28Surface water storage and fluxes in rivers, lakes, reservoirs and wetlands are currently poorly 29 observed at the global scale, even though they represent major components of the water cycle and 30 deeply impact human societies. In situ networks are heterogeneously distributed in space, and many 31 river basins and most lakesespecially in the developing world and in sparsely populated regions -32 remain unmonitored. Satellite remote sensing has provided useful complementary observations, but 33 no past or current satellite mission has yet been specifically designed to observe, at the global scale, 34 surface water storage change and fluxes. This is the purpose of the planned Surface Water and 35Ocean Topography (SWOT) satellite mission. SWOT is a collaboration among the (U.S.) National 36Aeronautics and Space Administration (NASA), Centre National d"Études Spatiales (CNES, the 37 French Spatial Agency), the Canadian Space Agency (CSA), and the United-Kingdom Space 38 Agency (UKSA), with launch planned in late 2020. SWOT is both a continental hydrology and 39 oceanography mission. However, only the hydrology capabilities of SWOT are discussed here. 40After a description of the SWOT mission requirements and measurement capabilities, we review the 41 SWOT-related studies concerning land hydrology published to date. Beginning in 2007, studies 42 demonstrated the benefits of SWOT data for river hydrology, both through discharge estimation 43 directly from SWOT measurements and through assimilation of SWOT data into hydrodynamic and 44 hydrology models. A smaller number of studies have also addressed methods for computation of 45 lake and reservoir storage change or have quantified improvements expected from SWOT compared 46 to current knowledge of lake water storage variability. We also briefly review other land hydrology 47 capabilities of SWOT, including those related to transboundary river basins, human water 48 withdrawals, and wetland environments. Finally, we discuss additional studies needed before and 49 after the launch of the mission, along with perspectives on a potential successor to SWOT. 50 51 Keywords: Surface Water and Ocean Topography (SWOT) satellite mission; continental surface 52 waters; lakes; reservoirs; rivers 53 54 3 1. SWOT mission overview 55 56 1.1. The needs for a global water surface mission and its requirements 57 58 In the late 1990s and early 2000s, the crucial need for more quantitative data on spatiotemporal 59 dynamics of surface waters at a global scale became clear in context of a declining in situ gage 60 network and increasing need to observe and model the global water cycle (Alsdorf et al. 2003). To 61 address this challenge, Alsdorf and Lettenmaier (2003) advocated development of a "topographic 62 imager" satellite mission with ~100 m spatial resolution (to observe main channels, floodplains and 63 lakes), temporal resolution on the order of a few days (to sample flood waves and river dynamic at 64 basin scale), and capability to measure height changes that characterize vari...