Assessment of Water Resources Carrying Capacity of the River Basins Using the Simulation Approach and Index-Based Evaluation Method; Case Study: Zarrineh-Roud Basin

The study of impacts of human activities on the environment and the development of socio-economic systems compliant with a sustainable environment has became the center of attention in recent years due to the severe environmental destruction worldwide. Various methods have been developed to evaluate the effects of these activities on the environment and to simulate the coupling human-natural system. One of these methods is "Carrying capacity of water resources", which has been developed in the science of water resources management based on the concept of "Carrying capacity". This research applied this concept to evaluate water resources management and proposed a new framework for assessing the carrying capacity of water resources by developing previous methods, and by combining simulation, indicator-based evaluation and pressure-support factor. The research used a new approach for the carrying capacity evaluation which eliminated some challenges such as ignoring the environmental health status as well as the possibility of interchangeability between indicators. The proposed framework and approach were used for the water resources carrying capacity evaluation in the Zarrineh-roud River basin area, Iran, in the period of 1987 to 2015. The study period (1987-2015) was divided into three smaller periods; first (1987-1999), second (2000-2006) and third (2007-2015), to have proper annual and periodic analyses based on changes in evaluation indicators. The results showed that loading on water resources is in the range of water resources carrying capacity only in the first period and water resources are overloaded in the second and third periods. According to the evaluation standards, the carrying capacity of water resources and the environment health status had decreased one level in each period compared to the previous period, and eventually reached the lowest possible level in the third period. The analysis of pressure-support in water resources indicated that the pressure on water resources has increased and the ability to support water resources has decreased in each period compared to the previous period. These outcomes indicated that implemented policies in the basin have pursue rapid economic developments and have paid no attention to the ability to support water resources. Such policies did not improve the basin condition and made it much worse. Therefore, it is necessary to review the implemented policies and adopt the necessary policies as soon as possible to improve the carrying capacity of water resources. Since the results have well conformity with the realities of the basin and express the effectiveness of the implemented policies, the proposed framework can be used to review the implemented policies in other similar cases. In addition, the framework makes it possible to evaluate scenarios and predict future conditions. Also, it can evaluate the impact of different policies on basin’s water resources, society, economy and the environment and be a confident base for future research.