Remote sensing of volumetric storage changes in lakes

Three‐dimensional remote sensing promises a giant leap forward for surface‐water hydrology in much the same way that radar altimetry transformed physical oceanography. However, the complex geometries of small terrestrial water bodies introduce difficulties, particularly with respect to trade‐offs between changing water depth and inundation area. We use in situ measurements of water‐surface stage (ΔH/dt) and remotely‐sensed area (A) to compute time varying storage changes (ΔS) in nine lakes of the Peace‐Athabasca Delta, Canada. Despite their identical geomorphic setting, regression slopes between ΔH and A vary significantly between lakes, primarily from a predictable ‘area‐effect’ but also small bathymetric variations between basins. On average, lateral contraction/expansion (versus stage adjustment) contributes as little as 7% (versus 93%) to as much as 76% (versus 24%) of overall storage change ΔS. We conclude that both surface‐area and ΔH/dt, rather than just either alone, must be measured to confidently estimate ΔS from space. Copyright © 2009 John Wiley & Sons, Ltd.