Description of the Environmental Scenery
The challenge to make the environmental impact assessment, a more rational, practical, ethical, adaptive, rigorous, collaborative and substantive tool has required among other many approaches, the development of the Base Line Study (ELB).

What is an ELB? Without a formal definition, an ELB is defined as a "multidisciplinary study field" that takes place before or during the initial stage of a development project".

Are the ELB required by the Mexican Government? In Mexico, neither the Federal Registration of Procedures nor the Mexican Legislation includes any administrative act explicitly requesting the execution of an ELB. However, as stated in section IV of article 12 of the rules of the law of the ecological balance and the protection of the environment in terms of the environmental impact assessment, a Manifestation of Environmental Impact (MIA), must include a "Description of the environmental system and marking of the environmental problems detected in the area of influence of the project".

Why should an ELB be done? An ELB is the way in which CAM has answered to the need to have descriptions of the environmental setting, through the implementation of field studies that describe the physical, biological, and social aspects which can be affected by the implementation of a project, since it’s the description prior to its implementation.

In CAM, the descriptions are based in an area of potential influence of the project, not only within the polygon land marked initially by the client; which allows to make estimates of impact with better livelihoods and, in turn, propose more efficient measures of prevention, mitigation and compensation of likely impacts. This strategy aims to provide the client with better knowledge of the area in order to shield the project from possible questions or actions of antagonistic groups.

Who requires an ELB? The ELB are regularly requested by businesses searching compliance with standards of the World Bank and/or the International Finance Corporation (IFC), in such way that it supports a documented and defendable feasibility studies required for the granting of funding.

How long does it take the execution of an ELB? Its duration is also variable, because it depends largely on pre-existing knowledge had of the area. In most cases, it is highly recommended that the field work for the description of the vegetation and fauna include at least two seasons of an annual cycle (dry season and rainy season).

Is it enough that an ELB is developed in a bibliographic way?In fact, any ELB requires extensive bibliographic research, however, the information must be complemented with field studies. However, the most studied is an area, the verification of field should be simpler.

What is the usefulness of integrating information from an ELB in a geographic information system? Usually when it is time for formulating a project, the information that describes the infrastructure that must be built is still very vague, so levels of location of the various required installations have at that time, can be very different from those who will leave the final track of the project.

A GIS to incorporate information from an ELB will enable decision-makers to assessment exercises that incorporate environmental variables in an expeditious manner, without requiring a re-teaming of field. This fact is also an advantage when during the process of evaluating a MIA, the authority requests additional information to be able to rule.