Quantifying and characterizing contemporary riparian sedimentation

Abstract

Fluvial processes of erosion, sediment transport and deposition determine the changing form and sedimentary structure of naturally adjusting riparian zones. Riparian sediment storage has both scientific and management importance in relation to: (i) the quantities of sediment that are involved; (ii) the quality of the sediment; and (iii) the dispersal of biological materials, notably the vegetation propagules that are transported and deposited in association with the sediment.After discussing the significance of riparian sedimentation processes, this paper reviews methods for quantifying contemporary sediment deposition within water bodies and their margins. Methods for investigating contemporary riparian sedimentation are given particular emphasis, and the extent to which different methods provide comparable estimates and have been used to support the analysis of different physical and chemical properties of the sediment are outlined. The importance of the following are stressed: (i) selecting a sampling method that is suited to the sedimentation environment; (ii) incorporating careful cross-calibration if measurements from different methods are to be combined; and (iii) replicating measurements to give more robust estimates if small traps are employed. It is concluded that artificial turf mats provide a useful design of sediment trap across a range of environmental conditions because: (i) their surface roughness reduces problems of sediment removal by flood waters or rainfall; (ii) their pliability permits installation on irregular surfaces; (iii) they can be securely attached to the ground with metal pins to resist high shear stresses from river flows; (iv) they are robust and light and so easily manipulated in the field and laboratory; (v) it is possible to fully recover the deposited sediment to accurately determine the amount of sediment deposited and to support a range of other analyses.Results are presented to illustrate how artificial turf mats can be used to estimate the quantity and quality of deposited sediment and to explore the associated deposition of viable seeds. This provides one example of the important hydroecological role of riparian sedimentation processes and of the potential for the development of innovative, interdisciplinary research on riparian sediment dynamics.

Nutrient dynamics, transfer and retention along the aquatic continuum from land to ocean: towards integration of ecological and biogeochemical models

“…Biogeochemistry is an integrative discipline. However, terrestrial and aquatic subdisciplines have developed somewhat independently of each other due to physical and biological differences between aquatic and terrestrial ecosystems and because of differences in research traditions between terrestrial and aquatic ecologists Rip and McCann, 2011;Stergiou and Browman, 2005). Many different approaches for describing biogeochemical processes in the 6 A. F. Bouwman et al: Nutrient dynamics, transfer and retention along the aquatic continuum Table 2.…”

“…Floodplain deposition can lead to considerable trapping of sediment and POM amounting to 10-40 % of the annual load (e.g., Walling et al, 2003). Current estimates are based on measured conveyance losses (e.g., Lambert and Walling, 1987), deposition measured during post-event surveys (e.g., Middelkoop and Asselman, 1998;Steiger et al, 2003), and modeling studies (Hung, 2011;Middelkoop and Van der Perk, 1998;Nicholas and Walling, 1997). Sediment trapping efficiencies in floodplains depend on -apart from sediment settling rates -water discharge over the floodplain, the inundated floodplain area and depth, and residence time of the flood water.…”

“…Organisms require carbon (C), nitrogen (N), phosphorus (P) and other nutrients such as silicon (Si) for critical cellular processes (Sterner and Elser, 2002). Thus, knowledge of these element cycles is essential for our understanding of ecosystem biogeochemistry.…”

Nitrate leaching from short-hydroperiod floodplain soils

“…In GRASS and WIL-LOW BUSH where sedimentation was high, N sedimentation was determined using erosion pins (Steiger et al, 2003). In each plot, nine pins with a distance of 5 m to each other were piled 0.5 m into the ground forming a 3 × 3 square.…”

“…In MIXED FOREST, where the sedimentation was lower, three artificial turf mats (0.3 × 0.45 m) with 2 cm plastic tufts were installed at each plot before floodings predicted by discharge forecasting (Steiger et al, 2003;FOEN, 2011). After flooding, sediment traps were removed and sediments were washed out using deionized water and collected in plastic bins.…”