Global Assessment of Lake Surface Morphology and Its Impact on Water Volume Estimation

Abstract Lake surface morphology, an essential yet underexplored feature of hydrological systems, remains poorly understood, including its effects on water volume estimation. This study investigates north‐south surface profiles of 147 lakes worldwide using ICESat‐2 altimetry data (2018–2024). A meticulous selection process, followed by DBSCAN clustering and moving window averaging, enabled the construction of detailed elevation profiles. Based on metrics of linearity, concavity, and convexity, we classified lake surface morphology into four types: linear, concave, convex, and others. Concave surfaces were the most common (67/147 lakes), while convex surfaces were the least common (11/147 lakes). The formation of these surface types is influenced by factors such as groundwater flow, salinity gradients, and lakebed variations. Surface elevation differences ranged from 0.016 to 2.565 m, averaging 0.221 m. To address the impacts of these variations, we calculated equivalent water surface height ( h eq ) and demonstrated that concave lakes overestimate lake surface height by an average of 0.093 m. Although the volumetric overestimation may seem small (e.g., 0.78% for Lake Victoria), 41% of lakes showed surface elevation differences exceeding their mean monthly variation, posing a risk of trend misinterpretation (e.g., Lake Victoria: elevation difference 0.59 m, standard deviation 0.16 m, monthly variation 0.044 m). These results underscore the critical importance of incorporating lake surface morphology into hydrological assessments, offering a new perspective that could lead to more accurate and comprehensive water volume estimations and ultimately improve global water resource management.