Application of Multi-Criteria Decision-Making Methods in Environmental Risk Assessment (Case Study: The International Wetland of Shadegan, Khur¬_e_ Omayyeh and Khur_e_Mousa Estuary)

1. Introduction Wetland ecosystems are stable ecosystems on the earth providing considerable ecosystem characteristics. Although remarkable advances have been observed in the quantity and valuing some key ecosystem products and the services provided by these habitats, there are still some major challenges with the lack of sufficient knowledge about the relationship between the changes developed in the structure of the ecosystem and the performance of these ecosystems in providing services being the greatest challenge. Based on this, monitoring the trend of the changes in wetlands and their surrounding lands can be effective in the management of these valuable ecosystems. Investigating the environmental risk is a suitable instrument for evaluating and ensuring understanding of the relationships between stressor factors and environmental effects especially in wetland ecosystems. In general, application of methods of evaluating environmental risk is one of the important tools in studying environmental management along with identifying and mitigating potential environmental damaging factors in wetland regions in order to achieve sustainable development. Today, multi-criteria decision-making methods are employed in evaluating the risk in many studies. Examining the background of applying multi-criteria decision-making methods in risk evaluation indicates that these methods have been used in different cases either alone or together with other methods for risk evaluation. This research has been conducted with the aim of identifying the factors of destruction and threat of the Shadegan International Wetland, Alomieh Estuary, Moussa Estuary and their analysis through multi-criteria decision-making methods in order to ordain efficient rules and adopt suitable mechanisms in confrontation with destructors and present managerial solutions to lower the consequences of these factors.
2. Material and Methods In the first phase of this study, to identify and screen the main criteria of project selection, Delphi method was used. In this study, the panel of interest was determined based on a combination of experts with different expertise and out of a sample of 20 individuals, in which experts with various expertise gave a score from 1 to 5 (Likert scale) to each criterion, where the criteria whose mean scores were lower than 3 were removed. In this way, 35 criteria were identified as the most important and considerable risk for Shadegan Wetland and further proceeded to the second phase for prioritization and analysis. In this stage, multi-criteria decision-making methods were used, in which hierarchical analysis process was employed for prioritizing the criteria using Expert Choice 11 software. In order to explain the risk, the concept of ALARP principle was used. The indices of risk evaluation including the impact intensity, incidence probability, and the sensitivity of the receptive environment in environmental risk evaluation of wetlands do not have an equal value and significance. For this purpose, to weight the factors effective in estimating risk level and for prioritization of risk options, the technique for order of preference by similarly to ideal solution (TOPSIS) and Excel software were benefited from for calculations. The spectrum of scoring to each of the indices of incidence probability, impact intensity, and the sensitivity of the receiving environment was chosen from very low (1) to very high (9) based on hour spectrum. Following investigation of the types and frequency of indices along with the method of score determination of these indices, three indices of risk intensity (C1), risk incidence probability (C2), and the sensitivity of the receiving environment (C3) were chosen for risk ranking using TOPSIS model. Next, after determination of risk priority number using TOPSIS, the risk levels were calculated and evaluated using normal distribution method for each risk. To determine the degree of risk-taking, risks are organized in a descending order, where the elements of the number of the class and the length of the class are determined based on Relations 1 and 2 (n is the number of risks). Next, the risks are categorized based on these classes. Considering the concept of ALARP, the risks under investigation are divided into high risks, medium risks, and low risks. In this study, considering the number and length of classes, the studied risks were categorized in six levels (i.e. critical, intolerable, considerable, medium, tolerable, and trivial risks).
1)The number of classes=1.3 log (n)
2)The length of the classes= the greatest risk value - the smallest risk value/the number of classes
3. Results and Discussion In the first step, the final indices of the wetland's environmental risk were identified and the development of hierarchical tree and classification of the risks threatening wetlands along with their incidence probability in two groups of natural and environmental criteria was performed. Eventually, the final weight of criteria resulting from paired comparisons was obtained in Expert Choice 11 to achieve the score of incidence probability of each risk. Based on the results, among the natural, social, economic, physiochemical, Biological, and cultural criteria, drought and climate change, discharge and disposal of waste in the wetland, dam construction, oil contamination, existence of nonnative species, and application of unauthorized equipment were of high priority. The results obtained from ranking the risks threatening Shadegan Wetland using TOPSIS suggest that drought and climate change, water withdrawal in the upstream and water development plan, dam construction in the upstream and oil contamination, industrial wastewaters, commuting of launch boats, floats and boats, nonnative species, agricultural wastewaters, construction of industries and factories within the wetland range, and urban and rural wastewaters were of the first to tenth priority, respectively. Drought and climate change, water withdrawal in the upstream (water development plan), dam construction at critical level and oil contamination, industrial wastes and commuting of launch boats, floats and boats lied within the intolerable range for wetlands.
