontal axis. The curve can be standardized by scaling elevation and area by maximum values, allowing hydrologists and geomorphologists to assess watershed similarity.
In the original paper on this topic, Arthur Strahler proposed a curve with three parameters to fit different hypsometric relations. Subsequent research using two-dimensional landscape evolution models has questioned the general applicability of this fit and the curve's ability to handle scale-dependent effects. A modified curve with one additional parameter has been proposed to improve the fit. Hypsometric curves are also used in limnology to represent the relationship between lake surface area and depth and to calculate total lake volume.
Reader's Guide
Hypsometry provides a fundamental framework for understanding Earth's topographic structure and comparing it with other planetary bodies. The bimodal elevation distribution on Earth, theorized to result from crustal density differences, contrasts sharply with the unimodal distributions on other planets, highlighting the unique role of plate tectonics. The hypsometric curve, introduced by Arthur Strahler, remains a key tool for geomorphologists and hydrologists to characterize landscapes and watersheds, though its general applicability has been questioned by later studies using landscape evolution models.
The curve's ability to be standardized allows for meaningful comparisons across different scales and regions. In limnology, hypsometric curves are practical for calculating lake volume and predicting characteristics such as productivity, chemical dilution, and water mixing potential. Despite debates about its fit and scale dependence, hypsometry continues to be essential for analyzing Earth's surface and for comparative planetology.
Frequently Asked Questions
What is Hypsometry and what does it measure?
Hypsometry is the physical-geography discipline devoted to quantifying how far Earth's surface features stand above or sink below mean sea level. It treats both positive elevations and negative depths as part of a single continuous record.
Which scientific fields does Hypsometry sit at the crossroads of?
It bridges geomorphology, hydrology, and limnology, tying landform shape analysis to the behavior of rivers, lakes, and other water bodies.
More in Physical Geography & Elevation
Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: Hypsometry (CC BY-SA 4.0).
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