4.1 Introduction

EIA methods are usually taken to include the means of gathering and analysing data, the sequence of steps in preparing a report, and the procedure (who does what and when). The essential ingredients of the EIA process, such as scoping, IEE, and detailed EIA, are universally agreed upon, but EIA techniques vary widely.

Considering the complexity of the interacting systems that constitute the environment, and the infinite variety of possible impacting actions, it seems unlikely that a single method would be able to meet all the above criteria. The general applicability of all methods also has to be balanced against the administrative and economic constraints within which they are employed.

There is no single approved method for an EIA study. Therefore, what is important is the ability to think in a systematic way:

• to understand the interactions of the environment and technological change;
• to meet, in a practical way, the needs of the development manager; and
• to follow the fundamental process of preparing an EIA.

A distinction between EIA methods and tools must be carefully noted. The four fundamental methods which are commonly used as methods for conducting an EIA are checklists, matrices, networks, and overlays. Tools for EIA support the application of the above basic methods. Some of the commonly used tools are prediction models, geographical information systems, and expert systems. These tools can be used for purposes other than EIA.

Generally, more than one method and tool are used, depending on the tier of the EIA process, to accomplish the best results. Recommendations for the use of methods and tools are made in the form of a comprehensive flow chart (Fig. 4.1).