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Systems in Water and Carbon Cycles

Water and carbon cycles as systems

Systems in Geography
A systems approach is hugely important in Geography and can be applied to many of the human and physical geography concepts that we investigate.  For example, from a human geography perspective, cities can be seen to operate as a system as they have inputs of energy and matter coming from outside of the city (such as electricity, raw materials), processes and stores within the city (such as manufacturing or the construction of new buildings) and then outputs of matter and energy (such as pollution, products and waste). 

Indeed, when looking at systems, we must consider the TYPE of system, then its inputs, processes/stores and outputs.

Types of system:
Open Systems – these are any system which has external inputs and external outputs of both energy AND matter. E.g. a drainage basin

Open system diagram

Isolated systems -  these have no interactions with anything outside of the system boundary. There is no input or output of energy or matter. These are rare in reality and tend only to exist in scientific experiments
Closed systems - these have transfers of energy both into and beyond the system boundary but NOT transfer of matter. Planet Earth is generally considered a closed system, with energy coming from the sun, balanced by radiant energy lost from the Earth.

Closed systems
Cascading system - the transfer of mass and energy along a chain of component subsystems, such that the output from one subsystem becomes the input for the adjacent subsystem. River sediment cascades into the coastal zone for example.

 

Characteristics of systems in Geography
Most systems in Geography share the same common characteristics. These common characteristics include the following:
1. Systems are a generalisation of reality – they give us an idea of what is happening in the system but the reality is often more complex and requires detailed study
2. They have a structure that is defined by its parts and processes.
3. Systems tend to function in the same way. This involves the inputs and outputs of material (energy and/or matter) that is then processed causing it to change in some way.
4. The various parts of a system have relationships between each other. They are often Connected and integrated together.
5. The fact that functional relationships exist between the parts suggests the flow and transfer of some type of energy and/or matter.
6. SOME systems often exchange energy and/or matter beyond their defined boundary with the outside environment, and other systems, through various input and output processes.
7. Functional relationships can only occur because of the presence of a driving force.
SOURCE – Adapted from http://www.physicalgeography.net/fundamentals/4b.html (this website is thoroughly recommended, it is an amazing Geographical resource)

 

FEEDBACK in SYSTEMS
Within systems we also get different types of feedback. 

Positive feedback - enhances or amplifies an effect by it having an influence on the process which gave rise to it. Often, this means that the consequences of the change are ironically more severe.
Positive feedback loop
Negative feedback - dampens or reduces an effect by it having an influence on the process that gave rise to it.  This often means that the consequences of a change are less severe.
Negative feedback loop
Most systems are said to be in dynamic equilibrium - lack of change in a system as inputs and outputs remain in balance over periods of time. A good example of this would be a river system, rivers are generally in balance between the inputs of energy and outputs.  Water and sediment budgets will balance out over years.  However, at times big storms might disrupt this balance for a short period of time, resulting in flooding and huge changes to sediment budgets.  Eventually, after a flood event, rivers will return to their normal functions, and dynamic equilibrium will be restored.

The Earth’s major systems
Our planet has 4 major systems, which are all interconnected.  There are also subsystems in those 4 systems – the lithosphere contains soil and rock systems for example.
1. Atmospheric system - the inputs, flows and outputs all associated with the layer of gasses surrounding our planet
2. Lithospheric system - the inputs, flows and outputs all associated with the cold, hard solid land of the planet's crust (surface)
3. Hydrospheric system - the inputs, flows and outputs all associated with the water on our planet
4. Biospheric system - the inputs, flows and outputs all associated with the biology and ecosystems of our planet
Source -

Michael Pidwirny (2014). Introduction to Systems Theory.  PhysicalGeography.net FUNDAMENTALS eBOOK. Retrieved from http://www.cotf.edu/ete/ess/essspheres.html

Written 23/9/2018 - by Robert Gamesby

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