28 FOUR SEASONS BREEZE | APRIL 2023
CONTROLLING EROSION The clay soil banks of our Potrero
Creek and its feeder stream (S branch) are subject to erosion. During
construction of Four Seasons, artificial slopes were installed to slow
erosion without diminishing the energy of the flowing water.
A gabion is a cage, cylinder, or box filled with rocks, concrete, or
sometimes sand and soil for protecting banks of water courses.
Riprap, also known as rip rap, rip-rap, shot rock, rock armour (in
British English) or rubble, is human-placed rock or other material
used to protect shoreline structures against scour and water, wave,
or ice erosion. Ripraps are used to armor shorelines, stream beds,
bridge abutments, foundational infrastructure supports and other
shoreline structures.
Riprap affects the amount of organic material in a waterbody by
acting as a filter, catching wood and leaves before they can enter the
water. Riprap also covers and prevents plants from growing through,
which can reduce shade over the water.
Introducing ripraps creates a rocky environment which can
affect the ecology of a waterbody by making the ecosystem more
heterogeneous. While it can negatively affect some organisms by
removing shoreline vegetation, the rock can provide important refuge
for invertebrates and small fish. By preventing woody plants from
growing and shading the water, riprap can also increase the amount
of algae and hydrophytes. ~ Len Tavernetti, ltavernetti@hotmail.
com
Conservancy
