Rainfall random variability and its effects on flood risk management in Iran

Changes in rainfall and topography are two essential factors in flooding changes and flood risk management. In this study, we investigated rainfall (random changes) and topographic changes in the flooding in Iran. Rainfall series on 140 synoptic stations and topographic data at six watersheds during 1975–2017 were collected. Average error equal to zero, equal frequency, MiniMax, MinMAD, the least-squares, and equal frequency least-squares methods have been used to assess the random effects of rainfall on flood changes. In this study, we studied the random effects of rainfall on flood changes and their relationship with topographic distribution based on the increased rate of rainfall randomness and topographic distribution. Results showed that spatial analysis of flood risk has randomness-dependent relationships. When the randomness rate of rainfall increases, flood variability increases more substantially based on topographic distribution. The results of the study present risk-based spatiotemporal patterns of floods for environmental planning.