Analysis and estimation of deforestation using satellite imagery and GIS

Analysis and estimation of deforestation using satellite imagery and GIS

Mesgari Saadi
Geodesy and Geomatics Dept., Faculty of Civil Engineering, K.N. Toosi University of Technology, Tehran, Iran.
Tel and Fax: +98-21-8786215,
Email: Mesgari@jik-ac.org

Ranjbar Abolfazl
Geodesy and Geomatics Dept., Faculty of Civil Engineering, K.N. Toosi University of Technology, Tehran, Iran.
Tel and Fax: +98-21-8786215
Email: ranjbar57@yahoo.com

Introduction
Forests amongst other natural resources have been degraded during the last decades continuously. The following factors are the main causes for such degradation:

Changing of landuse from forest into pasture, agriculture and urban, as a result of population growth and general land scarcity,
Cutting down of forests for timber production and wood industries,
Use of the wood as a source of heat and energy in economically poor area,
General degradation of forests caused by industrial growth, environmental pollution, increase in fuel consumption and global warming.

It is obvious that the most important factor in the destruction of forests is the human activities. For a better and sustainable management of such resources we need to know:

The amount and location of deforestation,
The rate and speed of deforestation, and
Reasons and causes of deforestation,

The science and technologies of GIS and remote sensing could be a perfect tool for answering the above questions. Remote sensing can be the basis of fast and inexpensive data collection and the analytical capabilities of a GIS can be used for analyzing the types, location and rates of changes. The final aim in this research is to study and estimate the changes (damages) in the forest areas of Arasbaran, north-west of Iran and to evaluate the importance of different factors in this phenomenon.

Study area
The study area, called Arasbaran, is a mountainous area with elevation between 300 and 2700 meter above the see level. It is in the north of Azarbayejan province and very near to the Caspian sea. The area is located between 38º40´ and 39º09´ latitude and between 46º42´ and 47º03´ longitude. It covers a diversity of elevation, slope, population and landuse and includes a variety of see shore, rivers, etc. Beside the undamaged natural environment in some parts, a big part of the area has been changed by agriculture and grazing activities. This includes the thinly scattered woods, pastures, about 66 villages and differently cultivated areas.

The data set used
The satellite images used in this study are a Landsat TM image of 1987 and a Landsat ETM+ image of 2001 with a general resolution of about 28.5 meters. The old 1:50000 topographic maps of the Army’s Geographic Organization and the new 1:25000 digital topographic maps of the National Cartographic Center of Iran have been used for geo-referencing of the two images. The contour lines of the topographic maps are used for the generation of three maps. These maps represent values of elevation, slope and aspect in the area. Moreover, the location of the villages are extracted and used for generating the map of distance from the population centers.

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