Abstract
<jats:p>Floodplains sustain fisheries, water supply, and climate regulation, and the services they deliver depend on the water regime — the extent, depth, frequency, duration, and connectivity of inundation — which dams, drought, and land-use change are altering. Remote sensing (RS) and Geographic Information Systems (GIS) can supply the evidence needed to manage these systems sustainably, yet the methods remain dispersed and their fit to management needs has not been assessed. Following the PRISMA-ScR framework and a publicly posted protocol, peer-reviewed studies were retrieved from two databases (Dimensions and OpenAlex, 2004–2026) and screened in two stages by two independent reviewers; data were charted on study area, sensors, methods, water-regime variables, and drivers, and the variables were then mapped onto the decisions and Sustainable Development Goal targets they inform. Of 132 studies, 52% appeared since 2021. Inundation extent dominates (54%), mapped mainly with Landsat (36%) and radar, whereas water level (28%), connectivity (20%), hydroperiod (16%), storage (14%), and depth (8%) remain scarce, as does evidence from data-scarce and transboundary basins such as those of Central Asia. The attributes most needed for environmental-flow, allocation, and restoration decisions are thus the least observed — a decision–observation mismatch that sets the priorities for floodplain monitoring.</jats:p>