Great Salt Lake Hydrologic Model
 Models in general 
 My Model (explanation) 
 The Model
Click image to see a GSL location map
Click image to see the GSLs watershed
What is a model? 
   A model is a simplified version of reality.  Scientists use models to represent natural events or cycles. 

What does a model do? 
   Models allow scientists to predict changes that might happen in the environment.  Models simplify exchanges of material or energy that occur in nature, making the exchanges easier to understand.  Models may be as simple as a line drawing or flow chart, or complex mathematical equations.   

How do models work? 
   Some models work through mathematics.  The model's exchanges have equations describing them.  These equations control how rapidly or how much transfer occurs when each exchange takes place. 

Great Salt Lake Model 
   The USGS has been working on a complex model to simulate movement of salt and water between the north and south arms of the great salt lake.  They have constructed the model below to help understand how the lake regulates salinity and level.  This is important to know because salinity affects algal and brine shrimp growth in the lake.  

model courtesy USGS

What is my model? 
    My model is a simplification of the Great Salt Lake hydrologic cycle.  It illustrates the inflows and outflows of the Great Salt Lake. Inflows are sources that add water to the lake, such as rivers, streams, springs, and rain.  Outflows, such as evaporation, take water away from the lake. 

What is the purpose of my model? 
   The purpose of my simplified model is to predict lake level changes in relation to rainfall, river and stream flows, and evaporation.  All these factors would be influenced by future climate change, so this model could serve as a useful tool to predict the effects of global climate change. 

Why is modeling the GSL and lake level change important? 
   Modeling lake level change in the Great Salt Lake is very important because lake levels play a very important role in the Great Salt Lake ecosystem.  The fluctuation of the lake changes the shoreline, and affects the plants and animals living on or near the shore.  Animals affected include Plover, Avocets, and various Insects. Pickle weed, Salt grass and Iodine Bush are the main plants that are affected.  The changing lake levels changes the salt content of the soils in which Pickle weed and Iodine Brush grow.  The lake rises, covering the slat playas with water, and adding salt to the soil.  As the water retreats or evaporates, the salt is left behind.  Only a few types of plants can grow in these extremely salty soils.  Over time, rain washes the salt out of the higher elevation soils, and deposits it on the lower elevation salt flats.  In these ways the lake controls the life growing not only in it, but also around it. 

How did I create my model? 
   I used a software program calle Stella to create my model.  Steall is a visual modeling program that allows for the easy creation of mathematical models by laying them out in a flowchart type format.  For more information on Stella, you may visit the HPS webpage at

Due to time constraints and software conflicts, the model is not up and running yet.  Keep checking back in and the great salt lake model should be here.

World, S.R.  Thomas, B.E.  Waddell, K.M.  (1997).  Water and Salt Balance of Great Salt Lake, Utah, and Simulation of Water Movement Through the Causeway  
(1998, June 16) USGS Great Salt Lake page (1999, Dec 6)  

For More Information

U.S.G.S. Great Salt Lake, Utah

High Preformance Systems, Inc.

Special thanks to Brian L. Loving of the U.S.G.S. for information, data, and images.
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