4.2 System elements
If you compare any ‘thing’ you are concerned about against it, you can find parts in agreement and parts that disagree. In the example below, a local stream visited by Professor Simon Bell is compared with the ‘ideal type’ system.
Table 1 A stream as a system
|Ideal system of a local stream||Simon’s stream|
|Interconnecting parts functioning as a whole.||Yes, but the stream is adversely affected now by occasional floods as drainage off nearby fields has been ‘improved’.|
|It is changed if you take away pieces or add more pieces. If you cut the system in half you do not get two smaller systems, but a damaged system that will not function properly.||The stream is a whole and functions as such, but recently the stream has been shaped and moulded to meet changing field patterns. The stream is intact but changing.|
|The arrangement of pieces is crucial.||As above. As tributary ditches coming into the stream change (e.g. number/silting/damming), so does the stream.|
|The parts are connected and work together.||Absolutely. Another problem is that in very dry spells the stream ‘disappears’. This has impacts on the wider system, a small river.|
|Its behaviour depends on the total structure. Change the structure and the behaviour changes.||Yes indeed. Change local drainage, ditch channels and take into account drought conditions, and the behaviour of the whole stream changes.|
In this simple example, you can see how the stream as a whole (the system) is dependent on the arrangement and interconnected functioning of its component parts. Just as with drought, if you divide the stream into smaller parts – its components – the stream itself ‘disappears’ and you are left with something quite different. As you’ll briefly explore in this unit, managing for the whole (the stream) or managing for one of its components (a tributary) can be profoundly different with different outcomes.