The results of investigating the physiochemical parameters of water using Hilsenhoff index indicate that the factors of contamination of Shadegan Wetland that are of significance include entrance of household wastewaters of the villages around the wetland, followed by the wastewater of cane sugar and steel industries. Over the past few decades, the wetland's water regime has undergone major changes in the quantity and quality along with seasonal changes in response to implementation of irrigation development plans at large scales in the upstream of the river's basin. It is estimated that with the development of irrigation system in the basin, around 1200-1500 million m3 of the river's water resources are used for producing crops. This figure is twice the extent of water consumption since the 1991s. Among the factors that have caused destruction and manipulation in the lands within Shadegan wetland range are development of Shadegan city and the surrounding villages, changing wetland land use to agricultural lands, construction of Shadegan-Abadan Road, Shadegan-Imam Khomeini Port (Chamran City), Shadegan-Ahwaz Road, and Abadan-Ahwaz, which go through the middle part of freshwater in the wetland. Similarly, Shadegan Darkhovin's road, development of industrial city or Imam Khomeini Port or Shahid Chamran, development of cane sugar lands together with different agro-industries, construction of nuclear plant, construction of dam in river route Jarahi to Shadegan Wetland one in Ramshir town and the other in Jarahi village, Shadegan Steel industries (under construction), Shadegan Industrial Town, Imam Khomeini Port Industrial Town, Shadegan Petrochemicals (under construction), the tourism station of Shadegan Wetland, wetland land use change to agricultural lands, passage of oil pipes and construction of high-voltage masts along with embankment in the wetland, development of urbanization in Imam Port and existence along with construction of numerous waterfronts within the range of Moussa Estuary. All of these human constructions have caused fragmentation of the habitat.
Recent droughts have caused the drying of around 80% of vegetation populations along with emigration and fatality of about 40% of local cattle. Investigation of the extent of changes in the area of Shadegan Wetland in 1990, 2000, 2003, and 2011 represents 6% reduction in the area of the wetland over these years. The area of the wetland in 1990 and 2000 was the highest and lowest, respectively, due to incidence of severe drought in 2000.
In this study, similar to the study done by Jahed Manesh (2014) together with Jozi and Shafiei (2009) for identifying the risks, Delphi method was used. For weighting the environmental and natural risks and their sub-criteria, similar to the study by Makvandi et al. (2013), Jozi and Shafiei (2009), Rahimi Balouchi et al. (2013), etc. AHP method was employed. For risk ranking through TOPSIS method, unlike Makvandi et al (2013) who used 4 indices of ranking, here similar to Jahed Manesh and Rahimi Baluchi and Malek Mohammadi, three indices were used for ranking. Overall, the results indicated that same as this research, wetland ecosystems are subject to many threatening factors, resulting in ecological imbalance and abnormal appearance of the wetland, putting the wetland entity into danger of extinction in terms of fauna and flora.
4. Conclusion Today, for assessment of environmental risk, various methods are used, each of which has positive and negative points given the studied environment and the conditions governing it. Therefore, one cannot reject or approve one method with total confidence. By employing novel methods in risk evaluation, the intensity of risk incidences and, in turn, the damages and losses incurred to the environment can be prevented or at least mitigated. Further, it is also possible to move in line with proper and optimal management of environmental resources, especially wetlands and with sustainable development. Overall, one can attribute the root of Iran’s wetlands problems to economic poverty, scientific and cultural weakness, and greed, with the results being weakened biodiversity, services, and functions of the country’s wetlands together with economic, social, and cultural disorders. The best approach for integrating wetland science and evaluating risk that could improve risk evaluation process in wetland ecosystems is ecosystem-based approach. Ecosystem management of wetlands can be implemented through developing a managerial plan to decrease major threats in wetland regions. In general, management of coastal regions and especially marine coastal wetlands includes organization of developmental process through interdisciplinary planning. In other words, marine-coastal regions are one of the natural systems requiring adoption of novel managerial methods for achieving sustainable development. Overall, integrative management of coasts can be regarded as a dynamic process in developing a logical and plausible balance between government, society, and culture in achieving sustainable development in marine-coastal regions.