Cross section of soil/saprolite/bedrock at the Betasso CZO site

 

 

Particle-based modeling of critical zone evolution

 

 

 

 

 

 

Modeling landscape response

Geomorphology is the study of landforms and the processes that shape them. Geomorphologists use several types of models to evaluate spatial patterns of the earth.

MODELS

What are computer models?
Scientists often describe nature’s behavior using mathematical equations. Mathematics provides a highly precise language for expressing the relationships between natural phenomena, such as how the speed of water in the stream depends on the depth of the water and the slope of its bed. Computers are very good at performing the calculations behind these equations and displaying the results graphically. A “computer model” is a computer program that simulates a natural process solving a particular set of equations or implementing a particular algorithm that represents a hypothesis about how that process works. By comparing model calculations with measurements of the actual phenomenon in question, scientists are able to determine whether or not their hypotheses are correct. When model calculations do not agree with data, it shows that something is wrong about the hypothesis, and often suggests what the missing ingredient might be. Models also commonly help identify the most critical measurements that need to be made. Computer models are often commonly deliberately designed to be much simpler than the natural world. By keeping their hypotheses as simple as possible, scientists can determine how much of a particular natural phenomenon can be explained by a fundamental underlying principle, irrespective of the many details that we observe in the natural world.

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Models and the CZO
Scientific study of the critical zone involves many different types of models, including models that calculate the runoff in streams in response to rainfall and snow melt, models that calculate the weathering rates of rock and soil particles, and models that simulate the evolution of the landscape over many thousands of years.

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Landscape Evolution Models
A Landscape Evolution Model, or “LEM,” is a computer model that simulates how the terrain slowly (and sometimes not so slowly) changes shape in response to erosion and sedimentation. LEMs normally calculate the flow of both water and sediment across the land surface. They can, for example, simulate the tendency for valleys to form and grow at locations where runoff comes together to form larger rivers and streams. The figure at left shows a simulation of a hypothetical version of the Colorado Front Range in the vicinity of Boulder Creek, as it might have looked at the time when motion on the main fault ceased, some time during the early Tertiary period (a few tens of millions of years ago). Researchers are using this type of model to explore the feasibility of different hypotheses to explain why the edges of the mountain range underwent a change from deposition to erosion about five million years ago.

Written by Greg Tucker