Stream banks and shorelines: erosion
What is stream and shoreline erosion?
Erosion is a natural process of soil, rocks, and sediment being transported over time. Erosion becomes a problem when it is sped up by poor management or other human impacts. Severe waterfront erosion is defined by the Wisconsin DNR as i) steep shore/stream bank, ii) visual change of land over short period of time, iii) exposed tree roots, iv) murky water along waterfront, specially during a rain event, and iv) shallow or wide areas in a stream.
Why is it a problem?
Actively eroding shoreline and streambanks can undercut or weaken infrastructure, lead to a loss of the shoreline and add sediment to the waterway resulting in sediment pollution and accumulation. Sediment accumulation and deposition can clog reservoirs, dams, and streams which can result in localized flooding, as well as alter the shape of a waterbody. Excessive suspended sediment in the water can impact fisheries, increase algal growth, limit aquatic recreation, and increase water treatment costs.
What causes Erosion?
Improper storm stormwater management: When stormwater is directed into one path, (such as out of a downspout), the volume and speed of that water dramatically increases. A large amount of quickly moving water is incredibly efficient at wearing away the land and depositing sediment into a waterbody.
Removal of native vegetation: Removing vegetation exposes soils, which then are highly susceptible to wave, wind, rain, and runoff.
Human activity: Excessive or chronic activity close to the shoreline can loosen the soil. Highly trafficked areas can cause shorelines to destabilize, while recreational activities like boating create consistent and continuous waves that batter the shore.
What can you do?
Follow proper shoreline landscaping.
Reduced human disturbance in sensitive waterfront areas. Keep construction 100ft away from shore.
Human-placed rock (i.e rip-rap) or other material used to protect shoreline structures against scour and water, wave, or ice erosion