Analysis of the occupancy rates of İstanbul Dams and optimum water management strategies against climate change effects

İstanbul is facing an increasingly deepening water management crisis due to its growing population, rapid urbanization, and climate change. This study aims to assess the current status of urban water management using over 23 years of daily occupancy data from İstanbul's ten main dams. The dataset, provided by the İstanbul Water and Sewerage Administration (İSKİ), underwent extensive preprocessing, including eliminating missing observations, cleaning of outliers, and normalization. Statistical analysis of occupancy rate differences among dams was performed using the nonparametric Friedman test (<i>Q</i> = 8,083.929; <i>p</i> < 0.0001), revealing significant performance inequalities with a high significance level. The inequitable distribution of water resources was measured using the Gini coefficient, and a value of 0.65 indicated a striking imbalance in the current system. Geographical analysis revealed that dams located in the north have stable occupancy rates, while dams closer to the city center and under urban pressure exhibit erratic and underperforming conditions. Time series analyses revealed distinct seasonal fluctuations across dams. These patterns reflect the dams' responses to different climatic and spatial conditions, and no direct assessment has been made of factors such as climate change. The study revealed that the occupancy fluctuations and inequalities exhibited by the İstanbul dam system over time vary significantly depending on the dam's location, basin characteristics, and operational conditions. This suggests that the current dam structure is far from a spatially homogeneous entity and that management approaches should consider this diversity. This study aims to contribute to developing sustainable and climate-adapted water policies for megacities like İstanbul through a data-driven governance approach.