Willow tree branches are still used ins some modern hydrailic infrastructure construction today. And nor for historical reasons, it is still practical and cost

Willow tree branches are still used ins some modern hydrailic infrastructure construction today. And nor for historical reasons, it is still practical and cost effective. In the past the branches had two functions: as a rigid frame and as a filter layer (to prevent soil from being washed away from under the erosion protection). The frame functions to make the filter a rigid structure that one can sink to the bottom in a controlled manner by dumbing rocks on it. In modern construction geotextiles are used as filters, but these are sometimes made rigid with bundles of willow tree branches.