Environmental Vulnerability Assessment of Lorestan Province Using Multi Criteria Decision Analysis

The environment and development are two major concerns worldwide. The state of being under the influence of human activities and the increase in demands for resources utilization is a factor which prompts researchers to vulnerable areas and take necessary measures where it is required to manage and protect the environment and sustainable development. In this study, environmental vulnerability index EVI of Lorestan province with characteristics of natural impacts (topography, climate, geology, vegetation index NDVI, water density), environmental impacts (erosion, land use, DRASTIC index) and human impacts (road density, population density and waste depot location), have been investigated. For this purpose, two analytic hierarchy process AHP and weighted linear combination WLC , based on the geographic information system, have been used. Environmental vulnerability impact maps of the two methods were categorized in 5 classes of very low, low, moderate, high and extreme vulnerability. Based on the results of the AHP method, 1.76% of the province with an area of 482.1 km2 is located in the category of extreme vulnerability. Also, based on the results of the WLC method, 14.18% with an area of 3998.4 km2 was placed in the category of extreme vulnerability. Hot spots in the province include the center and south of Aleshtar City, the center and east of Khorramabad City, the center and east of Boroujerd City, Doroud center, north and east of Aligoudarz and northern Azna. In the cities of Kouhdasht, Rumeshkan, Doureh and in the west of the city of Poldokhtar and northwest and south west of Nourabad known as hot spots. Finally, the priority of vulnerability to surface and underground water resources, vegetation and soil was determined in the province.
Extended Abstract
1- The environment and development are two major concerns worldwide. The state of being under the influence of human activities and the increase in demands for resources utilization are the factors which prompt researchers to identify vulnerable areas and take necessary measures when it is required to manage and protect the environment and express sustainable development. Therefore, the aim of this study is to determine the spatial pattern of environmental vulnerability in Lorestan Province, through which the critical points of the province and the contribution of natural and human factors to the vulnerability of the regions are identified.
2- Environmental vulnerability index (EVI) of Lorestan Province has been investigated with characteristics of natural impacts (topography, climate, geology, Normalized Difference Vegetation Index (NDVI), and water density), environmental impacts (land use, DRASTIC vulnerability index and erosion) and human impacts (road density, population density and waste depot location). For this purpose, two methods of analytic hierarchy process (AHP) and weighted linear combination (WLC) have been used. To apply AHP, a questionnaire was designed to handle paired comparison between the criteria and their classes. Then, the relative importance of the elements was determined by 15 environmental experts and the weights ware calculated using the Expert Choice software. Subsequently, the vulnerability map was prepared according to this method. Also, for the weighted linear combination method, considering the importance of the classes of criteria and the expert opinion in relation to the terms of the study area, the threshold for the criteria was determined and the maps were standardized using the scale of 0-255 in Idrisi TerrSet software environment. So that, the symmetric fuzzy function was used for height, slope and vegetation index, the decreasing function was used for the average rainfall and waste depot location criteria. Besides, increasing function was used for geology, mean temperature, water density, road density, population density, land use, DRASTIC index and erodibility criteria. Then the vulnerability map was prepared and eventually, maps of the eenvironmental vulnerability index derived from the two methods were categorized into five classes of extremely low, low, moderate, high and severe vulnerability.
3- The results showed that according to the analytic hierarchy process, 15.2 percent of the province's area was very vulnerable, 44.38 percent had a low vulnerability, 42.22 percent had a moderate vulnerability, 9.51 percent was located in the high vulnerable class and 1.76% was placed in severely vulnerable category. Therefore, the most area of the province was located in the low vulnerability category. According to the weighted linear combination method, 1.94 percent of the province's area was very vulnerable, 12.25 percent had a low vulnerability, 30.50 percent had a moderate vulnerability, 41.14 percent was located in the high vulnerable class and 14.18% was placed in severely vulnerable category. Therefore, based on this method the most area of the province was located in the high vulnerability category. Compared to the analytic hierarchy process, the hot spots in the province through weighted linear combination method were more extensive. The size of the environmental vulnerability classes differentiated by elevation categories showed that the altitudes of 191-1000 includes the highest range of hot spots compared to the extent of its province's coverage. After that, the altitudes of 1000-2000 and 2000-3000 were ranked second and third, respectively. The extent of the vulnerability classes differed by the counties of Lorestan Province showed that based on the area of each county, Aleshtar has the highest rate of vulnerability than any county. Subsequently, Boroujerd, Doroud, Khorramabad, Poldokhtar, Aligoudarz, Nourabad, Azna, Roumeshkan, and Kouhdasht are in next categories respectively. Most identified hot spots were distributed in center and south of Aleshtar, center and east of Khorramabad, center and east of Boroujerd, north and east of Aligoudarz and north of Azna. Also these spots can be recognized dispersedly in Kouhdasht, Roumeshkan and Doureh, north of Poldokhtar and northeast and south of Nourabad.
4- The investigation of the vulnerability condition of recognized hot spots in the counties of the province showed that the effective factors in the increasing of environmental vulnerability vary based on the county. This means that in Aleshtar, Khorramabad, Boroujerd, Doroud, Aligoudarz and Azna counties, agricultural and urban land uses had the highest role in the environmental vulnerability, while in Kouhdasht, Roumeshkan and Doureh counties oak forests and in Polodokhtar and Nourabad, agricultural lands and sensitive geological structure have been effective in the increasing of vulnerability and recognition of hot spots. Recognizing the vulnerability hot spots and their most important formation factors in county level can determine the priority of environmental policy and planning for mitigating the environmental vulnerability level.