Spatial variability in floodplain sedimentation: the use of generalized linear mixed-effects models
- 1Pyrenean Institute of Ecology-Spanish Research Council, IPE-CSIC. 1005 Avd. Montañana, 50080 Zaragoza, Spain
- 2Leibniz-Institute of Freshwater Ecology and Inland Fisheries, IGB, Müggelseedamm 301, 12587 Berlin, Germany
- 3Aula Dei Experimental Station – Spanish Research Council, EEAD-CSIC. 1005 Avda. Montañana, 50080 Zaragoza, Spain
Abstract. Sediment, Total Organic Carbon (TOC) and total nitrogen (TN) accumulation during one overbank flood (1.15 y return interval) were examined at one reach of the Middle Ebro River (NE Spain) for elucidating spatial patterns. To achieve this goal, four areas with different geomorphological features and located within the study reach were examined by using artificial grass mats. Within each area, 1 m2 study plots consisting of three pseudo-replicates were placed in a semi-regular grid oriented perpendicular to the main channel. TOC, TN and Particle-Size composition of deposited sediments were examined and accumulation rates estimated. Generalized linear mixed-effects models were used to analyze sedimentation patterns in order to handle clustered sampling units, specific-site effects and spatial self-correlation between observations. Our results confirm the importance of channel-floodplain morphology and site micro-topography in explaining sediment, TOC and TN deposition patterns, although the importance of other factors as vegetation pattern should be included in further studies to explain small-scale variability. Generalized linear mixed-effect models provide a good framework to deal with the high spatial heterogeneity of this phenomenon at different spatial scales, and should be further investigated in order to explore its validity when examining the importance of factors such as flood magnitude or suspended sediment concentration.