Spatial variability in river bed porosity determined by nuclear density gauging: A case study from a French gravel‐bed river

Porosity is one of the key properties fluvial sediments. It defined as ratio pore volume to total volume. In river science, porosity often assumed be spatially constant, which might a gross simplification reality. Ignoring spatial variations in can cause errors morphological, ecological, hydrological, hydrogeological and sedimentological applications. Although detailed information about obtained from measurements at field sites, such has never been collected where these important. this study, were carried out quantify magnitude variation for four different environments braided river: confluence, tributary delta, braid bar secondary channel. A nuclear density gauge was used measurement porosity. The proved time-saving labour-saving technique that produces accurate values with root mean square error 0.03. showed significant differences porosity, being lower confluence than delta Semi-variogram analysis absence any correlation distances beyond 4 m. This shows distance cannot parameter extrapolation system unless less At least eight are required obtain reliable estimate sedimentary environment, i.e. uncertainty <0.03. grain size characteristics found have impact on relationships between parameters not very strong study. unique dataset, presented article, provides valuable source researchers managers.