Lake Water Storage

Lake Water Storage (LWS) refers to the volume of water contained within a lake or reservoir, i.e. the amount of water held below the lake’s surface elevation at a given time. In the literature, LWS is often used interchangeably with terms such as lake storage, lake water volume or storage capacity (Yao et al. 2023). While “lake area” (from imagery) or “lake level” (from altimetry) describe single dimensions, LWS specifically denotes volume, usually derived by combining water surface height (altimetry or SWOT), water surface area (optical/SAR) and bathymetric or hypsometric relationships. The concept is widely applied in global hydrology, climate impact studies and satellite water balance assessments, with major datasets (e.g. GloLakes, Database for Hydrological Time Series of Inland Waters (DAHITI), G-REALM, SWOT hydrology products) using LWS as a key variable to quantify temporal changes in inland surface water resources (Séries Temporelles 2025), (Foreign Agricultural Service 2025), (Deutsches Geodätisches Forschungsinstitut der Technischen Universität München (DGFI-TUM) 2025), (Hou et al. 2024).

LWS is estimated by combining water surface height (WSH) and water surface area (WSA). “Water surface height and area can be combined to calculate volume changes between consecutive dates (Crétaux et al., 2016; Gao et al., 2012; Li et al., 2020; Luo et al., 2022; Song et al., 2013; Terekhov et al., 2020). This can be done using simultaneous observations of water surface height and area or using the height-area (H-A) relationship (Abileah et al., 2011), which synthesizes the lake's bathymetry information into a function that describes changes in surface area as a function of water level. Once the height-area relationship has been constructed, volume change can be calculated by integration (Carabajal & Boy, 2021; Duan & Bastiaanssen, 2013; Magome et al., 2003) and using only one of the two variables.” (Girard et al. 2025).