Evaluation of the Environmental Risks of Jiroft Dam During the Utilization Phase

Dams are economically, politically, and socially important structures and their roles in the development of countries are undeniable. The purpose of this study was to investigate the environmental risks of Jiroft Dam in the utilization phase so as to reduce its negative effects. Construction of a large dam can threat the environment in various ways. In this research, the physico-chemical, natural, biological, socio-economic and cultural, and safety and health risks of Jiroft Dam were evaluated. 

In this study, EFMEA method was used to assess the environmental risks of Jiroft Dam. To evaluate the relevant risks, 29 parameters in 5 groups, including physico-chemical, natural, socio-economic and cultural, biological, and safety and health risks were chosen. The data were collected by interviewing the experts. The risk factors were evaluated by using EFMEA method based on the probability of occurrence and severity and probability of detection. To determine priorities of the risk levels, the upper and lower limits of each risk and its average and standard deviation were obtained. 

Based on the Risk Priority Number (RPN), the soil erosion with RPN=100 and in river downstream morphology changes with RPN=12 showed the highest and lowest risk values related to the physico-chemical factors. Also, flood with RPN=60 and landslide with RPN=20 displayed the highest and lowest risk values related to the natural risk factors. Moreover, among the biological risk factors, the impacts on the habitat (RPN=75) and threats to the aquatic life of the downstream (RPN=80) demonstrated the highest numerical risk values. The lowest RPN was related to propagation of weeds in the downstream of the dam and changes in food chains (RPN=20). Also, land-use change (RPN=20) and social acceptance and security risks (RPN=6) revealed the highest and lowest risk levels related to the social, economic, and cultural factors. Furthermore, human mistakes before, during, and after the utilization phase, which were related to the safety (RPN=75) and health (RPN=48) risk factors depicted the highest levels of risk, while the growth of insects in Jiroft Dam Reservoir (RPN=12) indicated the lowest risk value. 

According to the findings, soil erosion and sedimentation showed high-risk levels in the group of physico-chemical risks. Moreover, their effects on water sources (thermal layering), pollution (air, sound, soil, and water), downstream-suspended solids, soil eutrophication, and soil compaction were classified in a moderate-risk class, while the river morphology change was classified in the low-risk class. The earthquake, flood, and landslide were classified in the moderate-risk class. Also, the habitat risk and threatening to the aquatic life of the downstream related to the biological risks were classified in the high-risk class. Effects on the vegetation, blocking of the migration route (animal movement), propagation of weeds in downstream of the dam, changes to the food chains, and degradation of harbor area were classified in the moderate-risk class. Among the socio-economic and cultural indices, the land use change as well as the reduced employment and income in the region were classified in the medium-risk class, while the social acceptance and security, tourism acceptance, and land acquisition were classified in the low-risk class. In the group of safety and health risks, human mistakes before, during, and after the utilization phase showed a high risk, while creating a suitable environment for the growth of insects in Jiroft Dam Reservoir displayed a low-risk level. The risks of explosions, war, and terrorism related to the dam, corrosion of facilities, and spread of diseases were classified in the moderate-risk class. The results of this research can significantly help to reduce the environmental hazards of the mentioned dam during the utilization phase.