Uncertainties in measuring and estimating water‐budget components: Current state of the science

Reducing uncertainty in quantifying basin‐scale water‐budget components is one of the most vexing problems for water‐resource managers. Although a vast literature addresses methods and scales of component estimates, uncertainty associated with these estimates is often lacking. Here we review sources of uncertainty and compile reported uncertainty estimates for measurement and estimation methods for six water‐budget components: precipitation, streamflow, evapotranspiration, subsurface discharge, infiltration, and recharge. Quantifying the uncertainty in each water‐budget component data is required before total water‐budget uncertainty can be determined. This article is categorized under: Science of Water > Hydrological Processes Science of Water > Methods Water budget data come in a range of spatial and temporal scales and uncertainty levels. In general, point measurements are more certain, and areal estimates which are required for water budgets have higher uncertainty. Data for subsurface storage and fluxes of water have the poorest spatially explicit data availability and highest uncertainty among water budget components.