Modified ICOLD Results Equivalency with the Aim of Using the Decision of Iranian Leopold Procedure in Water Resource Development Projects (Case Study: The Physical Environment of Peyghamchay Dam)

Different methods are used in environmental impact assessment (EIA), like matrix methods which are included Leopold, Moore, conventional and modified ICOLD and etc.  Since the conventional and modified ICOLD results are mainly qualitative and decision making for implementation or non- implementation of the project would be difficult. Therefore, the aim of present study is offering strategy to normalize the results of modified ICOLD in order to compare with the results of Iranian Leopold method, while investigation and comparison between the results of the EIA has been taken by using the conventional and modified ICOLD matrices.

For this purpose, we used the EIA tools on the physical environment and only at the construction phase of Peyghamchay embankment dam, as a case study. Initial scrutiny was performed using both conventional and modified ICOLD points out that although the number of positive and negative impacts are the same in groups (+96, -235), but the impact values was quite different in two methods.

The value of positive impacts of conventional and modified ICOLD are +156.0 and +260.2 and the value of negative impacts are -341.0 and -392.8, respectively. These amounts ​​indicate an increase in the value of positive and negative impacts of 66.8 and 15.2 percent in modified ICOLD method compared to conventional, respectively. The normalized results of modified ICOLD method point out that the final value of physical environment impacts compared with principles of decision-making in Iranian Leopold method amounts to +0.83 and -1.08 for positive and negative results, respectively. In this case, for the physical environment, implementation of the project can only be carried out by recommended reforms. Discussion and

Considering the strategy presented in this research (the normalization of the results in modified ICOLD method), this method can be utilized exclusively and effectively, therefore, there would be no need to use the both methods for evaluation at the same time.