SWOT: Reviewing Challenges and Opportunities in Hydrological Applications to Inland Waters

Monitoring inland waters presents various challenges, from technological limitations to environmental and management issues. The accuracy of data collection is often compromised by the difficulty of accessing remote areas and the temporal and spatial variability of water bodies. These obstacles complicate the implementation of effective strategies for sustainable water resource management and the response to extreme events such as floods and droughts. The SWOT (Surface Water and Ocean Topography) mission is a collaborative satellite project designed to measure and monitor Earth's surface water and ocean topography through time. The primary hydrologically relevant metrics derived from SWOT include: (i) water surface elevation (WSE), (ii) river width, (iii) water surface slope, (iv) discharge-related variables derived from hydraulic relationships and modeling approaches, and (v) lake and reservoir storage variations. Although early calibration and validation studies have demonstrated encouraging performance for key observables such as water surface elevation and river width, important questions remain regarding the robustness of these metrics under diverse geomorphological, climatic, and hydrological conditions. This article aims to provide a systematic literature review on the metrics obtained through SWOT data for inland water. The review critically evaluates current capabilities, methodological limitations, and practical challenges associated with SWOT-derived hydrological variables, with particular emphasis on product selection, filtering strategies, and integration with hydrological and hydraulic modeling. By consolidating recent advances and identifying persistent gaps, this review aims to support more consistent and operational use of SWOT observations for inland water monitoring and water resources management.