Experimental assessment of 2D flow velocity fields induced by plant biodiversity in open channels for seed transport.

The two main objectives of the project are resumed as follow :
* Testing innovative methods for the characterization of water mean velocity and turbulence fields, applied to seed transport in vegetated channels
* Conducting an integrated analysis for the understanding of water dynamics and seed transport induced by biodiversity (different morphotypes and plant spatial organizations)

Two types of seed release‘ experiments were conducted in the experimental channel : (i) The first one aimed at characterizing the retention rate of seeds in patches of vegetation with constant lengths in order to assess the effect of density, species and discharge on seed retention (ii) In the second experiment, the same plant density was planted on one to height panels in order to characterize the effect of the length of the patch on the retention and test the hypothesis of additivity of seed retention.

The results showed that the density, the discharge or the type of species significantly affect the rate of seed retention. Based on significant additive effect of the length of vegetated channel on the rate of seed capture, we proposed an additive model of recapture following a power law.

The project ECOFLOW, by using an innovative experiment, paves the way to a better understanding of hydrochorous dispersal in ditches, with consequences on the management of weeds in agricultural watersheds.