The usefulness of EIA as a robust and reliable tool for integration of environmental concerns in development planning has already been established the world over. Methodologies for EIA

are being constantly developed and refined to address the anticipated impacts of developments in different sectors on the valued components of the environment. The ecological impact assessment has now emerged out as a more specialized discipline within the larger domain of EIA. Increasing interest in this subject area has resulted in some recent efforts to develop appropriate methodologies (Bagri & Vorhies 1997; IEA 1995; Treweek 1999) for undertaking ecological assessments. The methodological approach adopted for this study (Fig. 2) conforms to the broad framework suggested for ecological assessments by the aforementioned workers.

2.1 Methodological Framework

2.1.1 Desk Studies
The profile of the proposed project, final pipeline route map provided by the authorities of BPCL and the corresponding topographical maps of the area on 1:50,000 scale that provided the spatial information of the area within the pipeline corridor were the primary sources of information for planning this study. Prior to embarking on field observations, all the areas of conservation interest along the pipeline route were identified on 1:50,000 topographic sheets for planning field based observations. The secondary sources of information included scientific and technical reports, working plans of the state forest departments and census records.

Extensive literature search provided the much-needed insight into floral and faunal values of the area. Discussions with the officials of the state forest departments, local NGOs, scientific and research personnel of academic institutions, naturalists and local people provided additional information on the regional ecology.

2.1.2 Site Visit
Once the final route alignment for the proposed pipeline was determined, site visit was undertaken within the identified pipeline corridor between the take off point at Manmad and the receiving point at Manglya in the month of March 2001. During this visit, extensive consultation with project authorities, forest officials and local communities was organised for improving understanding about the project and the environmental dimensions of the project area (Annexure 1).

2.1.2.1 Study Limits
The spatial limit for field studies confined to one kilometre wide pipeline corridor. The width of the corridor was primarily decided on the basis of limits of physical disturbances associated with the activities proposed under the project implementation, and this could be ascertained based on the past experiences of earlier assessments of pipeline projects.

The summary of the landuse within the route corridor of the pipeline is presented in Table 2.1 and the break up of the major landuse are presented in Table 2.2. It is evident that a substantial length (309.963 km) of pipeline traverses through cultivated areas in Maharashtra and Madhya Pradesh. The areas of pipeline corridor supporting the above landuse category was not considered for extensive field investigations, as this category of landuse does not fall within the scope of work outlined for this study. The aquatic and terrestrial wildlife habitats including the areas under wetlands (rivers, reservoirs and ponds) and the Reserved Forests were identified within the route corridor for detailed ecological studies.

Table 2.1 Land use pattern in the pipeline corridor (1 km on either side) based on remote sensing studies

Source: Bharat Petroleum Corporation Ltd.

Table 2.2 Landuse pattern along the total pipeline route in the two states

* The chainage reference for area under cultivation is not relevant to this study

2.1.3 Characterisation of Ecological Receptors

During the course of field work, the two ecologically distinct categories of habitats identified within the pipeline corridor included the forest areas (Table 2.3) and the major water bodies (Table 2.4).

Table 2.3 Forest areas en route the proposed pipeline

Table 2.4 Major water bodies en route the proposed pipeline

* The proposed pipeline is aligned along these water bodies and does not traverse them at any point

2.1.4 Development of Ecological Baseline
Development of ecological baseline would involve characterisation of the ecological conditions that pertain in absence of any superimposed activity or set of activities. This becomes important for consideration of `zero development scenario’ for impact prediction. This required characterization of ecological features of terrestrial and wetland habitat within the pipeline corridor.

2.1.4.2 Characterization of Aquatic Habitats
Hydroperiod is the single most important parameter that has a significant bearing on the wetland characteristics. The frequency, depth and duration of water’s influence determine to a significant extent the biological values and the functions that the wetland provides (Cowardin et al. 1979; Marvel 1992). This parameter was considered in the evaluation of the status of wetlands en route the pipeline. For all major rivers en route the pipeline, the River Corridor Survey (RCS) was developed based on the approaches adopted by National Rivers Authority (NRA 1992). A river corridor consisted of a stretch of river, its banks and the adjacent land (about 50 m) wide. Different parameters which have been recorded for the three sections of river are presented in Table 2.5.

Table 2.5 River corridor survey zones

2.1.4.3 Evaluation of Valued Ecosystems and their Conservation Significance

Identification of valued ecosystems and habitats of conservation significance was attempted based on the established criteria (Box 2.2) for prioritising ecosystems or their components that merit consideration of potential impacts of projects on them.

2.1.5 Impact Evaluation
Impact prediction essentially involves the assessment of future baseline conditions as influenced by activities under proposed development. This step involves development of a mental picture of project induced impacts on select ecological indicators identified for different valued ecosystems or critically important wildlife habitats. Development of impact matrices has been an accepted approach for the evaluation of impacts of pipeline projects (Rajvanshi 1999). Therefore a similar approach has been adopted for the impact evaluation in this study. Fig. 3 provides a generalised matrix representing the project actions and ecological indicators that have been considered in the evaluation of impacts of the pipeline project on specific areas of interest.

Finally, the evaluation of impacts against ecological thresholds and the determination of significance of potential impacts was based on established criteria (Ratcliffe, 1977; Margules and Usher, 1981) adopted in similar projects (WII 1995a; WII 1997).