Lecture notes Environmental Engineering and Hydrology (EBW2409) A Systems Approach to the Environmental Analysis of Pollution Minimization, ISBN: 9781000724158

PART I: INTRODUCTION TO SYSTEMS APPROACH TO ENVIRONMENTAL MANAGEMENT


EBW2409: SYSTEMS APPROACH TO ENVIRONMENTAL MANAGEMENT

1. SYSTEM CONCEPTS AND DEFINITIONS

1.1 System Concepts

1. The concept of a system is a way of describing something. When that something is
complex, it is not possible to think of it, nor practical to work with it, as a single entity;
and from the natural desire to subdivide it into simpler elements that can be treated at
first in isolation and that subsequently form the total entity by interacting, arises the
concept of a system as a set of interacting elements.

2. The system concept is only useful if there are certain characteristics that are common
to all systems, or to significant classes of systems, and if these characteristics can be
used (i.e. manipulated) in the design and optimization of systems. The larger the
class, the fewer the applicable characteristics (or system parameters); the process of
enlarging the class is called abstraction.

3. Because a system describes only the external functional behavior of an entity, it can
be said to be a model of that entity. Consequently, modeling is a central activity in
describing system behavior.

1.2 Importance of Systems

The word "system" is used more and more frequently in almost every area of human
endeavor; we have, for example, control systems, weapons systems, ecosystems,
transport systems and life support systems. This is a reflection of several related factors:

 The increasing complexity of society in general, due to the tighter coupling of its
components through the increased mobility of goods and information;

 An increasing capacity for abstract thought and the realization of complex relations
and dependencies, due to a higher average level of education;

 More immediate and serious effects of interactions that were negligible on a small-
scale of operations, and;

 Better means of describing and handling complex relations.

1.3 System Definitions and Elements

Definition

A system may be defined by any of the following definitions:

 An assemblage or combination of elements or parts forming a complex or unitary
whole (e.g., a river system, transport system, control system, weapons system,
ecosystem and life support system);

 Any assemblage or set of correlated members (e.g., a system of currency);

 An ordered and comprehensive assemblage of facts, principles, or doctrines in a
particular field of knowledge or thought (e.g. a system of philosophy);




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, PART I: INTRODUCTION TO SYSTEMS APPROACH TO ENVIRONMENTAL MANAGEMENT


 A coordinated body of methods or a complex scheme or plan of procedure (e.g. a
system of organization and management);

 Any regular or special method of plan of procedure (e.g. a system of marking,
numbering, or measuring).

Elements of a system

A system consists of three related sets:

 A set of elements (components, attributes and relationships) as described below;
 A set of interactions between the elements, and;
 A set of boundary conditions.

a) Components are the operating parts of a system consisting of input, process, and
output.

b) Attributes, which characterize a system, are the properties or distinct features of the
components of the system.

c) Relationships are the links between components and attributes.

Class exercise

 Highlight examples of systems found in agriculture and in agricultural approach to
management that fall into the above categories of definitions.

 What would one require to know in order to optimize the above-mentioned systems?

1.4 Questions

1. What characteristic of an object necessitates the introduction of the system concept?

2. Define the term "system".

3. Name two common subsets of the set of boundary conditions.

4. What is meant by "abstraction"?




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