Multi-Criteria Evaluation of Land use Effects on Environment using Quantitative Methods in GIS: The Talighan Basin (Iran)
Dr. Farshad Nourian and Mr. Ali Jahani (Iran)
Department of Urban and Regional Planning, Faculty of Fine Arts
University of Tehran, Tehran, Iran
Tel:+91-21-6409696 Fax: +91-21-6461504
E-mail: fnoorian@chamran.ut.ac.ir
Abstract
Rapid land use change has become a recurring phenomenon in the developing world, leading to a built up of pressure on environment. The objective of this study is to determine the effectiveness of the Minimum Distance to Ideal Point (MDIP) method when evaluating the land use effects on environment The results obtained from the MDIP is compared with the results from the more common overlay method, using the image processing of Landsat Thematic Mapper (TM) data and geographic information systems (GIS). It is shown here that MDIP method is more effective in reducing cost and facilitating the evaluation process since it takes advantage of and can be utilized with ease in a GIS environment.
Introduction
Rapid land use change has become a recurring phenomenon in the developing world. One reason is said to be the accelerated rate of urbanization in those nations; a rate much faster than in the developed ones (Pugh, 1996). Following a similar pattern in Iran, the growth of urban population and economy has created a higher urban land demand than previous decades, leading to significant change of landscape. The result has been a built up of pressure on environment. As urban regions grow, more land will be needed to satisfy further growth of urban population in the future (Yeh, and Li, 1998).
Thus, it is becoming increasingly important to effectively analyze ecological, economic, social and human resources in order to properly define the use for each piece of land (Tri, 1993). It is expected that the results of such studies lead to development of appropriate planning and policy making alternatives for affected regions before it is too late. (Pereira and Stein, 1993; Chafer and Wright, 1994).
In examination of any region's ecological characteristics, it is apparent that major factors which can define suitable land for particular use, are not equal in terms of significance. In fact, some factors are more important than others, and therefore, appropriate weights for each factor need to be considered (Makhdoum, 1993). There are a number of methods to help the researcher to decide on weights. (Bronsveld et al., 1994; Tri, 1993, p.377). Most ,methods, however, are based on qualitative decision-making and personal judgment. In effect, in such methods, the importance of each factor is considered in isolation and the interaction between factors is mainly ignored.
One such method, which has been traditionally used in evaluation of land use effects, is referred to as "overlaying"(Carver 1991; Pereira and Stein, 1993, p.420). In this article, the results obtained from the said method is compared with results of another using image processing of Landsat Thematic Mapper (TM) data and geographic information systems (GIS).
In the outset it needs to be mentioned that there are several methods which are more compatible with digitized data and raster GIS, including the "logical combination", "concordance-discordance analysis", "weighted linear combination" and "minimum distance to ideal point" (MDIP). It is only the latter, however, which is discussed in more detailed here. The objective of this study is to determine the effectiveness of the MDIP method as compared with the traditional one when evaluating the land use effects on environment. Here, the possibilities of analyzing land suitability using remote sensing data with GIS is explored.
Changing Character of the Study Region
The study area is located in the northern part of Iran, referred to as Talighan (figure 1). This region, which is now an agricultural spans, dissected by many creeks with villages scattered over the landscape, is bound to witness a great and rapid change soon. It is a combination of region's old and newly created attributes which is making her attractive to Iranians either as tourists or as prospective long-range settlers.
Figure 1: Proximity of Talighan to city of Tehran
First, the region is blessed with a natural beauty of its own: 240 square kilometers of mountain peaks and valleys surrounded by the snowy Alborz mountains and Alamut, Zyaran, Justan and Nesa watersheds sitting between 36 5' to 36 19'N and 50 36'E to 50 54'E. Second, a major dam over the Talighan River was recently completed and officially inaugurated. Besides the dam's utility for irrigation and electricity production, it is fast becoming an attractive site for fishing, boating and water-skiing enthusiasts.
