Developing the Drought Index in Natural and Engineering Sub-basins (Case Study: Zayandehrood Basin)

Today, due to climate change, we are witnessing limited water resources such as droughts and floods in all parts of the world. From the past until now, dams have been used for water storage, electricity production, and agricultural and industrial uses, which, along with their advantages, will cause environmental damage. The construction of dams will divide the basins into engineering and natural basins, and one of the approaches of this research is to explain the differences and performance of these two types of basins in terms of water resources and drought indicators. The purpose of this research is to review and evaluate the existing indicators and provide an integrated index including the influencing factors of drought, which was chosen as a case study due to the sensitive location of the Zayandeh Rood watershed in the central plateau of Iran. The imbalance between resources and consumption, especially in recent years, is considered as the main factor aggravating drought. The integrated drought index includes various factors such as meteorological and hydrological factors and is verified using agricultural factors. The results showed that in the studied natural basin, the correlation value of the index based on rainfall and evaporation and the validation index is 0.52 and 0.53, respectively, while the correlation of the bivariate index and the validation index is 0.66. In the studied engineering basin, the correlation difference varies from 0.26 and 0.41 respectively for the indices based on rainfall and evaporation to 0.91 for the bivariate index.