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Chapter 1: Introduction

The need for environmental assessment
Using the guide

The need for environmental assessment

Economic, social and environmental change is inherent to development. Whilst development aims to bring about positive change it can lead to conflicts. In the past, the promotion of economic growth as the motor for increased well-being was the main development thrust with little sensitivity to adverse social or environmental impacts. The need to avoid adverse impacts and to ensure long term benefits led to the concept of sustainability. This has become accepted as an essential feature of development if the aim of increased well-being and greater equity in fulfilling basic needs is to be met for this and future generations.

In order to predict environmental impacts of any development activity and to provide an opportunity to mitigate against negative impacts and enhance positive impacts, the environmental impact assessment (EIA) procedure was developed in the 1970s. An EIA may be defined as:

a formal process to predict the environmental consequences of human development activities and to plan appropriate measures to eliminate or reduce adverse effects and to augment positive effects.

EIA thus has three main functions:

• to predict problems,
• to find ways to avoid them, and
• to enhance positive effects.

The third function is of particular importance. The EIA provides a unique opportunity to demonstrate ways in which the environment may be improved as part of the development process. The EIA also predicts the conflicts and constraints between the proposed project, programme or sectoral plan and its environment. It provides an opportunity for mitigation measures to be incorporated to minimize problems. It enables monitoring programmes to be established to assess future impacts and provide data on which managers can take informed decisions to avoid environmental damage.

EIA is a management tool for planners and decision makers and complements other project studies on engineering and economics. Environmental assessment is now accepted as an essential part of development planning and management. It should become as familiar and important as economic analysis in project evaluation.

The aim of any EIA should be to facilitate sustainable development. Beneficial environmental effects are maximized while adverse effects are ameliorated or avoided to the greatest extent possible. EIA will help select and design projects, programmes or plans with long term viability and therefore improve cost effectiveness.

It is important that an EIA is not just considered as part of the approval process. Volumes of reports produced for such a purpose, which are neither read nor acted upon, will devalue the process. A key output of the EIA should be an action plan to be followed during implementation and after implementation during the monitoring phase. To enable the action plan to be effective the EIA may also recommend changes to laws and institutional structures.

Initially EIA was seen by some project promoters as a constraint to development but this view is gradually disappearing. It can, however, be a useful constraint to unsustainable development. It is now well understood that environment and development are complementary and interdependent and EIA is a technique for ensuring that the two are mutually reinforcing. A study carried out by the Environmental Protection Agency (USA) in 1980 showed that there were significant changes to projects during the EIA process, marked improvements in environmental protection measures and net financial benefits. The costs of EIA preparation and any delays were more than covered by savings accruing from modifications, (Wathern, 1988).

Irrigated agriculture is crucial to the economy, health and welfare of a very large part of the developing world. It is too important to be marginalized as it is vital for world food security. However, irrigated agriculture often radically changes land use and is a major consumer of freshwater. Irrigation development thus has a major impact on the environment. All new irrigation and drainage development results in some form of degradation. It is necessary to determine the acceptable level and to compensate for the degradation. This degradation may extend both upstream and downstream of the irrigated area. The impacts may be both to the natural, physical environment and to the human environment. All major donors consider large irrigation and drainage developments to be environmentally sensitive.

An EIA is concerned both with impacts of irrigation and drainage on the environment and with the sustainability of irrigation and drainage itself. Clearly an EIA will not resolve all problems. There will be trade-offs between economic development and environmental protection as in all development activities. However, without an objective EIA, informed decision making would be impossible.


This guide aims to assist staff in developing countries from various disciplines and backgrounds (government officials, consultants, planners) to incorporate environmental considerations into planning, designing, implementing and regulating irrigation and drainage programmes, plans and 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 non-specialists 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 single construction project. For example a programme to support small-holder development, through agricultural credit schemes to Water User Groups, may not warrant an EIA if each scheme is considered in isolation. However, the impact within a river basin or in the water sector in a region can be significant. A sectoral or basin-wide EIA would enable an assessment of the collective impact of the programme. In a further example from Tamil Nadu, India, a decision was made to provide free electricity to farmers to pump water for irrigation. Whilst this increased agricultural production it also led to groundwater mining: the reduction in the groundwater level in some areas has resulted in severe environmental and economic problems.

To enable the EIA process to be of maximum benefit, it must be incorporated into the planning process of a country. The social, institutional and legal issues concerned with the effective use of EIA are covered in Chapter 2. Chapter 5, on how to prepare terms of reference, has been prepared to assist those who need to employ others to carry out EIAs on their behalf. The mechanics of carrying out an EIA together with a description of the possible environmental impacts of irrigation and drainage are described, respectively, in Chapters 3 and 4.

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