ECM of Urban Land

By the end of this section the student/user will be able to:

     Describe erosion control measures of urban land.

Accompanying Exercise: (For students to print off, complete, and turn in for a grade)

     Erosion Control Measures of Urban Land- Exercise (pdf)

A major component of construction is the clearing and grading of land, which exposes, disturbs, and moves the soil. This inevitably increases an area’s susceptibility to erosion. Since in these situations it is not feasible to eliminate all erosion risk factors and, thus, all erosion, the goal of implementing erosion control measures is primarily to minimize erosion. The benefits of implementing effective erosion control measures include the reduction of soil washed off-site and reduced clogging of streets and drainage systems, as well as reduced damage to adjacent properties. There are several best management practices that can be implemented to reduce erosion in construction sites and minimize movement of sediment into drainage systems. When soils have been disturbed, erosion can be minimized with one or more of the following treatments.

Vegetative cover is efficient in reducing erosion and is a relatively inexpensive erosion control measure. Vegetative cover provides a canopy that covers the soil from the impacts of wind and water energy and a rooting system that holds soil particles together. Dense and short vegetative covers like grass are often more effective than tall and sparse vegetation for control of water erosion. Dense vegetation covers the soil surface and reduces the impact of energy of falling rain. On the other hand, dense and tall vegetative covers are more effective than short vegetation for control of wind erosion. This is because tall vegetation, depending on the wind speed, reduces the wind velocity, therefore, reducing its erosive energy.

     Maintaining or Preserving Vegetation:

     Existing vegetation is the best antidote for erosion. Trees, shrubs, and grasses that do not interfere with the construction process should be left undisturbed or maintained to minimize damage. The more vegetation area that is preserved the less area exposed to erosion.

     Planting New Vegetation:

     In areas of housing development, it is important to establish permanent vegetation to minimize soil exposure to water and wind erosion. Vegetation/plants that have fibrous root system with fast establishment of roots and ground cover are good options (see suggested list of shrubs).

     Temporary Seeding is the planting of grasses or plant materials that will quickly germinate and grow into protective cover for the soil until a permanent planting is established. Temporary seeding is recommended during the land grading and construction processes. Rapidly growing plants such as annual grasses, small grains, or legumes are appropriate temporary seeding options. Temporary seeding protects the soil and reduces mud and dust produced during construction. Thus, it is a short-term erosion control measure (Less than 1 year).

     Permanent Seeding is the establishment of the appropriate grasses or plants in the construction sites. Unlike temporary seeding, permanent seeding requires that the construction phase be complete. Only then more appropriate and/or desired plants are established. Thus, permanent seeding is for long-term control of soil erosion. If the season is not appropriate for permanent seeding, temporary seeding options are often considered to minimize bare soil exposure until permanent seeding can be done. Either temporary or permanent seeding can be done through hand seeding and/or hydroseeding. Hydroseeding is done if the land is especially steep and irregular for hand seeding.

                                                                         _{Images by www.trahonhydroseeding.com/pics.htm}

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/wy/technical/?cid=nrcs142p2_027264