Experiences with side channels along the river Rhine in the Netherlands

During the last decade five side channels were excavated in the floodplain of the river Rhine in the Netherlands. An extensive monitoring programme was designed and executed, mainly arranged around three objectives: checking possible risks, evaluating ecological and discharge targets and extending (scientific) knowledge on side channels. The (monitoring) results of three channels (within one flood-plain) are discussed in this paper. The ecological benefits (after 3 to 6 years) are as expected: establishment of specific riverine plant species as well as rheophilic (adapted to flowing water) fish and macro-invertebrate species. The hy-draulic and morphological processes did not result in too large risks or disadvantages (no decline of navigability of the main channel, nor uncontrollable destabilization of embankments). Bank erosion at the inlets of the side channels alternate with (sand) sedimentation on the bed of the channels. Because the (theoretical) period with flowing water conditions did not change dramatically, no dredging was needed so far to keep the side channels open.