NOTE: nature of impact

The Nature of Impacts

The environmental impacts of a project are those resultant changes in the environmental parameters, in space and time, compared with what would have happened had the project not been undertaken. The parameters may be any of the type of environmental receptors noted previously; air quality, water quality, noise, levels of local unemployment and crime.

Types of impact that may be encountered in EIA

-      Physical and socio-economic

-      Direct and indirect

-      Short-run and long-run

-      Adverse and beneficial

-      Reversible and irreversible

-      Quantitative and qualitative

-      Distribution by gp and/or area

-      Actual and perceived

-      Relative to other developments.

Biophysical and socio-economic impacts are often seen as synonyms in adverse and beneficial. Thus new developments may produce harmful wastes but also produce much needed jobs in areas of high unemployment. This correlation does not always apply. A project may bring physical benefits when, for example, previously polluted and derelict land is brought back into productive use; similarly the socio-economic impacts of a major project on a community could include pressure on local health services and on the local housing market, and increases in community conflict and crime. Projects may also have immediate and direct impacts that give rise to secondary and indirect impacts later.

A reservoir based on a river system not only takes land for the immediate body of water but also may have severe downstream in implications for flora and fauna and for human activities such and sailing.

The direct and indirect impacts may sometimes correlate with short-run and long-run impacts. For some impacts, the distinction between short-run and long-run may also relate to the distinction between a projects construction and its operational stage; however other construction-stage impacts, such as change in land use, are much more permanent. Impacts also have a spatial dimension. One distinction is between local and strategic, the later covering impacts on areas beyond the immediate locality. These are often regional but may sometimes be of national or even international significance.

Environmental resources cannot always be replaced; once destroyed, some may be lost for ever. The distinction between reversible and irreversible impacts is a very important one, and the irreversible impacts, not susceptible to mitigation, can constitute particular significant impacts in an EIA. It may be possible to replace, compensate for or reconstruct a lost resource in some cases, but substitutions are rarely ideal. The loss of a resource may become more serious later, and valuations need to allow for this.

Some impacts can be quantified, others are less tangible. The latter should not be ignored. Nor should the distributional impacts of a proposed development be ignored. Impacts do not fall evenly on affected parties and area. Although a particular project may be assessed as bringing a general benefit, some geographical areas may be receiving most of any adverse effects, the main benefits going to others else where.

There is also a distinction between actual and perceived impacts, subjective perceptions of impacts may significantly influence the responses and decisions of people towards a proposed development. They constitute an impact source of information, to be considered along side more objective prediction of impacts. Financially, all impacts should be compared with the “do nothing” situation, and the state of the environment predicted without the project. This can be widened to include comparison with anticipated impacts from alternative development scenarios for an area. The words “impact” and ‘effect’ are widely used in EIA effects and impacts can sometimes used synonymously.

FME procedural and sector guidelines on EIA in Nigeria. EIA procedure as illustrated in the figure requires the preparation and submission to FEPA of either a screening report for the project or activity that requires preliminary assessment, or a mandatory report for an action included in the mandatory study list.