LAUSR

Clogging of gravel‐bed rivers is a major issue affecting fish and macro‐invertebrate habitats as well as groundwater–river exchanges. River clogging consists mainly of the deposition and infiltration of fine sediments within the bed matrix, which is a natural phenomenon but can be exacerbated by human activities. Although there are several methods for estimating the degree of clogging, quantitative assessment of clogging remains challenging, not to mention the lack of comparison between these methods. To assess temporal and spatial clogging, such methods also need to be quick and easy to implement. To address this gap, we implemented three quantitative methods to estimate clogging (bed material sampling, infiltration test and interstitial water sampling) and evaluated their suitability for long‐term monitoring. These methods were applied to a natural river bed characterised by high spatial heterogeneity of clogging. The results show relatively good correlations between the different methods, and some equations are suggested to relate the different parameters (fine sediment content, hydraulic conductivity, interstitial fine sediment concentration and interstitial dissolved oxygen). However, some data variability is observed, likely due to methodological limitations related to sampling techniques or sampling depth constraints. The bed material sample obtained using a McNeil sampler allows an evaluation of the fine content, but remains very time‐consuming and limited to the first 15 cm below the surface. In contrast, the infiltration test and interstitial water sampling using a standpipe and a Bou‐Rouch pump allow deeper assessments, beyond 15 cm. The infiltration test appears to be effective for relatively low clogging, while interstitial water sampling is more efficient for high clogging. The results also show that the interstitial dissolved oxygen measurement alone may not be sufficient to accurately estimate physical clogging, particularly in cases of low clogging, but it appears to be a good and simple complementary method. Overall, the infiltration test and interstitial water‐sediment sampling are simple, quick and practical methods. Their combined application provides a reliable framework for assessing spatial clogging variations, enabling the investigation of a broad range of clogging intensities over time.