projects, thus leading to sustainable projects. The guide aims to be of general use throughout the
developing world and has three main functions:
• to describe the methodology and output of an EIA;
• to provide inter-disciplinary advice related to irrigation and drainage to those engaged in
preparing EIAs; and,
• to enhance institutional capacity for carrying out an EIA.
In developing countries irrigation development is mainly the responsibility of the public sector.
This document therefore concentrates on public sector irrigation projects. Whilst national
irrigation authorities will not usually carry out EIAs, they will commission them, either as part of
a feasibility study or separately. They must therefore be familiar with EIA in order to formulate
the terms of reference and to appraise the impact statement. Private developers should also be
required to demonstrate that their proposals are environmentally sound.
The objective has been to produce a brief reference text that will be of most benefit to nonspecialists in developing countries who are perhaps facing the need to carry out an environmental
assessment for the first time. To ensure brevity, and accessibility to all readers, technical,
scientific or engineering content has been kept to a minimum. It is assumed that this information
is readily available in other textbooks or manuals and that many readers will already be familiar
with some technical aspects.
Similarly, no detailed explanation of the philosophy of EIA is given as this is available in
standard general texts. Throughout the guide the terms EIA and environmental assessment have
been used synonymously. A glossary of terms and abbreviations used in the text are included in
Annex 1. Chapter 6 provides a guide to other publications considered of most use that are also
widely available. Recommended texts, which are considered particularly useful, are reviewed at
the start of Chapter 6.
Using the guide
Environmental assessment is appropriate for both site specific projects and wider programmes or
plans covering projects or sectoral activities over a wide geographic area. In this document the
term "project" is used interchangeably for both the site specific and wider meaning.
Rehabilitation or modernization programmes are more common than new green field projects
and raise special issues which need to be addressed by an EIA. They provide more opportunities
to correct situations where the environment is adversely affected and they are usually richer in
available data, (Tiffen, 1989). Also, operation and maintenance reforms for regions or basins will
benefit greatly from an EIA. As this guide has been specifically prepared to address irrigation
and drainage projects, plans and programmes, it is not sufficiently comprehensive to be used to
carry out environmental impact assessments of other water resources projects.
Initially EIA was used for specific, particularly large scale, projects such as dams, which have
obvious long-term consequences. Now, however, greater attention is given to the wider
relationship between development and the environment. The relatively insignificant actions of
many individual people may cumulatively have a much greater impact on the environment than a