Chapter 6: Shapes and Sizes of Lakes

What is maximum length (l) in lake surface dimension?

distance across the water between the two most separated points

What is breadth (b) in lake surface dimension?

width measured at a right angle to the axis of maximum length.  Can be used to calculate mean width

What is Length of Shoreline (L) in lake surface dimension?

perimeter, found by using computer programs or a carometer.

What is Shoreline Development Index (DL) in lake surface dimension?

Relates shoreline length to the circumference of a circle that has the same area as the lake.  Smallest possible index is 1.0

How did they use to calculate surface diemnsions of lakes before?

Through chronometers with altimeters and calculus

What does relative depth mean?

Maximum depth in relation to surface area (Z_r).  All larger lakes have relative depths less than 1%.  Crater Lake is 7.5%.  The Hawaiian volcanic crater Kauhako has a relative depth of 374%.

What is Cryptodepression?

Portion of the basin below sea level (Z_c).

• A LAKE CAN HAVE A MASSIVE SURFACE AREA WITH ALOST NO DEPTH/MINIMUM

• surface area outstrips depth

  • depth is a linear measurement

• area: goes up faster than depth

What is Bathymetry?

Bathymetry is the study of the ocean floor and the bottoms of rivers and lakes.

like topography but underwater lol

What is mean depth?

Lake volume divided by its surface area (Ż). Often functionally important to compare geographically proximate lakes.

what is a Hypsographic curve?

Measures the propotions of a lake

ex) 35,000 meters is ana rea of a lake

potential exam question: Using the following graph, what proportion of the lake is between these depths?

Look at the area under the curve. at 0-2 meters, area of the lake is around 16,000 meters cubed… i think

What does the following figure mean in regards to volume developments in lakes?

• a volume less than 1.0= a deep lake; funnel shaped

• volume above 1.0= shallow lake

How is morphometric data used?

helps to allow calculate other lake parameters such as

• photosynthesis

• respiration

• biomass

what is the Morphoedaphic index (MEI)?

Quotient or ratio of total dissolved solids (TDS) in milligrams per liter and mean depth in meters.

tldr comparing to total depth

lake paramters mean nothing is envr stresses great such as:

–salinity

–low nutrient levels

–very deep or shallow

–abnormal pH

Explain the following figure

• the Great Salt, Dead Sea, and lake Anguish have zero fish yield due to high TDS

• Open/non-shade cirlce= no fish…. shaded circle=fish present

• colder lakes produce less biomass

How are ring shaped lakes formed?

–astroblemes

–volcanic craters

Out the following lakes in the image, which is the largest lake?

Lake Baqikal is the largest lake on earth since the volume it holds is 23,000 km³ - meaning it holds 2x as much water than Lake Superior

Where do most interaction happen at a lake?

Interactions with sun, wind , and airborne materials can ONLY occur initially at the surface