M L Agrawal
Department of Civil Engineering
Indian Institute of Technology
Assistant Professor, Department of Civil Engineering, IIT, Kharagpur, India
Senior Scientist, Regional RS Service Center (ISRO), Kharagpur, India
Most of the ecological attributes are spatial in nature and for a rational assessment of ecological impacts it is necessary to quantify the impacts on individual attributes considering their spatial variations. In this paper a methodology is demonstrated with reference to a case study of highway development project in India, for the quantification of impact on individual ecological attributes based on the perception of public in the influence
Major road development projects have been formulated at national level under National Highway Development Project (NHDP), which will strengthen and widen 14,000 kilometers of National Highways by 2007 (Maitra et al., 2002). Various State Governments have also started projects for upgrading some of the state highways. Highway development projects cause ecological destabilization and habitat disturbance of the surroundings. Thompson et al., 1997). Development with environmental protection and sustainability are the main goal of the policies of Government of India. Assessment of impact on ecological attributes is one of the main components of EIA for highway project (IRC, 1989).
Highway development project may affect ecological components like plants, sensitive plants, amphibians, reptiles, mammals and sensitive fauna (Canter, 1996; Rau and Wooten, 1980; Agrawal and Dikshit, 2003). For predicting the impacts on ecological attributes the approaches available are qualitative approaches; habitat-based approach; physical-modeling approach and biodiversity based approach (Canter, 1996). All these generic approaches require an extensive database related to the ecological attributes of the project area as well as post-project impact data for the similar projects in the vicinity of the proposed project. In developing countries, normally such extensive database is not available due to the absence of post-project monitoring network.
Most of the ecological attributes are spatially distributed in nature and the traditional methods of impact assessment do not consider the spatial variation of impacts. As a result, the assessment of impact on ecological attributes becomes incomplete and inaccurate. GIS is an established tool for collecting, storing, retrieving, transforming and displaying spatial data (Burrough, 1986).
Study Area and Selection of Ecological Attributes
A 56 km long stretch of National Highway (NH-60) from Jaleshwar to Kharagpur in India is selected for the present work. This stretch of National Highway is in the process of being upgraded from two lanes to four lanes. In order to assess the ecological impacts due to the development of study road stretch, approximately 15 km on either side of the road with existing physical boundaries, are considered. The location plan of the study area is shown in Fig.1. Six ecological attributes are considered for assessing impacts due to highway development project in this study based on information available in the literature (Rau and Wooten, 1980; IRC, 1989; Canter, 1996; NHAI, 2000; Agrawal and Dikshit, 2003). The biological attributes used for the present work are as follows.
- Impact on Plants
- Impact on Sensitive Plants
- Impact on Amphibians
- Impact on Mammals
- Impact on Reptiles
- Impact on Sensitive Faunas
A methodology is formulated for designing of questionnaire; collection of data; preparation of spatial database; and quantification of impacts. Major steps are described below.
- Designing questionnaire There were two major components of the questionnaire. The first part consisted of information regarding respondent’s socioeconomic status like income, education, occupation, age, sex, etc. The next part of the questionnaire consisted of respondent’s perception about the likely impacts on various ecological attributes due to the development of highway.
- Collection of data For collecting data related with public perception about likely impacts on ecological attributes, the respondents were selected from different locations along the study road stretch and also at different distances from the centerline of the highway. A detailed description of the ecological attributes was made available to respondents before they were asked to express opinions about perceived impacts on different attributes. For obtaining likely impact on each attribute, respondents were asked to select one of the five impact categories as Highly adverse/Moderately adverse/No impact/ Moderately positive/Highly positive.
- Preparation of spatial database For preparing spatial database, the responses obtained in the form of five impact categories were coded in GIS database using the discrete impact scores (Antunes et al., 2001). The impact scores at intermediate points were obtained by generating a surface of impact score in GIS environment. As the change of impact is continuous, the impact categories were redefined based on selected ranges of impact score rather than discrete values.
- Quantification of ecological impacts For spatial quantification of impacts the area under each impact category was estimated for different ecological attributes. With the help of GIS database, the impact values for different ecological attributes were also estimated by multiplying the area impacted with the impact score. This impact value is a summary measure for the extent of impact on each attribute considering both the impact score and the area affected.