Amirkabir University of Technology AUT Journal of Civil Engineering 2588-2899 9 1 2025 06 01 Integrating Multi-hazard Risk Assessment and Climate Change Projections for Adaptive Water Resource Management: A Case Study of the Ajichai River Basin 3 18 5707 10.22060/ajce.2025.23579.5883 EN Jafar Chabokpour Department of Civil Engineering, University of Maragheh, Maragheh, Iran. Journal Article 2024 10 03 This research develops an in-depth hydrologic risk analysis for the Ajichai River catchment by using the flow series at the Veniar station for the period from 1966 to 2013. A complete methodology was used to analyze the flood and drought risks, as well as the long-term trends and eventual impact of climate change on the flow regime of the river. Annual maximum flow data were fitted using the Generalized Extreme Value distribution and provided a 100-year flood estimate of 224.9 m³/s, 95% CI: 177.7-272.1 m³/s. A significant decreasing trend in annual mean flow was detected: Sen's slope -0.25 m³/s/year, p < 0.01. The low-flow frequency analysis yielded a high value of the coefficient of correlation r = 0.98, which explained the duration and severity relationship of droughts described by the power-law equation S = 0.0012 × D^1.85. It is evident from the seasonal analysis that during the spring season, 68.7% of the annual maximum flow occurs with an average peak flow of 89.6 m³/s. There was a very important shift in the timing of the floods, a 26-day earlier date of annual maximum flows between the 1970s and the 2010s. It quantified the relationship between annual maximum flow and precipitation: Q = 0.0015×P^2.1, R2 = 0.88, underlining the probable impact of the changes in precipitation on flood risk. In fact, it exposes the complex and dynamic hydrological environment of the Ajichai River basin and signifies a requirement for adaptable water management that concurrently contributes to decreasing flood and drought risks in response to climate change. https://ajce.aut.ac.ir/article_5707_b45c024256f0625350840c2ca5be3269.pdf