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The choice of analytical method and sample pretreatment has significant consequences for the shape of particlesize distribution (PSD) frequency curves, and therefore for the evaluation of soil textural parameters. Here, the comparison of several granulometric methods based on different physical principles is presented: wet sieving (WS), based on gravity and the mechanical force of water, was combined with pipette (PP) sedimentation/settling velocity, Micromeritics SediGraph (MS) sedimentation/x-ray attenuation and Coulter Counter (CC) electroresistance particle counting. The Malvern Mastersizer (MM), an instrument based on laser diffraction, was used without WS. Twelve typical temperate-region soil types were chosen for this study on the basis of their mineral composition, organic matter content, conductivity and magnetic susceptibility. The modalities of PSD frequency curves obtained by different methods were compared. The results showed considerably larger clayfraction contents determined with the sedimentation techniques, PP and MS, than that obtained by CC or MM. Statistical correlation and regression models were used to compare the fractions of clay, silt and sand obtained with different methods. Linear correlations were found in almost all cases, except those comparing clay fractions obtained by CC with those obtained by MM, PP and MS methods. These correlations were non-linear. The observed difference was attributed to the presence of aggregates and/or magnetic properties of soil particles. However, more data are needed to verify this hypothesis. The implications of sample pre-treatment with dispersant and hydrogen peroxide (H 2 O 2 ) were evaluated by the MS and CC techniques and observed by the scanning electron microscope. H 2 O 2 was found to be an efficient disaggregating agent. The use of dispersant resulted in the increased amount of the clay fraction measured by the MS method.

This paper proposes a coastal erosion monitoring system for beach erosion management, which we demonstrate on natural and artificial pocket gravel beaches in Croatia. The approach uses low-cost Structure-from-Motion (SfM) photogrammetric imaging and multi-view stereo (MVS) to produce high-resolution 3D beach models for detecting morphological changes and erosion occurrence.Coastal state indicators, such as the shoreline position and subaerial beach volume, are derived from the 3D models and used to quantify changes between surveys. The method is illustrated through two case studies and, to our knowledge, these are the first repetitive measurements taken on the Croatian eastern Adriatic Coast (CEAC). In case of the natural Brseč beach, beach rotation was found to be a response to natural forcing from waves of various incident directions. For the artificial Dugi Rat beach, which loses sediment every winter and is subsequently re-nourished every spring, monitoring showed that beach nourishment is of limited durability. Both case studies showed that the SfM-MVS technique is suitable for the rapid and frequent acquisition of 3D survey data, from which quantitative coastal indicators can be derived to inform future coastal management interventions. Significantly, this low-cost data acquisition has a great potential for regular beach management survey. The introduction of beach monitoring in Croatia is timely because emerging Integrated CoastalZone Management (ICZM) practices will require data-based approaches. Moreover, rare natural pocket beaches and the ever-increasing number of artificial beaches are extremely vulnerable to natural and man-made changes. Adaptive beach management, based on systematic monitoring data, should be included in the ICZM, and we detail how SfM-MVS-based monitoring can be used at different levels of the ICZM. Implementing robust ICZM monitoring will require broad considerations and consultation with all stakeholders, so we propose that SfM-MVS beach surveys should be initially integrated into the existing monitoring practices for CEAC sea water bathing quality. Extension of the existing database with rapidly-gathered low-cost 3D beach survey data, from a number of targeted beaches, could be used to provide a crucial baseline for the ICZM and strategic coastal monitoring of the CEAC.

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