Rio Segura- plastic sheeting?

A quick question for all our Sunday brainboxes.
What is the function of the black plastic/tarpaulin sheeting covering the banks of the Segura downstream from Rojales town centre?
Thanks in advance.

To suppress weeds.

Thanks Yan,
Fighting a losing battle then!

Its in the corner of the river,to enable the water flow to take the corner quicker without erroding the banking and of course as stated to suppress weeds /no weeds/bamboo,the water flows past quicker in flood times

Thanks Gustav