Decreasing lateral migration and increasing planform complexity of the Dommel river during the Holocene

Abstract

River planform and lateral activity largely result from the balance of flow strength, i.e. stream power, and bank erodibility (Nanson and Croke,
1992; Kleinhans, 2010). Floodplains of meandering rivers consist of a variety of
depositional units with different erodibilities, such as point bar, backswamp and natural levee deposits (Allen, 1965; Nanson and Croke, 1992; Smith et al., 2009). Low-energy meandering rivers can have sufficient stream power to erode
the non-cohesive units, but insufficient stream power to erode the cohesive units. Theoretically, low-energy meandering rivers may become laterally stable when the proportion of erosionresistant floodplain deposits gradually increases, e.g. due to steady accumulation of fine-grained counter-point bar deposits (Makaske and Weerts, 2005; Smith et al., 2009). However, limited field evidence exists on the long-term evolution of lowenergy meandering rivers, to test this relationship between lateral channel stability and the evolution of floodplain sediment composition. Therefore, we investigated the planform evolution of the lowenergy Dommel River in the southern Netherlands, along with the Holocene evolution of its floodplain deposits.