Morphological effects of plant colonization of near-bank bars

Abstract

Nature manifests itself in sometimes surprisingly simple patterns, even though we know that the underlying coupled equations are complex and highly non-linear.
Alluvial estuaries, thNew floodplain formation starts with the development of near-bank sediment deposits such as alternate bars and point bars (e.g. Hickin, 1984). An important step of this process is the colonization of the areas emerging during low flow by plants. Vegetation protects local soil from erosion during subsequent high flows and enhances local sedimentation, increasing the vertical growth of colonized areas. The morphological effects of bar colonization by plants has been studied using numerical models (e.g. Crosato and Samir Saleh, 2011), but laboratory experiments have so far focused on the effects of floodplain vegetation (e.g. Tal and Paola, 2010). This work describes the effects of alternate bar colonization by plants on channel morphology in a large-scale laboratory setting with variable discharge and sediment recirculation. Three situations are analysed and compared: without vegetation (a), with vegetated floodplains only (b) and with vegetation colonizing also the areas emerging during low flows (c). at are the result of interacting forces of nature within a mobile sedimentary medium, are a clear manifestation of such patterns. But what constrains
the formation of shape? Which physical laws are behind it? The author does not have the answers, but raises some pertinent questions.