Examining changes in daily rainfall patterns attributable to urbanization: a study of watershed hydrology transformation.

Urbanization significantly alters land use, impacting local hydrological processes in rapidly developing areas like the Tehran watershed in Iran. This study examined how transitions from agricultural and natural landscapes to urban environments affect daily rainfall patterns, using multifractal spectrum diagrams, correlation dimensions, Lyapunov exponents, and approximate entropy. Certain stations demonstrated considerable changes in approximate entropy, with the maximum standard deviation increasing by as much as 88.61 units, indicating a rise in the unpredictability of rainfall patterns, likely due to environmental alterations driven by urban expansion. Furthermore, several stations experienced a notable increase in the Lyapunov exponent, with the maximum standard deviation escalating by 56.82 units, suggesting a trend towards increased chaos in rainfall dynamics, which could elevate the risk of flooding. Conversely, lower correlation dimensions recorded at some stations implied more stable hydrological responses, reflecting resilience to extreme weather events, thus emphasizing the intricate relationship between land use and hydrological systems. Overall, stations located closer to urban centers exhibited an increase in both the frequency and intensity of daily rainfall events. This research provides valuable insights into the interplay between land use changes and hydrological processes, underscoring the importance of sustainable urban planning and effective water resource management. This research offers critical insights for flood risk management and urban policy in Tehran, informing adaptive drainage systems, green infrastructure, and zoning regulations to mitigate flood risks and enhance water sustainability in urbanizing regions.