Urban Water Budget Assessment Based on ALS and Satellite Hydrological Data

Abstract

Urbanization modifies hydrological processes by altering water balance components and increasing drought vulnerability. This study proposes an integrated multi-scale framework combining airborne laser scanning (ALS)-based terrain classification with satellite-derived hydrological datasets (GLDAS and GRACE/GRACE-FO) to assess urban water budget (WB) dynamics. ALS data were used to identify permeable and impervious surfaces, while time-series decomposition was applied to evaluate trends, seasonality, and variability of WB components. The results show that permeable surfaces dominate the study area (71.23%), limiting surface runoff. The WB demonstrates pronounced seasonal variability, with increased fluctuations after 2015, while long-term trends remain statistically insignificant. Surface sealing corrections for evapotranspiration and runoff strongly correspond with the original WB (R = 0.977 and R = 0.998), confirming precipitation as the main controlling factor. The proposed framework improves the representation of urban hydrological processes by linking detailed surface characteristics with large-scale climate observations and supports urban water management and climate adaptation planning.